1 files changed, 181 insertions, 111 deletions

diff --git a/builtin-checkout.c b/builtin-checkout.c
index 141a9e1873..cff0179159 100644
--- a/builtin-checkout.c
+++ b/builtin-checkout.c
@@ -12,6 +12,7 @@
 #include "branch.h"
 #include "diff.h"
 #include "revision.h"
+#include "remote.h"
 
 static const char * const checkout_usage[] = {
 	"git checkout [options] <branch>",
@@ -42,7 +43,7 @@ static int post_checkout_hook(struct commit *old, struct commit *new,
 }
 
 static int update_some(const unsigned char *sha1, const char *base, int baselen,
-		       const char *pathname, unsigned mode, int stage)
+		const char *pathname, unsigned mode, int stage, void *context)
 {
 	int len;
 	struct cache_entry *ce;
@@ -66,16 +67,7 @@ static int update_some(const unsigned char *sha1, const char *base, int baselen,
 
 static int read_tree_some(struct tree *tree, const char **pathspec)
 {
-	int newfd;
-	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
-	newfd = hold_locked_index(lock_file, 1);
-	read_cache();
-
-	read_tree_recursive(tree, "", 0, 0, pathspec, update_some);
-
-	if (write_cache(newfd, active_cache, active_nr) ||
-	    commit_locked_index(lock_file))
-		die("unable to write new index file");
+	read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
 
 	/* update the index with the given tree's info
 	 * for all args, expanding wildcards, and exit
@@ -84,7 +76,7 @@ static int read_tree_some(struct tree *tree, const char **pathspec)
 	return 0;
 }
 
-static int checkout_paths(const char **pathspec)
+static int checkout_paths(struct tree *source_tree, const char **pathspec)
 {
 	int pos;
 	struct checkout state;
@@ -92,6 +84,16 @@ static int checkout_paths(const char **pathspec)
 	unsigned char rev[20];
 	int flag;
 	struct commit *head;
+	int errs = 0;
+
+	int newfd;
+	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
+
+	newfd = hold_locked_index(lock_file, 1);
+	read_cache();
+
+	if (source_tree)
+		read_tree_some(source_tree, pathspec);
 
 	for (pos = 0; pathspec[pos]; pos++)
 		;
@@ -105,20 +107,26 @@ static int checkout_paths(const char **pathspec)
 	if (report_path_error(ps_matched, pathspec, 0))
 		return 1;
 
+	/* Now we are committed to check them out */
 	memset(&state, 0, sizeof(state));
 	state.force = 1;
 	state.refresh_cache = 1;
 	for (pos = 0; pos < active_nr; pos++) {
 		struct cache_entry *ce = active_cache[pos];
 		if (pathspec_match(pathspec, NULL, ce->name, 0)) {
-			checkout_entry(ce, &state, NULL);
+			errs |= checkout_entry(ce, &state, NULL);
 		}
 	}
 
+	if (write_cache(newfd, active_cache, active_nr) ||
+	    commit_locked_index(lock_file))
+		die("unable to write new index file");
+
 	resolve_ref("HEAD", rev, 0, &flag);
 	head = lookup_commit_reference_gently(rev, 1);
 
-	return post_checkout_hook(head, head, 0);
+	errs |= post_checkout_hook(head, head, 0);
+	return errs;
 }
 
 static void show_local_changes(struct object *head)
@@ -137,57 +145,56 @@ static void describe_detached_head(char *msg, struct commit *commit)
 	struct strbuf sb;
 	strbuf_init(&sb, 0);
 	parse_commit(commit);
-	pretty_print_commit(CMIT_FMT_ONELINE, commit, &sb, 0, "", "", 0, 0);
+	pretty_print_commit(CMIT_FMT_ONELINE, commit, &sb, 0, NULL, NULL, 0, 0);
 	fprintf(stderr, "%s %s... %s\n", msg,
 		find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
 	strbuf_release(&sb);
 }
 
-static int reset_to_new(struct tree *tree, int quiet)
-{
-	struct unpack_trees_options opts;
-	struct tree_desc tree_desc;
-	memset(&opts, 0, sizeof(opts));
-	opts.head_idx = -1;
-	opts.update = 1;
-	opts.reset = 1;
-	opts.merge = 1;
-	opts.fn = oneway_merge;
-	opts.verbose_update = !quiet;
-	parse_tree(tree);
-	init_tree_desc(&tree_desc, tree->buffer, tree->size);
-	if (unpack_trees(1, &tree_desc, &opts))
-		return 128;
-	return 0;
-}
+struct checkout_opts {
+	int quiet;
+	int merge;
+	int force;
+	int writeout_error;
+
+	char *new_branch;
+	int new_branch_log;
+	enum branch_track track;
+};
 
-static void reset_clean_to_new(struct tree *tree, int quiet)
+static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
 {
 	struct unpack_trees_options opts;
 	struct tree_desc tree_desc;
+
 	memset(&opts, 0, sizeof(opts));
 	opts.head_idx = -1;
-	opts.skip_unmerged = 1;
+	opts.update = worktree;
+	opts.skip_unmerged = !worktree;
 	opts.reset = 1;
 	opts.merge = 1;
 	opts.fn = oneway_merge;
-	opts.verbose_update = !quiet;
+	opts.verbose_update = !o->quiet;
+	opts.src_index = &the_index;
+	opts.dst_index = &the_index;
 	parse_tree(tree);
 	init_tree_desc(&tree_desc, tree->buffer, tree->size);
-	if (unpack_trees(1, &tree_desc, &opts))
-		exit(128);
+	switch (unpack_trees(1, &tree_desc, &opts)) {
+	case -2:
+		o->writeout_error = 1;
+		/*
+		 * We return 0 nevertheless, as the index is all right
+		 * and more importantly we have made best efforts to
+		 * update paths in the work tree, and we cannot revert
+		 * them.
+		 */
+	case 0:
+		return 0;
+	default:
+		return 128;
+	}
 }
 
-struct checkout_opts {
-	int quiet;
-	int merge;
-	int force;
-
-	char *new_branch;
-	int new_branch_log;
-	int track;
-};
-
 struct branch_info {
 	const char *name; /* The short name used */
 	const char *path; /* The full name of a real branch */
@@ -204,8 +211,7 @@ static void setup_branch_path(struct branch_info *branch)
 }
 
 static int merge_working_tree(struct checkout_opts *opts,
-			      struct branch_info *old, struct branch_info *new,
-			      const char *prefix)
+			      struct branch_info *old, struct branch_info *new)
 {
 	int ret;
 	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
@@ -213,37 +219,44 @@ static int merge_working_tree(struct checkout_opts *opts,
 	read_cache();
 
 	if (opts->force) {
-		ret = reset_to_new(new->commit->tree, opts->quiet);
+		ret = reset_tree(new->commit->tree, opts, 1);
 		if (ret)
 			return ret;
 	} else {
 		struct tree_desc trees[2];
 		struct tree *tree;
 		struct unpack_trees_options topts;
+
 		memset(&topts, 0, sizeof(topts));
 		topts.head_idx = -1;
+		topts.src_index = &the_index;
+		topts.dst_index = &the_index;
+
+		topts.msgs.not_uptodate_file = "You have local changes to '%s'; cannot switch branches.";
 
 		refresh_cache(REFRESH_QUIET);
 
 		if (unmerged_cache()) {
-			ret = opts->merge ? -1 :
-				error("you need to resolve your current index first");
-		} else {
-			topts.update = 1;
-			topts.merge = 1;
-			topts.gently = opts->merge;
-			topts.fn = twoway_merge;
-			topts.dir = xcalloc(1, sizeof(*topts.dir));
-			topts.dir->show_ignored = 1;
-			topts.dir->exclude_per_dir = ".gitignore";
-			topts.prefix = prefix;
-			tree = parse_tree_indirect(old->commit->object.sha1);
-			init_tree_desc(&trees[0], tree->buffer, tree->size);
-			tree = parse_tree_indirect(new->commit->object.sha1);
-			init_tree_desc(&trees[1], tree->buffer, tree->size);
-			ret = unpack_trees(2, trees, &topts);
+			error("you need to resolve your current index first");
+			return 1;
 		}
-		if (ret) {
+
+		/* 2-way merge to the new branch */
+		topts.update = 1;
+		topts.merge = 1;
+		topts.gently = opts->merge;
+		topts.verbose_update = !opts->quiet;
+		topts.fn = twoway_merge;
+		topts.dir = xcalloc(1, sizeof(*topts.dir));
+		topts.dir->show_ignored = 1;
+		topts.dir->exclude_per_dir = ".gitignore";
+		tree = parse_tree_indirect(old->commit->object.sha1);
+		init_tree_desc(&trees[0], tree->buffer, tree->size);
+		tree = parse_tree_indirect(new->commit->object.sha1);
+		init_tree_desc(&trees[1], tree->buffer, tree->size);
+
+		ret = unpack_trees(2, trees, &topts);
+		if (ret == -1) {
 			/*
 			 * Unpack couldn't do a trivial merge; either
 			 * give up or do a real merge, depending on
@@ -268,15 +281,17 @@ static int merge_working_tree(struct checkout_opts *opts,
 			 * entries in the index.
 			 */
 
-			add_files_to_cache(0, NULL, NULL);
+			add_files_to_cache(NULL, NULL, 0);
 			work = write_tree_from_memory();
 
-			ret = reset_to_new(new->commit->tree, opts->quiet);
+			ret = reset_tree(new->commit->tree, opts, 1);
 			if (ret)
 				return ret;
 			merge_trees(new->commit->tree, work, old->commit->tree,
 				    new->name, "local", &result);
-			reset_clean_to_new(new->commit->tree, opts->quiet);
+			ret = reset_tree(new->commit->tree, opts, 0);
+			if (ret)
+				return ret;
 		}
 	}
 
@@ -290,6 +305,17 @@ static int merge_working_tree(struct checkout_opts *opts,
 	return 0;
 }
 
+static void report_tracking(struct branch_info *new)
+{
+	struct strbuf sb = STRBUF_INIT;
+	struct branch *branch = branch_get(new->name);
+
+	if (!format_tracking_info(branch, &sb))
+		return;
+	fputs(sb.buf, stdout);
+	strbuf_release(&sb);
+}
+
 static void update_refs_for_switch(struct checkout_opts *opts,
 				   struct branch_info *old,
 				   struct branch_info *new)
@@ -332,10 +358,11 @@ static void update_refs_for_switch(struct checkout_opts *opts,
 	}
 	remove_branch_state();
 	strbuf_release(&msg);
+	if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
+		report_tracking(new);
 }
 
-static int switch_branches(struct checkout_opts *opts,
-			   struct branch_info *new, const char *prefix)
+static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
 {
 	int ret = 0;
 	struct branch_info old;
@@ -378,23 +405,15 @@ static int switch_branches(struct checkout_opts *opts,
 		opts->force = 1;
 	}
 
-	ret = merge_working_tree(opts, &old, new, prefix);
+	ret = merge_working_tree(opts, &old, new);
 	if (ret)
 		return ret;
 
 	update_refs_for_switch(opts, &old, new);
-	free((char *)old.path);
-	return post_checkout_hook(old.commit, new->commit, 1);
-}
 
-static int branch_track = 0;
-
-static int git_checkout_config(const char *var, const char *value)
-{
-	if (!strcmp(var, "branch.autosetupmerge"))
-		branch_track = git_config_bool(var, value);
-
-	return git_default_config(var, value);
+	ret = post_checkout_hook(old.commit, new->commit, 1);
+	free((char *)old.path);
+	return ret || opts->writeout_error;
 }
 
 int cmd_checkout(int argc, const char **argv, const char *prefix)
@@ -408,24 +427,72 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 		OPT__QUIET(&opts.quiet),
 		OPT_STRING('b', NULL, &opts.new_branch, "new branch", "branch"),
 		OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "log for new branch"),
-		OPT_BOOLEAN( 0 , "track", &opts.track, "track"),
+		OPT_SET_INT('t', "track",  &opts.track, "track",
+			BRANCH_TRACK_EXPLICIT),
 		OPT_BOOLEAN('f', NULL, &opts.force, "force"),
 		OPT_BOOLEAN('m', NULL, &opts.merge, "merge"),
+		OPT_END(),
 	};
+	int has_dash_dash;
 
 	memset(&opts, 0, sizeof(opts));
 	memset(&new, 0, sizeof(new));
 
-	git_config(git_checkout_config);
+	git_config(git_default_config, NULL);
 
-	opts.track = branch_track;
+	opts.track = git_branch_track;
+
+	argc = parse_options(argc, argv, options, checkout_usage,
+			     PARSE_OPT_KEEP_DASHDASH);
+
+	if (!opts.new_branch && (opts.track != git_branch_track))
+		die("git checkout: --track and --no-track require -b");
 
-	argc = parse_options(argc, argv, options, checkout_usage, 0);
+	if (opts.force && opts.merge)
+		die("git checkout: -f and -m are incompatible");
+
+	/*
+	 * case 1: git checkout <ref> -- [<paths>]
+	 *
+	 *   <ref> must be a valid tree, everything after the '--' must be
+	 *   a path.
+	 *
+	 * case 2: git checkout -- [<paths>]
+	 *
+	 *   everything after the '--' must be paths.
+	 *
+	 * case 3: git checkout <something> [<paths>]
+	 *
+	 *   With no paths, if <something> is a commit, that is to
+	 *   switch to the branch or detach HEAD at it.
+	 *
+	 *   Otherwise <something> shall not be ambiguous.
+	 *   - If it's *only* a reference, treat it like case (1).
+	 *   - If it's only a path, treat it like case (2).
+	 *   - else: fail.
+	 *
+	 */
 	if (argc) {
+		if (!strcmp(argv[0], "--")) {       /* case (2) */
+			argv++;
+			argc--;
+			goto no_reference;
+		}
+
 		arg = argv[0];
-		if (get_sha1(arg, rev))
-			;
-		else if ((new.commit = lookup_commit_reference_gently(rev, 1))) {
+		has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
+
+		if (get_sha1(arg, rev)) {
+			if (has_dash_dash)          /* case (1) */
+				die("invalid reference: %s", arg);
+			goto no_reference;          /* case (3 -> 2) */
+		}
+
+		/* we can't end up being in (2) anymore, eat the argument */
+		argv++;
+		argc--;
+
+		if ((new.commit = lookup_commit_reference_gently(rev, 1))) {
 			new.name = arg;
 			setup_branch_path(&new);
 			if (resolve_ref(new.path, rev, 1, NULL))
@@ -434,27 +501,34 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 				new.path = NULL;
 			parse_commit(new.commit);
 			source_tree = new.commit->tree;
-			argv++;
-			argc--;
-		} else if ((source_tree = parse_tree_indirect(rev))) {
+		} else
+			source_tree = parse_tree_indirect(rev);
+
+		if (!source_tree)                   /* case (1): want a tree */
+			die("reference is not a tree: %s", arg);
+		if (!has_dash_dash) {/* case (3 -> 1) */
+			/*
+			 * Do not complain the most common case
+			 *	git checkout branch
+			 * even if there happen to be a file called 'branch';
+			 * it would be extremely annoying.
+			 */
+			if (argc)
+				verify_non_filename(NULL, arg);
+		}
+		else {
 			argv++;
 			argc--;
 		}
 	}
 
-	if (argc && !strcmp(argv[0], "--")) {
-		argv++;
-		argc--;
-	}
-
-	if (!opts.new_branch && (opts.track != branch_track))
-		die("git checkout: --track and --no-track require -b");
-
-	if (opts.force && opts.merge)
-		die("git checkout: -f and -m are incompatible");
-
+no_reference:
 	if (argc) {
 		const char **pathspec = get_pathspec(prefix, argv);
+
+		if (!pathspec)
+			die("invalid path specification");
+
 		/* Checkout paths */
 		if (opts.new_branch || opts.force || opts.merge) {
 			if (argc == 1) {
@@ -464,16 +538,12 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 			}
 		}
 
-		if (source_tree)
-			read_tree_some(source_tree, pathspec);
-		else
-			read_cache();
-		return checkout_paths(pathspec);
+		return checkout_paths(source_tree, pathspec);
 	}
 
 	if (new.name && !new.commit) {
 		die("Cannot switch branch to a non-commit.");
 	}
 
-	return switch_branches(&opts, &new, prefix);
+	return switch_branches(&opts, &new);
 }