git-fetch--tool: start rewriting parts of git-fetch in C.

Signed-off-by: Junio C Hamano <junkio@cox.net>

5 files changed, 227 insertions, 124 deletions

diff --git a/Makefile b/Makefile
index 40bdcff696..181ad94279 100644
--- a/Makefile
+++ b/Makefile
@@ -282,6 +282,7 @@ BUILTIN_OBJS = \
 	builtin-diff-index.o \
 	builtin-diff-stages.o \
 	builtin-diff-tree.o \
+	builtin-fetch--tool.o \
 	builtin-fmt-merge-msg.o \
 	builtin-for-each-ref.o \
 	builtin-fsck.o \
diff --git a/builtin-fetch--tool.c b/builtin-fetch--tool.c
new file mode 100644
index 0000000000..3075ba04af
--- /dev/null
+++ b/builtin-fetch--tool.c
@@ -0,0 +1,214 @@
+#include "cache.h"
+#include "refs.h"
+#include "commit.h"
+
+static void show_new(char *type, unsigned char *sha1_new)
+{
+	fprintf(stderr, "  %s: %s\n", type,
+		find_unique_abbrev(sha1_new, DEFAULT_ABBREV));
+}
+
+static int update_ref(const char *action,
+		      const char *refname,
+		      unsigned char *sha1,
+		      unsigned char *oldval)
+{
+	int len;
+	char msg[1024];
+	char *rla = getenv("GIT_REFLOG_ACTION");
+	static struct ref_lock *lock;
+
+	if (!rla)
+		rla = "(reflog update)";
+	len = snprintf(msg, sizeof(msg), "%s: %s", rla, action);
+	if (sizeof(msg) <= len)
+		die("insanely long action");
+	lock = lock_any_ref_for_update(refname, oldval);
+	if (!lock)
+		return 1;
+	if (write_ref_sha1(lock, sha1, msg) < 0)
+		return 1;
+	return 0;
+}
+
+static int update_local_ref(const char *name,
+			    const char *new_head,
+			    const char *note,
+			    int verbose, int force)
+{
+	char type[20];
+	unsigned char sha1_old[20], sha1_new[20];
+	char oldh[41], newh[41];
+	struct commit *current, *updated;
+
+	if (get_sha1_hex(new_head, sha1_new))
+		die("malformed object name %s", new_head);
+	if (sha1_object_info(sha1_new, type, NULL))
+		die("object %s not found", new_head);
+
+	if (!*name) {
+		/* Not storing */
+		if (verbose) {
+			fprintf(stderr, "* fetched %s\n", note);
+			show_new(type, sha1_new);
+		}
+		return 0;
+	}
+
+	if (get_sha1(name, sha1_old)) {
+		char *msg;
+	just_store:
+		/* new ref */
+		if (!strncmp(name, "refs/tags/", 10))
+			msg = "storing tag";
+		else
+			msg = "storing head";
+		fprintf(stderr, "* %s: storing %s\n",
+			name, note);
+		show_new(type, sha1_new);
+		return update_ref(msg, name, sha1_new, NULL);
+	}
+
+	if (!hashcmp(sha1_old, sha1_new)) {
+		if (verbose) {
+			fprintf(stderr, "* %s: same as %s\n", name, note);
+			show_new(type, sha1_new);
+		}
+		return 0;
+	}
+
+	if (!strncmp(name, "refs/tags/", 10)) {
+		fprintf(stderr, "* %s: updating with %s\n", name, note);
+		show_new(type, sha1_new);
+		return update_ref("updating tag", name, sha1_new, NULL);
+	}
+
+	current = lookup_commit_reference(sha1_old);
+	updated = lookup_commit_reference(sha1_new);
+	if (!current || !updated)
+		goto just_store;
+
+	strcpy(oldh, find_unique_abbrev(current->object.sha1, DEFAULT_ABBREV));
+	strcpy(newh, find_unique_abbrev(sha1_new, DEFAULT_ABBREV));
+
+	if (in_merge_bases(current, &updated, 1)) {
+		fprintf(stderr, "* %s: fast forward to %s\n",
+			name, note);
+		fprintf(stderr, "  old..new: %s..%s\n", oldh, newh);
+		return update_ref("fast forward", name, sha1_new, sha1_old);
+	}
+	if (!force) {
+		fprintf(stderr,
+			"* %s: not updating to non-fast forward %s\n",
+			name, note);
+		fprintf(stderr,
+			"  old...new: %s...%s\n", oldh, newh);
+		return 1;
+	}
+	fprintf(stderr,
+		"* %s: forcing update to non-fast forward %s\n",
+		name, note);
+	fprintf(stderr, "  old...new: %s...%s\n", oldh, newh);
+	return update_ref("forced-update", name, sha1_new, sha1_old);
+}
+
+static int append_fetch_head(FILE *fp,
+			     const char *head, const char *remote,
+			     const char *remote_name, const char *remote_nick,
+			     const char *local_name, int not_for_merge,
+			     int verbose, int force)
+{
+	struct commit *commit;
+	int remote_len, i, note_len;
+	unsigned char sha1[20];
+	char note[1024];
+	const char *what, *kind;
+
+	if (get_sha1(head, sha1))
+		return error("Not a valid object name: %s", head);
+	commit = lookup_commit_reference(sha1);
+	if (!commit)
+		not_for_merge = 1;
+
+	if (!strcmp(remote_name, "HEAD")) {
+		kind = "";
+		what = "";
+	}
+	else if (!strncmp(remote_name, "refs/heads/", 11)) {
+		kind = "branch";
+		what = remote_name + 11;
+	}
+	else if (!strncmp(remote_name, "refs/tags/", 10)) {
+		kind = "tag";
+		what = remote_name + 10;
+	}
+	else if (!strncmp(remote_name, "refs/remotes/", 13)) {
+		kind = "remote branch";
+		what = remote_name + 13;
+	}
+	else {
+		kind = "";
+		what = remote_name;
+	}
+
+	remote_len = strlen(remote);
+	for (i = remote_len - 1; remote[i] == '/' && 0 <= i; i--)
+		;
+	remote_len = i + 1;
+	if (4 < i && !strncmp(".git", remote + i - 3, 4))
+		remote_len = i - 3;
+	note_len = sprintf(note, "%s\t%s\t",
+			   sha1_to_hex(commit ? commit->object.sha1 : sha1),
+			   not_for_merge ? "not-for-merge" : "");
+	if (*what) {
+		if (*kind)
+			note_len += sprintf(note + note_len, "%s ", kind);
+		note_len += sprintf(note + note_len, "'%s' of ", what);
+	}
+	note_len += sprintf(note + note_len, "%.*s", remote_len, remote);
+	fprintf(fp, "%s\n", note);
+	return update_local_ref(local_name, head, note, verbose, force);
+}
+
+int cmd_fetch__tool(int argc, const char **argv, const char *prefix)
+{
+	int verbose = 0;
+	int force = 0;
+
+	while (1 < argc) {
+		const char *arg = argv[1];
+		if (!strcmp("-v", arg))
+			verbose = 1;
+		else if (!strcmp("-f", arg))
+			force = 1;
+		else
+			break;
+		argc--;
+		argv++;
+	}
+
+	if (argc <= 1)
+		return error("Missing subcommand");
+
+	if (!strcmp("append-fetch-head", argv[1])) {
+		int result;
+		FILE *fp;
+
+		if (argc != 8)
+			return error("append-fetch-head takes 6 args");
+		fp = fopen(git_path("FETCH_HEAD"), "a");
+		result = append_fetch_head(fp, argv[2], argv[3],
+					   argv[4], argv[5],
+					   argv[6], !!argv[7][0],
+					   verbose, force);
+		fclose(fp);
+		return result;
+	}
+	if (!strcmp("update-local-ref", argv[1])) {
+		if (argc != 5)
+			return error("update-local-ref takes 3 args");
+		return update_local_ref(argv[2], argv[3], argv[4],
+					verbose, force);
+	}
+	return error("Unknown subcommand: %s", argv[1]);
+}
diff --git a/builtin.h b/builtin.h
index 5108fd2d74..3cad4028d2 100644
--- a/builtin.h
+++ b/builtin.h
@@ -31,6 +31,7 @@ extern int cmd_diff_index(int argc, const char **argv, const char *prefix);
 extern int cmd_diff(int argc, const char **argv, const char *prefix);
 extern int cmd_diff_stages(int argc, const char **argv, const char *prefix);
 extern int cmd_diff_tree(int argc, const char **argv, const char *prefix);
+extern int cmd_fetch__tool(int argc, const char **argv, const char *prefix);
 extern int cmd_fmt_merge_msg(int argc, const char **argv, const char *prefix);
 extern int cmd_for_each_ref(int argc, const char **argv, const char *prefix);
 extern int cmd_format_patch(int argc, const char **argv, const char *prefix);
diff --git a/git-fetch.sh b/git-fetch.sh
index 3e01265160..2aa34b3992 100755
--- a/git-fetch.sh
+++ b/git-fetch.sh
@@ -107,133 +107,19 @@ ls_remote_result=$(git ls-remote $exec "$remote") ||
 	die "Cannot get the repository state from $remote"
 
 append_fetch_head () {
-    head_="$1"
-    remote_="$2"
-    remote_name_="$3"
-    remote_nick_="$4"
-    local_name_="$5"
-    case "$6" in
-    t) not_for_merge_='not-for-merge' ;;
-    '') not_for_merge_= ;;
-    esac
-
-    # remote-nick is the URL given on the command line (or a shorthand)
-    # remote-name is the $GIT_DIR relative refs/ path we computed
-    # for this refspec.
-
-    # the $note_ variable will be fed to git-fmt-merge-msg for further
-    # processing.
-    case "$remote_name_" in
-    HEAD)
-	note_= ;;
-    refs/heads/*)
-	note_="$(expr "$remote_name_" : 'refs/heads/\(.*\)')"
-	note_="branch '$note_' of " ;;
-    refs/tags/*)
-	note_="$(expr "$remote_name_" : 'refs/tags/\(.*\)')"
-	note_="tag '$note_' of " ;;
-    refs/remotes/*)
-	note_="$(expr "$remote_name_" : 'refs/remotes/\(.*\)')"
-	note_="remote branch '$note_' of " ;;
-    *)
-	note_="$remote_name of " ;;
-    esac
-    remote_1_=$(expr "z$remote_" : 'z\(.*\)\.git/*$') &&
-	remote_="$remote_1_"
-    note_="$note_$remote_"
-
-    # 2.6.11-tree tag would not be happy to be fed to resolve.
-    if git-cat-file commit "$head_" >/dev/null 2>&1
-    then
-	headc_=$(git-rev-parse --verify "$head_^0") || exit
-	echo "$headc_	$not_for_merge_	$note_" >>"$GIT_DIR/FETCH_HEAD"
-    else
-	echo "$head_	not-for-merge	$note_" >>"$GIT_DIR/FETCH_HEAD"
-    fi
-
-    update_local_ref "$local_name_" "$head_" "$note_"
+	flags=
+	test -n "$verbose" && flags="$flags -v"
+	test -n "$force" && flags="$flags -f"
+	GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION" \
+		git-fetch--tool append-fetch-head $flags "$@"
 }
 
 update_local_ref () {
-    # If we are storing the head locally make sure that it is
-    # a fast forward (aka "reverse push").
-
-    label_=$(git-cat-file -t $2)
-    newshort_=$(git-rev-parse --short $2)
-    if test -z "$1" ; then
-	[ "$verbose" ] && echo >&2 "* fetched $3"
-	[ "$verbose" ] && echo >&2 "  $label_: $newshort_"
-	return 0
-    fi
-    oldshort_=$(git show-ref --hash --abbrev "$1" 2>/dev/null)
-
-    case "$1" in
-    refs/tags/*)
-	# Tags need not be pointing at commits so there
-	# is no way to guarantee "fast-forward" anyway.
-	if test -n "$oldshort_"
-	then
-		if now_=$(git show-ref --hash "$1") && test "$now_" = "$2"
-		then
-			[ "$verbose" ] && echo >&2 "* $1: same as $3"
-			[ "$verbose" ] && echo >&2 "  $label_: $newshort_" ||:
-		else
-			echo >&2 "* $1: updating with $3"
-			echo >&2 "  $label_: $newshort_"
-			git-update-ref -m "$GIT_REFLOG_ACTION: updating tag" "$1" "$2"
-		fi
-	else
-		echo >&2 "* $1: storing $3"
-		echo >&2 "  $label_: $newshort_"
-		git-update-ref -m "$GIT_REFLOG_ACTION: storing tag" "$1" "$2"
-	fi
-	;;
-
-    refs/heads/* | refs/remotes/*)
-	# $1 is the ref being updated.
-	# $2 is the new value for the ref.
-	local=$(git-rev-parse --verify "$1^0" 2>/dev/null)
-	if test "$local"
-	then
-	    # Require fast-forward.
-	    mb=$(git-merge-base "$local" "$2") &&
-	    case "$2,$mb" in
-	    $local,*)
-	        if test -n "$verbose"
-		then
-			echo >&2 "* $1: same as $3"
-			echo >&2 "  $label_: $newshort_"
-		fi
-		;;
-	    *,$local)
-		echo >&2 "* $1: fast forward to $3"
-		echo >&2 "  old..new: $oldshort_..$newshort_"
-		git-update-ref -m "$GIT_REFLOG_ACTION: fast-forward" "$1" "$2" "$local"
-		;;
-	    *)
-		false
-		;;
-	    esac || {
-		case ",$force,$single_force," in
-		*,t,*)
-			echo >&2 "* $1: forcing update to non-fast forward $3"
-			echo >&2 "  old...new: $oldshort_...$newshort_"
-			git-update-ref -m "$GIT_REFLOG_ACTION: forced-update" "$1" "$2" "$local"
-			;;
-		*)
-			echo >&2 "* $1: not updating to non-fast forward $3"
-			echo >&2 "  old...new: $oldshort_...$newshort_"
-			exit 1
-			;;
-		esac
-	    }
-	else
-	    echo >&2 "* $1: storing $3"
-	    echo >&2 "  $label_: $newshort_"
-	    git-update-ref -m "$GIT_REFLOG_ACTION: storing head" "$1" "$2"
-	fi
-	;;
-    esac
+	flags=
+	test -n "$verbose" && flags="$flags -v"
+	test -n "$force" && flags="$flags -f"
+	GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION" \
+		git-fetch--tool update-local-ref $flags "$@"
 }
 
 # updating the current HEAD with git-fetch in a bare
diff --git a/git.c b/git.c
index 45265f14d0..a167b1e42e 100644
--- a/git.c
+++ b/git.c
@@ -242,6 +242,7 @@ static void handle_internal_command(int argc, const char **argv, char **envp)
 		{ "diff-index", cmd_diff_index, RUN_SETUP },
 		{ "diff-stages", cmd_diff_stages, RUN_SETUP },
 		{ "diff-tree", cmd_diff_tree, RUN_SETUP },
+		{ "fetch--tool", cmd_fetch__tool, RUN_SETUP },
 		{ "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
 		{ "for-each-ref", cmd_for_each_ref, RUN_SETUP },
 		{ "format-patch", cmd_format_patch, RUN_SETUP },