Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7

1 files changed, 1749 insertions, 0 deletions

diff --git a/fetch-pack.c b/fetch-pack.c
new file mode 100644
index 000000000000..65be043f2afa
--- /dev/null
+++ b/fetch-pack.c
@@ -0,0 +1,1749 @@
+#include "cache.h"
+#include "repository.h"
+#include "config.h"
+#include "lockfile.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"
+#include "remote.h"
+#include "run-command.h"
+#include "connect.h"
+#include "transport.h"
+#include "version.h"
+#include "sha1-array.h"
+#include "oidset.h"
+#include "packfile.h"
+#include "object-store.h"
+#include "connected.h"
+#include "fetch-negotiator.h"
+#include "fsck.h"
+
+static int transfer_unpack_limit = -1;
+static int fetch_unpack_limit = -1;
+static int unpack_limit = 100;
+static int prefer_ofs_delta = 1;
+static int no_done;
+static int deepen_since_ok;
+static int deepen_not_ok;
+static int fetch_fsck_objects = -1;
+static int transfer_fsck_objects = -1;
+static int agent_supported;
+static int server_supports_filtering;
+static struct lock_file shallow_lock;
+static const char *alternate_shallow_file;
+static char *negotiation_algorithm;
+static struct strbuf fsck_msg_types = STRBUF_INIT;
+
+/* Remember to update object flag allocation in object.h */
+#define COMPLETE	(1U << 0)
+#define ALTERNATE	(1U << 1)
+
+/*
+ * 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 int multi_ack, use_sideband;
+/* Allow specifying sha1 if it is a ref tip. */
+#define ALLOW_TIP_SHA1	01
+/* Allow request of a sha1 if it is reachable from a ref (possibly hidden ref). */
+#define ALLOW_REACHABLE_SHA1	02
+static unsigned int allow_unadvertised_object_request;
+
+__attribute__((format (printf, 2, 3)))
+static inline void print_verbose(const struct fetch_pack_args *args,
+				 const char *fmt, ...)
+{
+	va_list params;
+
+	if (!args->verbose)
+		return;
+
+	va_start(params, fmt);
+	vfprintf(stderr, fmt, params);
+	va_end(params);
+	fputc('\n', stderr);
+}
+
+struct alternate_object_cache {
+	struct object **items;
+	size_t nr, alloc;
+};
+
+static void cache_one_alternate(const struct object_id *oid,
+				void *vcache)
+{
+	struct alternate_object_cache *cache = vcache;
+	struct object *obj = parse_object(the_repository, oid);
+
+	if (!obj || (obj->flags & ALTERNATE))
+		return;
+
+	obj->flags |= ALTERNATE;
+	ALLOC_GROW(cache->items, cache->nr + 1, cache->alloc);
+	cache->items[cache->nr++] = obj;
+}
+
+static void for_each_cached_alternate(struct fetch_negotiator *negotiator,
+				      void (*cb)(struct fetch_negotiator *,
+						 struct object *))
+{
+	static int initialized;
+	static struct alternate_object_cache cache;
+	size_t i;
+
+	if (!initialized) {
+		for_each_alternate_ref(cache_one_alternate, &cache);
+		initialized = 1;
+	}
+
+	for (i = 0; i < cache.nr; i++)
+		cb(negotiator, cache.items[i]);
+}
+
+static int rev_list_insert_ref(struct fetch_negotiator *negotiator,
+			       const char *refname,
+			       const struct object_id *oid)
+{
+	struct object *o = deref_tag(the_repository,
+				     parse_object(the_repository, oid),
+				     refname, 0);
+
+	if (o && o->type == OBJ_COMMIT)
+		negotiator->add_tip(negotiator, (struct commit *)o);
+
+	return 0;
+}
+
+static int rev_list_insert_ref_oid(const char *refname, const struct object_id *oid,
+				   int flag, void *cb_data)
+{
+	return rev_list_insert_ref(cb_data, refname, oid);
+}
+
+enum ack_type {
+	NAK = 0,
+	ACK,
+	ACK_continue,
+	ACK_common,
+	ACK_ready
+};
+
+static void consume_shallow_list(struct fetch_pack_args *args,
+				 struct packet_reader *reader)
+{
+	if (args->stateless_rpc && args->deepen) {
+		/* If we sent a depth we will get back "duplicate"
+		 * shallow and unshallow commands every time there
+		 * is a block of have lines exchanged.
+		 */
+		while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
+			if (starts_with(reader->line, "shallow "))
+				continue;
+			if (starts_with(reader->line, "unshallow "))
+				continue;
+			die(_("git fetch-pack: expected shallow list"));
+		}
+		if (reader->status != PACKET_READ_FLUSH)
+			die(_("git fetch-pack: expected a flush packet after shallow list"));
+	}
+}
+
+static enum ack_type get_ack(struct packet_reader *reader,
+			     struct object_id *result_oid)
+{
+	int len;
+	const char *arg;
+
+	if (packet_reader_read(reader) != PACKET_READ_NORMAL)
+		die(_("git fetch-pack: expected ACK/NAK, got a flush packet"));
+	len = reader->pktlen;
+
+	if (!strcmp(reader->line, "NAK"))
+		return NAK;
+	if (skip_prefix(reader->line, "ACK ", &arg)) {
+		if (!get_oid_hex(arg, result_oid)) {
+			arg += 40;
+			len -= arg - reader->line;
+			if (len < 1)
+				return ACK;
+			if (strstr(arg, "continue"))
+				return ACK_continue;
+			if (strstr(arg, "common"))
+				return ACK_common;
+			if (strstr(arg, "ready"))
+				return ACK_ready;
+			return ACK;
+		}
+	}
+	die(_("git fetch-pack: expected ACK/NAK, got '%s'"), reader->line);
+}
+
+static void send_request(struct fetch_pack_args *args,
+			 int fd, struct strbuf *buf)
+{
+	if (args->stateless_rpc) {
+		send_sideband(fd, -1, buf->buf, buf->len, LARGE_PACKET_MAX);
+		packet_flush(fd);
+	} else {
+		if (write_in_full(fd, buf->buf, buf->len) < 0)
+			die_errno(_("unable to write to remote"));
+	}
+}
+
+static void insert_one_alternate_object(struct fetch_negotiator *negotiator,
+					struct object *obj)
+{
+	rev_list_insert_ref(negotiator, NULL, &obj->oid);
+}
+
+#define INITIAL_FLUSH 16
+#define PIPESAFE_FLUSH 32
+#define LARGE_FLUSH 16384
+
+static int next_flush(int stateless_rpc, int count)
+{
+	if (stateless_rpc) {
+		if (count < LARGE_FLUSH)
+			count <<= 1;
+		else
+			count = count * 11 / 10;
+	} else {
+		if (count < PIPESAFE_FLUSH)
+			count <<= 1;
+		else
+			count += PIPESAFE_FLUSH;
+	}
+	return count;
+}
+
+static void mark_tips(struct fetch_negotiator *negotiator,
+		      const struct oid_array *negotiation_tips)
+{
+	int i;
+
+	if (!negotiation_tips) {
+		for_each_ref(rev_list_insert_ref_oid, negotiator);
+		return;
+	}
+
+	for (i = 0; i < negotiation_tips->nr; i++)
+		rev_list_insert_ref(negotiator, NULL,
+				    &negotiation_tips->oid[i]);
+	return;
+}
+
+static int find_common(struct fetch_negotiator *negotiator,
+		       struct fetch_pack_args *args,
+		       int fd[2], struct object_id *result_oid,
+		       struct ref *refs)
+{
+	int fetching;
+	int count = 0, flushes = 0, flush_at = INITIAL_FLUSH, retval;
+	const struct object_id *oid;
+	unsigned in_vain = 0;
+	int got_continue = 0;
+	int got_ready = 0;
+	struct strbuf req_buf = STRBUF_INIT;
+	size_t state_len = 0;
+	struct packet_reader reader;
+
+	if (args->stateless_rpc && multi_ack == 1)
+		die(_("--stateless-rpc requires multi_ack_detailed"));
+
+	packet_reader_init(&reader, fd[0], NULL, 0,
+			   PACKET_READ_CHOMP_NEWLINE |
+			   PACKET_READ_DIE_ON_ERR_PACKET);
+
+	if (!args->no_dependents) {
+		mark_tips(negotiator, args->negotiation_tips);
+		for_each_cached_alternate(negotiator, insert_one_alternate_object);
+	}
+
+	fetching = 0;
+	for ( ; refs ; refs = refs->next) {
+		struct object_id *remote = &refs->old_oid;
+		const char *remote_hex;
+		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.
+		 *
+		 * Do this only if args->no_dependents is false (if it is true,
+		 * we cannot trust the object flags).
+		 */
+		if (!args->no_dependents &&
+		    ((o = lookup_object(the_repository, remote)) != NULL) &&
+				(o->flags & COMPLETE)) {
+			continue;
+		}
+
+		remote_hex = oid_to_hex(remote);
+		if (!fetching) {
+			struct strbuf c = STRBUF_INIT;
+			if (multi_ack == 2)     strbuf_addstr(&c, " multi_ack_detailed");
+			if (multi_ack == 1)     strbuf_addstr(&c, " multi_ack");
+			if (no_done)            strbuf_addstr(&c, " no-done");
+			if (use_sideband == 2)  strbuf_addstr(&c, " side-band-64k");
+			if (use_sideband == 1)  strbuf_addstr(&c, " side-band");
+			if (args->deepen_relative) strbuf_addstr(&c, " deepen-relative");
+			if (args->use_thin_pack) strbuf_addstr(&c, " thin-pack");
+			if (args->no_progress)   strbuf_addstr(&c, " no-progress");
+			if (args->include_tag)   strbuf_addstr(&c, " include-tag");
+			if (prefer_ofs_delta)   strbuf_addstr(&c, " ofs-delta");
+			if (deepen_since_ok)    strbuf_addstr(&c, " deepen-since");
+			if (deepen_not_ok)      strbuf_addstr(&c, " deepen-not");
+			if (agent_supported)    strbuf_addf(&c, " agent=%s",
+							    git_user_agent_sanitized());
+			if (args->filter_options.choice)
+				strbuf_addstr(&c, " filter");
+			packet_buf_write(&req_buf, "want %s%s\n", remote_hex, c.buf);
+			strbuf_release(&c);
+		} else
+			packet_buf_write(&req_buf, "want %s\n", remote_hex);
+		fetching++;
+	}
+
+	if (!fetching) {
+		strbuf_release(&req_buf);
+		packet_flush(fd[1]);
+		return 1;
+	}
+
+	if (is_repository_shallow(the_repository))
+		write_shallow_commits(&req_buf, 1, NULL);
+	if (args->depth > 0)
+		packet_buf_write(&req_buf, "deepen %d", args->depth);
+	if (args->deepen_since) {
+		timestamp_t max_age = approxidate(args->deepen_since);
+		packet_buf_write(&req_buf, "deepen-since %"PRItime, max_age);
+	}
+	if (args->deepen_not) {
+		int i;
+		for (i = 0; i < args->deepen_not->nr; i++) {
+			struct string_list_item *s = args->deepen_not->items + i;
+			packet_buf_write(&req_buf, "deepen-not %s", s->string);
+		}
+	}
+	if (server_supports_filtering && args->filter_options.choice) {
+		struct strbuf expanded_filter_spec = STRBUF_INIT;
+		expand_list_objects_filter_spec(&args->filter_options,
+						&expanded_filter_spec);
+		packet_buf_write(&req_buf, "filter %s",
+				 expanded_filter_spec.buf);
+		strbuf_release(&expanded_filter_spec);
+	}
+	packet_buf_flush(&req_buf);
+	state_len = req_buf.len;
+
+	if (args->deepen) {
+		const char *arg;
+		struct object_id oid;
+
+		send_request(args, fd[1], &req_buf);
+		while (packet_reader_read(&reader) == PACKET_READ_NORMAL) {
+			if (skip_prefix(reader.line, "shallow ", &arg)) {
+				if (get_oid_hex(arg, &oid))
+					die(_("invalid shallow line: %s"), reader.line);
+				register_shallow(the_repository, &oid);
+				continue;
+			}
+			if (skip_prefix(reader.line, "unshallow ", &arg)) {
+				if (get_oid_hex(arg, &oid))
+					die(_("invalid unshallow line: %s"), reader.line);
+				if (!lookup_object(the_repository, &oid))
+					die(_("object not found: %s"), reader.line);
+				/* make sure that it is parsed as shallow */
+				if (!parse_object(the_repository, &oid))
+					die(_("error in object: %s"), reader.line);
+				if (unregister_shallow(&oid))
+					die(_("no shallow found: %s"), reader.line);
+				continue;
+			}
+			die(_("expected shallow/unshallow, got %s"), reader.line);
+		}
+	} else if (!args->stateless_rpc)
+		send_request(args, fd[1], &req_buf);
+
+	if (!args->stateless_rpc) {
+		/* If we aren't using the stateless-rpc interface
+		 * we don't need to retain the headers.
+		 */
+		strbuf_setlen(&req_buf, 0);
+		state_len = 0;
+	}
+
+	flushes = 0;
+	retval = -1;
+	if (args->no_dependents)
+		goto done;
+	while ((oid = negotiator->next(negotiator))) {
+		packet_buf_write(&req_buf, "have %s\n", oid_to_hex(oid));
+		print_verbose(args, "have %s", oid_to_hex(oid));
+		in_vain++;
+		if (flush_at <= ++count) {
+			int ack;
+
+			packet_buf_flush(&req_buf);
+			send_request(args, fd[1], &req_buf);
+			strbuf_setlen(&req_buf, state_len);
+			flushes++;
+			flush_at = next_flush(args->stateless_rpc, count);
+
+			/*
+			 * We keep one window "ahead" of the other side, and
+			 * will wait for an ACK only on the next one
+			 */
+			if (!args->stateless_rpc && count == INITIAL_FLUSH)
+				continue;
+
+			consume_shallow_list(args, &reader);
+			do {
+				ack = get_ack(&reader, result_oid);
+				if (ack)
+					print_verbose(args, _("got %s %d %s"), "ack",
+						      ack, oid_to_hex(result_oid));
+				switch (ack) {
+				case ACK:
+					flushes = 0;
+					multi_ack = 0;
+					retval = 0;
+					goto done;
+				case ACK_common:
+				case ACK_ready:
+				case ACK_continue: {
+					struct commit *commit =
+						lookup_commit(the_repository,
+							      result_oid);
+					int was_common;
+
+					if (!commit)
+						die(_("invalid commit %s"), oid_to_hex(result_oid));
+					was_common = negotiator->ack(negotiator, commit);
+					if (args->stateless_rpc
+					 && ack == ACK_common
+					 && !was_common) {
+						/* We need to replay the have for this object
+						 * on the next RPC request so the peer knows
+						 * it is in common with us.
+						 */
+						const char *hex = oid_to_hex(result_oid);
+						packet_buf_write(&req_buf, "have %s\n", hex);
+						state_len = req_buf.len;
+						/*
+						 * Reset in_vain because an ack
+						 * for this commit has not been
+						 * seen.
+						 */
+						in_vain = 0;
+					} else if (!args->stateless_rpc
+						   || ack != ACK_common)
+						in_vain = 0;
+					retval = 0;
+					got_continue = 1;
+					if (ack == ACK_ready)
+						got_ready = 1;
+					break;
+					}
+				}
+			} while (ack);
+			flushes--;
+			if (got_continue && MAX_IN_VAIN < in_vain) {
+				print_verbose(args, _("giving up"));
+				break; /* give up */
+			}
+			if (got_ready)
+				break;
+		}
+	}
+done:
+	if (!got_ready || !no_done) {
+		packet_buf_write(&req_buf, "done\n");
+		send_request(args, fd[1], &req_buf);
+	}
+	print_verbose(args, _("done"));
+	if (retval != 0) {
+		multi_ack = 0;
+		flushes++;
+	}
+	strbuf_release(&req_buf);
+
+	if (!got_ready || !no_done)
+		consume_shallow_list(args, &reader);
+	while (flushes || multi_ack) {
+		int ack = get_ack(&reader, result_oid);
+		if (ack) {
+			print_verbose(args, _("got %s (%d) %s"), "ack",
+				      ack, oid_to_hex(result_oid));
+			if (ack == ACK)
+				return 0;
+			multi_ack = 1;
+			continue;
+		}
+		flushes--;
+	}
+	/* it is no error to fetch into a completely empty repo */
+	return count ? retval : 0;
+}
+
+static struct commit_list *complete;
+
+static int mark_complete(const struct object_id *oid)
+{
+	struct object *o = parse_object(the_repository, oid);
+
+	while (o && o->type == OBJ_TAG) {
+		struct tag *t = (struct tag *) o;
+		if (!t->tagged)
+			break; /* broken repository */
+		o->flags |= COMPLETE;
+		o = parse_object(the_repository, &t->tagged->oid);
+	}
+	if (o && o->type == OBJ_COMMIT) {
+		struct commit *commit = (struct commit *)o;
+		if (!(commit->object.flags & COMPLETE)) {
+			commit->object.flags |= COMPLETE;
+			commit_list_insert(commit, &complete);
+		}
+	}
+	return 0;
+}
+
+static int mark_complete_oid(const char *refname, const struct object_id *oid,
+			     int flag, void *cb_data)
+{
+	return mark_complete(oid);
+}
+
+static void mark_recent_complete_commits(struct fetch_pack_args *args,
+					 timestamp_t cutoff)
+{
+	while (complete && cutoff <= complete->item->date) {
+		print_verbose(args, _("Marking %s as complete"),
+			      oid_to_hex(&complete->item->object.oid));
+		pop_most_recent_commit(&complete, COMPLETE);
+	}
+}
+
+static void add_refs_to_oidset(struct oidset *oids, struct ref *refs)
+{
+	for (; refs; refs = refs->next)
+		oidset_insert(oids, &refs->old_oid);
+}
+
+static int is_unmatched_ref(const struct ref *ref)
+{
+	struct object_id oid;
+	const char *p;
+	return	ref->match_status == REF_NOT_MATCHED &&
+		!parse_oid_hex(ref->name, &oid, &p) &&
+		*p == '\0' &&
+		oideq(&oid, &ref->old_oid);
+}
+
+static void filter_refs(struct fetch_pack_args *args,
+			struct ref **refs,
+			struct ref **sought, int nr_sought)
+{
+	struct ref *newlist = NULL;
+	struct ref **newtail = &newlist;
+	struct ref *unmatched = NULL;
+	struct ref *ref, *next;
+	struct oidset tip_oids = OIDSET_INIT;
+	int i;
+	int strict = !(allow_unadvertised_object_request &
+		       (ALLOW_TIP_SHA1 | ALLOW_REACHABLE_SHA1));
+
+	i = 0;
+	for (ref = *refs; ref; ref = next) {
+		int keep = 0;
+		next = ref->next;
+
+		if (starts_with(ref->name, "refs/") &&
+		    check_refname_format(ref->name, 0)) {
+			/*
+			 * trash or a peeled value; do not even add it to
+			 * unmatched list
+			 */
+			free_one_ref(ref);
+			continue;
+		} else {
+			while (i < nr_sought) {
+				int cmp = strcmp(ref->name, sought[i]->name);
+				if (cmp < 0)
+					break; /* definitely do not have it */
+				else if (cmp == 0) {
+					keep = 1; /* definitely have it */
+					sought[i]->match_status = REF_MATCHED;
+				}
+				i++;
+			}
+
+			if (!keep && args->fetch_all &&
+			    (!args->deepen || !starts_with(ref->name, "refs/tags/")))
+				keep = 1;
+		}
+
+		if (keep) {
+			*newtail = ref;
+			ref->next = NULL;
+			newtail = &ref->next;
+		} else {
+			ref->next = unmatched;
+			unmatched = ref;
+		}
+	}
+
+	if (strict) {
+		for (i = 0; i < nr_sought; i++) {
+			ref = sought[i];
+			if (!is_unmatched_ref(ref))
+				continue;
+
+			add_refs_to_oidset(&tip_oids, unmatched);
+			add_refs_to_oidset(&tip_oids, newlist);
+			break;
+		}
+	}
+
+	/* Append unmatched requests to the list */
+	for (i = 0; i < nr_sought; i++) {
+		ref = sought[i];
+		if (!is_unmatched_ref(ref))
+			continue;
+
+		if (!strict || oidset_contains(&tip_oids, &ref->old_oid)) {
+			ref->match_status = REF_MATCHED;
+			*newtail = copy_ref(ref);
+			newtail = &(*newtail)->next;
+		} else {
+			ref->match_status = REF_UNADVERTISED_NOT_ALLOWED;
+		}
+	}
+
+	oidset_clear(&tip_oids);
+	free_refs(unmatched);
+
+	*refs = newlist;
+}
+
+static void mark_alternate_complete(struct fetch_negotiator *unused,
+				    struct object *obj)
+{
+	mark_complete(&obj->oid);
+}
+
+struct loose_object_iter {
+	struct oidset *loose_object_set;
+	struct ref *refs;
+};
+
+/*
+ * Mark recent commits available locally and reachable from a local ref as
+ * COMPLETE. If args->no_dependents is false, also mark COMPLETE remote refs as
+ * COMMON_REF (otherwise, we are not planning to participate in negotiation, and
+ * thus do not need COMMON_REF marks).
+ *
+ * The cutoff time for recency is determined by this heuristic: it is the
+ * earliest commit time of the objects in refs that are commits and that we know
+ * the commit time of.
+ */
+static void mark_complete_and_common_ref(struct fetch_negotiator *negotiator,
+					 struct fetch_pack_args *args,
+					 struct ref **refs)
+{
+	struct ref *ref;
+	int old_save_commit_buffer = save_commit_buffer;
+	timestamp_t cutoff = 0;
+
+	save_commit_buffer = 0;
+
+	for (ref = *refs; ref; ref = ref->next) {
+		struct object *o;
+
+		if (!has_object_file_with_flags(&ref->old_oid,
+						OBJECT_INFO_QUICK))
+			continue;
+		o = parse_object(the_repository, &ref->old_oid);
+		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 (!args->deepen) {
+		for_each_ref(mark_complete_oid, NULL);
+		for_each_cached_alternate(NULL, mark_alternate_complete);
+		commit_list_sort_by_date(&complete);
+		if (cutoff)
+			mark_recent_complete_commits(args, 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(the_repository,
+					     lookup_object(the_repository,
+					     &ref->old_oid),
+					     NULL, 0);
+
+		if (!o || o->type != OBJ_COMMIT || !(o->flags & COMPLETE))
+			continue;
+
+		negotiator->known_common(negotiator,
+					 (struct commit *)o);
+	}
+
+	save_commit_buffer = old_save_commit_buffer;
+}
+
+/*
+ * Returns 1 if every object pointed to by the given remote refs is available
+ * locally and reachable from a local ref, and 0 otherwise.
+ */
+static int everything_local(struct fetch_pack_args *args,
+			    struct ref **refs)
+{
+	struct ref *ref;
+	int retval;
+
+	for (retval = 1, ref = *refs; ref ; ref = ref->next) {
+		const struct object_id *remote = &ref->old_oid;
+		struct object *o;
+
+		o = lookup_object(the_repository, remote);
+		if (!o || !(o->flags & COMPLETE)) {
+			retval = 0;
+			print_verbose(args, "want %s (%s)", oid_to_hex(remote),
+				      ref->name);
+			continue;
+		}
+		print_verbose(args, _("already have %s (%s)"), oid_to_hex(remote),
+			      ref->name);
+	}
+
+	return retval;
+}
+
+static int sideband_demux(int in, int out, void *data)
+{
+	int *xd = data;
+	int ret;
+
+	ret = recv_sideband("fetch-pack", xd[0], out);
+	close(out);
+	return ret;
+}
+
+static int get_pack(struct fetch_pack_args *args,
+		    int xd[2], char **pack_lockfile)
+{
+	struct async demux;
+	int do_keep = args->keep_pack;
+	const char *cmd_name;
+	struct pack_header header;
+	int pass_header = 0;
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	int ret;
+
+	memset(&demux, 0, sizeof(demux));
+	if (use_sideband) {
+		/* xd[] is talking with upload-pack; subprocess reads from
+		 * xd[0], spits out band#2 to stderr, and feeds us band#1
+		 * through demux->out.
+		 */
+		demux.proc = sideband_demux;
+		demux.data = xd;
+		demux.out = -1;
+		demux.isolate_sigpipe = 1;
+		if (start_async(&demux))
+			die(_("fetch-pack: unable to fork off sideband demultiplexer"));
+	}
+	else
+		demux.out = xd[0];
+
+	if (!args->keep_pack && unpack_limit) {
+
+		if (read_pack_header(demux.out, &header))
+			die(_("protocol error: bad pack header"));
+		pass_header = 1;
+		if (ntohl(header.hdr_entries) < unpack_limit)
+			do_keep = 0;
+		else
+			do_keep = 1;
+	}
+
+	if (alternate_shallow_file) {
+		argv_array_push(&cmd.args, "--shallow-file");
+		argv_array_push(&cmd.args, alternate_shallow_file);
+	}
+
+	if (do_keep || args->from_promisor) {
+		if (pack_lockfile)
+			cmd.out = -1;
+		cmd_name = "index-pack";
+		argv_array_push(&cmd.args, cmd_name);
+		argv_array_push(&cmd.args, "--stdin");
+		if (!args->quiet && !args->no_progress)
+			argv_array_push(&cmd.args, "-v");
+		if (args->use_thin_pack)
+			argv_array_push(&cmd.args, "--fix-thin");
+		if (do_keep && (args->lock_pack || unpack_limit)) {
+			char hostname[HOST_NAME_MAX + 1];
+			if (xgethostname(hostname, sizeof(hostname)))
+				xsnprintf(hostname, sizeof(hostname), "localhost");
+			argv_array_pushf(&cmd.args,
+					"--keep=fetch-pack %"PRIuMAX " on %s",
+					(uintmax_t)getpid(), hostname);
+		}
+		if (args->check_self_contained_and_connected)
+			argv_array_push(&cmd.args, "--check-self-contained-and-connected");
+		if (args->from_promisor)
+			argv_array_push(&cmd.args, "--promisor");
+	}
+	else {
+		cmd_name = "unpack-objects";
+		argv_array_push(&cmd.args, cmd_name);
+		if (args->quiet || args->no_progress)
+			argv_array_push(&cmd.args, "-q");
+		args->check_self_contained_and_connected = 0;
+	}
+
+	if (pass_header)
+		argv_array_pushf(&cmd.args, "--pack_header=%"PRIu32",%"PRIu32,
+				 ntohl(header.hdr_version),
+				 ntohl(header.hdr_entries));
+	if (fetch_fsck_objects >= 0
+	    ? fetch_fsck_objects
+	    : transfer_fsck_objects >= 0
+	    ? transfer_fsck_objects
+	    : 0) {
+		if (args->from_promisor)
+			/*
+			 * We cannot use --strict in index-pack because it
+			 * checks both broken objects and links, but we only
+			 * want to check for broken objects.
+			 */
+			argv_array_push(&cmd.args, "--fsck-objects");
+		else
+			argv_array_pushf(&cmd.args, "--strict%s",
+					 fsck_msg_types.buf);
+	}
+
+	cmd.in = demux.out;
+	cmd.git_cmd = 1;
+	if (start_command(&cmd))
+		die(_("fetch-pack: unable to fork off %s"), cmd_name);
+	if (do_keep && pack_lockfile) {
+		*pack_lockfile = index_pack_lockfile(cmd.out);
+		close(cmd.out);
+	}
+
+	if (!use_sideband)
+		/* Closed by start_command() */
+		xd[0] = -1;
+
+	ret = finish_command(&cmd);
+	if (!ret || (args->check_self_contained_and_connected && ret == 1))
+		args->self_contained_and_connected =
+			args->check_self_contained_and_connected &&
+			ret == 0;
+	else
+		die(_("%s failed"), cmd_name);
+	if (use_sideband && finish_async(&demux))
+		die(_("error in sideband demultiplexer"));
+	return 0;
+}
+
+static int cmp_ref_by_name(const void *a_, const void *b_)
+{
+	const struct ref *a = *((const struct ref **)a_);
+	const struct ref *b = *((const struct ref **)b_);
+	return strcmp(a->name, b->name);
+}
+
+static struct ref *do_fetch_pack(struct fetch_pack_args *args,
+				 int fd[2],
+				 const struct ref *orig_ref,
+				 struct ref **sought, int nr_sought,
+				 struct shallow_info *si,
+				 char **pack_lockfile)
+{
+	struct ref *ref = copy_ref_list(orig_ref);
+	struct object_id oid;
+	const char *agent_feature;
+	int agent_len;
+	struct fetch_negotiator negotiator;
+	fetch_negotiator_init(&negotiator, negotiation_algorithm);
+
+	sort_ref_list(&ref, ref_compare_name);
+	QSORT(sought, nr_sought, cmp_ref_by_name);
+
+	if ((agent_feature = server_feature_value("agent", &agent_len))) {
+		agent_supported = 1;
+		if (agent_len)
+			print_verbose(args, _("Server version is %.*s"),
+				      agent_len, agent_feature);
+	}
+
+	if (server_supports("shallow"))
+		print_verbose(args, _("Server supports %s"), "shallow");
+	else if (args->depth > 0 || is_repository_shallow(the_repository))
+		die(_("Server does not support shallow clients"));
+	if (args->depth > 0 || args->deepen_since || args->deepen_not)
+		args->deepen = 1;
+	if (server_supports("multi_ack_detailed")) {
+		print_verbose(args, _("Server supports %s"), "multi_ack_detailed");
+		multi_ack = 2;
+		if (server_supports("no-done")) {
+			print_verbose(args, _("Server supports %s"), "no-done");
+			if (args->stateless_rpc)
+				no_done = 1;
+		}
+	}
+	else if (server_supports("multi_ack")) {
+		print_verbose(args, _("Server supports %s"), "multi_ack");
+		multi_ack = 1;
+	}
+	if (server_supports("side-band-64k")) {
+		print_verbose(args, _("Server supports %s"), "side-band-64k");
+		use_sideband = 2;
+	}
+	else if (server_supports("side-band")) {
+		print_verbose(args, _("Server supports %s"), "side-band");
+		use_sideband = 1;
+	}
+	if (server_supports("allow-tip-sha1-in-want")) {
+		print_verbose(args, _("Server supports %s"), "allow-tip-sha1-in-want");
+		allow_unadvertised_object_request |= ALLOW_TIP_SHA1;
+	}
+	if (server_supports("allow-reachable-sha1-in-want")) {
+		print_verbose(args, _("Server supports %s"), "allow-reachable-sha1-in-want");
+		allow_unadvertised_object_request |= ALLOW_REACHABLE_SHA1;
+	}
+	if (server_supports("thin-pack"))
+		print_verbose(args, _("Server supports %s"), "thin-pack");
+	else
+		args->use_thin_pack = 0;
+	if (server_supports("no-progress"))
+		print_verbose(args, _("Server supports %s"), "no-progress");
+	else
+		args->no_progress = 0;
+	if (server_supports("include-tag"))
+		print_verbose(args, _("Server supports %s"), "include-tag");
+	else
+		args->include_tag = 0;
+	if (server_supports("ofs-delta"))
+		print_verbose(args, _("Server supports %s"), "ofs-delta");
+	else
+		prefer_ofs_delta = 0;
+
+	if (server_supports("filter")) {
+		server_supports_filtering = 1;
+		print_verbose(args, _("Server supports %s"), "filter");
+	} else if (args->filter_options.choice) {
+		warning("filtering not recognized by server, ignoring");
+	}
+
+	if (server_supports("deepen-since")) {
+		print_verbose(args, _("Server supports %s"), "deepen-since");
+		deepen_since_ok = 1;
+	} else if (args->deepen_since)
+		die(_("Server does not support --shallow-since"));
+	if (server_supports("deepen-not")) {
+		print_verbose(args, _("Server supports %s"), "deepen-not");
+		deepen_not_ok = 1;
+	} else if (args->deepen_not)
+		die(_("Server does not support --shallow-exclude"));
+	if (server_supports("deepen-relative"))
+		print_verbose(args, _("Server supports %s"), "deepen-relative");
+	else if (args->deepen_relative)
+		die(_("Server does not support --deepen"));
+
+	if (!args->no_dependents) {
+		mark_complete_and_common_ref(&negotiator, args, &ref);
+		filter_refs(args, &ref, sought, nr_sought);
+		if (everything_local(args, &ref)) {
+			packet_flush(fd[1]);
+			goto all_done;
+		}
+	} else {
+		filter_refs(args, &ref, sought, nr_sought);
+	}
+	if (find_common(&negotiator, args, fd, &oid, ref) < 0)
+		if (!args->keep_pack)
+			/* When cloning, it is not unusual to have
+			 * no common commit.
+			 */
+			warning(_("no common commits"));
+
+	if (args->stateless_rpc)
+		packet_flush(fd[1]);
+	if (args->deepen)
+		setup_alternate_shallow(&shallow_lock, &alternate_shallow_file,
+					NULL);
+	else if (si->nr_ours || si->nr_theirs)
+		alternate_shallow_file = setup_temporary_shallow(si->shallow);
+	else
+		alternate_shallow_file = NULL;
+	if (get_pack(args, fd, pack_lockfile))
+		die(_("git fetch-pack: fetch failed."));
+
+ all_done:
+	negotiator.release(&negotiator);
+	return ref;
+}
+
+static void add_shallow_requests(struct strbuf *req_buf,
+				 const struct fetch_pack_args *args)
+{
+	if (is_repository_shallow(the_repository))
+		write_shallow_commits(req_buf, 1, NULL);
+	if (args->depth > 0)
+		packet_buf_write(req_buf, "deepen %d", args->depth);
+	if (args->deepen_since) {
+		timestamp_t max_age = approxidate(args->deepen_since);
+		packet_buf_write(req_buf, "deepen-since %"PRItime, max_age);
+	}
+	if (args->deepen_not) {
+		int i;
+		for (i = 0; i < args->deepen_not->nr; i++) {
+			struct string_list_item *s = args->deepen_not->items + i;
+			packet_buf_write(req_buf, "deepen-not %s", s->string);
+		}
+	}
+	if (args->deepen_relative)
+		packet_buf_write(req_buf, "deepen-relative\n");
+}
+
+static void add_wants(int no_dependents, const struct ref *wants, struct strbuf *req_buf)
+{
+	int use_ref_in_want = server_supports_feature("fetch", "ref-in-want", 0);
+
+	for ( ; wants ; wants = wants->next) {
+		const struct object_id *remote = &wants->old_oid;
+		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.
+		 *
+		 * Do this only if args->no_dependents is false (if it is true,
+		 * we cannot trust the object flags).
+		 */
+		if (!no_dependents &&
+		    ((o = lookup_object(the_repository, remote)) != NULL) &&
+		    (o->flags & COMPLETE)) {
+			continue;
+		}
+
+		if (!use_ref_in_want || wants->exact_oid)
+			packet_buf_write(req_buf, "want %s\n", oid_to_hex(remote));
+		else
+			packet_buf_write(req_buf, "want-ref %s\n", wants->name);
+	}
+}
+
+static void add_common(struct strbuf *req_buf, struct oidset *common)
+{
+	struct oidset_iter iter;
+	const struct object_id *oid;
+	oidset_iter_init(common, &iter);
+
+	while ((oid = oidset_iter_next(&iter))) {
+		packet_buf_write(req_buf, "have %s\n", oid_to_hex(oid));
+	}
+}
+
+static int add_haves(struct fetch_negotiator *negotiator,
+		     struct strbuf *req_buf,
+		     int *haves_to_send, int *in_vain)
+{
+	int ret = 0;
+	int haves_added = 0;
+	const struct object_id *oid;
+
+	while ((oid = negotiator->next(negotiator))) {
+		packet_buf_write(req_buf, "have %s\n", oid_to_hex(oid));
+		if (++haves_added >= *haves_to_send)
+			break;
+	}
+
+	*in_vain += haves_added;
+	if (!haves_added || *in_vain >= MAX_IN_VAIN) {
+		/* Send Done */
+		packet_buf_write(req_buf, "done\n");
+		ret = 1;
+	}
+
+	/* Increase haves to send on next round */
+	*haves_to_send = next_flush(1, *haves_to_send);
+
+	return ret;
+}
+
+static int send_fetch_request(struct fetch_negotiator *negotiator, int fd_out,
+			      const struct fetch_pack_args *args,
+			      const struct ref *wants, struct oidset *common,
+			      int *haves_to_send, int *in_vain,
+			      int sideband_all)
+{
+	int ret = 0;
+	struct strbuf req_buf = STRBUF_INIT;
+
+	if (server_supports_v2("fetch", 1))
+		packet_buf_write(&req_buf, "command=fetch");
+	if (server_supports_v2("agent", 0))
+		packet_buf_write(&req_buf, "agent=%s", git_user_agent_sanitized());
+	if (args->server_options && args->server_options->nr &&
+	    server_supports_v2("server-option", 1)) {
+		int i;
+		for (i = 0; i < args->server_options->nr; i++)
+			packet_buf_write(&req_buf, "server-option=%s",
+					 args->server_options->items[i].string);
+	}
+
+	packet_buf_delim(&req_buf);
+	if (args->use_thin_pack)
+		packet_buf_write(&req_buf, "thin-pack");
+	if (args->no_progress)
+		packet_buf_write(&req_buf, "no-progress");
+	if (args->include_tag)
+		packet_buf_write(&req_buf, "include-tag");
+	if (prefer_ofs_delta)
+		packet_buf_write(&req_buf, "ofs-delta");
+	if (sideband_all)
+		packet_buf_write(&req_buf, "sideband-all");
+
+	/* Add shallow-info and deepen request */
+	if (server_supports_feature("fetch", "shallow", 0))
+		add_shallow_requests(&req_buf, args);
+	else if (is_repository_shallow(the_repository) || args->deepen)
+		die(_("Server does not support shallow requests"));
+
+	/* Add filter */
+	if (server_supports_feature("fetch", "filter", 0) &&
+	    args->filter_options.choice) {
+		struct strbuf expanded_filter_spec = STRBUF_INIT;
+		print_verbose(args, _("Server supports filter"));
+		expand_list_objects_filter_spec(&args->filter_options,
+						&expanded_filter_spec);
+		packet_buf_write(&req_buf, "filter %s",
+				 expanded_filter_spec.buf);
+		strbuf_release(&expanded_filter_spec);
+	} else if (args->filter_options.choice) {
+		warning("filtering not recognized by server, ignoring");
+	}
+
+	/* add wants */
+	add_wants(args->no_dependents, wants, &req_buf);
+
+	if (args->no_dependents) {
+		packet_buf_write(&req_buf, "done");
+		ret = 1;
+	} else {
+		/* Add all of the common commits we've found in previous rounds */
+		add_common(&req_buf, common);
+
+		/* Add initial haves */
+		ret = add_haves(negotiator, &req_buf, haves_to_send, in_vain);
+	}
+
+	/* Send request */
+	packet_buf_flush(&req_buf);
+	if (write_in_full(fd_out, req_buf.buf, req_buf.len) < 0)
+		die_errno(_("unable to write request to remote"));
+
+	strbuf_release(&req_buf);
+	return ret;
+}
+
+/*
+ * Processes a section header in a server's response and checks if it matches
+ * `section`.  If the value of `peek` is 1, the header line will be peeked (and
+ * not consumed); if 0, the line will be consumed and the function will die if
+ * the section header doesn't match what was expected.
+ */
+static int process_section_header(struct packet_reader *reader,
+				  const char *section, int peek)
+{
+	int ret;
+
+	if (packet_reader_peek(reader) != PACKET_READ_NORMAL)
+		die(_("error reading section header '%s'"), section);
+
+	ret = !strcmp(reader->line, section);
+
+	if (!peek) {
+		if (!ret)
+			die(_("expected '%s', received '%s'"),
+			    section, reader->line);
+		packet_reader_read(reader);
+	}
+
+	return ret;
+}
+
+static int process_acks(struct fetch_negotiator *negotiator,
+			struct packet_reader *reader,
+			struct oidset *common)
+{
+	/* received */
+	int received_ready = 0;
+	int received_ack = 0;
+
+	process_section_header(reader, "acknowledgments", 0);
+	while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
+		const char *arg;
+
+		if (!strcmp(reader->line, "NAK"))
+			continue;
+
+		if (skip_prefix(reader->line, "ACK ", &arg)) {
+			struct object_id oid;
+			if (!get_oid_hex(arg, &oid)) {
+				struct commit *commit;
+				oidset_insert(common, &oid);
+				commit = lookup_commit(the_repository, &oid);
+				negotiator->ack(negotiator, commit);
+			}
+			continue;
+		}
+
+		if (!strcmp(reader->line, "ready")) {
+			received_ready = 1;
+			continue;
+		}
+
+		die(_("unexpected acknowledgment line: '%s'"), reader->line);
+	}
+
+	if (reader->status != PACKET_READ_FLUSH &&
+	    reader->status != PACKET_READ_DELIM)
+		die(_("error processing acks: %d"), reader->status);
+
+	/*
+	 * If an "acknowledgments" section is sent, a packfile is sent if and
+	 * only if "ready" was sent in this section. The other sections
+	 * ("shallow-info" and "wanted-refs") are sent only if a packfile is
+	 * sent. Therefore, a DELIM is expected if "ready" is sent, and a FLUSH
+	 * otherwise.
+	 */
+	if (received_ready && reader->status != PACKET_READ_DELIM)
+		die(_("expected packfile to be sent after 'ready'"));
+	if (!received_ready && reader->status != PACKET_READ_FLUSH)
+		die(_("expected no other sections to be sent after no 'ready'"));
+
+	/* return 0 if no common, 1 if there are common, or 2 if ready */
+	return received_ready ? 2 : (received_ack ? 1 : 0);
+}
+
+static void receive_shallow_info(struct fetch_pack_args *args,
+				 struct packet_reader *reader,
+				 struct oid_array *shallows,
+				 struct shallow_info *si)
+{
+	int unshallow_received = 0;
+
+	process_section_header(reader, "shallow-info", 0);
+	while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
+		const char *arg;
+		struct object_id oid;
+
+		if (skip_prefix(reader->line, "shallow ", &arg)) {
+			if (get_oid_hex(arg, &oid))
+				die(_("invalid shallow line: %s"), reader->line);
+			oid_array_append(shallows, &oid);
+			continue;
+		}
+		if (skip_prefix(reader->line, "unshallow ", &arg)) {
+			if (get_oid_hex(arg, &oid))
+				die(_("invalid unshallow line: %s"), reader->line);
+			if (!lookup_object(the_repository, &oid))
+				die(_("object not found: %s"), reader->line);
+			/* make sure that it is parsed as shallow */
+			if (!parse_object(the_repository, &oid))
+				die(_("error in object: %s"), reader->line);
+			if (unregister_shallow(&oid))
+				die(_("no shallow found: %s"), reader->line);
+			unshallow_received = 1;
+			continue;
+		}
+		die(_("expected shallow/unshallow, got %s"), reader->line);
+	}
+
+	if (reader->status != PACKET_READ_FLUSH &&
+	    reader->status != PACKET_READ_DELIM)
+		die(_("error processing shallow info: %d"), reader->status);
+
+	if (args->deepen || unshallow_received) {
+		/*
+		 * Treat these as shallow lines caused by our depth settings.
+		 * In v0, these lines cannot cause refs to be rejected; do the
+		 * same.
+		 */
+		int i;
+
+		for (i = 0; i < shallows->nr; i++)
+			register_shallow(the_repository, &shallows->oid[i]);
+		setup_alternate_shallow(&shallow_lock, &alternate_shallow_file,
+					NULL);
+		args->deepen = 1;
+	} else if (shallows->nr) {
+		/*
+		 * Treat these as shallow lines caused by the remote being
+		 * shallow. In v0, remote refs that reach these objects are
+		 * rejected (unless --update-shallow is set); do the same.
+		 */
+		prepare_shallow_info(si, shallows);
+		if (si->nr_ours || si->nr_theirs)
+			alternate_shallow_file =
+				setup_temporary_shallow(si->shallow);
+		else
+			alternate_shallow_file = NULL;
+	} else {
+		alternate_shallow_file = NULL;
+	}
+}
+
+static int cmp_name_ref(const void *name, const void *ref)
+{
+	return strcmp(name, (*(struct ref **)ref)->name);
+}
+
+static void receive_wanted_refs(struct packet_reader *reader,
+				struct ref **sought, int nr_sought)
+{
+	process_section_header(reader, "wanted-refs", 0);
+	while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
+		struct object_id oid;
+		const char *end;
+		struct ref **found;
+
+		if (parse_oid_hex(reader->line, &oid, &end) || *end++ != ' ')
+			die(_("expected wanted-ref, got '%s'"), reader->line);
+
+		found = bsearch(end, sought, nr_sought, sizeof(*sought),
+				cmp_name_ref);
+		if (!found)
+			die(_("unexpected wanted-ref: '%s'"), reader->line);
+		oidcpy(&(*found)->old_oid, &oid);
+	}
+
+	if (reader->status != PACKET_READ_DELIM)
+		die(_("error processing wanted refs: %d"), reader->status);
+}
+
+enum fetch_state {
+	FETCH_CHECK_LOCAL = 0,
+	FETCH_SEND_REQUEST,
+	FETCH_PROCESS_ACKS,
+	FETCH_GET_PACK,
+	FETCH_DONE,
+};
+
+static struct ref *do_fetch_pack_v2(struct fetch_pack_args *args,
+				    int fd[2],
+				    const struct ref *orig_ref,
+				    struct ref **sought, int nr_sought,
+				    struct oid_array *shallows,
+				    struct shallow_info *si,
+				    char **pack_lockfile)
+{
+	struct ref *ref = copy_ref_list(orig_ref);
+	enum fetch_state state = FETCH_CHECK_LOCAL;
+	struct oidset common = OIDSET_INIT;
+	struct packet_reader reader;
+	int in_vain = 0;
+	int haves_to_send = INITIAL_FLUSH;
+	struct fetch_negotiator negotiator;
+	fetch_negotiator_init(&negotiator, negotiation_algorithm);
+	packet_reader_init(&reader, fd[0], NULL, 0,
+			   PACKET_READ_CHOMP_NEWLINE |
+			   PACKET_READ_DIE_ON_ERR_PACKET);
+	if (git_env_bool("GIT_TEST_SIDEBAND_ALL", 1) &&
+	    server_supports_feature("fetch", "sideband-all", 0)) {
+		reader.use_sideband = 1;
+		reader.me = "fetch-pack";
+	}
+
+	while (state != FETCH_DONE) {
+		switch (state) {
+		case FETCH_CHECK_LOCAL:
+			sort_ref_list(&ref, ref_compare_name);
+			QSORT(sought, nr_sought, cmp_ref_by_name);
+
+			/* v2 supports these by default */
+			allow_unadvertised_object_request |= ALLOW_REACHABLE_SHA1;
+			use_sideband = 2;
+			if (args->depth > 0 || args->deepen_since || args->deepen_not)
+				args->deepen = 1;
+
+			/* Filter 'ref' by 'sought' and those that aren't local */
+			if (!args->no_dependents) {
+				mark_complete_and_common_ref(&negotiator, args, &ref);
+				filter_refs(args, &ref, sought, nr_sought);
+				if (everything_local(args, &ref))
+					state = FETCH_DONE;
+				else
+					state = FETCH_SEND_REQUEST;
+
+				mark_tips(&negotiator, args->negotiation_tips);
+				for_each_cached_alternate(&negotiator,
+							  insert_one_alternate_object);
+			} else {
+				filter_refs(args, &ref, sought, nr_sought);
+				state = FETCH_SEND_REQUEST;
+			}
+			break;
+		case FETCH_SEND_REQUEST:
+			if (send_fetch_request(&negotiator, fd[1], args, ref,
+					       &common,
+					       &haves_to_send, &in_vain,
+					       reader.use_sideband))
+				state = FETCH_GET_PACK;
+			else
+				state = FETCH_PROCESS_ACKS;
+			break;
+		case FETCH_PROCESS_ACKS:
+			/* Process ACKs/NAKs */
+			switch (process_acks(&negotiator, &reader, &common)) {
+			case 2:
+				state = FETCH_GET_PACK;
+				break;
+			case 1:
+				in_vain = 0;
+				/* fallthrough */
+			default:
+				state = FETCH_SEND_REQUEST;
+				break;
+			}
+			break;
+		case FETCH_GET_PACK:
+			/* Check for shallow-info section */
+			if (process_section_header(&reader, "shallow-info", 1))
+				receive_shallow_info(args, &reader, shallows, si);
+
+			if (process_section_header(&reader, "wanted-refs", 1))
+				receive_wanted_refs(&reader, sought, nr_sought);
+
+			/* get the pack */
+			process_section_header(&reader, "packfile", 0);
+			if (get_pack(args, fd, pack_lockfile))
+				die(_("git fetch-pack: fetch failed."));
+
+			state = FETCH_DONE;
+			break;
+		case FETCH_DONE:
+			continue;
+		}
+	}
+
+	negotiator.release(&negotiator);
+	oidset_clear(&common);
+	return ref;
+}
+
+static int fetch_pack_config_cb(const char *var, const char *value, void *cb)
+{
+	if (strcmp(var, "fetch.fsck.skiplist") == 0) {
+		const char *path;
+
+		if (git_config_pathname(&path, var, value))
+			return 1;
+		strbuf_addf(&fsck_msg_types, "%cskiplist=%s",
+			fsck_msg_types.len ? ',' : '=', path);
+		free((char *)path);
+		return 0;
+	}
+
+	if (skip_prefix(var, "fetch.fsck.", &var)) {
+		if (is_valid_msg_type(var, value))
+			strbuf_addf(&fsck_msg_types, "%c%s=%s",
+				fsck_msg_types.len ? ',' : '=', var, value);
+		else
+			warning("Skipping unknown msg id '%s'", var);
+		return 0;
+	}
+
+	return git_default_config(var, value, cb);
+}
+
+static void fetch_pack_config(void)
+{
+	git_config_get_int("fetch.unpacklimit", &fetch_unpack_limit);
+	git_config_get_int("transfer.unpacklimit", &transfer_unpack_limit);
+	git_config_get_bool("repack.usedeltabaseoffset", &prefer_ofs_delta);
+	git_config_get_bool("fetch.fsckobjects", &fetch_fsck_objects);
+	git_config_get_bool("transfer.fsckobjects", &transfer_fsck_objects);
+	git_config_get_string("fetch.negotiationalgorithm",
+			      &negotiation_algorithm);
+
+	git_config(fetch_pack_config_cb, NULL);
+}
+
+static void fetch_pack_setup(void)
+{
+	static int did_setup;
+	if (did_setup)
+		return;
+	fetch_pack_config();
+	if (0 <= transfer_unpack_limit)
+		unpack_limit = transfer_unpack_limit;
+	else if (0 <= fetch_unpack_limit)
+		unpack_limit = fetch_unpack_limit;
+	did_setup = 1;
+}
+
+static int remove_duplicates_in_refs(struct ref **ref, int nr)
+{
+	struct string_list names = STRING_LIST_INIT_NODUP;
+	int src, dst;
+
+	for (src = dst = 0; src < nr; src++) {
+		struct string_list_item *item;
+		item = string_list_insert(&names, ref[src]->name);
+		if (item->util)
+			continue; /* already have it */
+		item->util = ref[src];
+		if (src != dst)
+			ref[dst] = ref[src];
+		dst++;
+	}
+	for (src = dst; src < nr; src++)
+		ref[src] = NULL;
+	string_list_clear(&names, 0);
+	return dst;
+}
+
+static void update_shallow(struct fetch_pack_args *args,
+			   struct ref **sought, int nr_sought,
+			   struct shallow_info *si)
+{
+	struct oid_array ref = OID_ARRAY_INIT;
+	int *status;
+	int i;
+
+	if (args->deepen && alternate_shallow_file) {
+		if (*alternate_shallow_file == '\0') { /* --unshallow */
+			unlink_or_warn(git_path_shallow(the_repository));
+			rollback_lock_file(&shallow_lock);
+		} else
+			commit_lock_file(&shallow_lock);
+		alternate_shallow_file = NULL;
+		return;
+	}
+
+	if (!si->shallow || !si->shallow->nr)
+		return;
+
+	if (args->cloning) {
+		/*
+		 * remote is shallow, but this is a clone, there are
+		 * no objects in repo to worry about. Accept any
+		 * shallow points that exist in the pack (iow in repo
+		 * after get_pack() and reprepare_packed_git())
+		 */
+		struct oid_array extra = OID_ARRAY_INIT;
+		struct object_id *oid = si->shallow->oid;
+		for (i = 0; i < si->shallow->nr; i++)
+			if (has_object_file(&oid[i]))
+				oid_array_append(&extra, &oid[i]);
+		if (extra.nr) {
+			setup_alternate_shallow(&shallow_lock,
+						&alternate_shallow_file,
+						&extra);
+			commit_lock_file(&shallow_lock);
+			alternate_shallow_file = NULL;
+		}
+		oid_array_clear(&extra);
+		return;
+	}
+
+	if (!si->nr_ours && !si->nr_theirs)
+		return;
+
+	remove_nonexistent_theirs_shallow(si);
+	if (!si->nr_ours && !si->nr_theirs)
+		return;
+	for (i = 0; i < nr_sought; i++)
+		oid_array_append(&ref, &sought[i]->old_oid);
+	si->ref = &ref;
+
+	if (args->update_shallow) {
+		/*
+		 * remote is also shallow, .git/shallow may be updated
+		 * so all refs can be accepted. Make sure we only add
+		 * shallow roots that are actually reachable from new
+		 * refs.
+		 */
+		struct oid_array extra = OID_ARRAY_INIT;
+		struct object_id *oid = si->shallow->oid;
+		assign_shallow_commits_to_refs(si, NULL, NULL);
+		if (!si->nr_ours && !si->nr_theirs) {
+			oid_array_clear(&ref);
+			return;
+		}
+		for (i = 0; i < si->nr_ours; i++)
+			oid_array_append(&extra, &oid[si->ours[i]]);
+		for (i = 0; i < si->nr_theirs; i++)
+			oid_array_append(&extra, &oid[si->theirs[i]]);
+		setup_alternate_shallow(&shallow_lock,
+					&alternate_shallow_file,
+					&extra);
+		commit_lock_file(&shallow_lock);
+		oid_array_clear(&extra);
+		oid_array_clear(&ref);
+		alternate_shallow_file = NULL;
+		return;
+	}
+
+	/*
+	 * remote is also shallow, check what ref is safe to update
+	 * without updating .git/shallow
+	 */
+	status = xcalloc(nr_sought, sizeof(*status));
+	assign_shallow_commits_to_refs(si, NULL, status);
+	if (si->nr_ours || si->nr_theirs) {
+		for (i = 0; i < nr_sought; i++)
+			if (status[i])
+				sought[i]->status = REF_STATUS_REJECT_SHALLOW;
+	}
+	free(status);
+	oid_array_clear(&ref);
+}
+
+static int iterate_ref_map(void *cb_data, struct object_id *oid)
+{
+	struct ref **rm = cb_data;
+	struct ref *ref = *rm;
+
+	if (!ref)
+		return -1; /* end of the list */
+	*rm = ref->next;
+	oidcpy(oid, &ref->old_oid);
+	return 0;
+}
+
+struct ref *fetch_pack(struct fetch_pack_args *args,
+		       int fd[],
+		       const struct ref *ref,
+		       struct ref **sought, int nr_sought,
+		       struct oid_array *shallow,
+		       char **pack_lockfile,
+		       enum protocol_version version)
+{
+	struct ref *ref_cpy;
+	struct shallow_info si;
+	struct oid_array shallows_scratch = OID_ARRAY_INIT;
+
+	fetch_pack_setup();
+	if (nr_sought)
+		nr_sought = remove_duplicates_in_refs(sought, nr_sought);
+
+	if (args->no_dependents && !args->filter_options.choice) {
+		/*
+		 * The protocol does not support requesting that only the
+		 * wanted objects be sent, so approximate this by setting a
+		 * "blob:none" filter if no filter is already set. This works
+		 * for all object types: note that wanted blobs will still be
+		 * sent because they are directly specified as a "want".
+		 *
+		 * NEEDSWORK: Add an option in the protocol to request that
+		 * only the wanted objects be sent, and implement it.
+		 */
+		parse_list_objects_filter(&args->filter_options, "blob:none");
+	}
+
+	if (version != protocol_v2 && !ref) {
+		packet_flush(fd[1]);
+		die(_("no matching remote head"));
+	}
+	if (version == protocol_v2) {
+		if (shallow->nr)
+			BUG("Protocol V2 does not provide shallows at this point in the fetch");
+		memset(&si, 0, sizeof(si));
+		ref_cpy = do_fetch_pack_v2(args, fd, ref, sought, nr_sought,
+					   &shallows_scratch, &si,
+					   pack_lockfile);
+	} else {
+		prepare_shallow_info(&si, shallow);
+		ref_cpy = do_fetch_pack(args, fd, ref, sought, nr_sought,
+					&si, pack_lockfile);
+	}
+	reprepare_packed_git(the_repository);
+
+	if (!args->cloning && args->deepen) {
+		struct check_connected_options opt = CHECK_CONNECTED_INIT;
+		struct ref *iterator = ref_cpy;
+		opt.shallow_file = alternate_shallow_file;
+		if (args->deepen)
+			opt.is_deepening_fetch = 1;
+		if (check_connected(iterate_ref_map, &iterator, &opt)) {
+			error(_("remote did not send all necessary objects"));
+			free_refs(ref_cpy);
+			ref_cpy = NULL;
+			rollback_lock_file(&shallow_lock);
+			goto cleanup;
+		}
+		args->connectivity_checked = 1;
+	}
+
+	update_shallow(args, sought, nr_sought, &si);
+cleanup:
+	clear_shallow_info(&si);
+	oid_array_clear(&shallows_scratch);
+	return ref_cpy;
+}
+
+int report_unmatched_refs(struct ref **sought, int nr_sought)
+{
+	int i, ret = 0;
+
+	for (i = 0; i < nr_sought; i++) {
+		if (!sought[i])
+			continue;
+		switch (sought[i]->match_status) {
+		case REF_MATCHED:
+			continue;
+		case REF_NOT_MATCHED:
+			error(_("no such remote ref %s"), sought[i]->name);
+			break;
+		case REF_UNADVERTISED_NOT_ALLOWED:
+			error(_("Server does not allow request for unadvertised object %s"),
+			      sought[i]->name);
+			break;
+		}
+		ret = 1;
+	}
+	return ret;
+}