31 files changed, 2938 insertions, 718 deletions

diff --git a/builtin/add.c b/builtin/add.c
index 4bd98b799e..b2a5c57f0a 100644
--- a/builtin/add.c
+++ b/builtin/add.c
@@ -375,7 +375,6 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 
 	if (add_new_files) {
 		int baselen;
-		struct pathspec empty_pathspec;
 
 		/* Set up the default git porcelain excludes */
 		memset(&dir, 0, sizeof(dir));
@@ -384,7 +383,6 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 			setup_standard_excludes(&dir);
 		}
 
-		memset(&empty_pathspec, 0, sizeof(empty_pathspec));
 		/* This picks up the paths that are not tracked */
 		baselen = fill_directory(&dir, &pathspec);
 		if (pathspec.nr)
diff --git a/builtin/am.c b/builtin/am.c
new file mode 100644
index 0000000000..4f77e07b95
--- /dev/null
+++ b/builtin/am.c
@@ -0,0 +1,2411 @@
+/*
+ * Builtin "git am"
+ *
+ * Based on git-am.sh by Junio C Hamano.
+ */
+#include "cache.h"
+#include "builtin.h"
+#include "exec_cmd.h"
+#include "parse-options.h"
+#include "dir.h"
+#include "run-command.h"
+#include "quote.h"
+#include "tempfile.h"
+#include "lockfile.h"
+#include "cache-tree.h"
+#include "refs.h"
+#include "commit.h"
+#include "diff.h"
+#include "diffcore.h"
+#include "unpack-trees.h"
+#include "branch.h"
+#include "sequencer.h"
+#include "revision.h"
+#include "merge-recursive.h"
+#include "revision.h"
+#include "log-tree.h"
+#include "notes-utils.h"
+#include "rerere.h"
+#include "prompt.h"
+
+/**
+ * Returns 1 if the file is empty or does not exist, 0 otherwise.
+ */
+static int is_empty_file(const char *filename)
+{
+	struct stat st;
+
+	if (stat(filename, &st) < 0) {
+		if (errno == ENOENT)
+			return 1;
+		die_errno(_("could not stat %s"), filename);
+	}
+
+	return !st.st_size;
+}
+
+/**
+ * Like strbuf_getline(), but treats both '\n' and "\r\n" as line terminators.
+ */
+static int strbuf_getline_crlf(struct strbuf *sb, FILE *fp)
+{
+	if (strbuf_getwholeline(sb, fp, '\n'))
+		return EOF;
+	if (sb->buf[sb->len - 1] == '\n') {
+		strbuf_setlen(sb, sb->len - 1);
+		if (sb->len > 0 && sb->buf[sb->len - 1] == '\r')
+			strbuf_setlen(sb, sb->len - 1);
+	}
+	return 0;
+}
+
+/**
+ * Returns the length of the first line of msg.
+ */
+static int linelen(const char *msg)
+{
+	return strchrnul(msg, '\n') - msg;
+}
+
+/**
+ * Returns true if `str` consists of only whitespace, false otherwise.
+ */
+static int str_isspace(const char *str)
+{
+	for (; *str; str++)
+		if (!isspace(*str))
+			return 0;
+
+	return 1;
+}
+
+enum patch_format {
+	PATCH_FORMAT_UNKNOWN = 0,
+	PATCH_FORMAT_MBOX,
+	PATCH_FORMAT_STGIT,
+	PATCH_FORMAT_STGIT_SERIES,
+	PATCH_FORMAT_HG
+};
+
+enum keep_type {
+	KEEP_FALSE = 0,
+	KEEP_TRUE,      /* pass -k flag to git-mailinfo */
+	KEEP_NON_PATCH  /* pass -b flag to git-mailinfo */
+};
+
+enum scissors_type {
+	SCISSORS_UNSET = -1,
+	SCISSORS_FALSE = 0,  /* pass --no-scissors to git-mailinfo */
+	SCISSORS_TRUE        /* pass --scissors to git-mailinfo */
+};
+
+enum signoff_type {
+	SIGNOFF_FALSE = 0,
+	SIGNOFF_TRUE = 1,
+	SIGNOFF_EXPLICIT /* --signoff was set on the command-line */
+};
+
+struct am_state {
+	/* state directory path */
+	char *dir;
+
+	/* current and last patch numbers, 1-indexed */
+	int cur;
+	int last;
+
+	/* commit metadata and message */
+	char *author_name;
+	char *author_email;
+	char *author_date;
+	char *msg;
+	size_t msg_len;
+
+	/* when --rebasing, records the original commit the patch came from */
+	unsigned char orig_commit[GIT_SHA1_RAWSZ];
+
+	/* number of digits in patch filename */
+	int prec;
+
+	/* various operating modes and command line options */
+	int interactive;
+	int threeway;
+	int quiet;
+	int signoff; /* enum signoff_type */
+	int utf8;
+	int keep; /* enum keep_type */
+	int message_id;
+	int scissors; /* enum scissors_type */
+	struct argv_array git_apply_opts;
+	const char *resolvemsg;
+	int committer_date_is_author_date;
+	int ignore_date;
+	int allow_rerere_autoupdate;
+	const char *sign_commit;
+	int rebasing;
+};
+
+/**
+ * Initializes am_state with the default values. The state directory is set to
+ * dir.
+ */
+static void am_state_init(struct am_state *state, const char *dir)
+{
+	int gpgsign;
+
+	memset(state, 0, sizeof(*state));
+
+	assert(dir);
+	state->dir = xstrdup(dir);
+
+	state->prec = 4;
+
+	git_config_get_bool("am.threeway", &state->threeway);
+
+	state->utf8 = 1;
+
+	git_config_get_bool("am.messageid", &state->message_id);
+
+	state->scissors = SCISSORS_UNSET;
+
+	argv_array_init(&state->git_apply_opts);
+
+	if (!git_config_get_bool("commit.gpgsign", &gpgsign))
+		state->sign_commit = gpgsign ? "" : NULL;
+}
+
+/**
+ * Releases memory allocated by an am_state.
+ */
+static void am_state_release(struct am_state *state)
+{
+	free(state->dir);
+	free(state->author_name);
+	free(state->author_email);
+	free(state->author_date);
+	free(state->msg);
+	argv_array_clear(&state->git_apply_opts);
+}
+
+/**
+ * Returns path relative to the am_state directory.
+ */
+static inline const char *am_path(const struct am_state *state, const char *path)
+{
+	return mkpath("%s/%s", state->dir, path);
+}
+
+/**
+ * For convenience to call write_file()
+ */
+static int write_state_text(const struct am_state *state,
+			    const char *name, const char *string)
+{
+	return write_file(am_path(state, name), "%s", string);
+}
+
+static int write_state_count(const struct am_state *state,
+			     const char *name, int value)
+{
+	return write_file(am_path(state, name), "%d", value);
+}
+
+static int write_state_bool(const struct am_state *state,
+			    const char *name, int value)
+{
+	return write_state_text(state, name, value ? "t" : "f");
+}
+
+/**
+ * If state->quiet is false, calls fprintf(fp, fmt, ...), and appends a newline
+ * at the end.
+ */
+static void say(const struct am_state *state, FILE *fp, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	if (!state->quiet) {
+		vfprintf(fp, fmt, ap);
+		putc('\n', fp);
+	}
+	va_end(ap);
+}
+
+/**
+ * Returns 1 if there is an am session in progress, 0 otherwise.
+ */
+static int am_in_progress(const struct am_state *state)
+{
+	struct stat st;
+
+	if (lstat(state->dir, &st) < 0 || !S_ISDIR(st.st_mode))
+		return 0;
+	if (lstat(am_path(state, "last"), &st) || !S_ISREG(st.st_mode))
+		return 0;
+	if (lstat(am_path(state, "next"), &st) || !S_ISREG(st.st_mode))
+		return 0;
+	return 1;
+}
+
+/**
+ * Reads the contents of `file` in the `state` directory into `sb`. Returns the
+ * number of bytes read on success, -1 if the file does not exist. If `trim` is
+ * set, trailing whitespace will be removed.
+ */
+static int read_state_file(struct strbuf *sb, const struct am_state *state,
+			const char *file, int trim)
+{
+	strbuf_reset(sb);
+
+	if (strbuf_read_file(sb, am_path(state, file), 0) >= 0) {
+		if (trim)
+			strbuf_trim(sb);
+
+		return sb->len;
+	}
+
+	if (errno == ENOENT)
+		return -1;
+
+	die_errno(_("could not read '%s'"), am_path(state, file));
+}
+
+/**
+ * Reads a KEY=VALUE shell variable assignment from `fp`, returning the VALUE
+ * as a newly-allocated string. VALUE must be a quoted string, and the KEY must
+ * match `key`. Returns NULL on failure.
+ *
+ * This is used by read_author_script() to read the GIT_AUTHOR_* variables from
+ * the author-script.
+ */
+static char *read_shell_var(FILE *fp, const char *key)
+{
+	struct strbuf sb = STRBUF_INIT;
+	const char *str;
+
+	if (strbuf_getline(&sb, fp, '\n'))
+		goto fail;
+
+	if (!skip_prefix(sb.buf, key, &str))
+		goto fail;
+
+	if (!skip_prefix(str, "=", &str))
+		goto fail;
+
+	strbuf_remove(&sb, 0, str - sb.buf);
+
+	str = sq_dequote(sb.buf);
+	if (!str)
+		goto fail;
+
+	return strbuf_detach(&sb, NULL);
+
+fail:
+	strbuf_release(&sb);
+	return NULL;
+}
+
+/**
+ * Reads and parses the state directory's "author-script" file, and sets
+ * state->author_name, state->author_email and state->author_date accordingly.
+ * Returns 0 on success, -1 if the file could not be parsed.
+ *
+ * The author script is of the format:
+ *
+ *	GIT_AUTHOR_NAME='$author_name'
+ *	GIT_AUTHOR_EMAIL='$author_email'
+ *	GIT_AUTHOR_DATE='$author_date'
+ *
+ * where $author_name, $author_email and $author_date are quoted. We are strict
+ * with our parsing, as the file was meant to be eval'd in the old git-am.sh
+ * script, and thus if the file differs from what this function expects, it is
+ * better to bail out than to do something that the user does not expect.
+ */
+static int read_author_script(struct am_state *state)
+{
+	const char *filename = am_path(state, "author-script");
+	FILE *fp;
+
+	assert(!state->author_name);
+	assert(!state->author_email);
+	assert(!state->author_date);
+
+	fp = fopen(filename, "r");
+	if (!fp) {
+		if (errno == ENOENT)
+			return 0;
+		die_errno(_("could not open '%s' for reading"), filename);
+	}
+
+	state->author_name = read_shell_var(fp, "GIT_AUTHOR_NAME");
+	if (!state->author_name) {
+		fclose(fp);
+		return -1;
+	}
+
+	state->author_email = read_shell_var(fp, "GIT_AUTHOR_EMAIL");
+	if (!state->author_email) {
+		fclose(fp);
+		return -1;
+	}
+
+	state->author_date = read_shell_var(fp, "GIT_AUTHOR_DATE");
+	if (!state->author_date) {
+		fclose(fp);
+		return -1;
+	}
+
+	if (fgetc(fp) != EOF) {
+		fclose(fp);
+		return -1;
+	}
+
+	fclose(fp);
+	return 0;
+}
+
+/**
+ * Saves state->author_name, state->author_email and state->author_date in the
+ * state directory's "author-script" file.
+ */
+static void write_author_script(const struct am_state *state)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	strbuf_addstr(&sb, "GIT_AUTHOR_NAME=");
+	sq_quote_buf(&sb, state->author_name);
+	strbuf_addch(&sb, '\n');
+
+	strbuf_addstr(&sb, "GIT_AUTHOR_EMAIL=");
+	sq_quote_buf(&sb, state->author_email);
+	strbuf_addch(&sb, '\n');
+
+	strbuf_addstr(&sb, "GIT_AUTHOR_DATE=");
+	sq_quote_buf(&sb, state->author_date);
+	strbuf_addch(&sb, '\n');
+
+	write_state_text(state, "author-script", sb.buf);
+
+	strbuf_release(&sb);
+}
+
+/**
+ * Reads the commit message from the state directory's "final-commit" file,
+ * setting state->msg to its contents and state->msg_len to the length of its
+ * contents in bytes.
+ *
+ * Returns 0 on success, -1 if the file does not exist.
+ */
+static int read_commit_msg(struct am_state *state)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	assert(!state->msg);
+
+	if (read_state_file(&sb, state, "final-commit", 0) < 0) {
+		strbuf_release(&sb);
+		return -1;
+	}
+
+	state->msg = strbuf_detach(&sb, &state->msg_len);
+	return 0;
+}
+
+/**
+ * Saves state->msg in the state directory's "final-commit" file.
+ */
+static void write_commit_msg(const struct am_state *state)
+{
+	int fd;
+	const char *filename = am_path(state, "final-commit");
+
+	fd = xopen(filename, O_WRONLY | O_CREAT, 0666);
+	if (write_in_full(fd, state->msg, state->msg_len) < 0)
+		die_errno(_("could not write to %s"), filename);
+	close(fd);
+}
+
+/**
+ * Loads state from disk.
+ */
+static void am_load(struct am_state *state)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	if (read_state_file(&sb, state, "next", 1) < 0)
+		die("BUG: state file 'next' does not exist");
+	state->cur = strtol(sb.buf, NULL, 10);
+
+	if (read_state_file(&sb, state, "last", 1) < 0)
+		die("BUG: state file 'last' does not exist");
+	state->last = strtol(sb.buf, NULL, 10);
+
+	if (read_author_script(state) < 0)
+		die(_("could not parse author script"));
+
+	read_commit_msg(state);
+
+	if (read_state_file(&sb, state, "original-commit", 1) < 0)
+		hashclr(state->orig_commit);
+	else if (get_sha1_hex(sb.buf, state->orig_commit) < 0)
+		die(_("could not parse %s"), am_path(state, "original-commit"));
+
+	read_state_file(&sb, state, "threeway", 1);
+	state->threeway = !strcmp(sb.buf, "t");
+
+	read_state_file(&sb, state, "quiet", 1);
+	state->quiet = !strcmp(sb.buf, "t");
+
+	read_state_file(&sb, state, "sign", 1);
+	state->signoff = !strcmp(sb.buf, "t");
+
+	read_state_file(&sb, state, "utf8", 1);
+	state->utf8 = !strcmp(sb.buf, "t");
+
+	read_state_file(&sb, state, "keep", 1);
+	if (!strcmp(sb.buf, "t"))
+		state->keep = KEEP_TRUE;
+	else if (!strcmp(sb.buf, "b"))
+		state->keep = KEEP_NON_PATCH;
+	else
+		state->keep = KEEP_FALSE;
+
+	read_state_file(&sb, state, "messageid", 1);
+	state->message_id = !strcmp(sb.buf, "t");
+
+	read_state_file(&sb, state, "scissors", 1);
+	if (!strcmp(sb.buf, "t"))
+		state->scissors = SCISSORS_TRUE;
+	else if (!strcmp(sb.buf, "f"))
+		state->scissors = SCISSORS_FALSE;
+	else
+		state->scissors = SCISSORS_UNSET;
+
+	read_state_file(&sb, state, "apply-opt", 1);
+	argv_array_clear(&state->git_apply_opts);
+	if (sq_dequote_to_argv_array(sb.buf, &state->git_apply_opts) < 0)
+		die(_("could not parse %s"), am_path(state, "apply-opt"));
+
+	state->rebasing = !!file_exists(am_path(state, "rebasing"));
+
+	strbuf_release(&sb);
+}
+
+/**
+ * Removes the am_state directory, forcefully terminating the current am
+ * session.
+ */
+static void am_destroy(const struct am_state *state)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	strbuf_addstr(&sb, state->dir);
+	remove_dir_recursively(&sb, 0);
+	strbuf_release(&sb);
+}
+
+/**
+ * Runs applypatch-msg hook. Returns its exit code.
+ */
+static int run_applypatch_msg_hook(struct am_state *state)
+{
+	int ret;
+
+	assert(state->msg);
+	ret = run_hook_le(NULL, "applypatch-msg", am_path(state, "final-commit"), NULL);
+
+	if (!ret) {
+		free(state->msg);
+		state->msg = NULL;
+		if (read_commit_msg(state) < 0)
+			die(_("'%s' was deleted by the applypatch-msg hook"),
+				am_path(state, "final-commit"));
+	}
+
+	return ret;
+}
+
+/**
+ * Runs post-rewrite hook. Returns it exit code.
+ */
+static int run_post_rewrite_hook(const struct am_state *state)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	const char *hook = find_hook("post-rewrite");
+	int ret;
+
+	if (!hook)
+		return 0;
+
+	argv_array_push(&cp.args, hook);
+	argv_array_push(&cp.args, "rebase");
+
+	cp.in = xopen(am_path(state, "rewritten"), O_RDONLY);
+	cp.stdout_to_stderr = 1;
+
+	ret = run_command(&cp);
+
+	close(cp.in);
+	return ret;
+}
+
+/**
+ * Reads the state directory's "rewritten" file, and copies notes from the old
+ * commits listed in the file to their rewritten commits.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int copy_notes_for_rebase(const struct am_state *state)
+{
+	struct notes_rewrite_cfg *c;
+	struct strbuf sb = STRBUF_INIT;
+	const char *invalid_line = _("Malformed input line: '%s'.");
+	const char *msg = "Notes added by 'git rebase'";
+	FILE *fp;
+	int ret = 0;
+
+	assert(state->rebasing);
+
+	c = init_copy_notes_for_rewrite("rebase");
+	if (!c)
+		return 0;
+
+	fp = xfopen(am_path(state, "rewritten"), "r");
+
+	while (!strbuf_getline(&sb, fp, '\n')) {
+		unsigned char from_obj[GIT_SHA1_RAWSZ], to_obj[GIT_SHA1_RAWSZ];
+
+		if (sb.len != GIT_SHA1_HEXSZ * 2 + 1) {
+			ret = error(invalid_line, sb.buf);
+			goto finish;
+		}
+
+		if (get_sha1_hex(sb.buf, from_obj)) {
+			ret = error(invalid_line, sb.buf);
+			goto finish;
+		}
+
+		if (sb.buf[GIT_SHA1_HEXSZ] != ' ') {
+			ret = error(invalid_line, sb.buf);
+			goto finish;
+		}
+
+		if (get_sha1_hex(sb.buf + GIT_SHA1_HEXSZ + 1, to_obj)) {
+			ret = error(invalid_line, sb.buf);
+			goto finish;
+		}
+
+		if (copy_note_for_rewrite(c, from_obj, to_obj))
+			ret = error(_("Failed to copy notes from '%s' to '%s'"),
+					sha1_to_hex(from_obj), sha1_to_hex(to_obj));
+	}
+
+finish:
+	finish_copy_notes_for_rewrite(c, msg);
+	fclose(fp);
+	strbuf_release(&sb);
+	return ret;
+}
+
+/**
+ * Determines if the file looks like a piece of RFC2822 mail by grabbing all
+ * non-indented lines and checking if they look like they begin with valid
+ * header field names.
+ *
+ * Returns 1 if the file looks like a piece of mail, 0 otherwise.
+ */
+static int is_mail(FILE *fp)
+{
+	const char *header_regex = "^[!-9;-~]+:";
+	struct strbuf sb = STRBUF_INIT;
+	regex_t regex;
+	int ret = 1;
+
+	if (fseek(fp, 0L, SEEK_SET))
+		die_errno(_("fseek failed"));
+
+	if (regcomp(&regex, header_regex, REG_NOSUB | REG_EXTENDED))
+		die("invalid pattern: %s", header_regex);
+
+	while (!strbuf_getline_crlf(&sb, fp)) {
+		if (!sb.len)
+			break; /* End of header */
+
+		/* Ignore indented folded lines */
+		if (*sb.buf == '\t' || *sb.buf == ' ')
+			continue;
+
+		/* It's a header if it matches header_regex */
+		if (regexec(&regex, sb.buf, 0, NULL, 0)) {
+			ret = 0;
+			goto done;
+		}
+	}
+
+done:
+	regfree(&regex);
+	strbuf_release(&sb);
+	return ret;
+}
+
+/**
+ * Attempts to detect the patch_format of the patches contained in `paths`,
+ * returning the PATCH_FORMAT_* enum value. Returns PATCH_FORMAT_UNKNOWN if
+ * detection fails.
+ */
+static int detect_patch_format(const char **paths)
+{
+	enum patch_format ret = PATCH_FORMAT_UNKNOWN;
+	struct strbuf l1 = STRBUF_INIT;
+	struct strbuf l2 = STRBUF_INIT;
+	struct strbuf l3 = STRBUF_INIT;
+	FILE *fp;
+
+	/*
+	 * We default to mbox format if input is from stdin and for directories
+	 */
+	if (!*paths || !strcmp(*paths, "-") || is_directory(*paths))
+		return PATCH_FORMAT_MBOX;
+
+	/*
+	 * Otherwise, check the first few lines of the first patch, starting
+	 * from the first non-blank line, to try to detect its format.
+	 */
+
+	fp = xfopen(*paths, "r");
+
+	while (!strbuf_getline_crlf(&l1, fp)) {
+		if (l1.len)
+			break;
+	}
+
+	if (starts_with(l1.buf, "From ") || starts_with(l1.buf, "From: ")) {
+		ret = PATCH_FORMAT_MBOX;
+		goto done;
+	}
+
+	if (starts_with(l1.buf, "# This series applies on GIT commit")) {
+		ret = PATCH_FORMAT_STGIT_SERIES;
+		goto done;
+	}
+
+	if (!strcmp(l1.buf, "# HG changeset patch")) {
+		ret = PATCH_FORMAT_HG;
+		goto done;
+	}
+
+	strbuf_reset(&l2);
+	strbuf_getline_crlf(&l2, fp);
+	strbuf_reset(&l3);
+	strbuf_getline_crlf(&l3, fp);
+
+	/*
+	 * If the second line is empty and the third is a From, Author or Date
+	 * entry, this is likely an StGit patch.
+	 */
+	if (l1.len && !l2.len &&
+		(starts_with(l3.buf, "From:") ||
+		 starts_with(l3.buf, "Author:") ||
+		 starts_with(l3.buf, "Date:"))) {
+		ret = PATCH_FORMAT_STGIT;
+		goto done;
+	}
+
+	if (l1.len && is_mail(fp)) {
+		ret = PATCH_FORMAT_MBOX;
+		goto done;
+	}
+
+done:
+	fclose(fp);
+	strbuf_release(&l1);
+	return ret;
+}
+
+/**
+ * Splits out individual email patches from `paths`, where each path is either
+ * a mbox file or a Maildir. Returns 0 on success, -1 on failure.
+ */
+static int split_mail_mbox(struct am_state *state, const char **paths, int keep_cr)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	struct strbuf last = STRBUF_INIT;
+
+	cp.git_cmd = 1;
+	argv_array_push(&cp.args, "mailsplit");
+	argv_array_pushf(&cp.args, "-d%d", state->prec);
+	argv_array_pushf(&cp.args, "-o%s", state->dir);
+	argv_array_push(&cp.args, "-b");
+	if (keep_cr)
+		argv_array_push(&cp.args, "--keep-cr");
+	argv_array_push(&cp.args, "--");
+	argv_array_pushv(&cp.args, paths);
+
+	if (capture_command(&cp, &last, 8))
+		return -1;
+
+	state->cur = 1;
+	state->last = strtol(last.buf, NULL, 10);
+
+	return 0;
+}
+
+/**
+ * Callback signature for split_mail_conv(). The foreign patch should be
+ * read from `in`, and the converted patch (in RFC2822 mail format) should be
+ * written to `out`. Return 0 on success, or -1 on failure.
+ */
+typedef int (*mail_conv_fn)(FILE *out, FILE *in, int keep_cr);
+
+/**
+ * Calls `fn` for each file in `paths` to convert the foreign patch to the
+ * RFC2822 mail format suitable for parsing with git-mailinfo.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int split_mail_conv(mail_conv_fn fn, struct am_state *state,
+			const char **paths, int keep_cr)
+{
+	static const char *stdin_only[] = {"-", NULL};
+	int i;
+
+	if (!*paths)
+		paths = stdin_only;
+
+	for (i = 0; *paths; paths++, i++) {
+		FILE *in, *out;
+		const char *mail;
+		int ret;
+
+		if (!strcmp(*paths, "-"))
+			in = stdin;
+		else
+			in = fopen(*paths, "r");
+
+		if (!in)
+			return error(_("could not open '%s' for reading: %s"),
+					*paths, strerror(errno));
+
+		mail = mkpath("%s/%0*d", state->dir, state->prec, i + 1);
+
+		out = fopen(mail, "w");
+		if (!out)
+			return error(_("could not open '%s' for writing: %s"),
+					mail, strerror(errno));
+
+		ret = fn(out, in, keep_cr);
+
+		fclose(out);
+		fclose(in);
+
+		if (ret)
+			return error(_("could not parse patch '%s'"), *paths);
+	}
+
+	state->cur = 1;
+	state->last = i;
+	return 0;
+}
+
+/**
+ * A split_mail_conv() callback that converts an StGit patch to an RFC2822
+ * message suitable for parsing with git-mailinfo.
+ */
+static int stgit_patch_to_mail(FILE *out, FILE *in, int keep_cr)
+{
+	struct strbuf sb = STRBUF_INIT;
+	int subject_printed = 0;
+
+	while (!strbuf_getline(&sb, in, '\n')) {
+		const char *str;
+
+		if (str_isspace(sb.buf))
+			continue;
+		else if (skip_prefix(sb.buf, "Author:", &str))
+			fprintf(out, "From:%s\n", str);
+		else if (starts_with(sb.buf, "From") || starts_with(sb.buf, "Date"))
+			fprintf(out, "%s\n", sb.buf);
+		else if (!subject_printed) {
+			fprintf(out, "Subject: %s\n", sb.buf);
+			subject_printed = 1;
+		} else {
+			fprintf(out, "\n%s\n", sb.buf);
+			break;
+		}
+	}
+
+	strbuf_reset(&sb);
+	while (strbuf_fread(&sb, 8192, in) > 0) {
+		fwrite(sb.buf, 1, sb.len, out);
+		strbuf_reset(&sb);
+	}
+
+	strbuf_release(&sb);
+	return 0;
+}
+
+/**
+ * This function only supports a single StGit series file in `paths`.
+ *
+ * Given an StGit series file, converts the StGit patches in the series into
+ * RFC2822 messages suitable for parsing with git-mailinfo, and queues them in
+ * the state directory.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int split_mail_stgit_series(struct am_state *state, const char **paths,
+					int keep_cr)
+{
+	const char *series_dir;
+	char *series_dir_buf;
+	FILE *fp;
+	struct argv_array patches = ARGV_ARRAY_INIT;
+	struct strbuf sb = STRBUF_INIT;
+	int ret;
+
+	if (!paths[0] || paths[1])
+		return error(_("Only one StGIT patch series can be applied at once"));
+
+	series_dir_buf = xstrdup(*paths);
+	series_dir = dirname(series_dir_buf);
+
+	fp = fopen(*paths, "r");
+	if (!fp)
+		return error(_("could not open '%s' for reading: %s"), *paths,
+				strerror(errno));
+
+	while (!strbuf_getline(&sb, fp, '\n')) {
+		if (*sb.buf == '#')
+			continue; /* skip comment lines */
+
+		argv_array_push(&patches, mkpath("%s/%s", series_dir, sb.buf));
+	}
+
+	fclose(fp);
+	strbuf_release(&sb);
+	free(series_dir_buf);
+
+	ret = split_mail_conv(stgit_patch_to_mail, state, patches.argv, keep_cr);
+
+	argv_array_clear(&patches);
+	return ret;
+}
+
+/**
+ * A split_patches_conv() callback that converts a mercurial patch to a RFC2822
+ * message suitable for parsing with git-mailinfo.
+ */
+static int hg_patch_to_mail(FILE *out, FILE *in, int keep_cr)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	while (!strbuf_getline(&sb, in, '\n')) {
+		const char *str;
+
+		if (skip_prefix(sb.buf, "# User ", &str))
+			fprintf(out, "From: %s\n", str);
+		else if (skip_prefix(sb.buf, "# Date ", &str)) {
+			unsigned long timestamp;
+			long tz, tz2;
+			char *end;
+
+			errno = 0;
+			timestamp = strtoul(str, &end, 10);
+			if (errno)
+				return error(_("invalid timestamp"));
+
+			if (!skip_prefix(end, " ", &str))
+				return error(_("invalid Date line"));
+
+			errno = 0;
+			tz = strtol(str, &end, 10);
+			if (errno)
+				return error(_("invalid timezone offset"));
+
+			if (*end)
+				return error(_("invalid Date line"));
+
+			/*
+			 * mercurial's timezone is in seconds west of UTC,
+			 * however git's timezone is in hours + minutes east of
+			 * UTC. Convert it.
+			 */
+			tz2 = labs(tz) / 3600 * 100 + labs(tz) % 3600 / 60;
+			if (tz > 0)
+				tz2 = -tz2;
+
+			fprintf(out, "Date: %s\n", show_date(timestamp, tz2, DATE_MODE(RFC2822)));
+		} else if (starts_with(sb.buf, "# ")) {
+			continue;
+		} else {
+			fprintf(out, "\n%s\n", sb.buf);
+			break;
+		}
+	}
+
+	strbuf_reset(&sb);
+	while (strbuf_fread(&sb, 8192, in) > 0) {
+		fwrite(sb.buf, 1, sb.len, out);
+		strbuf_reset(&sb);
+	}
+
+	strbuf_release(&sb);
+	return 0;
+}
+
+/**
+ * Splits a list of files/directories into individual email patches. Each path
+ * in `paths` must be a file/directory that is formatted according to
+ * `patch_format`.
+ *
+ * Once split out, the individual email patches will be stored in the state
+ * directory, with each patch's filename being its index, padded to state->prec
+ * digits.
+ *
+ * state->cur will be set to the index of the first mail, and state->last will
+ * be set to the index of the last mail.
+ *
+ * Set keep_cr to 0 to convert all lines ending with \r\n to end with \n, 1
+ * to disable this behavior, -1 to use the default configured setting.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int split_mail(struct am_state *state, enum patch_format patch_format,
+			const char **paths, int keep_cr)
+{
+	if (keep_cr < 0) {
+		keep_cr = 0;
+		git_config_get_bool("am.keepcr", &keep_cr);
+	}
+
+	switch (patch_format) {
+	case PATCH_FORMAT_MBOX:
+		return split_mail_mbox(state, paths, keep_cr);
+	case PATCH_FORMAT_STGIT:
+		return split_mail_conv(stgit_patch_to_mail, state, paths, keep_cr);
+	case PATCH_FORMAT_STGIT_SERIES:
+		return split_mail_stgit_series(state, paths, keep_cr);
+	case PATCH_FORMAT_HG:
+		return split_mail_conv(hg_patch_to_mail, state, paths, keep_cr);
+	default:
+		die("BUG: invalid patch_format");
+	}
+	return -1;
+}
+
+/**
+ * Setup a new am session for applying patches
+ */
+static void am_setup(struct am_state *state, enum patch_format patch_format,
+			const char **paths, int keep_cr)
+{
+	unsigned char curr_head[GIT_SHA1_RAWSZ];
+	const char *str;
+	struct strbuf sb = STRBUF_INIT;
+
+	if (!patch_format)
+		patch_format = detect_patch_format(paths);
+
+	if (!patch_format) {
+		fprintf_ln(stderr, _("Patch format detection failed."));
+		exit(128);
+	}
+
+	if (mkdir(state->dir, 0777) < 0 && errno != EEXIST)
+		die_errno(_("failed to create directory '%s'"), state->dir);
+
+	if (split_mail(state, patch_format, paths, keep_cr) < 0) {
+		am_destroy(state);
+		die(_("Failed to split patches."));
+	}
+
+	if (state->rebasing)
+		state->threeway = 1;
+
+	write_state_bool(state, "threeway", state->threeway);
+	write_state_bool(state, "quiet", state->quiet);
+	write_state_bool(state, "sign", state->signoff);
+	write_state_bool(state, "utf8", state->utf8);
+
+	switch (state->keep) {
+	case KEEP_FALSE:
+		str = "f";
+		break;
+	case KEEP_TRUE:
+		str = "t";
+		break;
+	case KEEP_NON_PATCH:
+		str = "b";
+		break;
+	default:
+		die("BUG: invalid value for state->keep");
+	}
+
+	write_state_text(state, "keep", str);
+	write_state_bool(state, "messageid", state->message_id);
+
+	switch (state->scissors) {
+	case SCISSORS_UNSET:
+		str = "";
+		break;
+	case SCISSORS_FALSE:
+		str = "f";
+		break;
+	case SCISSORS_TRUE:
+		str = "t";
+		break;
+	default:
+		die("BUG: invalid value for state->scissors");
+	}
+	write_state_text(state, "scissors", str);
+
+	sq_quote_argv(&sb, state->git_apply_opts.argv, 0);
+	write_state_text(state, "apply-opt", sb.buf);
+
+	if (state->rebasing)
+		write_state_text(state, "rebasing", "");
+	else
+		write_state_text(state, "applying", "");
+
+	if (!get_sha1("HEAD", curr_head)) {
+		write_state_text(state, "abort-safety", sha1_to_hex(curr_head));
+		if (!state->rebasing)
+			update_ref("am", "ORIG_HEAD", curr_head, NULL, 0,
+					UPDATE_REFS_DIE_ON_ERR);
+	} else {
+		write_state_text(state, "abort-safety", "");
+		if (!state->rebasing)
+			delete_ref("ORIG_HEAD", NULL, 0);
+	}
+
+	/*
+	 * NOTE: Since the "next" and "last" files determine if an am_state
+	 * session is in progress, they should be written last.
+	 */
+
+	write_state_count(state, "next", state->cur);
+	write_state_count(state, "last", state->last);
+
+	strbuf_release(&sb);
+}
+
+/**
+ * Increments the patch pointer, and cleans am_state for the application of the
+ * next patch.
+ */
+static void am_next(struct am_state *state)
+{
+	unsigned char head[GIT_SHA1_RAWSZ];
+
+	free(state->author_name);
+	state->author_name = NULL;
+
+	free(state->author_email);
+	state->author_email = NULL;
+
+	free(state->author_date);
+	state->author_date = NULL;
+
+	free(state->msg);
+	state->msg = NULL;
+	state->msg_len = 0;
+
+	unlink(am_path(state, "author-script"));
+	unlink(am_path(state, "final-commit"));
+
+	hashclr(state->orig_commit);
+	unlink(am_path(state, "original-commit"));
+
+	if (!get_sha1("HEAD", head))
+		write_state_text(state, "abort-safety", sha1_to_hex(head));
+	else
+		write_state_text(state, "abort-safety", "");
+
+	state->cur++;
+	write_state_count(state, "next", state->cur);
+}
+
+/**
+ * Returns the filename of the current patch email.
+ */
+static const char *msgnum(const struct am_state *state)
+{
+	static struct strbuf sb = STRBUF_INIT;
+
+	strbuf_reset(&sb);
+	strbuf_addf(&sb, "%0*d", state->prec, state->cur);
+
+	return sb.buf;
+}
+
+/**
+ * Refresh and write index.
+ */
+static void refresh_and_write_cache(void)
+{
+	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
+
+	hold_locked_index(lock_file, 1);
+	refresh_cache(REFRESH_QUIET);
+	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
+		die(_("unable to write index file"));
+}
+
+/**
+ * Returns 1 if the index differs from HEAD, 0 otherwise. When on an unborn
+ * branch, returns 1 if there are entries in the index, 0 otherwise. If an
+ * strbuf is provided, the space-separated list of files that differ will be
+ * appended to it.
+ */
+static int index_has_changes(struct strbuf *sb)
+{
+	unsigned char head[GIT_SHA1_RAWSZ];
+	int i;
+
+	if (!get_sha1_tree("HEAD", head)) {
+		struct diff_options opt;
+
+		diff_setup(&opt);
+		DIFF_OPT_SET(&opt, EXIT_WITH_STATUS);
+		if (!sb)
+			DIFF_OPT_SET(&opt, QUICK);
+		do_diff_cache(head, &opt);
+		diffcore_std(&opt);
+		for (i = 0; sb && i < diff_queued_diff.nr; i++) {
+			if (i)
+				strbuf_addch(sb, ' ');
+			strbuf_addstr(sb, diff_queued_diff.queue[i]->two->path);
+		}
+		diff_flush(&opt);
+		return DIFF_OPT_TST(&opt, HAS_CHANGES) != 0;
+	} else {
+		for (i = 0; sb && i < active_nr; i++) {
+			if (i)
+				strbuf_addch(sb, ' ');
+			strbuf_addstr(sb, active_cache[i]->name);
+		}
+		return !!active_nr;
+	}
+}
+
+/**
+ * Dies with a user-friendly message on how to proceed after resolving the
+ * problem. This message can be overridden with state->resolvemsg.
+ */
+static void NORETURN die_user_resolve(const struct am_state *state)
+{
+	if (state->resolvemsg) {
+		printf_ln("%s", state->resolvemsg);
+	} else {
+		const char *cmdline = state->interactive ? "git am -i" : "git am";
+
+		printf_ln(_("When you have resolved this problem, run \"%s --continue\"."), cmdline);
+		printf_ln(_("If you prefer to skip this patch, run \"%s --skip\" instead."), cmdline);
+		printf_ln(_("To restore the original branch and stop patching, run \"%s --abort\"."), cmdline);
+	}
+
+	exit(128);
+}
+
+static void am_signoff(struct strbuf *sb)
+{
+	char *cp;
+	struct strbuf mine = STRBUF_INIT;
+
+	/* Does it end with our own sign-off? */
+	strbuf_addf(&mine, "\n%s%s\n",
+		    sign_off_header,
+		    fmt_name(getenv("GIT_COMMITTER_NAME"),
+			     getenv("GIT_COMMITTER_EMAIL")));
+	if (mine.len < sb->len &&
+	    !strcmp(mine.buf, sb->buf + sb->len - mine.len))
+		goto exit; /* no need to duplicate */
+
+	/* Does it have any Signed-off-by: in the text */
+	for (cp = sb->buf;
+	     cp && *cp && (cp = strstr(cp, sign_off_header)) != NULL;
+	     cp = strchr(cp, '\n')) {
+		if (sb->buf == cp || cp[-1] == '\n')
+			break;
+	}
+
+	strbuf_addstr(sb, mine.buf + !!cp);
+exit:
+	strbuf_release(&mine);
+}
+
+/**
+ * Appends signoff to the "msg" field of the am_state.
+ */
+static void am_append_signoff(struct am_state *state)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	strbuf_attach(&sb, state->msg, state->msg_len, state->msg_len);
+	am_signoff(&sb);
+	state->msg = strbuf_detach(&sb, &state->msg_len);
+}
+
+/**
+ * Parses `mail` using git-mailinfo, extracting its patch and authorship info.
+ * state->msg will be set to the patch message. state->author_name,
+ * state->author_email and state->author_date will be set to the patch author's
+ * name, email and date respectively. The patch body will be written to the
+ * state directory's "patch" file.
+ *
+ * Returns 1 if the patch should be skipped, 0 otherwise.
+ */
+static int parse_mail(struct am_state *state, const char *mail)
+{
+	FILE *fp;
+	struct child_process cp = CHILD_PROCESS_INIT;
+	struct strbuf sb = STRBUF_INIT;
+	struct strbuf msg = STRBUF_INIT;
+	struct strbuf author_name = STRBUF_INIT;
+	struct strbuf author_date = STRBUF_INIT;
+	struct strbuf author_email = STRBUF_INIT;
+	int ret = 0;
+
+	cp.git_cmd = 1;
+	cp.in = xopen(mail, O_RDONLY, 0);
+	cp.out = xopen(am_path(state, "info"), O_WRONLY | O_CREAT, 0777);
+
+	argv_array_push(&cp.args, "mailinfo");
+	argv_array_push(&cp.args, state->utf8 ? "-u" : "-n");
+
+	switch (state->keep) {
+	case KEEP_FALSE:
+		break;
+	case KEEP_TRUE:
+		argv_array_push(&cp.args, "-k");
+		break;
+	case KEEP_NON_PATCH:
+		argv_array_push(&cp.args, "-b");
+		break;
+	default:
+		die("BUG: invalid value for state->keep");
+	}
+
+	if (state->message_id)
+		argv_array_push(&cp.args, "-m");
+
+	switch (state->scissors) {
+	case SCISSORS_UNSET:
+		break;
+	case SCISSORS_FALSE:
+		argv_array_push(&cp.args, "--no-scissors");
+		break;
+	case SCISSORS_TRUE:
+		argv_array_push(&cp.args, "--scissors");
+		break;
+	default:
+		die("BUG: invalid value for state->scissors");
+	}
+
+	argv_array_push(&cp.args, am_path(state, "msg"));
+	argv_array_push(&cp.args, am_path(state, "patch"));
+
+	if (run_command(&cp) < 0)
+		die("could not parse patch");
+
+	close(cp.in);
+	close(cp.out);
+
+	/* Extract message and author information */
+	fp = xfopen(am_path(state, "info"), "r");
+	while (!strbuf_getline(&sb, fp, '\n')) {
+		const char *x;
+
+		if (skip_prefix(sb.buf, "Subject: ", &x)) {
+			if (msg.len)
+				strbuf_addch(&msg, '\n');
+			strbuf_addstr(&msg, x);
+		} else if (skip_prefix(sb.buf, "Author: ", &x))
+			strbuf_addstr(&author_name, x);
+		else if (skip_prefix(sb.buf, "Email: ", &x))
+			strbuf_addstr(&author_email, x);
+		else if (skip_prefix(sb.buf, "Date: ", &x))
+			strbuf_addstr(&author_date, x);
+	}
+	fclose(fp);
+
+	/* Skip pine's internal folder data */
+	if (!strcmp(author_name.buf, "Mail System Internal Data")) {
+		ret = 1;
+		goto finish;
+	}
+
+	if (is_empty_file(am_path(state, "patch"))) {
+		printf_ln(_("Patch is empty. Was it split wrong?"));
+		die_user_resolve(state);
+	}
+
+	strbuf_addstr(&msg, "\n\n");
+	if (strbuf_read_file(&msg, am_path(state, "msg"), 0) < 0)
+		die_errno(_("could not read '%s'"), am_path(state, "msg"));
+	stripspace(&msg, 0);
+
+	if (state->signoff)
+		am_signoff(&msg);
+
+	assert(!state->author_name);
+	state->author_name = strbuf_detach(&author_name, NULL);
+
+	assert(!state->author_email);
+	state->author_email = strbuf_detach(&author_email, NULL);
+
+	assert(!state->author_date);
+	state->author_date = strbuf_detach(&author_date, NULL);
+
+	assert(!state->msg);
+	state->msg = strbuf_detach(&msg, &state->msg_len);
+
+finish:
+	strbuf_release(&msg);
+	strbuf_release(&author_date);
+	strbuf_release(&author_email);
+	strbuf_release(&author_name);
+	strbuf_release(&sb);
+	return ret;
+}
+
+/**
+ * Sets commit_id to the commit hash where the mail was generated from.
+ * Returns 0 on success, -1 on failure.
+ */
+static int get_mail_commit_sha1(unsigned char *commit_id, const char *mail)
+{
+	struct strbuf sb = STRBUF_INIT;
+	FILE *fp = xfopen(mail, "r");
+	const char *x;
+
+	if (strbuf_getline(&sb, fp, '\n'))
+		return -1;
+
+	if (!skip_prefix(sb.buf, "From ", &x))
+		return -1;
+
+	if (get_sha1_hex(x, commit_id) < 0)
+		return -1;
+
+	strbuf_release(&sb);
+	fclose(fp);
+	return 0;
+}
+
+/**
+ * Sets state->msg, state->author_name, state->author_email, state->author_date
+ * to the commit's respective info.
+ */
+static void get_commit_info(struct am_state *state, struct commit *commit)
+{
+	const char *buffer, *ident_line, *author_date, *msg;
+	size_t ident_len;
+	struct ident_split ident_split;
+	struct strbuf sb = STRBUF_INIT;
+
+	buffer = logmsg_reencode(commit, NULL, get_commit_output_encoding());
+
+	ident_line = find_commit_header(buffer, "author", &ident_len);
+
+	if (split_ident_line(&ident_split, ident_line, ident_len) < 0) {
+		strbuf_add(&sb, ident_line, ident_len);
+		die(_("invalid ident line: %s"), sb.buf);
+	}
+
+	assert(!state->author_name);
+	if (ident_split.name_begin) {
+		strbuf_add(&sb, ident_split.name_begin,
+			ident_split.name_end - ident_split.name_begin);
+		state->author_name = strbuf_detach(&sb, NULL);
+	} else
+		state->author_name = xstrdup("");
+
+	assert(!state->author_email);
+	if (ident_split.mail_begin) {
+		strbuf_add(&sb, ident_split.mail_begin,
+			ident_split.mail_end - ident_split.mail_begin);
+		state->author_email = strbuf_detach(&sb, NULL);
+	} else
+		state->author_email = xstrdup("");
+
+	author_date = show_ident_date(&ident_split, DATE_MODE(NORMAL));
+	strbuf_addstr(&sb, author_date);
+	assert(!state->author_date);
+	state->author_date = strbuf_detach(&sb, NULL);
+
+	assert(!state->msg);
+	msg = strstr(buffer, "\n\n");
+	if (!msg)
+		die(_("unable to parse commit %s"), sha1_to_hex(commit->object.sha1));
+	state->msg = xstrdup(msg + 2);
+	state->msg_len = strlen(state->msg);
+}
+
+/**
+ * Writes `commit` as a patch to the state directory's "patch" file.
+ */
+static void write_commit_patch(const struct am_state *state, struct commit *commit)
+{
+	struct rev_info rev_info;
+	FILE *fp;
+
+	fp = xfopen(am_path(state, "patch"), "w");
+	init_revisions(&rev_info, NULL);
+	rev_info.diff = 1;
+	rev_info.abbrev = 0;
+	rev_info.disable_stdin = 1;
+	rev_info.show_root_diff = 1;
+	rev_info.diffopt.output_format = DIFF_FORMAT_PATCH;
+	rev_info.no_commit_id = 1;
+	DIFF_OPT_SET(&rev_info.diffopt, BINARY);
+	DIFF_OPT_SET(&rev_info.diffopt, FULL_INDEX);
+	rev_info.diffopt.use_color = 0;
+	rev_info.diffopt.file = fp;
+	rev_info.diffopt.close_file = 1;
+	add_pending_object(&rev_info, &commit->object, "");
+	diff_setup_done(&rev_info.diffopt);
+	log_tree_commit(&rev_info, commit);
+}
+
+/**
+ * Writes the diff of the index against HEAD as a patch to the state
+ * directory's "patch" file.
+ */
+static void write_index_patch(const struct am_state *state)
+{
+	struct tree *tree;
+	unsigned char head[GIT_SHA1_RAWSZ];
+	struct rev_info rev_info;
+	FILE *fp;
+
+	if (!get_sha1_tree("HEAD", head))
+		tree = lookup_tree(head);
+	else
+		tree = lookup_tree(EMPTY_TREE_SHA1_BIN);
+
+	fp = xfopen(am_path(state, "patch"), "w");
+	init_revisions(&rev_info, NULL);
+	rev_info.diff = 1;
+	rev_info.disable_stdin = 1;
+	rev_info.no_commit_id = 1;
+	rev_info.diffopt.output_format = DIFF_FORMAT_PATCH;
+	rev_info.diffopt.use_color = 0;
+	rev_info.diffopt.file = fp;
+	rev_info.diffopt.close_file = 1;
+	add_pending_object(&rev_info, &tree->object, "");
+	diff_setup_done(&rev_info.diffopt);
+	run_diff_index(&rev_info, 1);
+}
+
+/**
+ * Like parse_mail(), but parses the mail by looking up its commit ID
+ * directly. This is used in --rebasing mode to bypass git-mailinfo's munging
+ * of patches.
+ *
+ * state->orig_commit will be set to the original commit ID.
+ *
+ * Will always return 0 as the patch should never be skipped.
+ */
+static int parse_mail_rebase(struct am_state *state, const char *mail)
+{
+	struct commit *commit;
+	unsigned char commit_sha1[GIT_SHA1_RAWSZ];
+
+	if (get_mail_commit_sha1(commit_sha1, mail) < 0)
+		die(_("could not parse %s"), mail);
+
+	commit = lookup_commit_or_die(commit_sha1, mail);
+
+	get_commit_info(state, commit);
+
+	write_commit_patch(state, commit);
+
+	hashcpy(state->orig_commit, commit_sha1);
+	write_state_text(state, "original-commit", sha1_to_hex(commit_sha1));
+
+	return 0;
+}
+
+/**
+ * Applies current patch with git-apply. Returns 0 on success, -1 otherwise. If
+ * `index_file` is not NULL, the patch will be applied to that index.
+ */
+static int run_apply(const struct am_state *state, const char *index_file)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+
+	cp.git_cmd = 1;
+
+	if (index_file)
+		argv_array_pushf(&cp.env_array, "GIT_INDEX_FILE=%s", index_file);
+
+	/*
+	 * If we are allowed to fall back on 3-way merge, don't give false
+	 * errors during the initial attempt.
+	 */
+	if (state->threeway && !index_file) {
+		cp.no_stdout = 1;
+		cp.no_stderr = 1;
+	}
+
+	argv_array_push(&cp.args, "apply");
+
+	argv_array_pushv(&cp.args, state->git_apply_opts.argv);
+
+	if (index_file)
+		argv_array_push(&cp.args, "--cached");
+	else
+		argv_array_push(&cp.args, "--index");
+
+	argv_array_push(&cp.args, am_path(state, "patch"));
+
+	if (run_command(&cp))
+		return -1;
+
+	/* Reload index as git-apply will have modified it. */
+	discard_cache();
+	read_cache_from(index_file ? index_file : get_index_file());
+
+	return 0;
+}
+
+/**
+ * Builds an index that contains just the blobs needed for a 3way merge.
+ */
+static int build_fake_ancestor(const struct am_state *state, const char *index_file)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+
+	cp.git_cmd = 1;
+	argv_array_push(&cp.args, "apply");
+	argv_array_pushv(&cp.args, state->git_apply_opts.argv);
+	argv_array_pushf(&cp.args, "--build-fake-ancestor=%s", index_file);
+	argv_array_push(&cp.args, am_path(state, "patch"));
+
+	if (run_command(&cp))
+		return -1;
+
+	return 0;
+}
+
+/**
+ * Attempt a threeway merge, using index_path as the temporary index.
+ */
+static int fall_back_threeway(const struct am_state *state, const char *index_path)
+{
+	unsigned char orig_tree[GIT_SHA1_RAWSZ], his_tree[GIT_SHA1_RAWSZ],
+		      our_tree[GIT_SHA1_RAWSZ];
+	const unsigned char *bases[1] = {orig_tree};
+	struct merge_options o;
+	struct commit *result;
+	char *his_tree_name;
+
+	if (get_sha1("HEAD", our_tree) < 0)
+		hashcpy(our_tree, EMPTY_TREE_SHA1_BIN);
+
+	if (build_fake_ancestor(state, index_path))
+		return error("could not build fake ancestor");
+
+	discard_cache();
+	read_cache_from(index_path);
+
+	if (write_index_as_tree(orig_tree, &the_index, index_path, 0, NULL))
+		return error(_("Repository lacks necessary blobs to fall back on 3-way merge."));
+
+	say(state, stdout, _("Using index info to reconstruct a base tree..."));
+
+	if (!state->quiet) {
+		/*
+		 * List paths that needed 3-way fallback, so that the user can
+		 * review them with extra care to spot mismerges.
+		 */
+		struct rev_info rev_info;
+		const char *diff_filter_str = "--diff-filter=AM";
+
+		init_revisions(&rev_info, NULL);
+		rev_info.diffopt.output_format = DIFF_FORMAT_NAME_STATUS;
+		diff_opt_parse(&rev_info.diffopt, &diff_filter_str, 1);
+		add_pending_sha1(&rev_info, "HEAD", our_tree, 0);
+		diff_setup_done(&rev_info.diffopt);
+		run_diff_index(&rev_info, 1);
+	}
+
+	if (run_apply(state, index_path))
+		return error(_("Did you hand edit your patch?\n"
+				"It does not apply to blobs recorded in its index."));
+
+	if (write_index_as_tree(his_tree, &the_index, index_path, 0, NULL))
+		return error("could not write tree");
+
+	say(state, stdout, _("Falling back to patching base and 3-way merge..."));
+
+	discard_cache();
+	read_cache();
+
+	/*
+	 * This is not so wrong. Depending on which base we picked, orig_tree
+	 * may be wildly different from ours, but his_tree has the same set of
+	 * wildly different changes in parts the patch did not touch, so
+	 * recursive ends up canceling them, saying that we reverted all those
+	 * changes.
+	 */
+
+	init_merge_options(&o);
+
+	o.branch1 = "HEAD";
+	his_tree_name = xstrfmt("%.*s", linelen(state->msg), state->msg);
+	o.branch2 = his_tree_name;
+
+	if (state->quiet)
+		o.verbosity = 0;
+
+	if (merge_recursive_generic(&o, our_tree, his_tree, 1, bases, &result)) {
+		rerere(state->allow_rerere_autoupdate);
+		free(his_tree_name);
+		return error(_("Failed to merge in the changes."));
+	}
+
+	free(his_tree_name);
+	return 0;
+}
+
+/**
+ * Commits the current index with state->msg as the commit message and
+ * state->author_name, state->author_email and state->author_date as the author
+ * information.
+ */
+static void do_commit(const struct am_state *state)
+{
+	unsigned char tree[GIT_SHA1_RAWSZ], parent[GIT_SHA1_RAWSZ],
+		      commit[GIT_SHA1_RAWSZ];
+	unsigned char *ptr;
+	struct commit_list *parents = NULL;
+	const char *reflog_msg, *author;
+	struct strbuf sb = STRBUF_INIT;
+
+	if (run_hook_le(NULL, "pre-applypatch", NULL))
+		exit(1);
+
+	if (write_cache_as_tree(tree, 0, NULL))
+		die(_("git write-tree failed to write a tree"));
+
+	if (!get_sha1_commit("HEAD", parent)) {
+		ptr = parent;
+		commit_list_insert(lookup_commit(parent), &parents);
+	} else {
+		ptr = NULL;
+		say(state, stderr, _("applying to an empty history"));
+	}
+
+	author = fmt_ident(state->author_name, state->author_email,
+			state->ignore_date ? NULL : state->author_date,
+			IDENT_STRICT);
+
+	if (state->committer_date_is_author_date)
+		setenv("GIT_COMMITTER_DATE",
+			state->ignore_date ? "" : state->author_date, 1);
+
+	if (commit_tree(state->msg, state->msg_len, tree, parents, commit,
+				author, state->sign_commit))
+		die(_("failed to write commit object"));
+
+	reflog_msg = getenv("GIT_REFLOG_ACTION");
+	if (!reflog_msg)
+		reflog_msg = "am";
+
+	strbuf_addf(&sb, "%s: %.*s", reflog_msg, linelen(state->msg),
+			state->msg);
+
+	update_ref(sb.buf, "HEAD", commit, ptr, 0, UPDATE_REFS_DIE_ON_ERR);
+
+	if (state->rebasing) {
+		FILE *fp = xfopen(am_path(state, "rewritten"), "a");
+
+		assert(!is_null_sha1(state->orig_commit));
+		fprintf(fp, "%s ", sha1_to_hex(state->orig_commit));
+		fprintf(fp, "%s\n", sha1_to_hex(commit));
+		fclose(fp);
+	}
+
+	run_hook_le(NULL, "post-applypatch", NULL);
+
+	strbuf_release(&sb);
+}
+
+/**
+ * Validates the am_state for resuming -- the "msg" and authorship fields must
+ * be filled up.
+ */
+static void validate_resume_state(const struct am_state *state)
+{
+	if (!state->msg)
+		die(_("cannot resume: %s does not exist."),
+			am_path(state, "final-commit"));
+
+	if (!state->author_name || !state->author_email || !state->author_date)
+		die(_("cannot resume: %s does not exist."),
+			am_path(state, "author-script"));
+}
+
+/**
+ * Interactively prompt the user on whether the current patch should be
+ * applied.
+ *
+ * Returns 0 if the user chooses to apply the patch, 1 if the user chooses to
+ * skip it.
+ */
+static int do_interactive(struct am_state *state)
+{
+	assert(state->msg);
+
+	if (!isatty(0))
+		die(_("cannot be interactive without stdin connected to a terminal."));
+
+	for (;;) {
+		const char *reply;
+
+		puts(_("Commit Body is:"));
+		puts("--------------------------");
+		printf("%s", state->msg);
+		puts("--------------------------");
+
+		/*
+		 * TRANSLATORS: Make sure to include [y], [n], [e], [v] and [a]
+		 * in your translation. The program will only accept English
+		 * input at this point.
+		 */
+		reply = git_prompt(_("Apply? [y]es/[n]o/[e]dit/[v]iew patch/[a]ccept all: "), PROMPT_ECHO);
+
+		if (!reply) {
+			continue;
+		} else if (*reply == 'y' || *reply == 'Y') {
+			return 0;
+		} else if (*reply == 'a' || *reply == 'A') {
+			state->interactive = 0;
+			return 0;
+		} else if (*reply == 'n' || *reply == 'N') {
+			return 1;
+		} else if (*reply == 'e' || *reply == 'E') {
+			struct strbuf msg = STRBUF_INIT;
+
+			if (!launch_editor(am_path(state, "final-commit"), &msg, NULL)) {
+				free(state->msg);
+				state->msg = strbuf_detach(&msg, &state->msg_len);
+			}
+			strbuf_release(&msg);
+		} else if (*reply == 'v' || *reply == 'V') {
+			const char *pager = git_pager(1);
+			struct child_process cp = CHILD_PROCESS_INIT;
+
+			if (!pager)
+				pager = "cat";
+			argv_array_push(&cp.args, pager);
+			argv_array_push(&cp.args, am_path(state, "patch"));
+			run_command(&cp);
+		}
+	}
+}
+
+/**
+ * Applies all queued mail.
+ *
+ * If `resume` is true, we are "resuming". The "msg" and authorship fields, as
+ * well as the state directory's "patch" file is used as-is for applying the
+ * patch and committing it.
+ */
+static void am_run(struct am_state *state, int resume)
+{
+	const char *argv_gc_auto[] = {"gc", "--auto", NULL};
+	struct strbuf sb = STRBUF_INIT;
+
+	unlink(am_path(state, "dirtyindex"));
+
+	refresh_and_write_cache();
+
+	if (index_has_changes(&sb)) {
+		write_state_bool(state, "dirtyindex", 1);
+		die(_("Dirty index: cannot apply patches (dirty: %s)"), sb.buf);
+	}
+
+	strbuf_release(&sb);
+
+	while (state->cur <= state->last) {
+		const char *mail = am_path(state, msgnum(state));
+		int apply_status;
+
+		if (!file_exists(mail))
+			goto next;
+
+		if (resume) {
+			validate_resume_state(state);
+		} else {
+			int skip;
+
+			if (state->rebasing)
+				skip = parse_mail_rebase(state, mail);
+			else
+				skip = parse_mail(state, mail);
+
+			if (skip)
+				goto next; /* mail should be skipped */
+
+			write_author_script(state);
+			write_commit_msg(state);
+		}
+
+		if (state->interactive && do_interactive(state))
+			goto next;
+
+		if (run_applypatch_msg_hook(state))
+			exit(1);
+
+		say(state, stdout, _("Applying: %.*s"), linelen(state->msg), state->msg);
+
+		apply_status = run_apply(state, NULL);
+
+		if (apply_status && state->threeway) {
+			struct strbuf sb = STRBUF_INIT;
+
+			strbuf_addstr(&sb, am_path(state, "patch-merge-index"));
+			apply_status = fall_back_threeway(state, sb.buf);
+			strbuf_release(&sb);
+
+			/*
+			 * Applying the patch to an earlier tree and merging
+			 * the result may have produced the same tree as ours.
+			 */
+			if (!apply_status && !index_has_changes(NULL)) {
+				say(state, stdout, _("No changes -- Patch already applied."));
+				goto next;
+			}
+		}
+
+		if (apply_status) {
+			int advice_amworkdir = 1;
+
+			printf_ln(_("Patch failed at %s %.*s"), msgnum(state),
+				linelen(state->msg), state->msg);
+
+			git_config_get_bool("advice.amworkdir", &advice_amworkdir);
+
+			if (advice_amworkdir)
+				printf_ln(_("The copy of the patch that failed is found in: %s"),
+						am_path(state, "patch"));
+
+			die_user_resolve(state);
+		}
+
+		do_commit(state);
+
+next:
+		am_next(state);
+
+		if (resume)
+			am_load(state);
+		resume = 0;
+	}
+
+	if (!is_empty_file(am_path(state, "rewritten"))) {
+		assert(state->rebasing);
+		copy_notes_for_rebase(state);
+		run_post_rewrite_hook(state);
+	}
+
+	/*
+	 * In rebasing mode, it's up to the caller to take care of
+	 * housekeeping.
+	 */
+	if (!state->rebasing) {
+		am_destroy(state);
+		run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
+	}
+}
+
+/**
+ * Resume the current am session after patch application failure. The user did
+ * all the hard work, and we do not have to do any patch application. Just
+ * trust and commit what the user has in the index and working tree.
+ */
+static void am_resolve(struct am_state *state)
+{
+	validate_resume_state(state);
+
+	say(state, stdout, _("Applying: %.*s"), linelen(state->msg), state->msg);
+
+	if (!index_has_changes(NULL)) {
+		printf_ln(_("No changes - did you forget to use 'git add'?\n"
+			"If there is nothing left to stage, chances are that something else\n"
+			"already introduced the same changes; you might want to skip this patch."));
+		die_user_resolve(state);
+	}
+
+	if (unmerged_cache()) {
+		printf_ln(_("You still have unmerged paths in your index.\n"
+			"Did you forget to use 'git add'?"));
+		die_user_resolve(state);
+	}
+
+	if (state->interactive) {
+		write_index_patch(state);
+		if (do_interactive(state))
+			goto next;
+	}
+
+	rerere(0);
+
+	do_commit(state);
+
+next:
+	am_next(state);
+	am_load(state);
+	am_run(state, 0);
+}
+
+/**
+ * Performs a checkout fast-forward from `head` to `remote`. If `reset` is
+ * true, any unmerged entries will be discarded. Returns 0 on success, -1 on
+ * failure.
+ */
+static int fast_forward_to(struct tree *head, struct tree *remote, int reset)
+{
+	struct lock_file *lock_file;
+	struct unpack_trees_options opts;
+	struct tree_desc t[2];
+
+	if (parse_tree(head) || parse_tree(remote))
+		return -1;
+
+	lock_file = xcalloc(1, sizeof(struct lock_file));
+	hold_locked_index(lock_file, 1);
+
+	refresh_cache(REFRESH_QUIET);
+
+	memset(&opts, 0, sizeof(opts));
+	opts.head_idx = 1;
+	opts.src_index = &the_index;
+	opts.dst_index = &the_index;
+	opts.update = 1;
+	opts.merge = 1;
+	opts.reset = reset;
+	opts.fn = twoway_merge;
+	init_tree_desc(&t[0], head->buffer, head->size);
+	init_tree_desc(&t[1], remote->buffer, remote->size);
+
+	if (unpack_trees(2, t, &opts)) {
+		rollback_lock_file(lock_file);
+		return -1;
+	}
+
+	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
+		die(_("unable to write new index file"));
+
+	return 0;
+}
+
+/**
+ * Merges a tree into the index. The index's stat info will take precedence
+ * over the merged tree's. Returns 0 on success, -1 on failure.
+ */
+static int merge_tree(struct tree *tree)
+{
+	struct lock_file *lock_file;
+	struct unpack_trees_options opts;
+	struct tree_desc t[1];
+
+	if (parse_tree(tree))
+		return -1;
+
+	lock_file = xcalloc(1, sizeof(struct lock_file));
+	hold_locked_index(lock_file, 1);
+
+	memset(&opts, 0, sizeof(opts));
+	opts.head_idx = 1;
+	opts.src_index = &the_index;
+	opts.dst_index = &the_index;
+	opts.merge = 1;
+	opts.fn = oneway_merge;
+	init_tree_desc(&t[0], tree->buffer, tree->size);
+
+	if (unpack_trees(1, t, &opts)) {
+		rollback_lock_file(lock_file);
+		return -1;
+	}
+
+	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
+		die(_("unable to write new index file"));
+
+	return 0;
+}
+
+/**
+ * Clean the index without touching entries that are not modified between
+ * `head` and `remote`.
+ */
+static int clean_index(const unsigned char *head, const unsigned char *remote)
+{
+	struct tree *head_tree, *remote_tree, *index_tree;
+	unsigned char index[GIT_SHA1_RAWSZ];
+
+	head_tree = parse_tree_indirect(head);
+	if (!head_tree)
+		return error(_("Could not parse object '%s'."), sha1_to_hex(head));
+
+	remote_tree = parse_tree_indirect(remote);
+	if (!remote_tree)
+		return error(_("Could not parse object '%s'."), sha1_to_hex(remote));
+
+	read_cache_unmerged();
+
+	if (fast_forward_to(head_tree, head_tree, 1))
+		return -1;
+
+	if (write_cache_as_tree(index, 0, NULL))
+		return -1;
+
+	index_tree = parse_tree_indirect(index);
+	if (!index_tree)
+		return error(_("Could not parse object '%s'."), sha1_to_hex(index));
+
+	if (fast_forward_to(index_tree, remote_tree, 0))
+		return -1;
+
+	if (merge_tree(remote_tree))
+		return -1;
+
+	remove_branch_state();
+
+	return 0;
+}
+
+/**
+ * Resets rerere's merge resolution metadata.
+ */
+static void am_rerere_clear(void)
+{
+	struct string_list merge_rr = STRING_LIST_INIT_DUP;
+	rerere_clear(&merge_rr);
+	string_list_clear(&merge_rr, 1);
+}
+
+/**
+ * Resume the current am session by skipping the current patch.
+ */
+static void am_skip(struct am_state *state)
+{
+	unsigned char head[GIT_SHA1_RAWSZ];
+
+	am_rerere_clear();
+
+	if (get_sha1("HEAD", head))
+		hashcpy(head, EMPTY_TREE_SHA1_BIN);
+
+	if (clean_index(head, head))
+		die(_("failed to clean index"));
+
+	am_next(state);
+	am_load(state);
+	am_run(state, 0);
+}
+
+/**
+ * Returns true if it is safe to reset HEAD to the ORIG_HEAD, false otherwise.
+ *
+ * It is not safe to reset HEAD when:
+ * 1. git-am previously failed because the index was dirty.
+ * 2. HEAD has moved since git-am previously failed.
+ */
+static int safe_to_abort(const struct am_state *state)
+{
+	struct strbuf sb = STRBUF_INIT;
+	unsigned char abort_safety[GIT_SHA1_RAWSZ], head[GIT_SHA1_RAWSZ];
+
+	if (file_exists(am_path(state, "dirtyindex")))
+		return 0;
+
+	if (read_state_file(&sb, state, "abort-safety", 1) > 0) {
+		if (get_sha1_hex(sb.buf, abort_safety))
+			die(_("could not parse %s"), am_path(state, "abort_safety"));
+	} else
+		hashclr(abort_safety);
+
+	if (get_sha1("HEAD", head))
+		hashclr(head);
+
+	if (!hashcmp(head, abort_safety))
+		return 1;
+
+	error(_("You seem to have moved HEAD since the last 'am' failure.\n"
+		"Not rewinding to ORIG_HEAD"));
+
+	return 0;
+}
+
+/**
+ * Aborts the current am session if it is safe to do so.
+ */
+static void am_abort(struct am_state *state)
+{
+	unsigned char curr_head[GIT_SHA1_RAWSZ], orig_head[GIT_SHA1_RAWSZ];
+	int has_curr_head, has_orig_head;
+	char *curr_branch;
+
+	if (!safe_to_abort(state)) {
+		am_destroy(state);
+		return;
+	}
+
+	am_rerere_clear();
+
+	curr_branch = resolve_refdup("HEAD", 0, curr_head, NULL);
+	has_curr_head = !is_null_sha1(curr_head);
+	if (!has_curr_head)
+		hashcpy(curr_head, EMPTY_TREE_SHA1_BIN);
+
+	has_orig_head = !get_sha1("ORIG_HEAD", orig_head);
+	if (!has_orig_head)
+		hashcpy(orig_head, EMPTY_TREE_SHA1_BIN);
+
+	clean_index(curr_head, orig_head);
+
+	if (has_orig_head)
+		update_ref("am --abort", "HEAD", orig_head,
+				has_curr_head ? curr_head : NULL, 0,
+				UPDATE_REFS_DIE_ON_ERR);
+	else if (curr_branch)
+		delete_ref(curr_branch, NULL, REF_NODEREF);
+
+	free(curr_branch);
+	am_destroy(state);
+}
+
+/**
+ * parse_options() callback that validates and sets opt->value to the
+ * PATCH_FORMAT_* enum value corresponding to `arg`.
+ */
+static int parse_opt_patchformat(const struct option *opt, const char *arg, int unset)
+{
+	int *opt_value = opt->value;
+
+	if (!strcmp(arg, "mbox"))
+		*opt_value = PATCH_FORMAT_MBOX;
+	else if (!strcmp(arg, "stgit"))
+		*opt_value = PATCH_FORMAT_STGIT;
+	else if (!strcmp(arg, "stgit-series"))
+		*opt_value = PATCH_FORMAT_STGIT_SERIES;
+	else if (!strcmp(arg, "hg"))
+		*opt_value = PATCH_FORMAT_HG;
+	else
+		return error(_("Invalid value for --patch-format: %s"), arg);
+	return 0;
+}
+
+enum resume_mode {
+	RESUME_FALSE = 0,
+	RESUME_APPLY,
+	RESUME_RESOLVED,
+	RESUME_SKIP,
+	RESUME_ABORT
+};
+
+int cmd_am(int argc, const char **argv, const char *prefix)
+{
+	struct am_state state;
+	int binary = -1;
+	int keep_cr = -1;
+	int patch_format = PATCH_FORMAT_UNKNOWN;
+	enum resume_mode resume = RESUME_FALSE;
+	int in_progress;
+
+	const char * const usage[] = {
+		N_("git am [options] [(<mbox>|<Maildir>)...]"),
+		N_("git am [options] (--continue | --skip | --abort)"),
+		NULL
+	};
+
+	struct option options[] = {
+		OPT_BOOL('i', "interactive", &state.interactive,
+			N_("run interactively")),
+		OPT_HIDDEN_BOOL('b', "binary", &binary,
+			N_("historical option -- no-op")),
+		OPT_BOOL('3', "3way", &state.threeway,
+			N_("allow fall back on 3way merging if needed")),
+		OPT__QUIET(&state.quiet, N_("be quiet")),
+		OPT_SET_INT('s', "signoff", &state.signoff,
+			N_("add a Signed-off-by line to the commit message"),
+			SIGNOFF_EXPLICIT),
+		OPT_BOOL('u', "utf8", &state.utf8,
+			N_("recode into utf8 (default)")),
+		OPT_SET_INT('k', "keep", &state.keep,
+			N_("pass -k flag to git-mailinfo"), KEEP_TRUE),
+		OPT_SET_INT(0, "keep-non-patch", &state.keep,
+			N_("pass -b flag to git-mailinfo"), KEEP_NON_PATCH),
+		OPT_BOOL('m', "message-id", &state.message_id,
+			N_("pass -m flag to git-mailinfo")),
+		{ OPTION_SET_INT, 0, "keep-cr", &keep_cr, NULL,
+		  N_("pass --keep-cr flag to git-mailsplit for mbox format"),
+		  PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1},
+		{ OPTION_SET_INT, 0, "no-keep-cr", &keep_cr, NULL,
+		  N_("do not pass --keep-cr flag to git-mailsplit independent of am.keepcr"),
+		  PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 0},
+		OPT_BOOL('c', "scissors", &state.scissors,
+			N_("strip everything before a scissors line")),
+		OPT_PASSTHRU_ARGV(0, "whitespace", &state.git_apply_opts, N_("action"),
+			N_("pass it through git-apply"),
+			0),
+		OPT_PASSTHRU_ARGV(0, "ignore-space-change", &state.git_apply_opts, NULL,
+			N_("pass it through git-apply"),
+			PARSE_OPT_NOARG),
+		OPT_PASSTHRU_ARGV(0, "ignore-whitespace", &state.git_apply_opts, NULL,
+			N_("pass it through git-apply"),
+			PARSE_OPT_NOARG),
+		OPT_PASSTHRU_ARGV(0, "directory", &state.git_apply_opts, N_("root"),
+			N_("pass it through git-apply"),
+			0),
+		OPT_PASSTHRU_ARGV(0, "exclude", &state.git_apply_opts, N_("path"),
+			N_("pass it through git-apply"),
+			0),
+		OPT_PASSTHRU_ARGV(0, "include", &state.git_apply_opts, N_("path"),
+			N_("pass it through git-apply"),
+			0),
+		OPT_PASSTHRU_ARGV('C', NULL, &state.git_apply_opts, N_("n"),
+			N_("pass it through git-apply"),
+			0),
+		OPT_PASSTHRU_ARGV('p', NULL, &state.git_apply_opts, N_("num"),
+			N_("pass it through git-apply"),
+			0),
+		OPT_CALLBACK(0, "patch-format", &patch_format, N_("format"),
+			N_("format the patch(es) are in"),
+			parse_opt_patchformat),
+		OPT_PASSTHRU_ARGV(0, "reject", &state.git_apply_opts, NULL,
+			N_("pass it through git-apply"),
+			PARSE_OPT_NOARG),
+		OPT_STRING(0, "resolvemsg", &state.resolvemsg, NULL,
+			N_("override error message when patch failure occurs")),
+		OPT_CMDMODE(0, "continue", &resume,
+			N_("continue applying patches after resolving a conflict"),
+			RESUME_RESOLVED),
+		OPT_CMDMODE('r', "resolved", &resume,
+			N_("synonyms for --continue"),
+			RESUME_RESOLVED),
+		OPT_CMDMODE(0, "skip", &resume,
+			N_("skip the current patch"),
+			RESUME_SKIP),
+		OPT_CMDMODE(0, "abort", &resume,
+			N_("restore the original branch and abort the patching operation."),
+			RESUME_ABORT),
+		OPT_BOOL(0, "committer-date-is-author-date",
+			&state.committer_date_is_author_date,
+			N_("lie about committer date")),
+		OPT_BOOL(0, "ignore-date", &state.ignore_date,
+			N_("use current timestamp for author date")),
+		OPT_RERERE_AUTOUPDATE(&state.allow_rerere_autoupdate),
+		{ OPTION_STRING, 'S', "gpg-sign", &state.sign_commit, N_("key-id"),
+		  N_("GPG-sign commits"),
+		  PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
+		OPT_HIDDEN_BOOL(0, "rebasing", &state.rebasing,
+			N_("(internal use for git-rebase)")),
+		OPT_END()
+	};
+
+	git_config(git_default_config, NULL);
+
+	am_state_init(&state, git_path("rebase-apply"));
+
+	in_progress = am_in_progress(&state);
+	if (in_progress)
+		am_load(&state);
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+
+	if (binary >= 0)
+		fprintf_ln(stderr, _("The -b/--binary option has been a no-op for long time, and\n"
+				"it will be removed. Please do not use it anymore."));
+
+	/* Ensure a valid committer ident can be constructed */
+	git_committer_info(IDENT_STRICT);
+
+	if (read_index_preload(&the_index, NULL) < 0)
+		die(_("failed to read the index"));
+
+	if (in_progress) {
+		/*
+		 * Catch user error to feed us patches when there is a session
+		 * in progress:
+		 *
+		 * 1. mbox path(s) are provided on the command-line.
+		 * 2. stdin is not a tty: the user is trying to feed us a patch
+		 *    from standard input. This is somewhat unreliable -- stdin
+		 *    could be /dev/null for example and the caller did not
+		 *    intend to feed us a patch but wanted to continue
+		 *    unattended.
+		 */
+		if (argc || (resume == RESUME_FALSE && !isatty(0)))
+			die(_("previous rebase directory %s still exists but mbox given."),
+				state.dir);
+
+		if (resume == RESUME_FALSE)
+			resume = RESUME_APPLY;
+
+		if (state.signoff == SIGNOFF_EXPLICIT)
+			am_append_signoff(&state);
+	} else {
+		struct argv_array paths = ARGV_ARRAY_INIT;
+		int i;
+
+		/*
+		 * Handle stray state directory in the independent-run case. In
+		 * the --rebasing case, it is up to the caller to take care of
+		 * stray directories.
+		 */
+		if (file_exists(state.dir) && !state.rebasing) {
+			if (resume == RESUME_ABORT) {
+				am_destroy(&state);
+				am_state_release(&state);
+				return 0;
+			}
+
+			die(_("Stray %s directory found.\n"
+				"Use \"git am --abort\" to remove it."),
+				state.dir);
+		}
+
+		if (resume)
+			die(_("Resolve operation not in progress, we are not resuming."));
+
+		for (i = 0; i < argc; i++) {
+			if (is_absolute_path(argv[i]) || !prefix)
+				argv_array_push(&paths, argv[i]);
+			else
+				argv_array_push(&paths, mkpath("%s/%s", prefix, argv[i]));
+		}
+
+		am_setup(&state, patch_format, paths.argv, keep_cr);
+
+		argv_array_clear(&paths);
+	}
+
+	switch (resume) {
+	case RESUME_FALSE:
+		am_run(&state, 0);
+		break;
+	case RESUME_APPLY:
+		am_run(&state, 1);
+		break;
+	case RESUME_RESOLVED:
+		am_resolve(&state);
+		break;
+	case RESUME_SKIP:
+		am_skip(&state);
+		break;
+	case RESUME_ABORT:
+		am_abort(&state);
+		break;
+	default:
+		die("BUG: invalid resume value");
+	}
+
+	am_state_release(&state);
+
+	return 0;
+}
diff --git a/builtin/apply.c b/builtin/apply.c
index 54aba4e351..4aa53f7fd8 100644
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -785,7 +785,7 @@ static int guess_p_value(const char *nameline)
 }
 
 /*
- * Does the ---/+++ line has the POSIX timestamp after the last HT?
+ * Does the ---/+++ line have the POSIX timestamp after the last HT?
  * GNU diff puts epoch there to signal a creation/deletion event.  Is
  * this such a timestamp?
  */
diff --git a/builtin/blame.c b/builtin/blame.c
index 4db01c195c..6fd1a63fc7 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -2600,7 +2600,6 @@ parse_done:
 		   fewer display columns. */
 		blame_date_width = utf8_strwidth(_("4 years, 11 months ago")) + 1; /* add the null */
 		break;
-	case DATE_LOCAL:
 	case DATE_NORMAL:
 		blame_date_width = sizeof("Thu Oct 19 16:00:04 2006 -0700");
 		break;
diff --git a/builtin/branch.c b/builtin/branch.c
index 58aa84f1e8..3ba4d1bd3b 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -636,6 +636,10 @@ static int print_ref_list(int kinds, int detached, int verbose, int abbrev, stru
 	cb.pattern = pattern;
 	cb.ret = 0;
 	for_each_rawref(append_ref, &cb);
+	/*
+	 * The following implementation is currently duplicated in ref-filter. It
+	 * will eventually be removed when we port branch.c to use ref-filter APIs.
+	 */
 	if (merge_filter != NO_FILTER) {
 		struct commit *filter;
 		filter = lookup_commit_reference_gently(merge_filter_ref, 0);
@@ -746,6 +750,10 @@ static void rename_branch(const char *oldname, const char *newname, int force)
 	strbuf_release(&newsection);
 }
 
+/*
+ * This function is duplicated in ref-filter. It will eventually be removed
+ * when we port branch.c to use ref-filter APIs.
+ */
 static int opt_parse_merge_filter(const struct option *opt, const char *arg, int unset)
 {
 	merge_filter = ((opt->long_name[0] == 'n')
@@ -776,7 +784,7 @@ static int edit_branch_description(const char *branch_name)
 		    "  %s\n"
 		    "Lines starting with '%c' will be stripped.\n",
 		    branch_name, comment_line_char);
-	if (write_file(git_path(edit_description), 0, "%s", buf.buf)) {
+	if (write_file_gently(git_path(edit_description), "%s", buf.buf)) {
 		strbuf_release(&buf);
 		return error(_("could not write branch description template: %s"),
 			     strerror(errno));
@@ -821,18 +829,8 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		OPT__COLOR(&branch_use_color, N_("use colored output")),
 		OPT_SET_INT('r', "remotes",     &kinds, N_("act on remote-tracking branches"),
 			REF_REMOTE_BRANCH),
-		{
-			OPTION_CALLBACK, 0, "contains", &with_commit, N_("commit"),
-			N_("print only branches that contain the commit"),
-			PARSE_OPT_LASTARG_DEFAULT,
-			parse_opt_with_commit, (intptr_t)"HEAD",
-		},
-		{
-			OPTION_CALLBACK, 0, "with", &with_commit, N_("commit"),
-			N_("print only branches that contain the commit"),
-			PARSE_OPT_HIDDEN | PARSE_OPT_LASTARG_DEFAULT,
-			parse_opt_with_commit, (intptr_t) "HEAD",
-		},
+		OPT_CONTAINS(&with_commit, N_("print only branches that contain the commit")),
+		OPT_WITH(&with_commit, N_("print only branches that contain the commit")),
 		OPT__ABBREV(&abbrev),
 
 		OPT_GROUP(N_("Specific git-branch actions:")),
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 7ea533e4ab..bc703c0f5e 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -49,8 +49,6 @@ struct checkout_opts {
 	const char *prefix;
 	struct pathspec pathspec;
 	struct tree *source_tree;
-
-	int new_worktree_mode;
 };
 
 static int post_checkout_hook(struct commit *old, struct commit *new,
@@ -283,7 +281,7 @@ static int checkout_paths(const struct checkout_opts *opts,
 	if (opts->source_tree)
 		read_tree_some(opts->source_tree, &opts->pathspec);
 
-	ps_matched = xcalloc(1, opts->pathspec.nr);
+	ps_matched = xcalloc(opts->pathspec.nr, 1);
 
 	/*
 	 * Make sure all pathspecs participated in locating the paths
@@ -510,7 +508,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			topts.dir->flags |= DIR_SHOW_IGNORED;
 			setup_standard_excludes(topts.dir);
 		}
-		tree = parse_tree_indirect(old->commit && !opts->new_worktree_mode ?
+		tree = parse_tree_indirect(old->commit ?
 					   old->commit->object.sha1 :
 					   EMPTY_TREE_SHA1_BIN);
 		init_tree_desc(&trees[0], tree->buffer, tree->size);
@@ -831,8 +829,7 @@ static int switch_branches(const struct checkout_opts *opts,
 		return ret;
 	}
 
-	if (!opts->quiet && !old.path && old.commit &&
-	    new->commit != old.commit && !opts->new_worktree_mode)
+	if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 		orphaned_commit_warning(old.commit, new->commit);
 
 	update_refs_for_switch(opts, &old, new);
@@ -897,71 +894,6 @@ static const char *unique_tracking_name(const char *name, unsigned char *sha1)
 	return NULL;
 }
 
-static void check_linked_checkout(struct branch_info *new, const char *id)
-{
-	struct strbuf sb = STRBUF_INIT;
-	struct strbuf path = STRBUF_INIT;
-	struct strbuf gitdir = STRBUF_INIT;
-	const char *start, *end;
-
-	if (id)
-		strbuf_addf(&path, "%s/worktrees/%s/HEAD", get_git_common_dir(), id);
-	else
-		strbuf_addf(&path, "%s/HEAD", get_git_common_dir());
-
-	if (strbuf_read_file(&sb, path.buf, 0) < 0 ||
-	    !skip_prefix(sb.buf, "ref:", &start))
-		goto done;
-	while (isspace(*start))
-		start++;
-	end = start;
-	while (*end && !isspace(*end))
-		end++;
-	if (strncmp(start, new->path, end - start) || new->path[end - start] != '\0')
-		goto done;
-	if (id) {
-		strbuf_reset(&path);
-		strbuf_addf(&path, "%s/worktrees/%s/gitdir", get_git_common_dir(), id);
-		if (strbuf_read_file(&gitdir, path.buf, 0) <= 0)
-			goto done;
-		strbuf_rtrim(&gitdir);
-	} else
-		strbuf_addstr(&gitdir, get_git_common_dir());
-	die(_("'%s' is already checked out at '%s'"), new->name, gitdir.buf);
-done:
-	strbuf_release(&path);
-	strbuf_release(&sb);
-	strbuf_release(&gitdir);
-}
-
-static void check_linked_checkouts(struct branch_info *new)
-{
-	struct strbuf path = STRBUF_INIT;
-	DIR *dir;
-	struct dirent *d;
-
-	strbuf_addf(&path, "%s/worktrees", get_git_common_dir());
-	if ((dir = opendir(path.buf)) == NULL) {
-		strbuf_release(&path);
-		return;
-	}
-
-	/*
-	 * $GIT_COMMON_DIR/HEAD is practically outside
-	 * $GIT_DIR so resolve_ref_unsafe() won't work (it
-	 * uses git_path). Parse the ref ourselves.
-	 */
-	check_linked_checkout(new, NULL);
-
-	while ((d = readdir(dir)) != NULL) {
-		if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
-			continue;
-		check_linked_checkout(new, d->d_name);
-	}
-	strbuf_release(&path);
-	closedir(dir);
-}
-
 static int parse_branchname_arg(int argc, const char **argv,
 				int dwim_new_local_branch_ok,
 				struct branch_info *new,
@@ -1169,14 +1101,14 @@ static int checkout_branch(struct checkout_opts *opts,
 		die(_("Cannot switch branch to a non-commit '%s'"),
 		    new->name);
 
-	if (new->path && !opts->force_detach && !opts->new_branch) {
+	if (new->path && !opts->force_detach && !opts->new_branch &&
+	    !opts->ignore_other_worktrees) {
 		unsigned char sha1[20];
 		int flag;
 		char *head_ref = resolve_refdup("HEAD", 0, sha1, &flag);
 		if (head_ref &&
-		    (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)) &&
-		    !opts->ignore_other_worktrees)
-			check_linked_checkouts(new);
+		    (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)))
+			die_if_checked_out(new->path);
 		free(head_ref);
 	}
 
@@ -1240,8 +1172,6 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, prefix, options, checkout_usage,
 			     PARSE_OPT_KEEP_DASHDASH);
 
-	opts.new_worktree_mode = getenv("GIT_CHECKOUT_NEW_WORKTREE") != NULL;
-
 	if (conflict_style) {
 		opts.merge = 1; /* implied */
 		git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
diff --git a/builtin/clone.c b/builtin/clone.c
index 5864ad15e1..578da85254 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -161,35 +161,78 @@ static char *get_repo_path(const char *repo, int *is_bundle)
 
 static char *guess_dir_name(const char *repo, int is_bundle, int is_bare)
 {
-	const char *end = repo + strlen(repo), *start;
+	const char *end = repo + strlen(repo), *start, *ptr;
 	size_t len;
 	char *dir;
 
 	/*
+	 * Skip scheme.
+	 */
+	start = strstr(repo, "://");
+	if (start == NULL)
+		start = repo;
+	else
+		start += 3;
+
+	/*
+	 * Skip authentication data. The stripping does happen
+	 * greedily, such that we strip up to the last '@' inside
+	 * the host part.
+	 */
+	for (ptr = start; ptr < end && !is_dir_sep(*ptr); ptr++) {
+		if (*ptr == '@')
+			start = ptr + 1;
+	}
+
+	/*
 	 * Strip trailing spaces, slashes and /.git
 	 */
-	while (repo < end && (is_dir_sep(end[-1]) || isspace(end[-1])))
+	while (start < end && (is_dir_sep(end[-1]) || isspace(end[-1])))
 		end--;
-	if (end - repo > 5 && is_dir_sep(end[-5]) &&
+	if (end - start > 5 && is_dir_sep(end[-5]) &&
 	    !strncmp(end - 4, ".git", 4)) {
 		end -= 5;
-		while (repo < end && is_dir_sep(end[-1]))
+		while (start < end && is_dir_sep(end[-1]))
 			end--;
 	}
 
 	/*
-	 * Find last component, but be prepared that repo could have
-	 * the form  "remote.example.com:foo.git", i.e. no slash
-	 * in the directory part.
+	 * Strip trailing port number if we've got only a
+	 * hostname (that is, there is no dir separator but a
+	 * colon). This check is required such that we do not
+	 * strip URI's like '/foo/bar:2222.git', which should
+	 * result in a dir '2222' being guessed due to backwards
+	 * compatibility.
+	 */
+	if (memchr(start, '/', end - start) == NULL
+	    && memchr(start, ':', end - start) != NULL) {
+		ptr = end;
+		while (start < ptr && isdigit(ptr[-1]) && ptr[-1] != ':')
+			ptr--;
+		if (start < ptr && ptr[-1] == ':')
+			end = ptr - 1;
+	}
+
+	/*
+	 * Find last component. To remain backwards compatible we
+	 * also regard colons as path separators, such that
+	 * cloning a repository 'foo:bar.git' would result in a
+	 * directory 'bar' being guessed.
 	 */
-	start = end;
-	while (repo < start && !is_dir_sep(start[-1]) && start[-1] != ':')
-		start--;
+	ptr = end;
+	while (start < ptr && !is_dir_sep(ptr[-1]) && ptr[-1] != ':')
+		ptr--;
+	start = ptr;
 
 	/*
 	 * Strip .{bundle,git}.
 	 */
-	strip_suffix(start, is_bundle ? ".bundle" : ".git" , &len);
+	len = end - start;
+	strip_suffix_mem(start, &len, is_bundle ? ".bundle" : ".git");
+
+	if (!len || (len == 1 && *start == '/'))
+	    die("No directory name could be guessed.\n"
+		"Please specify a directory on the command line");
 
 	if (is_bare)
 		dir = xstrfmt("%.*s.git", (int)len, start);
diff --git a/builtin/commit.c b/builtin/commit.c
index 4cbd5ff4de..63772d016a 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -324,6 +324,7 @@ static const char *prepare_index(int argc, const char **argv, const char *prefix
 	struct string_list partial;
 	struct pathspec pathspec;
 	int refresh_flags = REFRESH_QUIET;
+	const char *ret;
 
 	if (is_status)
 		refresh_flags |= REFRESH_UNMERGED;
@@ -344,7 +345,7 @@ static const char *prepare_index(int argc, const char **argv, const char *prefix
 			die(_("unable to create temporary index"));
 
 		old_index_env = getenv(INDEX_ENVIRONMENT);
-		setenv(INDEX_ENVIRONMENT, index_lock.filename.buf, 1);
+		setenv(INDEX_ENVIRONMENT, get_lock_file_path(&index_lock), 1);
 
 		if (interactive_add(argc, argv, prefix, patch_interactive) != 0)
 			die(_("interactive add failed"));
@@ -355,7 +356,7 @@ static const char *prepare_index(int argc, const char **argv, const char *prefix
 			unsetenv(INDEX_ENVIRONMENT);
 
 		discard_cache();
-		read_cache_from(index_lock.filename.buf);
+		read_cache_from(get_lock_file_path(&index_lock));
 		if (update_main_cache_tree(WRITE_TREE_SILENT) == 0) {
 			if (reopen_lock_file(&index_lock) < 0)
 				die(_("unable to write index file"));
@@ -365,7 +366,7 @@ static const char *prepare_index(int argc, const char **argv, const char *prefix
 			warning(_("Failed to update main cache tree"));
 
 		commit_style = COMMIT_NORMAL;
-		return index_lock.filename.buf;
+		return get_lock_file_path(&index_lock);
 	}
 
 	/*
@@ -388,7 +389,7 @@ static const char *prepare_index(int argc, const char **argv, const char *prefix
 		if (write_locked_index(&the_index, &index_lock, CLOSE_LOCK))
 			die(_("unable to write new_index file"));
 		commit_style = COMMIT_NORMAL;
-		return index_lock.filename.buf;
+		return get_lock_file_path(&index_lock);
 	}
 
 	/*
@@ -404,10 +405,8 @@ static const char *prepare_index(int argc, const char **argv, const char *prefix
 		hold_locked_index(&index_lock, 1);
 		refresh_cache_or_die(refresh_flags);
 		if (active_cache_changed
-		    || !cache_tree_fully_valid(active_cache_tree)) {
+		    || !cache_tree_fully_valid(active_cache_tree))
 			update_main_cache_tree(WRITE_TREE_SILENT);
-			active_cache_changed = 1;
-		}
 		if (active_cache_changed) {
 			if (write_locked_index(&the_index, &index_lock,
 					       COMMIT_LOCK))
@@ -475,9 +474,9 @@ static const char *prepare_index(int argc, const char **argv, const char *prefix
 		die(_("unable to write temporary index file"));
 
 	discard_cache();
-	read_cache_from(false_lock.filename.buf);
-
-	return false_lock.filename.buf;
+	ret = get_lock_file_path(&false_lock);
+	read_cache_from(ret);
+	return ret;
 }
 
 static int run_status(FILE *fp, const char *index_file, const char *prefix, int nowarn,
diff --git a/builtin/config.c b/builtin/config.c
index 7188405f7e..71acc44143 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -13,6 +13,7 @@ static char *key;
 static regex_t *key_regexp;
 static regex_t *regexp;
 static int show_keys;
+static int omit_values;
 static int use_key_regexp;
 static int do_all;
 static int do_not_match;
@@ -78,6 +79,7 @@ static struct option builtin_config_options[] = {
 	OPT_BIT(0, "path", &types, N_("value is a path (file or directory name)"), TYPE_PATH),
 	OPT_GROUP(N_("Other")),
 	OPT_BOOL('z', "null", &end_null, N_("terminate values with NUL byte")),
+	OPT_BOOL(0, "name-only", &omit_values, N_("show variable names only")),
 	OPT_BOOL(0, "includes", &respect_includes, N_("respect include directives on lookup")),
 	OPT_END(),
 };
@@ -91,7 +93,7 @@ static void check_argc(int argc, int min, int max) {
 
 static int show_all_config(const char *key_, const char *value_, void *cb)
 {
-	if (value_)
+	if (!omit_values && value_)
 		printf("%s%c%s%c", key_, delim, value_, term);
 	else
 		printf("%s%c", key_, term);
@@ -106,48 +108,40 @@ struct strbuf_list {
 
 static int format_config(struct strbuf *buf, const char *key_, const char *value_)
 {
-	int must_free_vptr = 0;
-	int must_print_delim = 0;
-	char value[256];
-	const char *vptr = value;
-
-	strbuf_init(buf, 0);
-
-	if (show_keys) {
+	if (show_keys)
 		strbuf_addstr(buf, key_);
-		must_print_delim = 1;
-	}
-	if (types == TYPE_INT)
-		sprintf(value, "%"PRId64,
-			git_config_int64(key_, value_ ? value_ : ""));
-	else if (types == TYPE_BOOL)
-		vptr = git_config_bool(key_, value_) ? "true" : "false";
-	else if (types == TYPE_BOOL_OR_INT) {
-		int is_bool, v;
-		v = git_config_bool_or_int(key_, value_, &is_bool);
-		if (is_bool)
-			vptr = v ? "true" : "false";
-		else
-			sprintf(value, "%d", v);
-	} else if (types == TYPE_PATH) {
-		if (git_config_pathname(&vptr, key_, value_) < 0)
-			return -1;
-		must_free_vptr = 1;
-	} else if (value_) {
-		vptr = value_;
-	} else {
-		/* Just show the key name */
-		vptr = "";
-		must_print_delim = 0;
-	}
+	if (!omit_values) {
+		if (show_keys)
+			strbuf_addch(buf, key_delim);
 
-	if (must_print_delim)
-		strbuf_addch(buf, key_delim);
-	strbuf_addstr(buf, vptr);
+		if (types == TYPE_INT)
+			strbuf_addf(buf, "%"PRId64,
+				    git_config_int64(key_, value_ ? value_ : ""));
+		else if (types == TYPE_BOOL)
+			strbuf_addstr(buf, git_config_bool(key_, value_) ?
+				      "true" : "false");
+		else if (types == TYPE_BOOL_OR_INT) {
+			int is_bool, v;
+			v = git_config_bool_or_int(key_, value_, &is_bool);
+			if (is_bool)
+				strbuf_addstr(buf, v ? "true" : "false");
+			else
+				strbuf_addf(buf, "%d", v);
+		} else if (types == TYPE_PATH) {
+			const char *v;
+			if (git_config_pathname(&v, key_, value_) < 0)
+				return -1;
+			strbuf_addstr(buf, v);
+			free((char *)v);
+		} else if (value_) {
+			strbuf_addstr(buf, value_);
+		} else {
+			/* Just show the key name; back out delimiter */
+			if (show_keys)
+				strbuf_setlen(buf, buf->len - 1);
+		}
+	}
 	strbuf_addch(buf, term);
-
-	if (must_free_vptr)
-		free((char *)vptr);
 	return 0;
 }
 
@@ -164,6 +158,7 @@ static int collect_config(const char *key_, const char *value_, void *cb)
 		return 0;
 
 	ALLOC_GROW(values->items, values->nr + 1, values->alloc);
+	strbuf_init(&values->items[values->nr], 0);
 
 	return format_config(&values->items[values->nr++], key_, value_);
 }
@@ -430,14 +425,11 @@ static int get_urlmatch(const char *var, const char *url)
 
 	for_each_string_list_item(item, &values) {
 		struct urlmatch_current_candidate_value *matched = item->util;
-		struct strbuf key = STRBUF_INIT;
 		struct strbuf buf = STRBUF_INIT;
 
-		strbuf_addstr(&key, item->string);
-		format_config(&buf, key.buf,
+		format_config(&buf, item->string,
 			      matched->value_is_null ? NULL : matched->value.buf);
 		fwrite(buf.buf, 1, buf.len, stdout);
-		strbuf_release(&key);
 		strbuf_release(&buf);
 
 		strbuf_release(&matched->value);
@@ -549,7 +541,11 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 		default:
 			usage_with_options(builtin_config_usage, builtin_config_options);
 		}
-
+	if (omit_values &&
+	    !(actions == ACTION_LIST || actions == ACTION_GET_REGEXP)) {
+		error("--name-only is only applicable to --list or --get-regexp");
+		usage_with_options(builtin_config_usage, builtin_config_options);
+	}
 	if (actions == ACTION_LIST) {
 		check_argc(argc, 0, 0);
 		if (git_config_with_options(show_all_config, NULL,
diff --git a/builtin/describe.c b/builtin/describe.c
index a36c829e57..7df554326b 100644
--- a/builtin/describe.c
+++ b/builtin/describe.c
@@ -443,10 +443,10 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 			if (pattern)
 				argv_array_pushf(&args, "--refs=refs/tags/%s", pattern);
 		}
-		while (*argv) {
-			argv_array_push(&args, *argv);
-			argv++;
-		}
+		if (argc)
+			argv_array_pushv(&args, argv);
+		else
+			argv_array_push(&args, "HEAD");
 		return cmd_name_rev(args.argc, args.argv, prefix);
 	}
 
diff --git a/builtin/fetch.c b/builtin/fetch.c
index ee1f1a93af..9a3869f4ff 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -989,17 +989,15 @@ static int get_remote_group(const char *key, const char *value, void *priv)
 {
 	struct remote_group_data *g = priv;
 
-	if (starts_with(key, "remotes.") &&
-			!strcmp(key + 8, g->name)) {
+	if (skip_prefix(key, "remotes.", &key) && !strcmp(key, g->name)) {
 		/* split list by white space */
-		int space = strcspn(value, " \t\n");
 		while (*value) {
-			if (space > 1) {
+			size_t wordlen = strcspn(value, " \t\n");
+
+			if (wordlen >= 1)
 				string_list_append(g->list,
-						   xstrndup(value, space));
-			}
-			value += space + (value[space] != '\0');
-			space = strcspn(value, " \t\n");
+						   xstrndup(value, wordlen));
+			value += wordlen + (value[wordlen] != '\0');
 		}
 	}
 
diff --git a/builtin/for-each-ref.c b/builtin/for-each-ref.c
index 7919206187..4e9f6c29bf 100644
--- a/builtin/for-each-ref.c
+++ b/builtin/for-each-ref.c
@@ -7,6 +7,9 @@
 
 static char const * const for_each_ref_usage[] = {
 	N_("git for-each-ref [<options>] [<pattern>]"),
+	N_("git for-each-ref [--points-at <object>]"),
+	N_("git for-each-ref [(--merged | --no-merged) [<object>]]"),
+	N_("git for-each-ref [--contains [<object>]]"),
 	NULL
 };
 
@@ -34,9 +37,18 @@ int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
 		OPT_STRING(  0 , "format", &format, N_("format"), N_("format to use for the output")),
 		OPT_CALLBACK(0 , "sort", sorting_tail, N_("key"),
 			    N_("field name to sort on"), &parse_opt_ref_sorting),
+		OPT_CALLBACK(0, "points-at", &filter.points_at,
+			     N_("object"), N_("print only refs which points at the given object"),
+			     parse_opt_object_name),
+		OPT_MERGED(&filter, N_("print only refs that are merged")),
+		OPT_NO_MERGED(&filter, N_("print only refs that are not merged")),
+		OPT_CONTAINS(&filter.with_commit, N_("print only refs which contain the commit")),
 		OPT_END(),
 	};
 
+	memset(&array, 0, sizeof(array));
+	memset(&filter, 0, sizeof(filter));
+
 	parse_options(argc, argv, prefix, opts, for_each_ref_usage, 0);
 	if (maxcount < 0) {
 		error("invalid --count argument: `%d'", maxcount);
@@ -55,9 +67,8 @@ int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
 	/* for warn_ambiguous_refs */
 	git_config(git_default_config, NULL);
 
-	memset(&array, 0, sizeof(array));
-	memset(&filter, 0, sizeof(filter));
 	filter.name_patterns = argv;
+	filter.match_as_path = 1;
 	filter_refs(&array, &filter, FILTER_REFS_ALL | FILTER_REFS_INCLUDE_BROKEN);
 	ref_array_sort(sorting, &array);
 
diff --git a/builtin/gc.c b/builtin/gc.c
index 4957c39032..0ad8d30b56 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -11,6 +11,7 @@
  */
 
 #include "builtin.h"
+#include "tempfile.h"
 #include "lockfile.h"
 #include "parse-options.h"
 #include "run-command.h"
@@ -42,20 +43,7 @@ static struct argv_array prune = ARGV_ARRAY_INIT;
 static struct argv_array prune_worktrees = ARGV_ARRAY_INIT;
 static struct argv_array rerere = ARGV_ARRAY_INIT;
 
-static char *pidfile;
-
-static void remove_pidfile(void)
-{
-	if (pidfile)
-		unlink(pidfile);
-}
-
-static void remove_pidfile_on_signal(int signo)
-{
-	remove_pidfile();
-	sigchain_pop(signo);
-	raise(signo);
-}
+static struct tempfile pidfile;
 
 static void git_config_date_string(const char *key, const char **output)
 {
@@ -85,7 +73,7 @@ static void gc_config(void)
 	git_config_get_int("gc.autopacklimit", &gc_auto_pack_limit);
 	git_config_get_bool("gc.autodetach", &detach_auto);
 	git_config_date_string("gc.pruneexpire", &prune_expire);
-	git_config_date_string("gc.pruneworktreesexpire", &prune_worktrees_expire);
+	git_config_date_string("gc.worktreepruneexpire", &prune_worktrees_expire);
 	git_config(git_default_config, NULL);
 }
 
@@ -199,20 +187,22 @@ static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
 	uintmax_t pid;
 	FILE *fp;
 	int fd;
+	char *pidfile_path;
 
-	if (pidfile)
+	if (is_tempfile_active(&pidfile))
 		/* already locked */
 		return NULL;
 
 	if (gethostname(my_host, sizeof(my_host)))
 		strcpy(my_host, "unknown");
 
-	fd = hold_lock_file_for_update(&lock, git_path("gc.pid"),
+	pidfile_path = git_pathdup("gc.pid");
+	fd = hold_lock_file_for_update(&lock, pidfile_path,
 				       LOCK_DIE_ON_ERROR);
 	if (!force) {
 		static char locking_host[128];
 		int should_exit;
-		fp = fopen(git_path("gc.pid"), "r");
+		fp = fopen(pidfile_path, "r");
 		memset(locking_host, 0, sizeof(locking_host));
 		should_exit =
 			fp != NULL &&
@@ -236,6 +226,7 @@ static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
 			if (fd >= 0)
 				rollback_lock_file(&lock);
 			*ret_pid = pid;
+			free(pidfile_path);
 			return locking_host;
 		}
 	}
@@ -245,11 +236,8 @@ static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
 	write_in_full(fd, sb.buf, sb.len);
 	strbuf_release(&sb);
 	commit_lock_file(&lock);
-
-	pidfile = git_pathdup("gc.pid");
-	sigchain_push_common(remove_pidfile_on_signal);
-	atexit(remove_pidfile);
-
+	register_tempfile(&pidfile, pidfile_path);
+	free(pidfile_path);
 	return NULL;
 }
 
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 3f10840441..3431de2362 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1421,7 +1421,7 @@ static void final(const char *final_pack_name, const char *curr_pack_name,
 				 get_object_directory(), sha1_to_hex(sha1));
 			final_pack_name = name;
 		}
-		if (move_temp_to_file(curr_pack_name, final_pack_name))
+		if (finalize_object_file(curr_pack_name, final_pack_name))
 			die(_("cannot store pack file"));
 	} else if (from_stdin)
 		chmod(final_pack_name, 0444);
@@ -1432,7 +1432,7 @@ static void final(const char *final_pack_name, const char *curr_pack_name,
 				 get_object_directory(), sha1_to_hex(sha1));
 			final_index_name = name;
 		}
-		if (move_temp_to_file(curr_index_name, final_index_name))
+		if (finalize_object_file(curr_index_name, final_index_name))
 			die(_("cannot store index file"));
 	} else
 		chmod(final_index_name, 0444);
diff --git a/builtin/init-db.c b/builtin/init-db.c
index 49df78d262..69323e186c 100644
--- a/builtin/init-db.c
+++ b/builtin/init-db.c
@@ -378,7 +378,7 @@ static void separate_git_dir(const char *git_dir)
 			die_errno(_("unable to move %s to %s"), src, git_dir);
 	}
 
-	write_file(git_link, 1, "gitdir: %s\n", git_dir);
+	write_file(git_link, "gitdir: %s", git_dir);
 }
 
 int init_db(const char *template_dir, unsigned int flags)
diff --git a/builtin/log.c b/builtin/log.c
index b50ef7510c..a491d3dea0 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -342,8 +342,7 @@ static int cmd_log_walk(struct rev_info *rev)
 	 * retain that state information if replacing rev->diffopt in this loop
 	 */
 	while ((commit = get_revision(rev)) != NULL) {
-		if (!log_tree_commit(rev, commit) &&
-		    rev->max_count >= 0)
+		if (!log_tree_commit(rev, commit) && rev->max_count >= 0)
 			/*
 			 * We decremented max_count in get_revision,
 			 * but we didn't actually show the commit.
@@ -504,7 +503,8 @@ static int show_tree_object(const unsigned char *sha1,
 	return 0;
 }
 
-static void show_rev_tweak_rev(struct rev_info *rev, struct setup_revision_opt *opt)
+static void show_setup_revisions_tweak(struct rev_info *rev,
+				       struct setup_revision_opt *opt)
 {
 	if (rev->ignore_merges) {
 		/* There was no "-m" on the command line */
@@ -539,7 +539,7 @@ int cmd_show(int argc, const char **argv, const char *prefix)
 
 	memset(&opt, 0, sizeof(opt));
 	opt.def = "HEAD";
-	opt.tweak = show_rev_tweak_rev;
+	opt.tweak = show_setup_revisions_tweak;
 	cmd_log_init(argc, argv, prefix, &rev, &opt);
 
 	if (!rev.no_walk)
@@ -626,12 +626,20 @@ int cmd_log_reflog(int argc, const char **argv, const char *prefix)
 	return cmd_log_walk(&rev);
 }
 
-static void default_follow_tweak(struct rev_info *rev,
-				 struct setup_revision_opt *opt)
+static void log_setup_revisions_tweak(struct rev_info *rev,
+				      struct setup_revision_opt *opt)
 {
 	if (DIFF_OPT_TST(&rev->diffopt, DEFAULT_FOLLOW_RENAMES) &&
 	    rev->prune_data.nr == 1)
 		DIFF_OPT_SET(&rev->diffopt, FOLLOW_RENAMES);
+
+	/* Turn --cc/-c into -p --cc/-c when -p was not given */
+	if (!rev->diffopt.output_format && rev->combine_merges)
+		rev->diffopt.output_format = DIFF_FORMAT_PATCH;
+
+	/* Turn -m on when --cc/-c was given */
+	if (rev->combine_merges)
+		rev->ignore_merges = 0;
 }
 
 int cmd_log(int argc, const char **argv, const char *prefix)
@@ -647,7 +655,7 @@ int cmd_log(int argc, const char **argv, const char *prefix)
 	memset(&opt, 0, sizeof(opt));
 	opt.def = "HEAD";
 	opt.revarg_opt = REVARG_COMMITTISH;
-	opt.tweak = default_follow_tweak;
+	opt.tweak = log_setup_revisions_tweak;
 	cmd_log_init(argc, argv, prefix, &rev, &opt);
 	return cmd_log_walk(&rev);
 }
@@ -1455,8 +1463,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			continue;
 		}
 
-		if (ignore_if_in_upstream &&
-				has_commit_patch_id(commit, &ids))
+		if (ignore_if_in_upstream && has_commit_patch_id(commit, &ids))
 			continue;
 
 		nr++;
diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index 6fa2205734..b6a7cb0c7c 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -516,7 +516,7 @@ int cmd_ls_files(int argc, const char **argv, const char *cmd_prefix)
 
 	/* Treat unmatching pathspec elements as errors */
 	if (pathspec.nr && error_unmatch)
-		ps_matched = xcalloc(1, pathspec.nr);
+		ps_matched = xcalloc(pathspec.nr, 1);
 
 	if ((dir.flags & DIR_SHOW_IGNORED) && !exc_given)
 		die("ls-files --ignored needs some exclude pattern");
diff --git a/builtin/notes.c b/builtin/notes.c
index 63f95fc554..3608c64785 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -19,6 +19,7 @@
 #include "string-list.h"
 #include "notes-merge.h"
 #include "notes-utils.h"
+#include "branch.h"
 
 static const char * const git_notes_usage[] = {
 	N_("git notes [--ref <notes-ref>] [list [<object>]]"),
@@ -737,6 +738,19 @@ static int merge_commit(struct notes_merge_options *o)
 	return ret;
 }
 
+static int git_config_get_notes_strategy(const char *key,
+					 enum notes_merge_strategy *strategy)
+{
+	const char *value;
+
+	if (git_config_get_string_const(key, &value))
+		return 1;
+	if (parse_notes_merge_strategy(value, strategy))
+		git_die_config(key, "unknown notes merge strategy %s", value);
+
+	return 0;
+}
+
 static int merge(int argc, const char **argv, const char *prefix)
 {
 	struct strbuf remote_ref = STRBUF_INIT, msg = STRBUF_INIT;
@@ -795,24 +809,28 @@ static int merge(int argc, const char **argv, const char *prefix)
 	expand_notes_ref(&remote_ref);
 	o.remote_ref = remote_ref.buf;
 
+	t = init_notes_check("merge");
+
 	if (strategy) {
-		if (!strcmp(strategy, "manual"))
-			o.strategy = NOTES_MERGE_RESOLVE_MANUAL;
-		else if (!strcmp(strategy, "ours"))
-			o.strategy = NOTES_MERGE_RESOLVE_OURS;
-		else if (!strcmp(strategy, "theirs"))
-			o.strategy = NOTES_MERGE_RESOLVE_THEIRS;
-		else if (!strcmp(strategy, "union"))
-			o.strategy = NOTES_MERGE_RESOLVE_UNION;
-		else if (!strcmp(strategy, "cat_sort_uniq"))
-			o.strategy = NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ;
-		else {
+		if (parse_notes_merge_strategy(strategy, &o.strategy)) {
 			error("Unknown -s/--strategy: %s", strategy);
 			usage_with_options(git_notes_merge_usage, options);
 		}
-	}
+	} else {
+		struct strbuf merge_key = STRBUF_INIT;
+		const char *short_ref = NULL;
 
-	t = init_notes_check("merge");
+		if (!skip_prefix(o.local_ref, "refs/notes/", &short_ref))
+			die("BUG: local ref %s is outside of refs/notes/",
+			    o.local_ref);
+
+		strbuf_addf(&merge_key, "notes.%s.mergeStrategy", short_ref);
+
+		if (git_config_get_notes_strategy(merge_key.buf, &o.strategy))
+			git_config_get_notes_strategy("notes.mergeStrategy", &o.strategy);
+
+		strbuf_release(&merge_key);
+	}
 
 	strbuf_addf(&msg, "notes: Merged notes from %s into %s",
 		    remote_ref.buf, default_notes_ref());
@@ -825,10 +843,15 @@ static int merge(int argc, const char **argv, const char *prefix)
 		update_ref(msg.buf, default_notes_ref(), result_sha1, NULL,
 			   0, UPDATE_REFS_DIE_ON_ERR);
 	else { /* Merge has unresolved conflicts */
+		char *existing;
 		/* Update .git/NOTES_MERGE_PARTIAL with partial merge result */
 		update_ref(msg.buf, "NOTES_MERGE_PARTIAL", result_sha1, NULL,
 			   0, UPDATE_REFS_DIE_ON_ERR);
 		/* Store ref-to-be-updated into .git/NOTES_MERGE_REF */
+		existing = find_shared_symref("NOTES_MERGE_REF", default_notes_ref());
+		if (existing)
+			die(_("A notes merge into %s is already in-progress at %s"),
+			    default_notes_ref(), existing);
 		if (create_symref("NOTES_MERGE_REF", default_notes_ref(), NULL))
 			die("Failed to store link to current notes ref (%s)",
 			    default_notes_ref());
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 62cc16ddc2..1c63f8f28c 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -25,8 +25,8 @@
 #include "argv-array.h"
 
 static const char *pack_usage[] = {
-	N_("git pack-objects --stdout [options...] [< ref-list | < object-list]"),
-	N_("git pack-objects [options...] base-name [< ref-list | < object-list]"),
+	N_("git pack-objects --stdout [<options>...] [< <ref-list> | < <object-list>]"),
+	N_("git pack-objects [<options>...] <base-name> [< <ref-list> | < <object-list>]"),
 	NULL
 };
 
diff --git a/builtin/pull.c b/builtin/pull.c
index 722a83c51b..a39bb0a11f 100644
--- a/builtin/pull.c
+++ b/builtin/pull.c
@@ -15,6 +15,7 @@
 #include "dir.h"
 #include "refs.h"
 #include "revision.h"
+#include "tempfile.h"
 #include "lockfile.h"
 
 enum rebase_type {
@@ -111,7 +112,7 @@ static struct option pull_options[] = {
 	/* Options passed to git-merge or git-rebase */
 	OPT_GROUP(N_("Options related to merging")),
 	{ OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
-	  N_("false|true|preserve"),
+	  "false|true|preserve",
 	  N_("incorporate changes by rebasing rather than merging"),
 	  PARSE_OPT_OPTARG, parse_opt_rebase },
 	OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
@@ -823,10 +824,14 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 		hashclr(orig_head);
 
 	if (opt_rebase) {
+		int autostash = 0;
+
 		if (is_null_sha1(orig_head) && !is_cache_unborn())
 			die(_("Updating an unborn branch with changes added to the index."));
 
-		die_on_unclean_work_tree(prefix);
+		git_config_get_bool("rebase.autostash", &autostash);
+		if (!autostash)
+			die_on_unclean_work_tree(prefix);
 
 		if (get_rebase_fork_point(rebase_fork_point, repo, *refspecs))
 			hashclr(rebase_fork_point);
diff --git a/builtin/push.c b/builtin/push.c
index 57c138bd7b..3bda430b6b 100644
--- a/builtin/push.c
+++ b/builtin/push.c
@@ -9,6 +9,7 @@
 #include "transport.h"
 #include "parse-options.h"
 #include "submodule.h"
+#include "send-pack.h"
 
 static const char * const push_usage[] = {
 	N_("git push [<options>] [<repository> [<refspec>...]]"),
@@ -471,6 +472,24 @@ static int option_parse_recurse_submodules(const struct option *opt,
 	return 0;
 }
 
+static void set_push_cert_flags(int *flags, int v)
+{
+	switch (v) {
+	case SEND_PACK_PUSH_CERT_NEVER:
+		*flags &= ~(TRANSPORT_PUSH_CERT_ALWAYS | TRANSPORT_PUSH_CERT_IF_ASKED);
+		break;
+	case SEND_PACK_PUSH_CERT_ALWAYS:
+		*flags |= TRANSPORT_PUSH_CERT_ALWAYS;
+		*flags &= ~TRANSPORT_PUSH_CERT_IF_ASKED;
+		break;
+	case SEND_PACK_PUSH_CERT_IF_ASKED:
+		*flags |= TRANSPORT_PUSH_CERT_IF_ASKED;
+		*flags &= ~TRANSPORT_PUSH_CERT_ALWAYS;
+		break;
+	}
+}
+
+
 static int git_push_config(const char *k, const char *v, void *cb)
 {
 	int *flags = cb;
@@ -486,6 +505,23 @@ static int git_push_config(const char *k, const char *v, void *cb)
 		else
 			*flags &= ~TRANSPORT_PUSH_FOLLOW_TAGS;
 		return 0;
+	} else if (!strcmp(k, "push.gpgsign")) {
+		const char *value;
+		if (!git_config_get_value("push.gpgsign", &value)) {
+			switch (git_config_maybe_bool("push.gpgsign", value)) {
+			case 0:
+				set_push_cert_flags(flags, SEND_PACK_PUSH_CERT_NEVER);
+				break;
+			case 1:
+				set_push_cert_flags(flags, SEND_PACK_PUSH_CERT_ALWAYS);
+				break;
+			default:
+				if (value && !strcasecmp(value, "if-asked"))
+					set_push_cert_flags(flags, SEND_PACK_PUSH_CERT_IF_ASKED);
+				else
+					return error("Invalid value for '%s'", k);
+			}
+		}
 	}
 
 	return git_default_config(k, v, NULL);
@@ -495,6 +531,7 @@ int cmd_push(int argc, const char **argv, const char *prefix)
 {
 	int flags = 0;
 	int tags = 0;
+	int push_cert = -1;
 	int rc;
 	const char *repo = NULL;	/* default repository */
 	struct option options[] = {
@@ -526,7 +563,9 @@ int cmd_push(int argc, const char **argv, const char *prefix)
 		OPT_BIT(0, "no-verify", &flags, N_("bypass pre-push hook"), TRANSPORT_PUSH_NO_HOOK),
 		OPT_BIT(0, "follow-tags", &flags, N_("push missing but relevant tags"),
 			TRANSPORT_PUSH_FOLLOW_TAGS),
-		OPT_BIT(0, "signed", &flags, N_("GPG sign the push"), TRANSPORT_PUSH_CERT),
+		{ OPTION_CALLBACK,
+		  0, "signed", &push_cert, "yes|no|if-asked", N_("GPG sign the push"),
+		  PARSE_OPT_OPTARG, option_parse_push_signed },
 		OPT_BIT(0, "atomic", &flags, N_("request atomic transaction on remote side"), TRANSPORT_PUSH_ATOMIC),
 		OPT_END()
 	};
@@ -534,6 +573,7 @@ int cmd_push(int argc, const char **argv, const char *prefix)
 	packet_trace_identity("push");
 	git_config(git_push_config, &flags);
 	argc = parse_options(argc, argv, prefix, options, push_usage, 0);
+	set_push_cert_flags(&flags, push_cert);
 
 	if (deleterefs && (tags || (flags & (TRANSPORT_PUSH_ALL | TRANSPORT_PUSH_MIRROR))))
 		die(_("--delete is incompatible with --all, --mirror and --tags"));
diff --git a/builtin/read-tree.c b/builtin/read-tree.c
index 43b47f72f1..2379e11069 100644
--- a/builtin/read-tree.c
+++ b/builtin/read-tree.c
@@ -34,7 +34,7 @@ static int list_tree(unsigned char *sha1)
 }
 
 static const char * const read_tree_usage[] = {
-	N_("git read-tree [[-m [--trivial] [--aggressive] | --reset | --prefix=<prefix>] [-u [--exclude-per-directory=<gitignore>] | -i]] [--no-sparse-checkout] [--index-output=<file>] (--empty | <tree-ish1> [<tree-ish2> [<tree-ish3>]])"),
+	N_("git read-tree [(-m [--trivial] [--aggressive] | --reset | --prefix=<prefix>) [-u [--exclude-per-directory=<gitignore>] | -i]] [--no-sparse-checkout] [--index-output=<file>] (--empty | <tree-ish1> [<tree-ish2> [<tree-ish3>]])"),
 	NULL
 };
 
diff --git a/builtin/reflog.c b/builtin/reflog.c
index 7ed0e8501c..f96ca2a27d 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -429,7 +429,7 @@ static int parse_expire_cfg_value(const char *var, const char *value, unsigned l
 	if (!value)
 		return config_error_nonbool(var);
 	if (parse_expiry_date(value, expire))
-		return error(_("%s' for '%s' is not a valid timestamp"),
+		return error(_("'%s' for '%s' is not a valid timestamp"),
 			     value, var);
 	return 0;
 }
diff --git a/builtin/rerere.c b/builtin/rerere.c
index 7afadd2ead..8c6cb6cdc6 100644
--- a/builtin/rerere.c
+++ b/builtin/rerere.c
@@ -50,7 +50,7 @@ static int diff_two(const char *file1, const char *label1,
 int cmd_rerere(int argc, const char **argv, const char *prefix)
 {
 	struct string_list merge_rr = STRING_LIST_INIT_DUP;
-	int i, fd, autoupdate = -1, flags = 0;
+	int i, autoupdate = -1, flags = 0;
 
 	struct option options[] = {
 		OPT_SET_INT(0, "rerere-autoupdate", &autoupdate,
@@ -79,18 +79,16 @@ int cmd_rerere(int argc, const char **argv, const char *prefix)
 		return rerere_forget(&pathspec);
 	}
 
-	fd = setup_rerere(&merge_rr, flags);
-	if (fd < 0)
-		return 0;
-
 	if (!strcmp(argv[0], "clear")) {
 		rerere_clear(&merge_rr);
 	} else if (!strcmp(argv[0], "gc"))
 		rerere_gc(&merge_rr);
-	else if (!strcmp(argv[0], "status"))
+	else if (!strcmp(argv[0], "status")) {
+		if (setup_rerere(&merge_rr, flags | RERERE_READONLY) < 0)
+			return 0;
 		for (i = 0; i < merge_rr.nr; i++)
 			printf("%s\n", merge_rr.items[i].string);
-	else if (!strcmp(argv[0], "remaining")) {
+	} else if (!strcmp(argv[0], "remaining")) {
 		rerere_remaining(&merge_rr);
 		for (i = 0; i < merge_rr.nr; i++) {
 			if (merge_rr.items[i].util != RERERE_RESOLVED)
@@ -100,13 +98,15 @@ int cmd_rerere(int argc, const char **argv, const char *prefix)
 				 * string_list_clear() */
 				merge_rr.items[i].util = NULL;
 		}
-	} else if (!strcmp(argv[0], "diff"))
+	} else if (!strcmp(argv[0], "diff")) {
+		if (setup_rerere(&merge_rr, flags | RERERE_READONLY) < 0)
+			return 0;
 		for (i = 0; i < merge_rr.nr; i++) {
 			const char *path = merge_rr.items[i].string;
-			const char *name = (const char *)merge_rr.items[i].util;
-			diff_two(rerere_path(name, "preimage"), path, path, path);
+			const struct rerere_id *id = merge_rr.items[i].util;
+			diff_two(rerere_path(id, "preimage"), path, path, path);
 		}
-	else
+	} else
 		usage_with_options(rerere_usage, options);
 
 	string_list_clear(&merge_rr, 1);
diff --git a/builtin/rev-list.c b/builtin/rev-list.c
index c0b4b53652..d80d1ed359 100644
--- a/builtin/rev-list.c
+++ b/builtin/rev-list.c
@@ -350,6 +350,9 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
 	    revs.diff)
 		usage(rev_list_usage);
 
+	if (revs.show_notes)
+		die(_("rev-list does not support display of notes"));
+
 	save_commit_buffer = (revs.verbose_header ||
 			      revs.grep_filter.pattern_list ||
 			      revs.grep_filter.header_list);
diff --git a/builtin/send-pack.c b/builtin/send-pack.c
index 23b2962cb0..f6e5d643c1 100644
--- a/builtin/send-pack.c
+++ b/builtin/send-pack.c
@@ -12,10 +12,15 @@
 #include "version.h"
 #include "sha1-array.h"
 #include "gpg-interface.h"
+#include "gettext.h"
 
-static const char send_pack_usage[] =
-"git send-pack [--all | --mirror] [--dry-run] [--force] [--receive-pack=<git-receive-pack>] [--verbose] [--thin] [--atomic] [<host>:]<directory> [<ref>...]\n"
-"  --all and explicit <ref> specification are mutually exclusive.";
+static const char * const send_pack_usage[] = {
+	N_("git send-pack [--all | --mirror] [--dry-run] [--force] "
+	  "[--receive-pack=<git-receive-pack>] [--verbose] [--thin] [--atomic] "
+	  "[<host>:]<directory> [<ref>...]\n"
+	  "  --all and explicit <ref> specification are mutually exclusive."),
+	NULL,
+};
 
 static struct send_pack_args args;
 
@@ -92,6 +97,31 @@ static void print_helper_status(struct ref *ref)
 	strbuf_release(&buf);
 }
 
+static int send_pack_config(const char *k, const char *v, void *cb)
+{
+	git_gpg_config(k, v, NULL);
+
+	if (!strcmp(k, "push.gpgsign")) {
+		const char *value;
+		if (!git_config_get_value("push.gpgsign", &value)) {
+			switch (git_config_maybe_bool("push.gpgsign", value)) {
+			case 0:
+				args.push_cert = SEND_PACK_PUSH_CERT_NEVER;
+				break;
+			case 1:
+				args.push_cert = SEND_PACK_PUSH_CERT_ALWAYS;
+				break;
+			default:
+				if (value && !strcasecmp(value, "if-asked"))
+					args.push_cert = SEND_PACK_PUSH_CERT_IF_ASKED;
+				else
+					return error("Invalid value for '%s'", k);
+			}
+		}
+	}
+	return 0;
+}
+
 int cmd_send_pack(int argc, const char **argv, const char *prefix)
 {
 	int i, nr_refspecs = 0;
@@ -107,116 +137,68 @@ int cmd_send_pack(int argc, const char **argv, const char *prefix)
 	int ret;
 	int helper_status = 0;
 	int send_all = 0;
+	int verbose = 0;
 	const char *receivepack = "git-receive-pack";
+	unsigned dry_run = 0;
+	unsigned send_mirror = 0;
+	unsigned force_update = 0;
+	unsigned quiet = 0;
+	int push_cert = 0;
+	unsigned use_thin_pack = 0;
+	unsigned atomic = 0;
+	unsigned stateless_rpc = 0;
 	int flags;
 	unsigned int reject_reasons;
 	int progress = -1;
 	int from_stdin = 0;
 	struct push_cas_option cas = {0};
 
-	git_config(git_gpg_config, NULL);
-
-	argv++;
-	for (i = 1; i < argc; i++, argv++) {
-		const char *arg = *argv;
-
-		if (*arg == '-') {
-			if (starts_with(arg, "--receive-pack=")) {
-				receivepack = arg + 15;
-				continue;
-			}
-			if (starts_with(arg, "--exec=")) {
-				receivepack = arg + 7;
-				continue;
-			}
-			if (starts_with(arg, "--remote=")) {
-				remote_name = arg + 9;
-				continue;
-			}
-			if (!strcmp(arg, "--all")) {
-				send_all = 1;
-				continue;
-			}
-			if (!strcmp(arg, "--dry-run")) {
-				args.dry_run = 1;
-				continue;
-			}
-			if (!strcmp(arg, "--mirror")) {
-				args.send_mirror = 1;
-				continue;
-			}
-			if (!strcmp(arg, "--force")) {
-				args.force_update = 1;
-				continue;
-			}
-			if (!strcmp(arg, "--quiet")) {
-				args.quiet = 1;
-				continue;
-			}
-			if (!strcmp(arg, "--verbose")) {
-				args.verbose = 1;
-				continue;
-			}
-			if (!strcmp(arg, "--signed")) {
-				args.push_cert = 1;
-				continue;
-			}
-			if (!strcmp(arg, "--progress")) {
-				progress = 1;
-				continue;
-			}
-			if (!strcmp(arg, "--no-progress")) {
-				progress = 0;
-				continue;
-			}
-			if (!strcmp(arg, "--thin")) {
-				args.use_thin_pack = 1;
-				continue;
-			}
-			if (!strcmp(arg, "--atomic")) {
-				args.atomic = 1;
-				continue;
-			}
-			if (!strcmp(arg, "--stateless-rpc")) {
-				args.stateless_rpc = 1;
-				continue;
-			}
-			if (!strcmp(arg, "--stdin")) {
-				from_stdin = 1;
-				continue;
-			}
-			if (!strcmp(arg, "--helper-status")) {
-				helper_status = 1;
-				continue;
-			}
-			if (!strcmp(arg, "--" CAS_OPT_NAME)) {
-				if (parse_push_cas_option(&cas, NULL, 0) < 0)
-					exit(1);
-				continue;
-			}
-			if (!strcmp(arg, "--no-" CAS_OPT_NAME)) {
-				if (parse_push_cas_option(&cas, NULL, 1) < 0)
-					exit(1);
-				continue;
-			}
-			if (starts_with(arg, "--" CAS_OPT_NAME "=")) {
-				if (parse_push_cas_option(&cas,
-							  strchr(arg, '=') + 1, 0) < 0)
-					exit(1);
-				continue;
-			}
-			usage(send_pack_usage);
-		}
-		if (!dest) {
-			dest = arg;
-			continue;
-		}
-		refspecs = (const char **) argv;
-		nr_refspecs = argc - i;
-		break;
+	struct option options[] = {
+		OPT__VERBOSITY(&verbose),
+		OPT_STRING(0, "receive-pack", &receivepack, "receive-pack", N_("receive pack program")),
+		OPT_STRING(0, "exec", &receivepack, "receive-pack", N_("receive pack program")),
+		OPT_STRING(0, "remote", &remote_name, "remote", N_("remote name")),
+		OPT_BOOL(0, "all", &send_all, N_("push all refs")),
+		OPT_BOOL('n' , "dry-run", &dry_run, N_("dry run")),
+		OPT_BOOL(0, "mirror", &send_mirror, N_("mirror all refs")),
+		OPT_BOOL('f', "force", &force_update, N_("force updates")),
+		{ OPTION_CALLBACK,
+		  0, "signed", &push_cert, "yes|no|if-asked", N_("GPG sign the push"),
+		  PARSE_OPT_OPTARG, option_parse_push_signed },
+		OPT_BOOL(0, "progress", &progress, N_("force progress reporting")),
+		OPT_BOOL(0, "thin", &use_thin_pack, N_("use thin pack")),
+		OPT_BOOL(0, "atomic", &atomic, N_("request atomic transaction on remote side")),
+		OPT_BOOL(0, "stateless-rpc", &stateless_rpc, N_("use stateless RPC protocol")),
+		OPT_BOOL(0, "stdin", &from_stdin, N_("read refs from stdin")),
+		OPT_BOOL(0, "helper-status", &helper_status, N_("print status from remote helper")),
+		{ OPTION_CALLBACK,
+		  0, CAS_OPT_NAME, &cas, N_("refname>:<expect"),
+		  N_("require old value of ref to be at this value"),
+		  PARSE_OPT_OPTARG, parseopt_push_cas_option },
+		OPT_END()
+	};
+
+	git_config(send_pack_config, NULL);
+	argc = parse_options(argc, argv, prefix, options, send_pack_usage, 0);
+	if (argc > 0) {
+		dest = argv[0];
+		refspecs = (const char **)(argv + 1);
+		nr_refspecs = argc - 1;
 	}
+
 	if (!dest)
-		usage(send_pack_usage);
+		usage_with_options(send_pack_usage, options);
+
+	args.verbose = verbose;
+	args.dry_run = dry_run;
+	args.send_mirror = send_mirror;
+	args.force_update = force_update;
+	args.quiet = quiet;
+	args.push_cert = push_cert;
+	args.progress = progress;
+	args.use_thin_pack = use_thin_pack;
+	args.atomic = atomic;
+	args.stateless_rpc = stateless_rpc;
 
 	if (from_stdin) {
 		struct argv_array all_refspecs = ARGV_ARRAY_INIT;
@@ -245,7 +227,7 @@ int cmd_send_pack(int argc, const char **argv, const char *prefix)
 	 */
 	if ((refspecs && (send_all || args.send_mirror)) ||
 	    (send_all && args.send_mirror))
-		usage(send_pack_usage);
+		usage_with_options(send_pack_usage, options);
 
 	if (remote_name) {
 		remote = remote_get(remote_name);
diff --git a/builtin/show-branch.c b/builtin/show-branch.c
index c87c46eb38..408ce70307 100644
--- a/builtin/show-branch.c
+++ b/builtin/show-branch.c
@@ -730,7 +730,6 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 
 	if (reflog) {
 		struct object_id oid;
-		char nth_desc[256];
 		char *ref;
 		int base = 0;
 		unsigned int flags = 0;
@@ -769,6 +768,7 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 
 		for (i = 0; i < reflog; i++) {
 			char *logmsg;
+			char *nth_desc;
 			const char *msg;
 			unsigned long timestamp;
 			int tz;
@@ -788,8 +788,10 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 							  DATE_MODE(RELATIVE)),
 						msg);
 			free(logmsg);
-			sprintf(nth_desc, "%s@{%d}", *av, base+i);
+
+			nth_desc = xstrfmt("%s@{%d}", *av, base+i);
 			append_ref(nth_desc, &oid, 1);
+			free(nth_desc);
 		}
 		free(ref);
 	}
diff --git a/builtin/show-ref.c b/builtin/show-ref.c
index dfbc314ac2..131ef28e5c 100644
--- a/builtin/show-ref.c
+++ b/builtin/show-ref.c
@@ -8,7 +8,7 @@
 
 static const char * const show_ref_usage[] = {
 	N_("git show-ref [-q | --quiet] [--verify] [--head] [-d | --dereference] [-s | --hash[=<n>]] [--abbrev[=<n>]] [--tags] [--heads] [--] [<pattern>...]"),
-	N_("git show-ref --exclude-existing[=pattern] < ref-list"),
+	N_("git show-ref --exclude-existing[=<pattern>] < <ref-list>"),
 	NULL
 };
 
diff --git a/builtin/tag.c b/builtin/tag.c
index cccca99104..9e17dca7ca 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -17,271 +17,49 @@
 #include "gpg-interface.h"
 #include "sha1-array.h"
 #include "column.h"
+#include "ref-filter.h"
 
 static const char * const git_tag_usage[] = {
 	N_("git tag [-a | -s | -u <key-id>] [-f] [-m <msg> | -F <file>] <tagname> [<head>]"),
 	N_("git tag -d <tagname>..."),
 	N_("git tag -l [-n[<num>]] [--contains <commit>] [--points-at <object>]"
-		"\n\t\t[<pattern>...]"),
+		"\n\t\t[--format=<format>] [--[no-]merged [<commit>]] [<pattern>...]"),
 	N_("git tag -v <tagname>..."),
 	NULL
 };
 
-#define STRCMP_SORT     0	/* must be zero */
-#define VERCMP_SORT     1
-#define SORT_MASK       0x7fff
-#define REVERSE_SORT    0x8000
-
-static int tag_sort;
-
-struct tag_filter {
-	const char **patterns;
-	int lines;
-	int sort;
-	struct string_list tags;
-	struct commit_list *with_commit;
-};
-
-static struct sha1_array points_at;
 static unsigned int colopts;
 
-static int match_pattern(const char **patterns, const char *ref)
-{
-	/* no pattern means match everything */
-	if (!*patterns)
-		return 1;
-	for (; *patterns; patterns++)
-		if (!wildmatch(*patterns, ref, 0, NULL))
-			return 1;
-	return 0;
-}
-
-static const unsigned char *match_points_at(const char *refname,
-					    const unsigned char *sha1)
-{
-	const unsigned char *tagged_sha1 = NULL;
-	struct object *obj;
-
-	if (sha1_array_lookup(&points_at, sha1) >= 0)
-		return sha1;
-	obj = parse_object(sha1);
-	if (!obj)
-		die(_("malformed object at '%s'"), refname);
-	if (obj->type == OBJ_TAG)
-		tagged_sha1 = ((struct tag *)obj)->tagged->sha1;
-	if (tagged_sha1 && sha1_array_lookup(&points_at, tagged_sha1) >= 0)
-		return tagged_sha1;
-	return NULL;
-}
-
-static int in_commit_list(const struct commit_list *want, struct commit *c)
-{
-	for (; want; want = want->next)
-		if (!hashcmp(want->item->object.sha1, c->object.sha1))
-			return 1;
-	return 0;
-}
-
-enum contains_result {
-	CONTAINS_UNKNOWN = -1,
-	CONTAINS_NO = 0,
-	CONTAINS_YES = 1
-};
-
-/*
- * Test whether the candidate or one of its parents is contained in the list.
- * Do not recurse to find out, though, but return -1 if inconclusive.
- */
-static enum contains_result contains_test(struct commit *candidate,
-			    const struct commit_list *want)
-{
-	/* was it previously marked as containing a want commit? */
-	if (candidate->object.flags & TMP_MARK)
-		return 1;
-	/* or marked as not possibly containing a want commit? */
-	if (candidate->object.flags & UNINTERESTING)
-		return 0;
-	/* or are we it? */
-	if (in_commit_list(want, candidate)) {
-		candidate->object.flags |= TMP_MARK;
-		return 1;
-	}
-
-	if (parse_commit(candidate) < 0)
-		return 0;
-
-	return -1;
-}
-
-/*
- * Mimicking the real stack, this stack lives on the heap, avoiding stack
- * overflows.
- *
- * At each recursion step, the stack items points to the commits whose
- * ancestors are to be inspected.
- */
-struct stack {
-	int nr, alloc;
-	struct stack_entry {
-		struct commit *commit;
-		struct commit_list *parents;
-	} *stack;
-};
-
-static void push_to_stack(struct commit *candidate, struct stack *stack)
-{
-	int index = stack->nr++;
-	ALLOC_GROW(stack->stack, stack->nr, stack->alloc);
-	stack->stack[index].commit = candidate;
-	stack->stack[index].parents = candidate->parents;
-}
-
-static enum contains_result contains(struct commit *candidate,
-		const struct commit_list *want)
-{
-	struct stack stack = { 0, 0, NULL };
-	int result = contains_test(candidate, want);
-
-	if (result != CONTAINS_UNKNOWN)
-		return result;
-
-	push_to_stack(candidate, &stack);
-	while (stack.nr) {
-		struct stack_entry *entry = &stack.stack[stack.nr - 1];
-		struct commit *commit = entry->commit;
-		struct commit_list *parents = entry->parents;
-
-		if (!parents) {
-			commit->object.flags |= UNINTERESTING;
-			stack.nr--;
-		}
-		/*
-		 * If we just popped the stack, parents->item has been marked,
-		 * therefore contains_test will return a meaningful 0 or 1.
-		 */
-		else switch (contains_test(parents->item, want)) {
-		case CONTAINS_YES:
-			commit->object.flags |= TMP_MARK;
-			stack.nr--;
-			break;
-		case CONTAINS_NO:
-			entry->parents = parents->next;
-			break;
-		case CONTAINS_UNKNOWN:
-			push_to_stack(parents->item, &stack);
-			break;
-		}
-	}
-	free(stack.stack);
-	return contains_test(candidate, want);
-}
-
-static void show_tag_lines(const struct object_id *oid, int lines)
+static int list_tags(struct ref_filter *filter, struct ref_sorting *sorting, const char *format)
 {
+	struct ref_array array;
+	char *to_free = NULL;
 	int i;
-	unsigned long size;
-	enum object_type type;
-	char *buf, *sp, *eol;
-	size_t len;
-
-	buf = read_sha1_file(oid->hash, &type, &size);
-	if (!buf)
-		die_errno("unable to read object %s", oid_to_hex(oid));
-	if (type != OBJ_COMMIT && type != OBJ_TAG)
-		goto free_return;
-	if (!size)
-		die("an empty %s object %s?",
-		    typename(type), oid_to_hex(oid));
-
-	/* skip header */
-	sp = strstr(buf, "\n\n");
-	if (!sp)
-		goto free_return;
-
-	/* only take up to "lines" lines, and strip the signature from a tag */
-	if (type == OBJ_TAG)
-		size = parse_signature(buf, size);
-	for (i = 0, sp += 2; i < lines && sp < buf + size; i++) {
-		if (i)
-			printf("\n    ");
-		eol = memchr(sp, '\n', size - (sp - buf));
-		len = eol ? eol - sp : size - (sp - buf);
-		fwrite(sp, len, 1, stdout);
-		if (!eol)
-			break;
-		sp = eol + 1;
-	}
-free_return:
-	free(buf);
-}
-
-static int show_reference(const char *refname, const struct object_id *oid,
-			  int flag, void *cb_data)
-{
-	struct tag_filter *filter = cb_data;
 
-	if (match_pattern(filter->patterns, refname)) {
-		if (filter->with_commit) {
-			struct commit *commit;
+	memset(&array, 0, sizeof(array));
 
-			commit = lookup_commit_reference_gently(oid->hash, 1);
-			if (!commit)
-				return 0;
-			if (!contains(commit, filter->with_commit))
-				return 0;
-		}
-
-		if (points_at.nr && !match_points_at(refname, oid->hash))
-			return 0;
+	if (filter->lines == -1)
+		filter->lines = 0;
 
-		if (!filter->lines) {
-			if (filter->sort)
-				string_list_append(&filter->tags, refname);
-			else
-				printf("%s\n", refname);
-			return 0;
-		}
-		printf("%-15s ", refname);
-		show_tag_lines(oid, filter->lines);
-		putchar('\n');
+	if (!format) {
+		if (filter->lines) {
+			to_free = xstrfmt("%s %%(contents:lines=%d)",
+					  "%(align:15)%(refname:short)%(end)",
+					  filter->lines);
+			format = to_free;
+		} else
+			format = "%(refname:short)";
 	}
 
-	return 0;
-}
+	verify_ref_format(format);
+	filter_refs(&array, filter, FILTER_REFS_TAGS);
+	ref_array_sort(sorting, &array);
 
-static int sort_by_version(const void *a_, const void *b_)
-{
-	const struct string_list_item *a = a_;
-	const struct string_list_item *b = b_;
-	return versioncmp(a->string, b->string);
-}
+	for (i = 0; i < array.nr; i++)
+		show_ref_array_item(array.items[i], format, 0);
+	ref_array_clear(&array);
+	free(to_free);
 
-static int list_tags(const char **patterns, int lines,
-		     struct commit_list *with_commit, int sort)
-{
-	struct tag_filter filter;
-
-	filter.patterns = patterns;
-	filter.lines = lines;
-	filter.sort = sort;
-	filter.with_commit = with_commit;
-	memset(&filter.tags, 0, sizeof(filter.tags));
-	filter.tags.strdup_strings = 1;
-
-	for_each_tag_ref(show_reference, (void *)&filter);
-	if (sort) {
-		int i;
-		if ((sort & SORT_MASK) == VERCMP_SORT)
-			qsort(filter.tags.items, filter.tags.nr,
-			      sizeof(struct string_list_item), sort_by_version);
-		if (sort & REVERSE_SORT)
-			for (i = filter.tags.nr - 1; i >= 0; i--)
-				printf("%s\n", filter.tags.items[i].string);
-		else
-			for (i = 0; i < filter.tags.nr; i++)
-				printf("%s\n", filter.tags.items[i].string);
-		string_list_clear(&filter.tags, 0);
-	}
 	return 0;
 }
 
@@ -348,35 +126,26 @@ static const char tag_template_nocleanup[] =
 	"Lines starting with '%c' will be kept; you may remove them"
 	" yourself if you want to.\n");
 
-/*
- * Parse a sort string, and return 0 if parsed successfully. Will return
- * non-zero when the sort string does not parse into a known type. If var is
- * given, the error message becomes a warning and includes information about
- * the configuration value.
- */
-static int parse_sort_string(const char *var, const char *arg, int *sort)
+/* Parse arg given and add it the ref_sorting array */
+static int parse_sorting_string(const char *arg, struct ref_sorting **sorting_tail)
 {
-	int type = 0, flags = 0;
+	struct ref_sorting *s;
+	int len;
 
-	if (skip_prefix(arg, "-", &arg))
-		flags |= REVERSE_SORT;
+	s = xcalloc(1, sizeof(*s));
+	s->next = *sorting_tail;
+	*sorting_tail = s;
 
-	if (skip_prefix(arg, "version:", &arg) || skip_prefix(arg, "v:", &arg))
-		type = VERCMP_SORT;
-	else
-		type = STRCMP_SORT;
-
-	if (strcmp(arg, "refname")) {
-		if (!var)
-			return error(_("unsupported sort specification '%s'"), arg);
-		else {
-			warning(_("unsupported sort specification '%s' in variable '%s'"),
-				var, arg);
-			return -1;
-		}
+	if (*arg == '-') {
+		s->reverse = 1;
+		arg++;
 	}
+	if (skip_prefix(arg, "version:", &arg) ||
+	    skip_prefix(arg, "v:", &arg))
+		s->version = 1;
 
-	*sort = (type | flags);
+	len = strlen(arg);
+	s->atom = parse_ref_filter_atom(arg, arg+len);
 
 	return 0;
 }
@@ -384,11 +153,12 @@ static int parse_sort_string(const char *var, const char *arg, int *sort)
 static int git_tag_config(const char *var, const char *value, void *cb)
 {
 	int status;
+	struct ref_sorting **sorting_tail = (struct ref_sorting **)cb;
 
 	if (!strcmp(var, "tag.sort")) {
 		if (!value)
 			return config_error_nonbool(var);
-		parse_sort_string(var, value, &tag_sort);
+		parse_sorting_string(value, sorting_tail);
 		return 0;
 	}
 
@@ -546,30 +316,6 @@ static int strbuf_check_tag_ref(struct strbuf *sb, const char *name)
 	return check_refname_format(sb->buf, 0);
 }
 
-static int parse_opt_points_at(const struct option *opt __attribute__((unused)),
-			const char *arg, int unset)
-{
-	unsigned char sha1[20];
-
-	if (unset) {
-		sha1_array_clear(&points_at);
-		return 0;
-	}
-	if (!arg)
-		return error(_("switch 'points-at' requires an object"));
-	if (get_sha1(arg, sha1))
-		return error(_("malformed object name '%s'"), arg);
-	sha1_array_append(&points_at, sha1);
-	return 0;
-}
-
-static int parse_opt_sort(const struct option *opt, const char *arg, int unset)
-{
-	int *sort = opt->value;
-
-	return parse_sort_string(NULL, arg, sort);
-}
-
 int cmd_tag(int argc, const char **argv, const char *prefix)
 {
 	struct strbuf buf = STRBUF_INIT;
@@ -578,17 +324,19 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 	const char *object_ref, *tag;
 	struct create_tag_options opt;
 	char *cleanup_arg = NULL;
-	int annotate = 0, force = 0, lines = -1;
 	int create_reflog = 0;
+	int annotate = 0, force = 0;
 	int cmdmode = 0;
 	const char *msgfile = NULL, *keyid = NULL;
 	struct msg_arg msg = { 0, STRBUF_INIT };
-	struct commit_list *with_commit = NULL;
 	struct ref_transaction *transaction;
 	struct strbuf err = STRBUF_INIT;
+	struct ref_filter filter;
+	static struct ref_sorting *sorting = NULL, **sorting_tail = &sorting;
+	const char *format = NULL;
 	struct option options[] = {
 		OPT_CMDMODE('l', "list", &cmdmode, N_("list tag names"), 'l'),
-		{ OPTION_INTEGER, 'n', NULL, &lines, N_("n"),
+		{ OPTION_INTEGER, 'n', NULL, &filter.lines, N_("n"),
 				N_("print <n> lines of each tag message"),
 				PARSE_OPT_OPTARG, NULL, 1 },
 		OPT_CMDMODE('d', "delete", &cmdmode, N_("delete tags"), 'd'),
@@ -606,36 +354,29 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 		OPT_STRING('u', "local-user", &keyid, N_("key-id"),
 					N_("use another key to sign the tag")),
 		OPT__FORCE(&force, N_("replace the tag if exists")),
-		OPT_BOOL(0, "create-reflog", &create_reflog, N_("create_reflog")),
+		OPT_BOOL(0, "create-reflog", &create_reflog, N_("create a reflog")),
 
 		OPT_GROUP(N_("Tag listing options")),
 		OPT_COLUMN(0, "column", &colopts, N_("show tag list in columns")),
+		OPT_CONTAINS(&filter.with_commit, N_("print only tags that contain the commit")),
+		OPT_WITH(&filter.with_commit, N_("print only tags that contain the commit")),
+		OPT_MERGED(&filter, N_("print only tags that are merged")),
+		OPT_NO_MERGED(&filter, N_("print only tags that are not merged")),
+		OPT_CALLBACK(0 , "sort", sorting_tail, N_("key"),
+			     N_("field name to sort on"), &parse_opt_ref_sorting),
 		{
-			OPTION_CALLBACK, 0, "sort", &tag_sort, N_("type"), N_("sort tags"),
-			PARSE_OPT_NONEG, parse_opt_sort
-		},
-		{
-			OPTION_CALLBACK, 0, "contains", &with_commit, N_("commit"),
-			N_("print only tags that contain the commit"),
-			PARSE_OPT_LASTARG_DEFAULT,
-			parse_opt_with_commit, (intptr_t)"HEAD",
-		},
-		{
-			OPTION_CALLBACK, 0, "with", &with_commit, N_("commit"),
-			N_("print only tags that contain the commit"),
-			PARSE_OPT_HIDDEN | PARSE_OPT_LASTARG_DEFAULT,
-			parse_opt_with_commit, (intptr_t)"HEAD",
-		},
-		{
-			OPTION_CALLBACK, 0, "points-at", NULL, N_("object"),
-			N_("print only tags of the object"), 0, parse_opt_points_at
+			OPTION_CALLBACK, 0, "points-at", &filter.points_at, N_("object"),
+			N_("print only tags of the object"), 0, parse_opt_object_name
 		},
+		OPT_STRING(  0 , "format", &format, N_("format"), N_("format to use for the output")),
 		OPT_END()
 	};
 
-	git_config(git_tag_config, NULL);
+	git_config(git_tag_config, sorting_tail);
 
 	memset(&opt, 0, sizeof(opt));
+	memset(&filter, 0, sizeof(filter));
+	filter.lines = -1;
 
 	argc = parse_options(argc, argv, prefix, options, git_tag_usage, 0);
 
@@ -652,11 +393,13 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 		usage_with_options(git_tag_usage, options);
 
 	finalize_colopts(&colopts, -1);
-	if (cmdmode == 'l' && lines != -1) {
+	if (cmdmode == 'l' && filter.lines != -1) {
 		if (explicitly_enable_column(colopts))
 			die(_("--column and -n are incompatible"));
 		colopts = 0;
 	}
+	if (!sorting)
+		sorting = ref_default_sorting();
 	if (cmdmode == 'l') {
 		int ret;
 		if (column_active(colopts)) {
@@ -665,19 +408,20 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 			copts.padding = 2;
 			run_column_filter(colopts, &copts);
 		}
-		if (lines != -1 && tag_sort)
-			die(_("--sort and -n are incompatible"));
-		ret = list_tags(argv, lines == -1 ? 0 : lines, with_commit, tag_sort);
+		filter.name_patterns = argv;
+		ret = list_tags(&filter, sorting, format);
 		if (column_active(colopts))
 			stop_column_filter();
 		return ret;
 	}
-	if (lines != -1)
+	if (filter.lines != -1)
 		die(_("-n option is only allowed with -l."));
-	if (with_commit)
+	if (filter.with_commit)
 		die(_("--contains option is only allowed with -l."));
-	if (points_at.nr)
+	if (filter.points_at.nr)
 		die(_("--points-at option is only allowed with -l."));
+	if (filter.merge_commit)
+		die(_("--merged and --no-merged option are only allowed with -l"));
 	if (cmdmode == 'd')
 		return for_each_tag_name(argv, delete_tag);
 	if (cmdmode == 'v')
diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index 04dd00f734..7f30d3a76f 100644
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c
@@ -365,7 +365,7 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
 					N_("update <refname> not the one it points to")),
 		OPT_BOOL('z', NULL, &end_null, N_("stdin has NUL-terminated arguments")),
 		OPT_BOOL( 0 , "stdin", &read_stdin, N_("read updates from stdin")),
-		OPT_BOOL( 0 , "create-reflog", &create_reflog, N_("create_reflog")),
+		OPT_BOOL( 0 , "create-reflog", &create_reflog, N_("create a reflog")),
 		OPT_END(),
 	};
 
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 6a264ee749..71bb770f7a 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -3,6 +3,8 @@
 #include "dir.h"
 #include "parse-options.h"
 #include "argv-array.h"
+#include "branch.h"
+#include "refs.h"
 #include "run-command.h"
 #include "sigchain.h"
 #include "refs.h"
@@ -13,6 +15,13 @@ static const char * const worktree_usage[] = {
 	NULL
 };
 
+struct add_opts {
+	int force;
+	int detach;
+	const char *new_branch;
+	int force_new_branch;
+};
+
 static int show_only;
 static int verbose;
 static unsigned long expire;
@@ -172,19 +181,35 @@ static const char *worktree_basename(const char *path, int *olen)
 	return name;
 }
 
-static int add_worktree(const char *path, const char **child_argv)
+static int add_worktree(const char *path, const char *refname,
+			const struct add_opts *opts)
 {
 	struct strbuf sb_git = STRBUF_INIT, sb_repo = STRBUF_INIT;
 	struct strbuf sb = STRBUF_INIT;
 	const char *name;
 	struct stat st;
 	struct child_process cp;
+	struct argv_array child_env = ARGV_ARRAY_INIT;
 	int counter = 0, len, ret;
-	unsigned char rev[20];
+	struct strbuf symref = STRBUF_INIT;
+	struct commit *commit = NULL;
 
 	if (file_exists(path) && !is_empty_dir(path))
 		die(_("'%s' already exists"), path);
 
+	/* is 'refname' a branch or commit? */
+	if (opts->force_new_branch) /* definitely a branch */
+		;
+	else if (!opts->detach && !strbuf_check_branch_ref(&symref, refname) &&
+		 ref_exists(symref.buf)) { /* it's a branch */
+		if (!opts->force)
+			die_if_checked_out(symref.buf);
+	} else { /* must be a commit */
+		commit = lookup_commit_reference_by_name(refname);
+		if (!commit)
+			die(_("invalid reference: %s"), refname);
+	}
+
 	name = worktree_basename(path, &len);
 	strbuf_addstr(&sb_repo,
 		      git_path("worktrees/%.*s", (int)(path + len - name), name));
@@ -213,7 +238,7 @@ static int add_worktree(const char *path, const char **child_argv)
 	 * after the preparation is over.
 	 */
 	strbuf_addf(&sb, "%s/locked", sb_repo.buf);
-	write_file(sb.buf, 1, "initializing\n");
+	write_file(sb.buf, "initializing");
 
 	strbuf_addf(&sb_git, "%s/.git", path);
 	if (safe_create_leading_directories_const(sb_git.buf))
@@ -223,37 +248,45 @@ static int add_worktree(const char *path, const char **child_argv)
 
 	strbuf_reset(&sb);
 	strbuf_addf(&sb, "%s/gitdir", sb_repo.buf);
-	write_file(sb.buf, 1, "%s\n", real_path(sb_git.buf));
-	write_file(sb_git.buf, 1, "gitdir: %s/worktrees/%s\n",
+	write_file(sb.buf, "%s", real_path(sb_git.buf));
+	write_file(sb_git.buf, "gitdir: %s/worktrees/%s",
 		   real_path(get_git_common_dir()), name);
 	/*
 	 * This is to keep resolve_ref() happy. We need a valid HEAD
-	 * or is_git_directory() will reject the directory. Moreover, HEAD
-	 * in the new worktree must resolve to the same value as HEAD in
-	 * the current tree since the command invoked to populate the new
-	 * worktree will be handed the branch/ref specified by the user.
-	 * For instance, if the user asks for the new worktree to be based
-	 * at HEAD~5, then the resolved HEAD~5 in the new worktree must
-	 * match the resolved HEAD~5 in the current tree in order to match
-	 * the user's expectation.
+	 * or is_git_directory() will reject the directory. Any value which
+	 * looks like an object ID will do since it will be immediately
+	 * replaced by the symbolic-ref or update-ref invocation in the new
+	 * worktree.
 	 */
-	if (!resolve_ref_unsafe("HEAD", 0, rev, NULL))
-		die(_("unable to resolve HEAD"));
 	strbuf_reset(&sb);
 	strbuf_addf(&sb, "%s/HEAD", sb_repo.buf);
-	write_file(sb.buf, 1, "%s\n", sha1_to_hex(rev));
+	write_file(sb.buf, "0000000000000000000000000000000000000000");
 	strbuf_reset(&sb);
 	strbuf_addf(&sb, "%s/commondir", sb_repo.buf);
-	write_file(sb.buf, 1, "../..\n");
+	write_file(sb.buf, "../..");
 
-	fprintf_ln(stderr, _("Enter %s (identifier %s)"), path, name);
+	fprintf_ln(stderr, _("Preparing %s (identifier %s)"), path, name);
 
-	setenv("GIT_CHECKOUT_NEW_WORKTREE", "1", 1);
-	setenv(GIT_DIR_ENVIRONMENT, sb_git.buf, 1);
-	setenv(GIT_WORK_TREE_ENVIRONMENT, path, 1);
+	argv_array_pushf(&child_env, "%s=%s", GIT_DIR_ENVIRONMENT, sb_git.buf);
+	argv_array_pushf(&child_env, "%s=%s", GIT_WORK_TREE_ENVIRONMENT, path);
 	memset(&cp, 0, sizeof(cp));
 	cp.git_cmd = 1;
-	cp.argv = child_argv;
+
+	if (commit)
+		argv_array_pushl(&cp.args, "update-ref", "HEAD",
+				 sha1_to_hex(commit->object.sha1), NULL);
+	else
+		argv_array_pushl(&cp.args, "symbolic-ref", "HEAD",
+				 symref.buf, NULL);
+	cp.env = child_env.argv;
+	ret = run_command(&cp);
+	if (ret)
+		goto done;
+
+	cp.argv = NULL;
+	argv_array_clear(&cp.args);
+	argv_array_pushl(&cp.args, "reset", "--hard", NULL);
+	cp.env = child_env.argv;
 	ret = run_command(&cp);
 	if (!ret) {
 		is_junk = 0;
@@ -262,10 +295,13 @@ static int add_worktree(const char *path, const char **child_argv)
 		junk_work_tree = NULL;
 		junk_git_dir = NULL;
 	}
+done:
 	strbuf_reset(&sb);
 	strbuf_addf(&sb, "%s/locked", sb_repo.buf);
 	unlink_or_warn(sb.buf);
+	argv_array_clear(&child_env);
 	strbuf_release(&sb);
+	strbuf_release(&symref);
 	strbuf_release(&sb_repo);
 	strbuf_release(&sb_git);
 	return ret;
@@ -273,47 +309,54 @@ static int add_worktree(const char *path, const char **child_argv)
 
 static int add(int ac, const char **av, const char *prefix)
 {
-	int force = 0, detach = 0;
-	const char *new_branch = NULL, *new_branch_force = NULL;
+	struct add_opts opts;
+	const char *new_branch_force = NULL;
 	const char *path, *branch;
-	struct argv_array cmd = ARGV_ARRAY_INIT;
 	struct option options[] = {
-		OPT__FORCE(&force, N_("checkout <branch> even if already checked out in other worktree")),
-		OPT_STRING('b', NULL, &new_branch, N_("branch"),
+		OPT__FORCE(&opts.force, N_("checkout <branch> even if already checked out in other worktree")),
+		OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
 			   N_("create a new branch")),
 		OPT_STRING('B', NULL, &new_branch_force, N_("branch"),
 			   N_("create or reset a branch")),
-		OPT_BOOL(0, "detach", &detach, N_("detach HEAD at named commit")),
+		OPT_BOOL(0, "detach", &opts.detach, N_("detach HEAD at named commit")),
 		OPT_END()
 	};
 
+	memset(&opts, 0, sizeof(opts));
 	ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
-	if (new_branch && new_branch_force)
-		die(_("-b and -B are mutually exclusive"));
+	if (!!opts.detach + !!opts.new_branch + !!new_branch_force > 1)
+		die(_("-b, -B, and --detach are mutually exclusive"));
 	if (ac < 1 || ac > 2)
 		usage_with_options(worktree_usage, options);
 
 	path = prefix ? prefix_filename(prefix, strlen(prefix), av[0]) : av[0];
 	branch = ac < 2 ? "HEAD" : av[1];
 
-	if (ac < 2 && !new_branch && !new_branch_force) {
+	opts.force_new_branch = !!new_branch_force;
+	if (opts.force_new_branch)
+		opts.new_branch = new_branch_force;
+
+	if (ac < 2 && !opts.new_branch && !opts.detach) {
 		int n;
 		const char *s = worktree_basename(path, &n);
-		new_branch = xstrndup(s, n);
+		opts.new_branch = xstrndup(s, n);
+	}
+
+	if (opts.new_branch) {
+		struct child_process cp;
+		memset(&cp, 0, sizeof(cp));
+		cp.git_cmd = 1;
+		argv_array_push(&cp.args, "branch");
+		if (opts.force_new_branch)
+			argv_array_push(&cp.args, "--force");
+		argv_array_push(&cp.args, opts.new_branch);
+		argv_array_push(&cp.args, branch);
+		if (run_command(&cp))
+			return -1;
+		branch = opts.new_branch;
 	}
 
-	argv_array_push(&cmd, "checkout");
-	if (force)
-		argv_array_push(&cmd, "--ignore-other-worktrees");
-	if (new_branch)
-		argv_array_pushl(&cmd, "-b", new_branch, NULL);
-	if (new_branch_force)
-		argv_array_pushl(&cmd, "-B", new_branch_force, NULL);
-	if (detach)
-		argv_array_push(&cmd, "--detach");
-	argv_array_push(&cmd, branch);
-
-	return add_worktree(path, cmd.argv);
+	return add_worktree(path, branch, &opts);
 }
 
 int cmd_worktree(int ac, const char **av, const char *prefix)