Make fetch-pack a builtin with an internal API

Signed-off-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 829 insertions, 0 deletions

diff --git a/builtin-fetch-pack.c b/builtin-fetch-pack.c
new file mode 100644
index 0000000000..3b217d96f0
--- /dev/null
+++ b/builtin-fetch-pack.c
@@ -0,0 +1,829 @@
+#include "cache.h"
+#include "refs.h"
+#include "pkt-line.h"
+#include "commit.h"
+#include "tag.h"
+#include "exec_cmd.h"
+#include "pack.h"
+#include "sideband.h"
+#include "fetch-pack.h"
+
+static int keep_pack;
+static int transfer_unpack_limit = -1;
+static int fetch_unpack_limit = -1;
+static int unpack_limit = 100;
+static int quiet;
+static int verbose;
+static int fetch_all;
+static int depth;
+static int no_progress;
+static const char fetch_pack_usage[] =
+"git-fetch-pack [--all] [--quiet|-q] [--keep|-k] [--thin] [--upload-pack=<git-upload-pack>] [--depth=<n>] [--no-progress] [-v] [<host>:]<directory> [<refs>...]";
+static const char *uploadpack = "git-upload-pack";
+
+#define COMPLETE	(1U << 0)
+#define COMMON		(1U << 1)
+#define COMMON_REF	(1U << 2)
+#define SEEN		(1U << 3)
+#define POPPED		(1U << 4)
+
+/*
+ * After sending this many "have"s if we do not get any new ACK , we
+ * give up traversing our history.
+ */
+#define MAX_IN_VAIN 256
+
+static struct commit_list *rev_list;
+static int non_common_revs, multi_ack, use_thin_pack, use_sideband;
+
+static void rev_list_push(struct commit *commit, int mark)
+{
+	if (!(commit->object.flags & mark)) {
+		commit->object.flags |= mark;
+
+		if (!(commit->object.parsed))
+			parse_commit(commit);
+
+		insert_by_date(commit, &rev_list);
+
+		if (!(commit->object.flags & COMMON))
+			non_common_revs++;
+	}
+}
+
+static int rev_list_insert_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
+{
+	struct object *o = deref_tag(parse_object(sha1), path, 0);
+
+	if (o && o->type == OBJ_COMMIT)
+		rev_list_push((struct commit *)o, SEEN);
+
+	return 0;
+}
+
+/*
+   This function marks a rev and its ancestors as common.
+   In some cases, it is desirable to mark only the ancestors (for example
+   when only the server does not yet know that they are common).
+*/
+
+static void mark_common(struct commit *commit,
+		int ancestors_only, int dont_parse)
+{
+	if (commit != NULL && !(commit->object.flags & COMMON)) {
+		struct object *o = (struct object *)commit;
+
+		if (!ancestors_only)
+			o->flags |= COMMON;
+
+		if (!(o->flags & SEEN))
+			rev_list_push(commit, SEEN);
+		else {
+			struct commit_list *parents;
+
+			if (!ancestors_only && !(o->flags & POPPED))
+				non_common_revs--;
+			if (!o->parsed && !dont_parse)
+				parse_commit(commit);
+
+			for (parents = commit->parents;
+					parents;
+					parents = parents->next)
+				mark_common(parents->item, 0, dont_parse);
+		}
+	}
+}
+
+/*
+  Get the next rev to send, ignoring the common.
+*/
+
+static const unsigned char* get_rev(void)
+{
+	struct commit *commit = NULL;
+
+	while (commit == NULL) {
+		unsigned int mark;
+		struct commit_list* parents;
+
+		if (rev_list == NULL || non_common_revs == 0)
+			return NULL;
+
+		commit = rev_list->item;
+		if (!(commit->object.parsed))
+			parse_commit(commit);
+		commit->object.flags |= POPPED;
+		if (!(commit->object.flags & COMMON))
+			non_common_revs--;
+
+		parents = commit->parents;
+
+		if (commit->object.flags & COMMON) {
+			/* do not send "have", and ignore ancestors */
+			commit = NULL;
+			mark = COMMON | SEEN;
+		} else if (commit->object.flags & COMMON_REF)
+			/* send "have", and ignore ancestors */
+			mark = COMMON | SEEN;
+		else
+			/* send "have", also for its ancestors */
+			mark = SEEN;
+
+		while (parents) {
+			if (!(parents->item->object.flags & SEEN))
+				rev_list_push(parents->item, mark);
+			if (mark & COMMON)
+				mark_common(parents->item, 1, 0);
+			parents = parents->next;
+		}
+
+		rev_list = rev_list->next;
+	}
+
+	return commit->object.sha1;
+}
+
+static int find_common(int fd[2], unsigned char *result_sha1,
+		       struct ref *refs)
+{
+	int fetching;
+	int count = 0, flushes = 0, retval;
+	const unsigned char *sha1;
+	unsigned in_vain = 0;
+	int got_continue = 0;
+
+	for_each_ref(rev_list_insert_ref, NULL);
+
+	fetching = 0;
+	for ( ; refs ; refs = refs->next) {
+		unsigned char *remote = refs->old_sha1;
+		struct object *o;
+
+		/*
+		 * If that object is complete (i.e. it is an ancestor of a
+		 * local ref), we tell them we have it but do not have to
+		 * tell them about its ancestors, which they already know
+		 * about.
+		 *
+		 * We use lookup_object here because we are only
+		 * interested in the case we *know* the object is
+		 * reachable and we have already scanned it.
+		 */
+		if (((o = lookup_object(remote)) != NULL) &&
+				(o->flags & COMPLETE)) {
+			continue;
+		}
+
+		if (!fetching)
+			packet_write(fd[1], "want %s%s%s%s%s%s%s\n",
+				     sha1_to_hex(remote),
+				     (multi_ack ? " multi_ack" : ""),
+				     (use_sideband == 2 ? " side-band-64k" : ""),
+				     (use_sideband == 1 ? " side-band" : ""),
+				     (use_thin_pack ? " thin-pack" : ""),
+				     (no_progress ? " no-progress" : ""),
+				     " ofs-delta");
+		else
+			packet_write(fd[1], "want %s\n", sha1_to_hex(remote));
+		fetching++;
+	}
+	if (is_repository_shallow())
+		write_shallow_commits(fd[1], 1);
+	if (depth > 0)
+		packet_write(fd[1], "deepen %d", depth);
+	packet_flush(fd[1]);
+	if (!fetching)
+		return 1;
+
+	if (depth > 0) {
+		char line[1024];
+		unsigned char sha1[20];
+		int len;
+
+		while ((len = packet_read_line(fd[0], line, sizeof(line)))) {
+			if (!prefixcmp(line, "shallow ")) {
+				if (get_sha1_hex(line + 8, sha1))
+					die("invalid shallow line: %s", line);
+				register_shallow(sha1);
+				continue;
+			}
+			if (!prefixcmp(line, "unshallow ")) {
+				if (get_sha1_hex(line + 10, sha1))
+					die("invalid unshallow line: %s", line);
+				if (!lookup_object(sha1))
+					die("object not found: %s", line);
+				/* make sure that it is parsed as shallow */
+				parse_object(sha1);
+				if (unregister_shallow(sha1))
+					die("no shallow found: %s", line);
+				continue;
+			}
+			die("expected shallow/unshallow, got %s", line);
+		}
+	}
+
+	flushes = 0;
+	retval = -1;
+	while ((sha1 = get_rev())) {
+		packet_write(fd[1], "have %s\n", sha1_to_hex(sha1));
+		if (verbose)
+			fprintf(stderr, "have %s\n", sha1_to_hex(sha1));
+		in_vain++;
+		if (!(31 & ++count)) {
+			int ack;
+
+			packet_flush(fd[1]);
+			flushes++;
+
+			/*
+			 * We keep one window "ahead" of the other side, and
+			 * will wait for an ACK only on the next one
+			 */
+			if (count == 32)
+				continue;
+
+			do {
+				ack = get_ack(fd[0], result_sha1);
+				if (verbose && ack)
+					fprintf(stderr, "got ack %d %s\n", ack,
+							sha1_to_hex(result_sha1));
+				if (ack == 1) {
+					flushes = 0;
+					multi_ack = 0;
+					retval = 0;
+					goto done;
+				} else if (ack == 2) {
+					struct commit *commit =
+						lookup_commit(result_sha1);
+					mark_common(commit, 0, 1);
+					retval = 0;
+					in_vain = 0;
+					got_continue = 1;
+				}
+			} while (ack);
+			flushes--;
+			if (got_continue && MAX_IN_VAIN < in_vain) {
+				if (verbose)
+					fprintf(stderr, "giving up\n");
+				break; /* give up */
+			}
+		}
+	}
+done:
+	packet_write(fd[1], "done\n");
+	if (verbose)
+		fprintf(stderr, "done\n");
+	if (retval != 0) {
+		multi_ack = 0;
+		flushes++;
+	}
+	while (flushes || multi_ack) {
+		int ack = get_ack(fd[0], result_sha1);
+		if (ack) {
+			if (verbose)
+				fprintf(stderr, "got ack (%d) %s\n", ack,
+					sha1_to_hex(result_sha1));
+			if (ack == 1)
+				return 0;
+			multi_ack = 1;
+			continue;
+		}
+		flushes--;
+	}
+	return retval;
+}
+
+static struct commit_list *complete;
+
+static int mark_complete(const char *path, const unsigned char *sha1, int flag, void *cb_data)
+{
+	struct object *o = parse_object(sha1);
+
+	while (o && o->type == OBJ_TAG) {
+		struct tag *t = (struct tag *) o;
+		if (!t->tagged)
+			break; /* broken repository */
+		o->flags |= COMPLETE;
+		o = parse_object(t->tagged->sha1);
+	}
+	if (o && o->type == OBJ_COMMIT) {
+		struct commit *commit = (struct commit *)o;
+		commit->object.flags |= COMPLETE;
+		insert_by_date(commit, &complete);
+	}
+	return 0;
+}
+
+static void mark_recent_complete_commits(unsigned long cutoff)
+{
+	while (complete && cutoff <= complete->item->date) {
+		if (verbose)
+			fprintf(stderr, "Marking %s as complete\n",
+				sha1_to_hex(complete->item->object.sha1));
+		pop_most_recent_commit(&complete, COMPLETE);
+	}
+}
+
+static void filter_refs(struct ref **refs, int nr_match, char **match)
+{
+	struct ref **return_refs;
+	struct ref *newlist = NULL;
+	struct ref **newtail = &newlist;
+	struct ref *ref, *next;
+	struct ref *fastarray[32];
+
+	if (nr_match && !fetch_all) {
+		if (ARRAY_SIZE(fastarray) < nr_match)
+			return_refs = xcalloc(nr_match, sizeof(struct ref *));
+		else {
+			return_refs = fastarray;
+			memset(return_refs, 0, sizeof(struct ref *) * nr_match);
+		}
+	}
+	else
+		return_refs = NULL;
+
+	for (ref = *refs; ref; ref = next) {
+		next = ref->next;
+		if (!memcmp(ref->name, "refs/", 5) &&
+		    check_ref_format(ref->name + 5))
+			; /* trash */
+		else if (fetch_all &&
+			 (!depth || prefixcmp(ref->name, "refs/tags/") )) {
+			*newtail = ref;
+			ref->next = NULL;
+			newtail = &ref->next;
+			continue;
+		}
+		else {
+			int order = path_match(ref->name, nr_match, match);
+			if (order) {
+				return_refs[order-1] = ref;
+				continue; /* we will link it later */
+			}
+		}
+		free(ref);
+	}
+
+	if (!fetch_all) {
+		int i;
+		for (i = 0; i < nr_match; i++) {
+			ref = return_refs[i];
+			if (ref) {
+				*newtail = ref;
+				ref->next = NULL;
+				newtail = &ref->next;
+			}
+		}
+		if (return_refs != fastarray)
+			free(return_refs);
+	}
+	*refs = newlist;
+}
+
+static int everything_local(struct ref **refs, int nr_match, char **match)
+{
+	struct ref *ref;
+	int retval;
+	unsigned long cutoff = 0;
+
+	track_object_refs = 0;
+	save_commit_buffer = 0;
+
+	for (ref = *refs; ref; ref = ref->next) {
+		struct object *o;
+
+		o = parse_object(ref->old_sha1);
+		if (!o)
+			continue;
+
+		/* We already have it -- which may mean that we were
+		 * in sync with the other side at some time after
+		 * that (it is OK if we guess wrong here).
+		 */
+		if (o->type == OBJ_COMMIT) {
+			struct commit *commit = (struct commit *)o;
+			if (!cutoff || cutoff < commit->date)
+				cutoff = commit->date;
+		}
+	}
+
+	if (!depth) {
+		for_each_ref(mark_complete, NULL);
+		if (cutoff)
+			mark_recent_complete_commits(cutoff);
+	}
+
+	/*
+	 * Mark all complete remote refs as common refs.
+	 * Don't mark them common yet; the server has to be told so first.
+	 */
+	for (ref = *refs; ref; ref = ref->next) {
+		struct object *o = deref_tag(lookup_object(ref->old_sha1),
+					     NULL, 0);
+
+		if (!o || o->type != OBJ_COMMIT || !(o->flags & COMPLETE))
+			continue;
+
+		if (!(o->flags & SEEN)) {
+			rev_list_push((struct commit *)o, COMMON_REF | SEEN);
+
+			mark_common((struct commit *)o, 1, 1);
+		}
+	}
+
+	filter_refs(refs, nr_match, match);
+
+	for (retval = 1, ref = *refs; ref ; ref = ref->next) {
+		const unsigned char *remote = ref->old_sha1;
+		unsigned char local[20];
+		struct object *o;
+
+		o = lookup_object(remote);
+		if (!o || !(o->flags & COMPLETE)) {
+			retval = 0;
+			if (!verbose)
+				continue;
+			fprintf(stderr,
+				"want %s (%s)\n", sha1_to_hex(remote),
+				ref->name);
+			continue;
+		}
+
+		hashcpy(ref->new_sha1, local);
+		if (!verbose)
+			continue;
+		fprintf(stderr,
+			"already have %s (%s)\n", sha1_to_hex(remote),
+			ref->name);
+	}
+	return retval;
+}
+
+static pid_t setup_sideband(int fd[2], int xd[2])
+{
+	pid_t side_pid;
+
+	if (!use_sideband) {
+		fd[0] = xd[0];
+		fd[1] = xd[1];
+		return 0;
+	}
+	/* xd[] is talking with upload-pack; subprocess reads from
+	 * xd[0], spits out band#2 to stderr, and feeds us band#1
+	 * through our fd[0].
+	 */
+	if (pipe(fd) < 0)
+		die("fetch-pack: unable to set up pipe");
+	side_pid = fork();
+	if (side_pid < 0)
+		die("fetch-pack: unable to fork off sideband demultiplexer");
+	if (!side_pid) {
+		/* subprocess */
+		close(fd[0]);
+		if (xd[0] != xd[1])
+			close(xd[1]);
+		if (recv_sideband("fetch-pack", xd[0], fd[1], 2))
+			exit(1);
+		exit(0);
+	}
+	close(xd[0]);
+	close(fd[1]);
+	fd[1] = xd[1];
+	return side_pid;
+}
+
+static int get_pack(int xd[2])
+{
+	int status;
+	pid_t pid, side_pid;
+	int fd[2];
+	const char *argv[20];
+	char keep_arg[256];
+	char hdr_arg[256];
+	const char **av;
+	int do_keep = keep_pack;
+
+	side_pid = setup_sideband(fd, xd);
+
+	av = argv;
+	*hdr_arg = 0;
+	if (unpack_limit) {
+		struct pack_header header;
+
+		if (read_pack_header(fd[0], &header))
+			die("protocol error: bad pack header");
+		snprintf(hdr_arg, sizeof(hdr_arg), "--pack_header=%u,%u",
+			 ntohl(header.hdr_version), ntohl(header.hdr_entries));
+		if (ntohl(header.hdr_entries) < unpack_limit)
+			do_keep = 0;
+		else
+			do_keep = 1;
+	}
+
+	if (do_keep) {
+		*av++ = "index-pack";
+		*av++ = "--stdin";
+		if (!quiet && !no_progress)
+			*av++ = "-v";
+		if (use_thin_pack)
+			*av++ = "--fix-thin";
+		if (keep_pack > 1 || unpack_limit) {
+			int s = sprintf(keep_arg,
+					"--keep=fetch-pack %d on ", getpid());
+			if (gethostname(keep_arg + s, sizeof(keep_arg) - s))
+				strcpy(keep_arg + s, "localhost");
+			*av++ = keep_arg;
+		}
+	}
+	else {
+		*av++ = "unpack-objects";
+		if (quiet)
+			*av++ = "-q";
+	}
+	if (*hdr_arg)
+		*av++ = hdr_arg;
+	*av++ = NULL;
+
+	pid = fork();
+	if (pid < 0)
+		die("fetch-pack: unable to fork off %s", argv[0]);
+	if (!pid) {
+		dup2(fd[0], 0);
+		close(fd[0]);
+		close(fd[1]);
+		execv_git_cmd(argv);
+		die("%s exec failed", argv[0]);
+	}
+	close(fd[0]);
+	close(fd[1]);
+	while (waitpid(pid, &status, 0) < 0) {
+		if (errno != EINTR)
+			die("waiting for %s: %s", argv[0], strerror(errno));
+	}
+	if (WIFEXITED(status)) {
+		int code = WEXITSTATUS(status);
+		if (code)
+			die("%s died with error code %d", argv[0], code);
+		return 0;
+	}
+	if (WIFSIGNALED(status)) {
+		int sig = WTERMSIG(status);
+		die("%s died of signal %d", argv[0], sig);
+	}
+	die("%s died of unnatural causes %d", argv[0], status);
+}
+
+static struct ref *do_fetch_pack(int fd[2], int nr_match, char **match)
+{
+	struct ref *ref;
+	unsigned char sha1[20];
+
+	get_remote_heads(fd[0], &ref, 0, NULL, 0);
+	if (is_repository_shallow() && !server_supports("shallow"))
+		die("Server does not support shallow clients");
+	if (server_supports("multi_ack")) {
+		if (verbose)
+			fprintf(stderr, "Server supports multi_ack\n");
+		multi_ack = 1;
+	}
+	if (server_supports("side-band-64k")) {
+		if (verbose)
+			fprintf(stderr, "Server supports side-band-64k\n");
+		use_sideband = 2;
+	}
+	else if (server_supports("side-band")) {
+		if (verbose)
+			fprintf(stderr, "Server supports side-band\n");
+		use_sideband = 1;
+	}
+	if (!ref) {
+		packet_flush(fd[1]);
+		die("no matching remote head");
+	}
+	if (everything_local(&ref, nr_match, match)) {
+		packet_flush(fd[1]);
+		goto all_done;
+	}
+	if (find_common(fd, sha1, ref) < 0)
+		if (keep_pack != 1)
+			/* When cloning, it is not unusual to have
+			 * no common commit.
+			 */
+			fprintf(stderr, "warning: no common commits\n");
+
+	if (get_pack(fd))
+		die("git-fetch-pack: fetch failed.");
+
+ all_done:
+	return ref;
+}
+
+static int remove_duplicates(int nr_heads, char **heads)
+{
+	int src, dst;
+
+	for (src = dst = 0; src < nr_heads; src++) {
+		/* If heads[src] is different from any of
+		 * heads[0..dst], push it in.
+		 */
+		int i;
+		for (i = 0; i < dst; i++) {
+			if (!strcmp(heads[i], heads[src]))
+				break;
+		}
+		if (i < dst)
+			continue;
+		if (src != dst)
+			heads[dst] = heads[src];
+		dst++;
+	}
+	heads[dst] = 0;
+	return dst;
+}
+
+static int fetch_pack_config(const char *var, const char *value)
+{
+	if (strcmp(var, "fetch.unpacklimit") == 0) {
+		fetch_unpack_limit = git_config_int(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "transfer.unpacklimit") == 0) {
+		transfer_unpack_limit = git_config_int(var, value);
+		return 0;
+	}
+
+	return git_default_config(var, value);
+}
+
+static struct lock_file lock;
+
+void setup_fetch_pack(struct fetch_pack_args *args)
+{
+	uploadpack = args->uploadpack;
+	quiet = args->quiet;
+	keep_pack = args->keep_pack;
+	if (args->unpacklimit >= 0)
+		unpack_limit = args->unpacklimit;
+	if (args->keep_pack)
+		unpack_limit = 0;
+	use_thin_pack = args->use_thin_pack;
+	fetch_all = args->fetch_all;
+	verbose = args->verbose;
+	depth = args->depth;
+	no_progress = args->no_progress;
+}
+
+int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
+{
+	int i, ret, nr_heads;
+	struct ref *ref;
+	char *dest = NULL, **heads;
+
+	git_config(fetch_pack_config);
+
+	if (0 <= transfer_unpack_limit)
+		unpack_limit = transfer_unpack_limit;
+	else if (0 <= fetch_unpack_limit)
+		unpack_limit = fetch_unpack_limit;
+
+	nr_heads = 0;
+	heads = NULL;
+	for (i = 1; i < argc; i++) {
+		const char *arg = argv[i];
+
+		if (*arg == '-') {
+			if (!prefixcmp(arg, "--upload-pack=")) {
+				uploadpack = arg + 14;
+				continue;
+			}
+			if (!prefixcmp(arg, "--exec=")) {
+				uploadpack = arg + 7;
+				continue;
+			}
+			if (!strcmp("--quiet", arg) || !strcmp("-q", arg)) {
+				quiet = 1;
+				continue;
+			}
+			if (!strcmp("--keep", arg) || !strcmp("-k", arg)) {
+				keep_pack++;
+				unpack_limit = 0;
+				continue;
+			}
+			if (!strcmp("--thin", arg)) {
+				use_thin_pack = 1;
+				continue;
+			}
+			if (!strcmp("--all", arg)) {
+				fetch_all = 1;
+				continue;
+			}
+			if (!strcmp("-v", arg)) {
+				verbose = 1;
+				continue;
+			}
+			if (!prefixcmp(arg, "--depth=")) {
+				depth = strtol(arg + 8, NULL, 0);
+				continue;
+			}
+			if (!strcmp("--no-progress", arg)) {
+				no_progress = 1;
+				continue;
+			}
+			usage(fetch_pack_usage);
+		}
+		dest = (char *)arg;
+		heads = (char **)(argv + i + 1);
+		nr_heads = argc - i - 1;
+		break;
+	}
+	if (!dest)
+		usage(fetch_pack_usage);
+
+	ref = fetch_pack(dest, nr_heads, heads);
+
+	ret = !ref;
+
+	while (ref) {
+		printf("%s %s\n",
+		       sha1_to_hex(ref->old_sha1), ref->name);
+		ref = ref->next;
+	}
+
+	return ret;
+}
+
+struct ref *fetch_pack(const char *dest, int nr_heads, char **heads)
+{
+	int i, ret;
+	int fd[2];
+	pid_t pid;
+	struct ref *ref;
+	struct stat st;
+
+	if (depth > 0) {
+		if (stat(git_path("shallow"), &st))
+			st.st_mtime = 0;
+	}
+
+	printf("connect to %s\n", dest);
+
+	pid = git_connect(fd, (char *)dest, uploadpack,
+                          verbose ? CONNECT_VERBOSE : 0);
+	if (pid < 0)
+		return NULL;
+	if (heads && nr_heads)
+		nr_heads = remove_duplicates(nr_heads, heads);
+	ref = do_fetch_pack(fd, nr_heads, heads);
+	close(fd[0]);
+	close(fd[1]);
+	ret = finish_connect(pid);
+
+	if (!ret && nr_heads) {
+		/* If the heads to pull were given, we should have
+		 * consumed all of them by matching the remote.
+		 * Otherwise, 'git-fetch remote no-such-ref' would
+		 * silently succeed without issuing an error.
+		 */
+		for (i = 0; i < nr_heads; i++)
+			if (heads[i] && heads[i][0]) {
+				error("no such remote ref %s", heads[i]);
+				ret = 1;
+			}
+	}
+
+	if (!ret && depth > 0) {
+		struct cache_time mtime;
+		char *shallow = git_path("shallow");
+		int fd;
+
+		mtime.sec = st.st_mtime;
+#ifdef USE_NSEC
+		mtime.usec = st.st_mtim.usec;
+#endif
+		if (stat(shallow, &st)) {
+			if (mtime.sec)
+				die("shallow file was removed during fetch");
+		} else if (st.st_mtime != mtime.sec
+#ifdef USE_NSEC
+				|| st.st_mtim.usec != mtime.usec
+#endif
+			  )
+			die("shallow file was changed during fetch");
+
+		fd = hold_lock_file_for_update(&lock, shallow, 1);
+		if (!write_shallow_commits(fd, 0)) {
+			unlink(shallow);
+			rollback_lock_file(&lock);
+		} else {
+			close(fd);
+			commit_lock_file(&lock);
+		}
+	}
+
+	if (ret)
+		ref = NULL;
+
+	return ref;
+}