#define USE_THE_REPOSITORY_VARIABLE
#define DISABLE_SIGN_COMPARE_WARNINGS

#include "git-compat-util.h"
#include "repository.h"
#include "config.h"
#include "date.h"
#include "environment.h"
#include "gettext.h"
#include "hex.h"
#include "lockfile.h"
#include "refs.h"
#include "pkt-line.h"
#include "commit.h"
#include "tag.h"
#include "pack.h"
#include "sideband.h"
#include "fetch-pack.h"
#include "remote.h"
#include "run-command.h"
#include "connect.h"
#include "trace2.h"
#include "version.h"
#include "oid-array.h"
#include "oidset.h"
#include "packfile.h"
#include "odb.h"
#include "path.h"
#include "connected.h"
#include "fetch-negotiator.h"
#include "fsck.h"
#include "shallow.h"
#include "commit-reach.h"
#include "commit-graph.h"
#include "sigchain.h"
#include "mergesort.h"
#include "prio-queue.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 int advertise_sid;
static struct shallow_lock shallow_lock;
static const char *alternate_shallow_file;
static struct fsck_options fsck_options = FSCK_OPTIONS_MISSING_GITMODULES;
static struct strbuf fsck_msg_types = STRBUF_INIT;
static struct string_list uri_protocols = STRING_LIST_INIT_DUP;

/* Remember to update object flag allocation in object.h */
#define COMPLETE	(1U << 0)
#define ALTERNATE	(1U << 1)
#define COMMON		(1U << 6)
#define REACH_SCRATCH	(1U << 7)

/*
 * 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) {
		odb_for_each_alternate_ref(the_repository->objects,
					   cache_one_alternate, &cache);
		initialized = 1;
	}

	for (i = 0; i < cache.nr; i++)
		cb(negotiator, cache.items[i]);
}

static void die_in_commit_graph_only(const struct object_id *oid)
{
	die(_("You are attempting to fetch %s, which is in the commit graph file but not in the object database.\n"
	      "This is probably due to repo corruption.\n"
	      "If you are attempting to repair this repo corruption by refetching the missing object, use 'git fetch --refetch' with the missing object."),
	      oid_to_hex(oid));
}

static struct commit *deref_without_lazy_fetch(const struct object_id *oid,
					       int mark_tags_complete_and_check_obj_db)
{
	enum object_type type;
	struct object_info info = { .typep = &type };
	struct commit *commit;

	commit = lookup_commit_in_graph(the_repository, oid);
	if (commit) {
		if (mark_tags_complete_and_check_obj_db) {
			if (!odb_has_object(the_repository->objects, oid,
					    HAS_OBJECT_RECHECK_PACKED))
				die_in_commit_graph_only(oid);
		}
		return commit;
	}

	while (1) {
		if (odb_read_object_info_extended(the_repository->objects, oid, &info,
						  OBJECT_INFO_SKIP_FETCH_OBJECT | OBJECT_INFO_QUICK))
			return NULL;
		if (type == OBJ_TAG) {
			struct tag *tag = (struct tag *)
				parse_object(the_repository, oid);

			if (!tag->tagged)
				return NULL;
			if (mark_tags_complete_and_check_obj_db)
				tag->object.flags |= COMPLETE;
			oid = &tag->tagged->oid;
		} else {
			break;
		}
	}

	if (type == OBJ_COMMIT) {
		struct commit *commit = lookup_commit(the_repository, oid);
		if (!commit || repo_parse_commit(the_repository, commit))
			return NULL;
		return commit;
	}

	return NULL;
}

static int rev_list_insert_ref(struct fetch_negotiator *negotiator,
			       const struct object_id *oid)
{
	struct commit *c = deref_without_lazy_fetch(oid, 0);

	if (c)
		negotiator->add_tip(negotiator, c);
	return 0;
}

static int rev_list_insert_ref_oid(const struct reference *ref, void *cb_data)
{
	return rev_list_insert_ref(cb_data, ref->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)) {
		const char *p;
		if (!parse_oid_hex(arg, result_oid, &p)) {
			len -= p - reader->line;
			if (len < 1)
				return ACK;
			if (strstr(p, "continue"))
				return ACK_continue;
			if (strstr(p, "common"))
				return ACK_common;
			if (strstr(p, "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, &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) {
		refs_for_each_rawref(get_main_ref_store(the_repository),
				     rev_list_insert_ref_oid, negotiator);
		return;
	}

	for (i = 0; i < negotiation_tips->nr; i++)
		rev_list_insert_ref(negotiator, &negotiation_tips->oid[i]);
	return;
}

static void send_filter(struct fetch_pack_args *args,
			struct strbuf *req_buf,
			int server_supports_filter)
{
	if (args->filter_options.choice) {
		const char *spec =
			expand_list_objects_filter_spec(&args->filter_options);
		if (server_supports_filter) {
			print_verbose(args, _("Server supports filter"));
			packet_buf_write(req_buf, "filter %s", spec);
			trace2_data_string("fetch", the_repository,
					   "filter/effective", spec);
		} else {
			warning("filtering not recognized by server, ignoring");
			trace2_data_string("fetch", the_repository,
					   "filter/unsupported", spec);
		}
	} else {
		trace2_data_string("fetch", the_repository,
				   "filter/none", "");
	}
}

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;
	int negotiation_round = 0, haves = 0;
	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(_("the option '%s' requires '%s'"), "--stateless-rpc", "multi_ack_detailed");

	packet_reader_init(&reader, fd[0], NULL, 0,
			   PACKET_READ_CHOMP_NEWLINE |
			   PACKET_READ_DIE_ON_ERR_PACKET);

	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 (!args->refetch) {
			/*
			* 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(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 (advertise_sid)
				strbuf_addf(&c, " session-id=%s", trace2_session_id());
			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);
		}
	}
	send_filter(args, &req_buf, server_supports_filtering);
	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;
	}

	trace2_region_enter("fetch-pack", "negotiation_v0_v1", the_repository);
	flushes = 0;
	retval = -1;
	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++;
		haves++;
		if (flush_at <= ++count) {
			int ack;

			negotiation_round++;
			trace2_region_enter_printf("negotiation_v0_v1", "round",
						   the_repository, "%d",
						   negotiation_round);
			trace2_data_intmax("negotiation_v0_v1", the_repository,
					   "haves_added", haves);
			trace2_data_intmax("negotiation_v0_v1", the_repository,
					   "in_vain", in_vain);
			haves = 0;
			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:
					trace2_region_leave_printf("negotiation_v0_v1", "round",
								   the_repository, "%d",
								   negotiation_round);
					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;
						haves++;
						/*
						 * 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--;
			trace2_region_leave_printf("negotiation_v0_v1", "round",
						   the_repository, "%d",
						   negotiation_round);
			if (got_continue && MAX_IN_VAIN < in_vain) {
				print_verbose(args, _("giving up"));
				break; /* give up */
			}
			if (got_ready)
				break;
		}
	}
done:
	trace2_region_leave("fetch-pack", "negotiation_v0_v1", the_repository);
	trace2_data_intmax("negotiation_v0_v1", the_repository, "total_rounds",
			   negotiation_round);
	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 prio_queue complete = { compare_commits_by_commit_date };

static int mark_complete(const struct object_id *oid)
{
	struct commit *commit = deref_without_lazy_fetch(oid, 1);

	if (commit && !(commit->object.flags & COMPLETE)) {
		commit->object.flags |= COMPLETE;
		prio_queue_put(&complete, commit);
	}
	return 0;
}

static int mark_complete_oid(const struct reference *ref, void *cb_data UNUSED)
{
	return mark_complete(ref->oid);
}

static void mark_recent_complete_commits(struct fetch_pack_args *args,
					 timestamp_t cutoff)
{
	while (complete.nr) {
		struct commit *item = prio_queue_peek(&complete);
		if (item->date < cutoff)
			break;
		print_verbose(args, _("Marking %s as complete"),
			      oid_to_hex(&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 *negotiator UNUSED,
				    struct object *obj)
{
	mark_complete(&obj->oid);
}

/*
 * Mark recent commits available locally and reachable from a local ref as
 * COMPLETE.
 *
 * 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;

	if (args->refetch)
		return;

	save_commit_buffer = 0;

	trace2_region_enter("fetch-pack", "parse_remote_refs_and_find_cutoff", NULL);
	for (ref = *refs; ref; ref = ref->next) {
		struct commit *commit;

		commit = lookup_commit_in_graph(the_repository, &ref->old_oid);
		if (!commit) {
			struct object *o;

			if (!odb_has_object(the_repository->objects, &ref->old_oid, 0))
				continue;
			o = parse_object(the_repository, &ref->old_oid);
			if (!o || o->type != OBJ_COMMIT)
				continue;

			commit = (struct commit *)o;
		}

		/*
		 * 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 (!cutoff || cutoff < commit->date)
			cutoff = commit->date;
	}
	trace2_region_leave("fetch-pack", "parse_remote_refs_and_find_cutoff", NULL);

	/*
	 * This block marks all local refs as COMPLETE, and then recursively marks all
	 * parents of those refs as COMPLETE.
	 */
	trace2_region_enter("fetch-pack", "mark_complete_local_refs", NULL);
	if (!args->deepen) {
		refs_for_each_rawref(get_main_ref_store(the_repository),
				     mark_complete_oid, NULL);
		for_each_cached_alternate(NULL, mark_alternate_complete);
		if (cutoff)
			mark_recent_complete_commits(args, cutoff);
	}
	trace2_region_leave("fetch-pack", "mark_complete_local_refs", NULL);

	/*
	 * Mark all complete remote refs as common refs.
	 * Don't mark them common yet; the server has to be told so first.
	 */
	trace2_region_enter("fetch-pack", "mark_common_remote_refs", NULL);
	for (ref = *refs; ref; ref = ref->next) {
		struct commit *c = deref_without_lazy_fetch(&ref->old_oid, 0);

		if (!c || !(c->object.flags & COMPLETE))
			continue;

		negotiator->known_common(negotiator, c);
	}
	trace2_region_leave("fetch-pack", "mark_common_remote_refs", NULL);

	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 UNUSED, int out, void *data)
{
	int *xd = data;
	int ret;

	ret = recv_sideband("fetch-pack", xd[0], out);
	close(out);
	return ret;
}

static void create_promisor_file(const char *keep_name,
				 struct ref **sought, int nr_sought)
{
	struct strbuf promisor_name = STRBUF_INIT;
	int suffix_stripped;

	strbuf_addstr(&promisor_name, keep_name);
	suffix_stripped = strbuf_strip_suffix(&promisor_name, ".keep");
	if (!suffix_stripped)
		BUG("name of pack lockfile should end with .keep (was '%s')",
		    keep_name);
	strbuf_addstr(&promisor_name, ".promisor");

	write_promisor_file(promisor_name.buf, sought, nr_sought);

	strbuf_release(&promisor_name);
}

static void parse_gitmodules_oids(int fd, struct oidset *gitmodules_oids)
{
	int len = the_hash_algo->hexsz + 1; /* hash + NL */

	do {
		char hex_hash[GIT_MAX_HEXSZ + 1];
		int read_len = read_in_full(fd, hex_hash, len);
		struct object_id oid;
		const char *end;

		if (!read_len)
			return;
		if (read_len != len)
			die("invalid length read %d", read_len);
		if (parse_oid_hex(hex_hash, &oid, &end) || *end != '\n')
			die("invalid hash");
		oidset_insert(gitmodules_oids, &oid);
	} while (1);
}

static void add_index_pack_keep_option(struct strvec *args)
{
	char hostname[HOST_NAME_MAX + 1];

	if (xgethostname(hostname, sizeof(hostname)))
		xsnprintf(hostname, sizeof(hostname), "localhost");
	strvec_pushf(args, "--keep=fetch-pack %"PRIuMAX " on %s",
		     (uintmax_t)getpid(), hostname);
}

/*
 * If packfile URIs were provided, pass a non-NULL pointer to index_pack_args.
 * The strings to pass as the --index-pack-arg arguments to http-fetch will be
 * stored there. (It must be freed by the caller.)
 */
static int get_pack(struct fetch_pack_args *args,
		    int xd[2], struct string_list *pack_lockfiles,
		    struct strvec *index_pack_args,
		    struct ref **sought, int nr_sought,
		    struct oidset *gitmodules_oids)
{
	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 fsck_objects = 0;
	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 && !index_pack_args) {

		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) {
		strvec_push(&cmd.args, "--shallow-file");
		strvec_push(&cmd.args, alternate_shallow_file);
	}

	fsck_objects = fetch_pack_fsck_objects();

	if (do_keep || args->from_promisor || index_pack_args || fsck_objects) {
		if (pack_lockfiles || fsck_objects)
			cmd.out = -1;
		cmd_name = "index-pack";
		strvec_push(&cmd.args, cmd_name);
		strvec_push(&cmd.args, "--stdin");
		if (!args->quiet && !args->no_progress)
			strvec_push(&cmd.args, "-v");
		if (args->use_thin_pack)
			strvec_push(&cmd.args, "--fix-thin");
		if ((do_keep || index_pack_args) && (args->lock_pack || unpack_limit))
			add_index_pack_keep_option(&cmd.args);
		if (!index_pack_args && args->check_self_contained_and_connected)
			strvec_push(&cmd.args, "--check-self-contained-and-connected");
		else
			/*
			 * We cannot perform any connectivity checks because
			 * not all packs have been downloaded; let the caller
			 * have this responsibility.
			 */
			args->check_self_contained_and_connected = 0;

		if (args->from_promisor)
			/*
			 * create_promisor_file() may be called afterwards but
			 * we still need index-pack to know that this is a
			 * promisor pack. For example, if transfer.fsckobjects
			 * is true, index-pack needs to know that .gitmodules
			 * is a promisor object (so that it won't complain if
			 * it is missing).
			 */
			strvec_push(&cmd.args, "--promisor");
	}
	else {
		cmd_name = "unpack-objects";
		strvec_push(&cmd.args, cmd_name);
		if (args->quiet || args->no_progress)
			strvec_push(&cmd.args, "-q");
		args->check_self_contained_and_connected = 0;
	}

	if (pass_header)
		strvec_pushf(&cmd.args, "--pack_header=%"PRIu32",%"PRIu32,
			     ntohl(header.hdr_version),
				 ntohl(header.hdr_entries));
	if (fsck_objects) {
		if (args->from_promisor || index_pack_args)
			/*
			 * We cannot use --strict in index-pack because it
			 * checks both broken objects and links, but we only
			 * want to check for broken objects.
			 */
			strvec_push(&cmd.args, "--fsck-objects");
		else
			strvec_pushf(&cmd.args, "--strict%s",
				     fsck_msg_types.buf);
	}

	if (index_pack_args) {
		int i;

		for (i = 0; i < cmd.args.nr; i++)
			strvec_push(index_pack_args, cmd.args.v[i]);
	}

	sigchain_push(SIGPIPE, SIG_IGN);

	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_lockfiles || fsck_objects)) {
		int is_well_formed;
		char *pack_lockfile = index_pack_lockfile(the_repository,
							  cmd.out,
							  &is_well_formed);

		if (!is_well_formed)
			die(_("fetch-pack: invalid index-pack output"));
		if (pack_lockfiles && pack_lockfile)
			string_list_append_nodup(pack_lockfiles, pack_lockfile);
		else
			free(pack_lockfile);
		parse_gitmodules_oids(cmd.out, gitmodules_oids);
		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"));

	sigchain_pop(SIGPIPE);

	/*
	 * Now that index-pack has succeeded, write the promisor file using the
	 * obtained .keep filename if necessary
	 */
	if (do_keep && pack_lockfiles && pack_lockfiles->nr && args->from_promisor)
		create_promisor_file(pack_lockfiles->items[0].string, sought, nr_sought);

	return 0;
}

static int ref_compare_name(const struct ref *a, const struct ref *b)
{
	return strcmp(a->name, b->name);
}

DEFINE_LIST_SORT(static, sort_ref_list, struct ref, next);

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,
				 struct string_list *pack_lockfiles)
{
	struct repository *r = the_repository;
	struct ref *ref = copy_ref_list(orig_ref);
	struct object_id oid;
	const char *agent_feature;
	size_t agent_len;
	struct fetch_negotiator negotiator_alloc;
	struct fetch_negotiator *negotiator;

	negotiator = &negotiator_alloc;
	if (args->refetch) {
		fetch_negotiator_init_noop(negotiator);
	} else {
		fetch_negotiator_init(r, negotiator);
	}

	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"),
				      (int)agent_len, agent_feature);
	}

	if (!server_supports("session-id"))
		advertise_sid = 0;

	if (server_supports("shallow"))
		print_verbose(args, _("Server supports %s"), "shallow");
	else if (args->depth > 0 || is_repository_shallow(r))
		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 (!server_supports_hash(the_hash_algo->name, NULL))
		die(_("Server does not support this repository's object format"));

	mark_complete_and_common_ref(negotiator, args, &ref);
	filter_refs(args, &ref, sought, nr_sought);
	if (!args->refetch && everything_local(args, &ref)) {
		packet_flush(fd[1]);
		goto all_done;
	}
	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) {
		if (args->reject_shallow_remote)
			die(_("source repository is shallow, reject to clone."));
		alternate_shallow_file = setup_temporary_shallow(si->shallow);
	} else
		alternate_shallow_file = NULL;
	if (get_pack(args, fd, pack_lockfiles, NULL, sought, nr_sought,
		     &fsck_options.gitmodules_found))
		die(_("git fetch-pack: fetch failed."));
	if (fsck_finish(&fsck_options))
		die("fsck failed");

 all_done:
	if (negotiator)
		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(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.
		 */
		if (((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 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;
	}

	/* Increase haves to send on next round */
	*haves_to_send = next_flush(1, *haves_to_send);

	return haves_added;
}

static void write_fetch_command_and_capabilities(struct strbuf *req_buf,
						 const struct string_list *server_options)
{
	const char *hash_name;

	ensure_server_supports_v2("fetch");
	packet_buf_write(req_buf, "command=fetch");
	if (server_supports_v2("agent"))
		packet_buf_write(req_buf, "agent=%s", git_user_agent_sanitized());
	if (advertise_sid && server_supports_v2("session-id"))
		packet_buf_write(req_buf, "session-id=%s", trace2_session_id());
	if (server_options && server_options->nr) {
		int i;
		ensure_server_supports_v2("server-option");
		for (i = 0; i < server_options->nr; i++)
			packet_buf_write(req_buf, "server-option=%s",
					 server_options->items[i].string);
	}

	if (server_feature_v2("object-format", &hash_name)) {
		int hash_algo = hash_algo_by_name(hash_name);
		if (hash_algo_by_ptr(the_hash_algo) != hash_algo)
			die(_("mismatched algorithms: client %s; server %s"),
			    the_hash_algo->name, hash_name);
		packet_buf_write(req_buf, "object-format=%s", the_hash_algo->name);
	} else if (hash_algo_by_ptr(the_hash_algo) != GIT_HASH_SHA1_LEGACY) {
		die(_("the server does not support algorithm '%s'"),
		    the_hash_algo->name);
	}
	packet_buf_delim(req_buf);
}

static int send_fetch_request(struct fetch_negotiator *negotiator, int fd_out,
			      struct fetch_pack_args *args,
			      const struct ref *wants, struct oidset *common,
			      int *haves_to_send, int *in_vain,
			      int sideband_all, int seen_ack)
{
	int haves_added;
	int done_sent = 0;
	struct strbuf req_buf = STRBUF_INIT;

	write_fetch_command_and_capabilities(&req_buf, args->server_options);

	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 */
	send_filter(args, &req_buf,
		    server_supports_feature("fetch", "filter", 0));

	if (server_supports_feature("fetch", "packfile-uris", 0)) {
		int i;
		struct strbuf to_send = STRBUF_INIT;

		for (i = 0; i < uri_protocols.nr; i++) {
			const char *s = uri_protocols.items[i].string;

			if (!strcmp(s, "https") || !strcmp(s, "http")) {
				if (to_send.len)
					strbuf_addch(&to_send, ',');
				strbuf_addstr(&to_send, s);
			}
		}
		if (to_send.len) {
			packet_buf_write(&req_buf, "packfile-uris %s",
					 to_send.buf);
			strbuf_release(&to_send);
		}
	}

	/* add wants */
	add_wants(wants, &req_buf);

	/* Add all of the common commits we've found in previous rounds */
	add_common(&req_buf, common);

	haves_added = add_haves(negotiator, &req_buf, haves_to_send);
	*in_vain += haves_added;
	trace2_data_intmax("negotiation_v2", the_repository, "haves_added", haves_added);
	trace2_data_intmax("negotiation_v2", the_repository, "in_vain", *in_vain);
	if (!haves_added || (seen_ack && *in_vain >= MAX_IN_VAIN)) {
		/* Send Done */
		packet_buf_write(&req_buf, "done\n");
		done_sent = 1;
	}

	/* 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 done_sent;
}

/*
 * 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 = 0;

	if (packet_reader_peek(reader) == PACKET_READ_NORMAL &&
	    !strcmp(reader->line, section))
		ret = 1;

	if (!peek) {
		if (!ret) {
			if (reader->line)
				die(_("expected '%s', received '%s'"),
				    section, reader->line);
			else
				die(_("expected '%s'"), section);
		}
		packet_reader_read(reader);
	}

	return ret;
}

static int process_ack(struct fetch_negotiator *negotiator,
		       struct packet_reader *reader,
		       struct object_id *common_oid,
		       int *received_ready)
{
	while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
		const char *arg;

		if (!strcmp(reader->line, "NAK"))
			continue;

		if (skip_prefix(reader->line, "ACK ", &arg)) {
			if (!get_oid_hex(arg, common_oid)) {
				struct commit *commit;
				commit = lookup_commit(the_repository, common_oid);
				if (negotiator)
					negotiator->ack(negotiator, commit);
			}
			return 1;
		}

		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)
		/*
		 * TRANSLATORS: The parameter will be 'ready', a protocol
		 * keyword.
		 */
		die(_("expected packfile to be sent after '%s'"), "ready");
	if (!*received_ready && reader->status != PACKET_READ_FLUSH)
		/*
		 * TRANSLATORS: The parameter will be 'ready', a protocol
		 * keyword.
		 */
		die(_("expected no other sections to be sent after no '%s'"), "ready");

	return 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) {
			if (args->reject_shallow_remote)
				die(_("source repository is shallow, reject to clone."));
			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);
}

static void receive_packfile_uris(struct packet_reader *reader,
				  struct string_list *uris)
{
	process_section_header(reader, "packfile-uris", 0);
	while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
		if (reader->pktlen < the_hash_algo->hexsz ||
		    reader->line[the_hash_algo->hexsz] != ' ')
			die("expected '<hash> <uri>', got: %s", reader->line);

		string_list_append(uris, reader->line);
	}
	if (reader->status != PACKET_READ_DELIM)
		die("expected DELIM");
}

enum fetch_state {
	FETCH_CHECK_LOCAL = 0,
	FETCH_SEND_REQUEST,
	FETCH_PROCESS_ACKS,
	FETCH_GET_PACK,
	FETCH_DONE,
};

static void do_check_stateless_delimiter(int stateless_rpc,
					 struct packet_reader *reader)
{
	check_stateless_delimiter(stateless_rpc, reader,
				  _("git fetch-pack: expected response end packet"));
}

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,
				    struct string_list *pack_lockfiles)
{
	struct repository *r = the_repository;
	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, negotiation_started = 0;
	int negotiation_round = 0;
	int haves_to_send = INITIAL_FLUSH;
	struct fetch_negotiator negotiator_alloc;
	struct fetch_negotiator *negotiator;
	int seen_ack = 0;
	struct object_id common_oid;
	int received_ready = 0;
	struct string_list packfile_uris = STRING_LIST_INIT_DUP;
	int i;
	struct strvec index_pack_args = STRVEC_INIT;

	negotiator = &negotiator_alloc;
	if (args->refetch)
		fetch_negotiator_init_noop(negotiator);
	else
		fetch_negotiator_init(r, negotiator);

	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 */
			mark_complete_and_common_ref(negotiator, args, &ref);
			filter_refs(args, &ref, sought, nr_sought);
			if (!args->refetch && 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);
			break;
		case FETCH_SEND_REQUEST:
			if (!negotiation_started) {
				negotiation_started = 1;
				trace2_region_enter("fetch-pack",
						    "negotiation_v2",
						    the_repository);
			}
			negotiation_round++;
			trace2_region_enter_printf("negotiation_v2", "round",
						   the_repository, "%d",
						   negotiation_round);
			if (send_fetch_request(negotiator, fd[1], args, ref,
					       &common,
					       &haves_to_send, &in_vain,
					       reader.use_sideband,
					       seen_ack)) {
				trace2_region_leave_printf("negotiation_v2", "round",
							   the_repository, "%d",
							   negotiation_round);
				state = FETCH_GET_PACK;
			}
			else
				state = FETCH_PROCESS_ACKS;
			break;
		case FETCH_PROCESS_ACKS:
			/* Process ACKs/NAKs */
			process_section_header(&reader, "acknowledgments", 0);
			while (process_ack(negotiator, &reader, &common_oid,
					   &received_ready)) {
				in_vain = 0;
				seen_ack = 1;
				oidset_insert(&common, &common_oid);
			}
			trace2_region_leave_printf("negotiation_v2", "round",
						   the_repository, "%d",
						   negotiation_round);
			if (received_ready) {
				/*
				 * Don't check for response delimiter; get_pack() will
				 * read the rest of this response.
				 */
				state = FETCH_GET_PACK;
			} else {
				do_check_stateless_delimiter(args->stateless_rpc, &reader);
				state = FETCH_SEND_REQUEST;
			}
			break;
		case FETCH_GET_PACK:
			trace2_region_leave("fetch-pack",
					    "negotiation_v2",
					    the_repository);
			trace2_data_intmax("negotiation_v2", the_repository,
					   "total_rounds", negotiation_round);
			/* 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(s) */
			if (git_env_bool("GIT_TRACE_REDACT", 1))
				reader.options |= PACKET_READ_REDACT_URI_PATH;
			if (process_section_header(&reader, "packfile-uris", 1))
				receive_packfile_uris(&reader, &packfile_uris);
			/* We don't expect more URIs. Reset to avoid expensive URI check. */
			reader.options &= ~PACKET_READ_REDACT_URI_PATH;

			process_section_header(&reader, "packfile", 0);

			/*
			 * this is the final request we'll make of the server;
			 * do a half-duplex shutdown to indicate that they can
			 * hang up as soon as the pack is sent.
			 */
			close(fd[1]);
			fd[1] = -1;

			if (get_pack(args, fd, pack_lockfiles,
				     packfile_uris.nr ? &index_pack_args : NULL,
				     sought, nr_sought, &fsck_options.gitmodules_found))
				die(_("git fetch-pack: fetch failed."));
			do_check_stateless_delimiter(args->stateless_rpc, &reader);

			state = FETCH_DONE;
			break;
		case FETCH_DONE:
			continue;
		}
	}

	for (i = 0; i < packfile_uris.nr; i++) {
		int j;
		struct child_process cmd = CHILD_PROCESS_INIT;
		char packname[GIT_MAX_HEXSZ + 1];
		const char *uri = packfile_uris.items[i].string +
			the_hash_algo->hexsz + 1;

		strvec_push(&cmd.args, "http-fetch");
		strvec_pushf(&cmd.args, "--packfile=%.*s",
			     (int) the_hash_algo->hexsz,
			     packfile_uris.items[i].string);
		for (j = 0; j < index_pack_args.nr; j++)
			strvec_pushf(&cmd.args, "--index-pack-arg=%s",
				     index_pack_args.v[j]);
		strvec_push(&cmd.args, uri);
		cmd.git_cmd = 1;
		cmd.no_stdin = 1;
		cmd.out = -1;
		if (start_command(&cmd))
			die("fetch-pack: unable to spawn http-fetch");

		if (read_in_full(cmd.out, packname, 5) < 0 ||
		    memcmp(packname, "keep\t", 5))
			die("fetch-pack: expected keep then TAB at start of http-fetch output");

		if (read_in_full(cmd.out, packname,
				 the_hash_algo->hexsz + 1) < 0 ||
		    packname[the_hash_algo->hexsz] != '\n')
			die("fetch-pack: expected hash then LF at end of http-fetch output");

		packname[the_hash_algo->hexsz] = '\0';

		parse_gitmodules_oids(cmd.out, &fsck_options.gitmodules_found);

		close(cmd.out);

		if (finish_command(&cmd))
			die("fetch-pack: unable to finish http-fetch");

		if (memcmp(packfile_uris.items[i].string, packname,
			   the_hash_algo->hexsz))
			die("fetch-pack: pack downloaded from %s does not match expected hash %.*s",
			    uri, (int) the_hash_algo->hexsz,
			    packfile_uris.items[i].string);

		string_list_append_nodup(pack_lockfiles,
					 xstrfmt("%s/pack/pack-%s.keep",
						 repo_get_object_directory(the_repository),
						 packname));
	}
	string_list_clear(&packfile_uris, 0);
	strvec_clear(&index_pack_args);

	if (fsck_finish(&fsck_options))
		die("fsck failed");

	if (negotiator)
		negotiator->release(negotiator);

	oidset_clear(&common);
	return ref;
}

int fetch_pack_fsck_config(const char *var, const char *value,
			   struct strbuf *msg_types)
{
	const char *msg_id;

	if (strcmp(var, "fetch.fsck.skiplist") == 0) {
		char *path ;

		if (git_config_pathname(&path, var, value))
			return -1;
		if (path)
			strbuf_addf(msg_types, "%cskiplist=%s",
				    msg_types->len ? ',' : '=', path);
		free(path);
		return 0;
	}

	if (skip_prefix(var, "fetch.fsck.", &msg_id)) {
		if (!value)
			return config_error_nonbool(var);
		if (is_valid_msg_type(msg_id, value))
			strbuf_addf(msg_types, "%c%s=%s",
				msg_types->len ? ',' : '=', msg_id, value);
		else
			warning("Skipping unknown msg id '%s'", msg_id);
		return 0;
	}

	return 1;
}

static int fetch_pack_config_cb(const char *var, const char *value,
				const struct config_context *ctx, void *cb)
{
	int ret = fetch_pack_fsck_config(var, value, &fsck_msg_types);
	if (ret > 0)
		return git_default_config(var, value, ctx, cb);

	return ret;
}

static void fetch_pack_config(void)
{
	repo_config_get_int(the_repository, "fetch.unpacklimit", &fetch_unpack_limit);
	repo_config_get_int(the_repository, "transfer.unpacklimit", &transfer_unpack_limit);
	repo_config_get_bool(the_repository, "repack.usedeltabaseoffset", &prefer_ofs_delta);
	repo_config_get_bool(the_repository, "fetch.fsckobjects", &fetch_fsck_objects);
	repo_config_get_bool(the_repository, "transfer.fsckobjects", &transfer_fsck_objects);
	repo_config_get_bool(the_repository, "transfer.advertisesid", &advertise_sid);
	if (!uri_protocols.nr) {
		char *str;

		if (!repo_config_get_string(the_repository, "fetch.uriprotocols", &str) && str) {
			string_list_split(&uri_protocols, str, ",", -1);
			free(str);
		}
	}

	repo_config(the_repository, fetch_pack_config_cb, NULL);
}

static void fetch_pack_setup(void)
{
	static int did_setup;
	if (did_setup)
		return;
	fetch_pack_config();
	if (0 <= fetch_unpack_limit)
		unpack_limit = fetch_unpack_limit;
	else if (0 <= transfer_unpack_limit)
		unpack_limit = transfer_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_shallow_file(the_repository, &shallow_lock);
		} else
			commit_shallow_file(the_repository, &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 odb_reprepare())
		 */
		struct oid_array extra = OID_ARRAY_INIT;
		struct object_id *oid = si->shallow->oid;
		for (i = 0; i < si->shallow->nr; i++)
			if (odb_has_object(the_repository->objects, &oid[i],
					   HAS_OBJECT_RECHECK_PACKED | HAS_OBJECT_FETCH_PROMISOR))
				oid_array_append(&extra, &oid[i]);
		if (extra.nr) {
			setup_alternate_shallow(&shallow_lock,
						&alternate_shallow_file,
						&extra);
			commit_shallow_file(the_repository, &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_shallow_file(the_repository, &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
	 */
	CALLOC_ARRAY(status, nr_sought);
	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 const struct object_id *iterate_ref_map(void *cb_data)
{
	struct ref **rm = cb_data;
	struct ref *ref = *rm;

	if (!ref)
		return NULL;
	*rm = ref->next;
	return &ref->old_oid;
}

int fetch_pack_fsck_objects(void)
{
	fetch_pack_setup();
	if (fetch_fsck_objects >= 0)
		return fetch_fsck_objects;
	if (transfer_fsck_objects >= 0)
		return transfer_fsck_objects;
	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,
		       struct string_list *pack_lockfiles,
		       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 (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_lockfiles);
	} else {
		prepare_shallow_info(&si, shallow);
		ref_cpy = do_fetch_pack(args, fd, ref, sought, nr_sought,
					&si, pack_lockfiles);
	}
	odb_reprepare(the_repository->objects);

	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_shallow_file(the_repository, &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;
}

static int add_to_object_array(const struct object_id *oid, void *data)
{
	struct object_array *a = data;

	add_object_array(lookup_object(the_repository, oid), "", a);
	return 0;
}

static void clear_common_flag(struct oidset *s)
{
	struct oidset_iter iter;
	const struct object_id *oid;
	oidset_iter_init(s, &iter);

	while ((oid = oidset_iter_next(&iter))) {
		struct object *obj = lookup_object(the_repository, oid);
		obj->flags &= ~COMMON;
	}
}

void negotiate_using_fetch(const struct oid_array *negotiation_tips,
			   const struct string_list *server_options,
			   int stateless_rpc,
			   int fd[],
			   struct oidset *acked_commits)
{
	struct fetch_negotiator negotiator;
	struct packet_reader reader;
	struct object_array nt_object_array = OBJECT_ARRAY_INIT;
	struct strbuf req_buf = STRBUF_INIT;
	int haves_to_send = INITIAL_FLUSH;
	int in_vain = 0;
	int seen_ack = 0;
	int last_iteration = 0;
	int negotiation_round = 0;
	timestamp_t min_generation = GENERATION_NUMBER_INFINITY;

	fetch_negotiator_init(the_repository, &negotiator);
	mark_tips(&negotiator, negotiation_tips);

	packet_reader_init(&reader, fd[0], NULL, 0,
			   PACKET_READ_CHOMP_NEWLINE |
			   PACKET_READ_DIE_ON_ERR_PACKET);

	oid_array_for_each((struct oid_array *) negotiation_tips,
			   add_to_object_array,
			   &nt_object_array);

	trace2_region_enter("fetch-pack", "negotiate_using_fetch", the_repository);
	while (!last_iteration) {
		int haves_added;
		struct object_id common_oid;
		int received_ready = 0;

		negotiation_round++;

		trace2_region_enter_printf("negotiate_using_fetch", "round",
					   the_repository, "%d",
					   negotiation_round);
		strbuf_reset(&req_buf);
		write_fetch_command_and_capabilities(&req_buf, server_options);

		packet_buf_write(&req_buf, "wait-for-done");

		haves_added = add_haves(&negotiator, &req_buf, &haves_to_send);
		in_vain += haves_added;
		if (!haves_added || (seen_ack && in_vain >= MAX_IN_VAIN))
			last_iteration = 1;

		trace2_data_intmax("negotiate_using_fetch", the_repository,
				   "haves_added", haves_added);
		trace2_data_intmax("negotiate_using_fetch", the_repository,
				   "in_vain", in_vain);

		/* Send request */
		packet_buf_flush(&req_buf);
		if (write_in_full(fd[1], req_buf.buf, req_buf.len) < 0)
			die_errno(_("unable to write request to remote"));

		/* Process ACKs/NAKs */
		process_section_header(&reader, "acknowledgments", 0);
		while (process_ack(&negotiator, &reader, &common_oid,
				   &received_ready)) {
			struct commit *commit = lookup_commit(the_repository,
							      &common_oid);
			if (commit) {
				timestamp_t generation;

				parse_commit_or_die(commit);
				commit->object.flags |= COMMON;
				generation = commit_graph_generation(commit);
				if (generation < min_generation)
					min_generation = generation;
			}
			in_vain = 0;
			seen_ack = 1;
			oidset_insert(acked_commits, &common_oid);
		}
		if (received_ready)
			die(_("unexpected 'ready' from remote"));
		else
			do_check_stateless_delimiter(stateless_rpc, &reader);
		if (can_all_from_reach_with_flag(&nt_object_array, COMMON,
						 REACH_SCRATCH, 0,
						 min_generation))
			last_iteration = 1;
		trace2_region_leave_printf("negotiation", "round",
					   the_repository, "%d",
					   negotiation_round);
	}
	trace2_region_leave("fetch-pack", "negotiate_using_fetch", the_repository);
	trace2_data_intmax("negotiate_using_fetch", the_repository,
			   "total_rounds", negotiation_round);

	clear_common_flag(acked_commits);
	object_array_clear(&nt_object_array);
	negotiator.release(&negotiator);
	strbuf_release(&req_buf);
}

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;
}
