merge(third_party/git): Merge squashed git subtree at v2.23.0 r/373

Merge commit '1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5' as 'third_party/git'

1 files changed, 2061 insertions, 0 deletions

diff --git a/third_party/git/builtin/receive-pack.c b/third_party/git/builtin/receive-pack.c
new file mode 100644
index 000000000000..dcf385511f07
--- /dev/null
+++ b/third_party/git/builtin/receive-pack.c
@@ -0,0 +1,2061 @@
+#include "builtin.h"
+#include "repository.h"
+#include "config.h"
+#include "lockfile.h"
+#include "pack.h"
+#include "refs.h"
+#include "pkt-line.h"
+#include "sideband.h"
+#include "run-command.h"
+#include "exec-cmd.h"
+#include "commit.h"
+#include "object.h"
+#include "remote.h"
+#include "connect.h"
+#include "string-list.h"
+#include "sha1-array.h"
+#include "connected.h"
+#include "argv-array.h"
+#include "version.h"
+#include "tag.h"
+#include "gpg-interface.h"
+#include "sigchain.h"
+#include "fsck.h"
+#include "tmp-objdir.h"
+#include "oidset.h"
+#include "packfile.h"
+#include "object-store.h"
+#include "protocol.h"
+#include "commit-reach.h"
+
+static const char * const receive_pack_usage[] = {
+	N_("git receive-pack <git-dir>"),
+	NULL
+};
+
+enum deny_action {
+	DENY_UNCONFIGURED,
+	DENY_IGNORE,
+	DENY_WARN,
+	DENY_REFUSE,
+	DENY_UPDATE_INSTEAD
+};
+
+static int deny_deletes;
+static int deny_non_fast_forwards;
+static enum deny_action deny_current_branch = DENY_UNCONFIGURED;
+static enum deny_action deny_delete_current = DENY_UNCONFIGURED;
+static int receive_fsck_objects = -1;
+static int transfer_fsck_objects = -1;
+static struct strbuf fsck_msg_types = STRBUF_INIT;
+static int receive_unpack_limit = -1;
+static int transfer_unpack_limit = -1;
+static int advertise_atomic_push = 1;
+static int advertise_push_options;
+static int unpack_limit = 100;
+static off_t max_input_size;
+static int report_status;
+static int use_sideband;
+static int use_atomic;
+static int use_push_options;
+static int quiet;
+static int prefer_ofs_delta = 1;
+static int auto_update_server_info;
+static int auto_gc = 1;
+static int reject_thin;
+static int stateless_rpc;
+static const char *service_dir;
+static const char *head_name;
+static void *head_name_to_free;
+static int sent_capabilities;
+static int shallow_update;
+static const char *alt_shallow_file;
+static struct strbuf push_cert = STRBUF_INIT;
+static struct object_id push_cert_oid;
+static struct signature_check sigcheck;
+static const char *push_cert_nonce;
+static const char *cert_nonce_seed;
+
+static const char *NONCE_UNSOLICITED = "UNSOLICITED";
+static const char *NONCE_BAD = "BAD";
+static const char *NONCE_MISSING = "MISSING";
+static const char *NONCE_OK = "OK";
+static const char *NONCE_SLOP = "SLOP";
+static const char *nonce_status;
+static long nonce_stamp_slop;
+static timestamp_t nonce_stamp_slop_limit;
+static struct ref_transaction *transaction;
+
+static enum {
+	KEEPALIVE_NEVER = 0,
+	KEEPALIVE_AFTER_NUL,
+	KEEPALIVE_ALWAYS
+} use_keepalive;
+static int keepalive_in_sec = 5;
+
+static struct tmp_objdir *tmp_objdir;
+
+static enum deny_action parse_deny_action(const char *var, const char *value)
+{
+	if (value) {
+		if (!strcasecmp(value, "ignore"))
+			return DENY_IGNORE;
+		if (!strcasecmp(value, "warn"))
+			return DENY_WARN;
+		if (!strcasecmp(value, "refuse"))
+			return DENY_REFUSE;
+		if (!strcasecmp(value, "updateinstead"))
+			return DENY_UPDATE_INSTEAD;
+	}
+	if (git_config_bool(var, value))
+		return DENY_REFUSE;
+	return DENY_IGNORE;
+}
+
+static int receive_pack_config(const char *var, const char *value, void *cb)
+{
+	int status = parse_hide_refs_config(var, value, "receive");
+
+	if (status)
+		return status;
+
+	if (strcmp(var, "receive.denydeletes") == 0) {
+		deny_deletes = git_config_bool(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "receive.denynonfastforwards") == 0) {
+		deny_non_fast_forwards = git_config_bool(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "receive.unpacklimit") == 0) {
+		receive_unpack_limit = git_config_int(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "transfer.unpacklimit") == 0) {
+		transfer_unpack_limit = git_config_int(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "receive.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, "receive.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;
+	}
+
+	if (strcmp(var, "receive.fsckobjects") == 0) {
+		receive_fsck_objects = git_config_bool(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "transfer.fsckobjects") == 0) {
+		transfer_fsck_objects = git_config_bool(var, value);
+		return 0;
+	}
+
+	if (!strcmp(var, "receive.denycurrentbranch")) {
+		deny_current_branch = parse_deny_action(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "receive.denydeletecurrent") == 0) {
+		deny_delete_current = parse_deny_action(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "repack.usedeltabaseoffset") == 0) {
+		prefer_ofs_delta = git_config_bool(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "receive.updateserverinfo") == 0) {
+		auto_update_server_info = git_config_bool(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "receive.autogc") == 0) {
+		auto_gc = git_config_bool(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "receive.shallowupdate") == 0) {
+		shallow_update = git_config_bool(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "receive.certnonceseed") == 0)
+		return git_config_string(&cert_nonce_seed, var, value);
+
+	if (strcmp(var, "receive.certnonceslop") == 0) {
+		nonce_stamp_slop_limit = git_config_ulong(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "receive.advertiseatomic") == 0) {
+		advertise_atomic_push = git_config_bool(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "receive.advertisepushoptions") == 0) {
+		advertise_push_options = git_config_bool(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "receive.keepalive") == 0) {
+		keepalive_in_sec = git_config_int(var, value);
+		return 0;
+	}
+
+	if (strcmp(var, "receive.maxinputsize") == 0) {
+		max_input_size = git_config_int64(var, value);
+		return 0;
+	}
+
+	return git_default_config(var, value, cb);
+}
+
+static void show_ref(const char *path, const struct object_id *oid)
+{
+	if (sent_capabilities) {
+		packet_write_fmt(1, "%s %s\n", oid_to_hex(oid), path);
+	} else {
+		struct strbuf cap = STRBUF_INIT;
+
+		strbuf_addstr(&cap,
+			      "report-status delete-refs side-band-64k quiet");
+		if (advertise_atomic_push)
+			strbuf_addstr(&cap, " atomic");
+		if (prefer_ofs_delta)
+			strbuf_addstr(&cap, " ofs-delta");
+		if (push_cert_nonce)
+			strbuf_addf(&cap, " push-cert=%s", push_cert_nonce);
+		if (advertise_push_options)
+			strbuf_addstr(&cap, " push-options");
+		strbuf_addf(&cap, " agent=%s", git_user_agent_sanitized());
+		packet_write_fmt(1, "%s %s%c%s\n",
+			     oid_to_hex(oid), path, 0, cap.buf);
+		strbuf_release(&cap);
+		sent_capabilities = 1;
+	}
+}
+
+static int show_ref_cb(const char *path_full, const struct object_id *oid,
+		       int flag, void *data)
+{
+	struct oidset *seen = data;
+	const char *path = strip_namespace(path_full);
+
+	if (ref_is_hidden(path, path_full))
+		return 0;
+
+	/*
+	 * Advertise refs outside our current namespace as ".have"
+	 * refs, so that the client can use them to minimize data
+	 * transfer but will otherwise ignore them.
+	 */
+	if (!path) {
+		if (oidset_insert(seen, oid))
+			return 0;
+		path = ".have";
+	} else {
+		oidset_insert(seen, oid);
+	}
+	show_ref(path, oid);
+	return 0;
+}
+
+static void show_one_alternate_ref(const struct object_id *oid,
+				   void *data)
+{
+	struct oidset *seen = data;
+
+	if (oidset_insert(seen, oid))
+		return;
+
+	show_ref(".have", oid);
+}
+
+static void write_head_info(void)
+{
+	static struct oidset seen = OIDSET_INIT;
+
+	for_each_ref(show_ref_cb, &seen);
+	for_each_alternate_ref(show_one_alternate_ref, &seen);
+	oidset_clear(&seen);
+	if (!sent_capabilities)
+		show_ref("capabilities^{}", &null_oid);
+
+	advertise_shallow_grafts(1);
+
+	/* EOF */
+	packet_flush(1);
+}
+
+struct command {
+	struct command *next;
+	const char *error_string;
+	unsigned int skip_update:1,
+		     did_not_exist:1;
+	int index;
+	struct object_id old_oid;
+	struct object_id new_oid;
+	char ref_name[FLEX_ARRAY]; /* more */
+};
+
+static void rp_error(const char *err, ...) __attribute__((format (printf, 1, 2)));
+static void rp_warning(const char *err, ...) __attribute__((format (printf, 1, 2)));
+
+static void report_message(const char *prefix, const char *err, va_list params)
+{
+	int sz;
+	char msg[4096];
+
+	sz = xsnprintf(msg, sizeof(msg), "%s", prefix);
+	sz += vsnprintf(msg + sz, sizeof(msg) - sz, err, params);
+	if (sz > (sizeof(msg) - 1))
+		sz = sizeof(msg) - 1;
+	msg[sz++] = '\n';
+
+	if (use_sideband)
+		send_sideband(1, 2, msg, sz, use_sideband);
+	else
+		xwrite(2, msg, sz);
+}
+
+static void rp_warning(const char *err, ...)
+{
+	va_list params;
+	va_start(params, err);
+	report_message("warning: ", err, params);
+	va_end(params);
+}
+
+static void rp_error(const char *err, ...)
+{
+	va_list params;
+	va_start(params, err);
+	report_message("error: ", err, params);
+	va_end(params);
+}
+
+static int copy_to_sideband(int in, int out, void *arg)
+{
+	char data[128];
+	int keepalive_active = 0;
+
+	if (keepalive_in_sec <= 0)
+		use_keepalive = KEEPALIVE_NEVER;
+	if (use_keepalive == KEEPALIVE_ALWAYS)
+		keepalive_active = 1;
+
+	while (1) {
+		ssize_t sz;
+
+		if (keepalive_active) {
+			struct pollfd pfd;
+			int ret;
+
+			pfd.fd = in;
+			pfd.events = POLLIN;
+			ret = poll(&pfd, 1, 1000 * keepalive_in_sec);
+
+			if (ret < 0) {
+				if (errno == EINTR)
+					continue;
+				else
+					break;
+			} else if (ret == 0) {
+				/* no data; send a keepalive packet */
+				static const char buf[] = "0005\1";
+				write_or_die(1, buf, sizeof(buf) - 1);
+				continue;
+			} /* else there is actual data to read */
+		}
+
+		sz = xread(in, data, sizeof(data));
+		if (sz <= 0)
+			break;
+
+		if (use_keepalive == KEEPALIVE_AFTER_NUL && !keepalive_active) {
+			const char *p = memchr(data, '\0', sz);
+			if (p) {
+				/*
+				 * The NUL tells us to start sending keepalives. Make
+				 * sure we send any other data we read along
+				 * with it.
+				 */
+				keepalive_active = 1;
+				send_sideband(1, 2, data, p - data, use_sideband);
+				send_sideband(1, 2, p + 1, sz - (p - data + 1), use_sideband);
+				continue;
+			}
+		}
+
+		/*
+		 * Either we're not looking for a NUL signal, or we didn't see
+		 * it yet; just pass along the data.
+		 */
+		send_sideband(1, 2, data, sz, use_sideband);
+	}
+	close(in);
+	return 0;
+}
+
+#define HMAC_BLOCK_SIZE 64
+
+static void hmac_sha1(unsigned char *out,
+		      const char *key_in, size_t key_len,
+		      const char *text, size_t text_len)
+{
+	unsigned char key[HMAC_BLOCK_SIZE];
+	unsigned char k_ipad[HMAC_BLOCK_SIZE];
+	unsigned char k_opad[HMAC_BLOCK_SIZE];
+	int i;
+	git_SHA_CTX ctx;
+
+	/* RFC 2104 2. (1) */
+	memset(key, '\0', HMAC_BLOCK_SIZE);
+	if (HMAC_BLOCK_SIZE < key_len) {
+		git_SHA1_Init(&ctx);
+		git_SHA1_Update(&ctx, key_in, key_len);
+		git_SHA1_Final(key, &ctx);
+	} else {
+		memcpy(key, key_in, key_len);
+	}
+
+	/* RFC 2104 2. (2) & (5) */
+	for (i = 0; i < sizeof(key); i++) {
+		k_ipad[i] = key[i] ^ 0x36;
+		k_opad[i] = key[i] ^ 0x5c;
+	}
+
+	/* RFC 2104 2. (3) & (4) */
+	git_SHA1_Init(&ctx);
+	git_SHA1_Update(&ctx, k_ipad, sizeof(k_ipad));
+	git_SHA1_Update(&ctx, text, text_len);
+	git_SHA1_Final(out, &ctx);
+
+	/* RFC 2104 2. (6) & (7) */
+	git_SHA1_Init(&ctx);
+	git_SHA1_Update(&ctx, k_opad, sizeof(k_opad));
+	git_SHA1_Update(&ctx, out, GIT_SHA1_RAWSZ);
+	git_SHA1_Final(out, &ctx);
+}
+
+static char *prepare_push_cert_nonce(const char *path, timestamp_t stamp)
+{
+	struct strbuf buf = STRBUF_INIT;
+	unsigned char sha1[GIT_SHA1_RAWSZ];
+
+	strbuf_addf(&buf, "%s:%"PRItime, path, stamp);
+	hmac_sha1(sha1, buf.buf, buf.len, cert_nonce_seed, strlen(cert_nonce_seed));
+	strbuf_release(&buf);
+
+	/* RFC 2104 5. HMAC-SHA1-80 */
+	strbuf_addf(&buf, "%"PRItime"-%.*s", stamp, GIT_SHA1_HEXSZ, sha1_to_hex(sha1));
+	return strbuf_detach(&buf, NULL);
+}
+
+/*
+ * NEEDSWORK: reuse find_commit_header() from jk/commit-author-parsing
+ * after dropping "_commit" from its name and possibly moving it out
+ * of commit.c
+ */
+static char *find_header(const char *msg, size_t len, const char *key,
+			 const char **next_line)
+{
+	int key_len = strlen(key);
+	const char *line = msg;
+
+	while (line && line < msg + len) {
+		const char *eol = strchrnul(line, '\n');
+
+		if ((msg + len <= eol) || line == eol)
+			return NULL;
+		if (line + key_len < eol &&
+		    !memcmp(line, key, key_len) && line[key_len] == ' ') {
+			int offset = key_len + 1;
+			if (next_line)
+				*next_line = *eol ? eol + 1 : eol;
+			return xmemdupz(line + offset, (eol - line) - offset);
+		}
+		line = *eol ? eol + 1 : NULL;
+	}
+	return NULL;
+}
+
+static const char *check_nonce(const char *buf, size_t len)
+{
+	char *nonce = find_header(buf, len, "nonce", NULL);
+	timestamp_t stamp, ostamp;
+	char *bohmac, *expect = NULL;
+	const char *retval = NONCE_BAD;
+
+	if (!nonce) {
+		retval = NONCE_MISSING;
+		goto leave;
+	} else if (!push_cert_nonce) {
+		retval = NONCE_UNSOLICITED;
+		goto leave;
+	} else if (!strcmp(push_cert_nonce, nonce)) {
+		retval = NONCE_OK;
+		goto leave;
+	}
+
+	if (!stateless_rpc) {
+		/* returned nonce MUST match what we gave out earlier */
+		retval = NONCE_BAD;
+		goto leave;
+	}
+
+	/*
+	 * In stateless mode, we may be receiving a nonce issued by
+	 * another instance of the server that serving the same
+	 * repository, and the timestamps may not match, but the
+	 * nonce-seed and dir should match, so we can recompute and
+	 * report the time slop.
+	 *
+	 * In addition, when a nonce issued by another instance has
+	 * timestamp within receive.certnonceslop seconds, we pretend
+	 * as if we issued that nonce when reporting to the hook.
+	 */
+
+	/* nonce is concat(<seconds-since-epoch>, "-", <hmac>) */
+	if (*nonce <= '0' || '9' < *nonce) {
+		retval = NONCE_BAD;
+		goto leave;
+	}
+	stamp = parse_timestamp(nonce, &bohmac, 10);
+	if (bohmac == nonce || bohmac[0] != '-') {
+		retval = NONCE_BAD;
+		goto leave;
+	}
+
+	expect = prepare_push_cert_nonce(service_dir, stamp);
+	if (strcmp(expect, nonce)) {
+		/* Not what we would have signed earlier */
+		retval = NONCE_BAD;
+		goto leave;
+	}
+
+	/*
+	 * By how many seconds is this nonce stale?  Negative value
+	 * would mean it was issued by another server with its clock
+	 * skewed in the future.
+	 */
+	ostamp = parse_timestamp(push_cert_nonce, NULL, 10);
+	nonce_stamp_slop = (long)ostamp - (long)stamp;
+
+	if (nonce_stamp_slop_limit &&
+	    labs(nonce_stamp_slop) <= nonce_stamp_slop_limit) {
+		/*
+		 * Pretend as if the received nonce (which passes the
+		 * HMAC check, so it is not a forged by third-party)
+		 * is what we issued.
+		 */
+		free((void *)push_cert_nonce);
+		push_cert_nonce = xstrdup(nonce);
+		retval = NONCE_OK;
+	} else {
+		retval = NONCE_SLOP;
+	}
+
+leave:
+	free(nonce);
+	free(expect);
+	return retval;
+}
+
+/*
+ * Return 1 if there is no push_cert or if the push options in push_cert are
+ * the same as those in the argument; 0 otherwise.
+ */
+static int check_cert_push_options(const struct string_list *push_options)
+{
+	const char *buf = push_cert.buf;
+	int len = push_cert.len;
+
+	char *option;
+	const char *next_line;
+	int options_seen = 0;
+
+	int retval = 1;
+
+	if (!len)
+		return 1;
+
+	while ((option = find_header(buf, len, "push-option", &next_line))) {
+		len -= (next_line - buf);
+		buf = next_line;
+		options_seen++;
+		if (options_seen > push_options->nr
+		    || strcmp(option,
+			      push_options->items[options_seen - 1].string)) {
+			retval = 0;
+			goto leave;
+		}
+		free(option);
+	}
+
+	if (options_seen != push_options->nr)
+		retval = 0;
+
+leave:
+	free(option);
+	return retval;
+}
+
+static void prepare_push_cert_sha1(struct child_process *proc)
+{
+	static int already_done;
+
+	if (!push_cert.len)
+		return;
+
+	if (!already_done) {
+		int bogs /* beginning_of_gpg_sig */;
+
+		already_done = 1;
+		if (write_object_file(push_cert.buf, push_cert.len, "blob",
+				      &push_cert_oid))
+			oidclr(&push_cert_oid);
+
+		memset(&sigcheck, '\0', sizeof(sigcheck));
+
+		bogs = parse_signature(push_cert.buf, push_cert.len);
+		check_signature(push_cert.buf, bogs, push_cert.buf + bogs,
+				push_cert.len - bogs, &sigcheck);
+
+		nonce_status = check_nonce(push_cert.buf, bogs);
+	}
+	if (!is_null_oid(&push_cert_oid)) {
+		argv_array_pushf(&proc->env_array, "GIT_PUSH_CERT=%s",
+				 oid_to_hex(&push_cert_oid));
+		argv_array_pushf(&proc->env_array, "GIT_PUSH_CERT_SIGNER=%s",
+				 sigcheck.signer ? sigcheck.signer : "");
+		argv_array_pushf(&proc->env_array, "GIT_PUSH_CERT_KEY=%s",
+				 sigcheck.key ? sigcheck.key : "");
+		argv_array_pushf(&proc->env_array, "GIT_PUSH_CERT_STATUS=%c",
+				 sigcheck.result);
+		if (push_cert_nonce) {
+			argv_array_pushf(&proc->env_array,
+					 "GIT_PUSH_CERT_NONCE=%s",
+					 push_cert_nonce);
+			argv_array_pushf(&proc->env_array,
+					 "GIT_PUSH_CERT_NONCE_STATUS=%s",
+					 nonce_status);
+			if (nonce_status == NONCE_SLOP)
+				argv_array_pushf(&proc->env_array,
+						 "GIT_PUSH_CERT_NONCE_SLOP=%ld",
+						 nonce_stamp_slop);
+		}
+	}
+}
+
+struct receive_hook_feed_state {
+	struct command *cmd;
+	int skip_broken;
+	struct strbuf buf;
+	const struct string_list *push_options;
+};
+
+typedef int (*feed_fn)(void *, const char **, size_t *);
+static int run_and_feed_hook(const char *hook_name, feed_fn feed,
+			     struct receive_hook_feed_state *feed_state)
+{
+	struct child_process proc = CHILD_PROCESS_INIT;
+	struct async muxer;
+	const char *argv[2];
+	int code;
+
+	argv[0] = find_hook(hook_name);
+	if (!argv[0])
+		return 0;
+
+	argv[1] = NULL;
+
+	proc.argv = argv;
+	proc.in = -1;
+	proc.stdout_to_stderr = 1;
+	proc.trace2_hook_name = hook_name;
+
+	if (feed_state->push_options) {
+		int i;
+		for (i = 0; i < feed_state->push_options->nr; i++)
+			argv_array_pushf(&proc.env_array,
+				"GIT_PUSH_OPTION_%d=%s", i,
+				feed_state->push_options->items[i].string);
+		argv_array_pushf(&proc.env_array, "GIT_PUSH_OPTION_COUNT=%d",
+				 feed_state->push_options->nr);
+	} else
+		argv_array_pushf(&proc.env_array, "GIT_PUSH_OPTION_COUNT");
+
+	if (tmp_objdir)
+		argv_array_pushv(&proc.env_array, tmp_objdir_env(tmp_objdir));
+
+	if (use_sideband) {
+		memset(&muxer, 0, sizeof(muxer));
+		muxer.proc = copy_to_sideband;
+		muxer.in = -1;
+		code = start_async(&muxer);
+		if (code)
+			return code;
+		proc.err = muxer.in;
+	}
+
+	prepare_push_cert_sha1(&proc);
+
+	code = start_command(&proc);
+	if (code) {
+		if (use_sideband)
+			finish_async(&muxer);
+		return code;
+	}
+
+	sigchain_push(SIGPIPE, SIG_IGN);
+
+	while (1) {
+		const char *buf;
+		size_t n;
+		if (feed(feed_state, &buf, &n))
+			break;
+		if (write_in_full(proc.in, buf, n) < 0)
+			break;
+	}
+	close(proc.in);
+	if (use_sideband)
+		finish_async(&muxer);
+
+	sigchain_pop(SIGPIPE);
+
+	return finish_command(&proc);
+}
+
+static int feed_receive_hook(void *state_, const char **bufp, size_t *sizep)
+{
+	struct receive_hook_feed_state *state = state_;
+	struct command *cmd = state->cmd;
+
+	while (cmd &&
+	       state->skip_broken && (cmd->error_string || cmd->did_not_exist))
+		cmd = cmd->next;
+	if (!cmd)
+		return -1; /* EOF */
+	strbuf_reset(&state->buf);
+	strbuf_addf(&state->buf, "%s %s %s\n",
+		    oid_to_hex(&cmd->old_oid), oid_to_hex(&cmd->new_oid),
+		    cmd->ref_name);
+	state->cmd = cmd->next;
+	if (bufp) {
+		*bufp = state->buf.buf;
+		*sizep = state->buf.len;
+	}
+	return 0;
+}
+
+static int run_receive_hook(struct command *commands,
+			    const char *hook_name,
+			    int skip_broken,
+			    const struct string_list *push_options)
+{
+	struct receive_hook_feed_state state;
+	int status;
+
+	strbuf_init(&state.buf, 0);
+	state.cmd = commands;
+	state.skip_broken = skip_broken;
+	if (feed_receive_hook(&state, NULL, NULL))
+		return 0;
+	state.cmd = commands;
+	state.push_options = push_options;
+	status = run_and_feed_hook(hook_name, feed_receive_hook, &state);
+	strbuf_release(&state.buf);
+	return status;
+}
+
+static int run_update_hook(struct command *cmd)
+{
+	const char *argv[5];
+	struct child_process proc = CHILD_PROCESS_INIT;
+	int code;
+
+	argv[0] = find_hook("update");
+	if (!argv[0])
+		return 0;
+
+	argv[1] = cmd->ref_name;
+	argv[2] = oid_to_hex(&cmd->old_oid);
+	argv[3] = oid_to_hex(&cmd->new_oid);
+	argv[4] = NULL;
+
+	proc.no_stdin = 1;
+	proc.stdout_to_stderr = 1;
+	proc.err = use_sideband ? -1 : 0;
+	proc.argv = argv;
+	proc.trace2_hook_name = "update";
+
+	code = start_command(&proc);
+	if (code)
+		return code;
+	if (use_sideband)
+		copy_to_sideband(proc.err, -1, NULL);
+	return finish_command(&proc);
+}
+
+static int is_ref_checked_out(const char *ref)
+{
+	if (is_bare_repository())
+		return 0;
+
+	if (!head_name)
+		return 0;
+	return !strcmp(head_name, ref);
+}
+
+static char *refuse_unconfigured_deny_msg =
+	N_("By default, updating the current branch in a non-bare repository\n"
+	   "is denied, because it will make the index and work tree inconsistent\n"
+	   "with what you pushed, and will require 'git reset --hard' to match\n"
+	   "the work tree to HEAD.\n"
+	   "\n"
+	   "You can set the 'receive.denyCurrentBranch' configuration variable\n"
+	   "to 'ignore' or 'warn' in the remote repository to allow pushing into\n"
+	   "its current branch; however, this is not recommended unless you\n"
+	   "arranged to update its work tree to match what you pushed in some\n"
+	   "other way.\n"
+	   "\n"
+	   "To squelch this message and still keep the default behaviour, set\n"
+	   "'receive.denyCurrentBranch' configuration variable to 'refuse'.");
+
+static void refuse_unconfigured_deny(void)
+{
+	rp_error("%s", _(refuse_unconfigured_deny_msg));
+}
+
+static char *refuse_unconfigured_deny_delete_current_msg =
+	N_("By default, deleting the current branch is denied, because the next\n"
+	   "'git clone' won't result in any file checked out, causing confusion.\n"
+	   "\n"
+	   "You can set 'receive.denyDeleteCurrent' configuration variable to\n"
+	   "'warn' or 'ignore' in the remote repository to allow deleting the\n"
+	   "current branch, with or without a warning message.\n"
+	   "\n"
+	   "To squelch this message, you can set it to 'refuse'.");
+
+static void refuse_unconfigured_deny_delete_current(void)
+{
+	rp_error("%s", _(refuse_unconfigured_deny_delete_current_msg));
+}
+
+static int command_singleton_iterator(void *cb_data, struct object_id *oid);
+static int update_shallow_ref(struct command *cmd, struct shallow_info *si)
+{
+	struct lock_file shallow_lock = LOCK_INIT;
+	struct oid_array extra = OID_ARRAY_INIT;
+	struct check_connected_options opt = CHECK_CONNECTED_INIT;
+	uint32_t mask = 1 << (cmd->index % 32);
+	int i;
+
+	trace_printf_key(&trace_shallow,
+			 "shallow: update_shallow_ref %s\n", cmd->ref_name);
+	for (i = 0; i < si->shallow->nr; i++)
+		if (si->used_shallow[i] &&
+		    (si->used_shallow[i][cmd->index / 32] & mask) &&
+		    !delayed_reachability_test(si, i))
+			oid_array_append(&extra, &si->shallow->oid[i]);
+
+	opt.env = tmp_objdir_env(tmp_objdir);
+	setup_alternate_shallow(&shallow_lock, &opt.shallow_file, &extra);
+	if (check_connected(command_singleton_iterator, cmd, &opt)) {
+		rollback_lock_file(&shallow_lock);
+		oid_array_clear(&extra);
+		return -1;
+	}
+
+	commit_lock_file(&shallow_lock);
+
+	/*
+	 * Make sure setup_alternate_shallow() for the next ref does
+	 * not lose these new roots..
+	 */
+	for (i = 0; i < extra.nr; i++)
+		register_shallow(the_repository, &extra.oid[i]);
+
+	si->shallow_ref[cmd->index] = 0;
+	oid_array_clear(&extra);
+	return 0;
+}
+
+/*
+ * NEEDSWORK: we should consolidate various implementions of "are we
+ * on an unborn branch?" test into one, and make the unified one more
+ * robust. !get_sha1() based check used here and elsewhere would not
+ * allow us to tell an unborn branch from corrupt ref, for example.
+ * For the purpose of fixing "deploy-to-update does not work when
+ * pushing into an empty repository" issue, this should suffice for
+ * now.
+ */
+static int head_has_history(void)
+{
+	struct object_id oid;
+
+	return !get_oid("HEAD", &oid);
+}
+
+static const char *push_to_deploy(unsigned char *sha1,
+				  struct argv_array *env,
+				  const char *work_tree)
+{
+	const char *update_refresh[] = {
+		"update-index", "-q", "--ignore-submodules", "--refresh", NULL
+	};
+	const char *diff_files[] = {
+		"diff-files", "--quiet", "--ignore-submodules", "--", NULL
+	};
+	const char *diff_index[] = {
+		"diff-index", "--quiet", "--cached", "--ignore-submodules",
+		NULL, "--", NULL
+	};
+	const char *read_tree[] = {
+		"read-tree", "-u", "-m", NULL, NULL
+	};
+	struct child_process child = CHILD_PROCESS_INIT;
+
+	child.argv = update_refresh;
+	child.env = env->argv;
+	child.dir = work_tree;
+	child.no_stdin = 1;
+	child.stdout_to_stderr = 1;
+	child.git_cmd = 1;
+	if (run_command(&child))
+		return "Up-to-date check failed";
+
+	/* run_command() does not clean up completely; reinitialize */
+	child_process_init(&child);
+	child.argv = diff_files;
+	child.env = env->argv;
+	child.dir = work_tree;
+	child.no_stdin = 1;
+	child.stdout_to_stderr = 1;
+	child.git_cmd = 1;
+	if (run_command(&child))
+		return "Working directory has unstaged changes";
+
+	/* diff-index with either HEAD or an empty tree */
+	diff_index[4] = head_has_history() ? "HEAD" : empty_tree_oid_hex();
+
+	child_process_init(&child);
+	child.argv = diff_index;
+	child.env = env->argv;
+	child.no_stdin = 1;
+	child.no_stdout = 1;
+	child.stdout_to_stderr = 0;
+	child.git_cmd = 1;
+	if (run_command(&child))
+		return "Working directory has staged changes";
+
+	read_tree[3] = sha1_to_hex(sha1);
+	child_process_init(&child);
+	child.argv = read_tree;
+	child.env = env->argv;
+	child.dir = work_tree;
+	child.no_stdin = 1;
+	child.no_stdout = 1;
+	child.stdout_to_stderr = 0;
+	child.git_cmd = 1;
+	if (run_command(&child))
+		return "Could not update working tree to new HEAD";
+
+	return NULL;
+}
+
+static const char *push_to_checkout_hook = "push-to-checkout";
+
+static const char *push_to_checkout(unsigned char *sha1,
+				    struct argv_array *env,
+				    const char *work_tree)
+{
+	argv_array_pushf(env, "GIT_WORK_TREE=%s", absolute_path(work_tree));
+	if (run_hook_le(env->argv, push_to_checkout_hook,
+			sha1_to_hex(sha1), NULL))
+		return "push-to-checkout hook declined";
+	else
+		return NULL;
+}
+
+static const char *update_worktree(unsigned char *sha1)
+{
+	const char *retval;
+	const char *work_tree = git_work_tree_cfg ? git_work_tree_cfg : "..";
+	struct argv_array env = ARGV_ARRAY_INIT;
+
+	if (is_bare_repository())
+		return "denyCurrentBranch = updateInstead needs a worktree";
+
+	argv_array_pushf(&env, "GIT_DIR=%s", absolute_path(get_git_dir()));
+
+	if (!find_hook(push_to_checkout_hook))
+		retval = push_to_deploy(sha1, &env, work_tree);
+	else
+		retval = push_to_checkout(sha1, &env, work_tree);
+
+	argv_array_clear(&env);
+	return retval;
+}
+
+static const char *update(struct command *cmd, struct shallow_info *si)
+{
+	const char *name = cmd->ref_name;
+	struct strbuf namespaced_name_buf = STRBUF_INIT;
+	static char *namespaced_name;
+	const char *ret;
+	struct object_id *old_oid = &cmd->old_oid;
+	struct object_id *new_oid = &cmd->new_oid;
+	int do_update_worktree = 0;
+
+	/* only refs/... are allowed */
+	if (!starts_with(name, "refs/") || check_refname_format(name + 5, 0)) {
+		rp_error("refusing to create funny ref '%s' remotely", name);
+		return "funny refname";
+	}
+
+	strbuf_addf(&namespaced_name_buf, "%s%s", get_git_namespace(), name);
+	free(namespaced_name);
+	namespaced_name = strbuf_detach(&namespaced_name_buf, NULL);
+
+	if (is_ref_checked_out(namespaced_name)) {
+		switch (deny_current_branch) {
+		case DENY_IGNORE:
+			break;
+		case DENY_WARN:
+			rp_warning("updating the current branch");
+			break;
+		case DENY_REFUSE:
+		case DENY_UNCONFIGURED:
+			rp_error("refusing to update checked out branch: %s", name);
+			if (deny_current_branch == DENY_UNCONFIGURED)
+				refuse_unconfigured_deny();
+			return "branch is currently checked out";
+		case DENY_UPDATE_INSTEAD:
+			/* pass -- let other checks intervene first */
+			do_update_worktree = 1;
+			break;
+		}
+	}
+
+	if (!is_null_oid(new_oid) && !has_object_file(new_oid)) {
+		error("unpack should have generated %s, "
+		      "but I can't find it!", oid_to_hex(new_oid));
+		return "bad pack";
+	}
+
+	if (!is_null_oid(old_oid) && is_null_oid(new_oid)) {
+		if (deny_deletes && starts_with(name, "refs/heads/")) {
+			rp_error("denying ref deletion for %s", name);
+			return "deletion prohibited";
+		}
+
+		if (head_name && !strcmp(namespaced_name, head_name)) {
+			switch (deny_delete_current) {
+			case DENY_IGNORE:
+				break;
+			case DENY_WARN:
+				rp_warning("deleting the current branch");
+				break;
+			case DENY_REFUSE:
+			case DENY_UNCONFIGURED:
+			case DENY_UPDATE_INSTEAD:
+				if (deny_delete_current == DENY_UNCONFIGURED)
+					refuse_unconfigured_deny_delete_current();
+				rp_error("refusing to delete the current branch: %s", name);
+				return "deletion of the current branch prohibited";
+			default:
+				return "Invalid denyDeleteCurrent setting";
+			}
+		}
+	}
+
+	if (deny_non_fast_forwards && !is_null_oid(new_oid) &&
+	    !is_null_oid(old_oid) &&
+	    starts_with(name, "refs/heads/")) {
+		struct object *old_object, *new_object;
+		struct commit *old_commit, *new_commit;
+
+		old_object = parse_object(the_repository, old_oid);
+		new_object = parse_object(the_repository, new_oid);
+
+		if (!old_object || !new_object ||
+		    old_object->type != OBJ_COMMIT ||
+		    new_object->type != OBJ_COMMIT) {
+			error("bad sha1 objects for %s", name);
+			return "bad ref";
+		}
+		old_commit = (struct commit *)old_object;
+		new_commit = (struct commit *)new_object;
+		if (!in_merge_bases(old_commit, new_commit)) {
+			rp_error("denying non-fast-forward %s"
+				 " (you should pull first)", name);
+			return "non-fast-forward";
+		}
+	}
+	if (run_update_hook(cmd)) {
+		rp_error("hook declined to update %s", name);
+		return "hook declined";
+	}
+
+	if (do_update_worktree) {
+		ret = update_worktree(new_oid->hash);
+		if (ret)
+			return ret;
+	}
+
+	if (is_null_oid(new_oid)) {
+		struct strbuf err = STRBUF_INIT;
+		if (!parse_object(the_repository, old_oid)) {
+			old_oid = NULL;
+			if (ref_exists(name)) {
+				rp_warning("Allowing deletion of corrupt ref.");
+			} else {
+				rp_warning("Deleting a non-existent ref.");
+				cmd->did_not_exist = 1;
+			}
+		}
+		if (ref_transaction_delete(transaction,
+					   namespaced_name,
+					   old_oid,
+					   0, "push", &err)) {
+			rp_error("%s", err.buf);
+			strbuf_release(&err);
+			return "failed to delete";
+		}
+		strbuf_release(&err);
+		return NULL; /* good */
+	}
+	else {
+		struct strbuf err = STRBUF_INIT;
+		if (shallow_update && si->shallow_ref[cmd->index] &&
+		    update_shallow_ref(cmd, si))
+			return "shallow error";
+
+		if (ref_transaction_update(transaction,
+					   namespaced_name,
+					   new_oid, old_oid,
+					   0, "push",
+					   &err)) {
+			rp_error("%s", err.buf);
+			strbuf_release(&err);
+
+			return "failed to update ref";
+		}
+		strbuf_release(&err);
+
+		return NULL; /* good */
+	}
+}
+
+static void run_update_post_hook(struct command *commands)
+{
+	struct command *cmd;
+	struct child_process proc = CHILD_PROCESS_INIT;
+	const char *hook;
+
+	hook = find_hook("post-update");
+	if (!hook)
+		return;
+
+	for (cmd = commands; cmd; cmd = cmd->next) {
+		if (cmd->error_string || cmd->did_not_exist)
+			continue;
+		if (!proc.args.argc)
+			argv_array_push(&proc.args, hook);
+		argv_array_push(&proc.args, cmd->ref_name);
+	}
+	if (!proc.args.argc)
+		return;
+
+	proc.no_stdin = 1;
+	proc.stdout_to_stderr = 1;
+	proc.err = use_sideband ? -1 : 0;
+	proc.trace2_hook_name = "post-update";
+
+	if (!start_command(&proc)) {
+		if (use_sideband)
+			copy_to_sideband(proc.err, -1, NULL);
+		finish_command(&proc);
+	}
+}
+
+static void check_aliased_update_internal(struct command *cmd,
+					  struct string_list *list,
+					  const char *dst_name, int flag)
+{
+	struct string_list_item *item;
+	struct command *dst_cmd;
+
+	if (!(flag & REF_ISSYMREF))
+		return;
+
+	if (!dst_name) {
+		rp_error("refusing update to broken symref '%s'", cmd->ref_name);
+		cmd->skip_update = 1;
+		cmd->error_string = "broken symref";
+		return;
+	}
+	dst_name = strip_namespace(dst_name);
+
+	if ((item = string_list_lookup(list, dst_name)) == NULL)
+		return;
+
+	cmd->skip_update = 1;
+
+	dst_cmd = (struct command *) item->util;
+
+	if (oideq(&cmd->old_oid, &dst_cmd->old_oid) &&
+	    oideq(&cmd->new_oid, &dst_cmd->new_oid))
+		return;
+
+	dst_cmd->skip_update = 1;
+
+	rp_error("refusing inconsistent update between symref '%s' (%s..%s) and"
+		 " its target '%s' (%s..%s)",
+		 cmd->ref_name,
+		 find_unique_abbrev(&cmd->old_oid, DEFAULT_ABBREV),
+		 find_unique_abbrev(&cmd->new_oid, DEFAULT_ABBREV),
+		 dst_cmd->ref_name,
+		 find_unique_abbrev(&dst_cmd->old_oid, DEFAULT_ABBREV),
+		 find_unique_abbrev(&dst_cmd->new_oid, DEFAULT_ABBREV));
+
+	cmd->error_string = dst_cmd->error_string =
+		"inconsistent aliased update";
+}
+
+static void check_aliased_update(struct command *cmd, struct string_list *list)
+{
+	struct strbuf buf = STRBUF_INIT;
+	const char *dst_name;
+	int flag;
+
+	strbuf_addf(&buf, "%s%s", get_git_namespace(), cmd->ref_name);
+	dst_name = resolve_ref_unsafe(buf.buf, 0, NULL, &flag);
+	check_aliased_update_internal(cmd, list, dst_name, flag);
+	strbuf_release(&buf);
+}
+
+static void check_aliased_updates(struct command *commands)
+{
+	struct command *cmd;
+	struct string_list ref_list = STRING_LIST_INIT_NODUP;
+
+	for (cmd = commands; cmd; cmd = cmd->next) {
+		struct string_list_item *item =
+			string_list_append(&ref_list, cmd->ref_name);
+		item->util = (void *)cmd;
+	}
+	string_list_sort(&ref_list);
+
+	for (cmd = commands; cmd; cmd = cmd->next) {
+		if (!cmd->error_string)
+			check_aliased_update(cmd, &ref_list);
+	}
+
+	string_list_clear(&ref_list, 0);
+}
+
+static int command_singleton_iterator(void *cb_data, struct object_id *oid)
+{
+	struct command **cmd_list = cb_data;
+	struct command *cmd = *cmd_list;
+
+	if (!cmd || is_null_oid(&cmd->new_oid))
+		return -1; /* end of list */
+	*cmd_list = NULL; /* this returns only one */
+	oidcpy(oid, &cmd->new_oid);
+	return 0;
+}
+
+static void set_connectivity_errors(struct command *commands,
+				    struct shallow_info *si)
+{
+	struct command *cmd;
+
+	for (cmd = commands; cmd; cmd = cmd->next) {
+		struct command *singleton = cmd;
+		struct check_connected_options opt = CHECK_CONNECTED_INIT;
+
+		if (shallow_update && si->shallow_ref[cmd->index])
+			/* to be checked in update_shallow_ref() */
+			continue;
+
+		opt.env = tmp_objdir_env(tmp_objdir);
+		if (!check_connected(command_singleton_iterator, &singleton,
+				     &opt))
+			continue;
+
+		cmd->error_string = "missing necessary objects";
+	}
+}
+
+struct iterate_data {
+	struct command *cmds;
+	struct shallow_info *si;
+};
+
+static int iterate_receive_command_list(void *cb_data, struct object_id *oid)
+{
+	struct iterate_data *data = cb_data;
+	struct command **cmd_list = &data->cmds;
+	struct command *cmd = *cmd_list;
+
+	for (; cmd; cmd = cmd->next) {
+		if (shallow_update && data->si->shallow_ref[cmd->index])
+			/* to be checked in update_shallow_ref() */
+			continue;
+		if (!is_null_oid(&cmd->new_oid) && !cmd->skip_update) {
+			oidcpy(oid, &cmd->new_oid);
+			*cmd_list = cmd->next;
+			return 0;
+		}
+	}
+	*cmd_list = NULL;
+	return -1; /* end of list */
+}
+
+static void reject_updates_to_hidden(struct command *commands)
+{
+	struct strbuf refname_full = STRBUF_INIT;
+	size_t prefix_len;
+	struct command *cmd;
+
+	strbuf_addstr(&refname_full, get_git_namespace());
+	prefix_len = refname_full.len;
+
+	for (cmd = commands; cmd; cmd = cmd->next) {
+		if (cmd->error_string)
+			continue;
+
+		strbuf_setlen(&refname_full, prefix_len);
+		strbuf_addstr(&refname_full, cmd->ref_name);
+
+		if (!ref_is_hidden(cmd->ref_name, refname_full.buf))
+			continue;
+		if (is_null_oid(&cmd->new_oid))
+			cmd->error_string = "deny deleting a hidden ref";
+		else
+			cmd->error_string = "deny updating a hidden ref";
+	}
+
+	strbuf_release(&refname_full);
+}
+
+static int should_process_cmd(struct command *cmd)
+{
+	return !cmd->error_string && !cmd->skip_update;
+}
+
+static void warn_if_skipped_connectivity_check(struct command *commands,
+					       struct shallow_info *si)
+{
+	struct command *cmd;
+	int checked_connectivity = 1;
+
+	for (cmd = commands; cmd; cmd = cmd->next) {
+		if (should_process_cmd(cmd) && si->shallow_ref[cmd->index]) {
+			error("BUG: connectivity check has not been run on ref %s",
+			      cmd->ref_name);
+			checked_connectivity = 0;
+		}
+	}
+	if (!checked_connectivity)
+		BUG("connectivity check skipped???");
+}
+
+static void execute_commands_non_atomic(struct command *commands,
+					struct shallow_info *si)
+{
+	struct command *cmd;
+	struct strbuf err = STRBUF_INIT;
+
+	for (cmd = commands; cmd; cmd = cmd->next) {
+		if (!should_process_cmd(cmd))
+			continue;
+
+		transaction = ref_transaction_begin(&err);
+		if (!transaction) {
+			rp_error("%s", err.buf);
+			strbuf_reset(&err);
+			cmd->error_string = "transaction failed to start";
+			continue;
+		}
+
+		cmd->error_string = update(cmd, si);
+
+		if (!cmd->error_string
+		    && ref_transaction_commit(transaction, &err)) {
+			rp_error("%s", err.buf);
+			strbuf_reset(&err);
+			cmd->error_string = "failed to update ref";
+		}
+		ref_transaction_free(transaction);
+	}
+	strbuf_release(&err);
+}
+
+static void execute_commands_atomic(struct command *commands,
+					struct shallow_info *si)
+{
+	struct command *cmd;
+	struct strbuf err = STRBUF_INIT;
+	const char *reported_error = "atomic push failure";
+
+	transaction = ref_transaction_begin(&err);
+	if (!transaction) {
+		rp_error("%s", err.buf);
+		strbuf_reset(&err);
+		reported_error = "transaction failed to start";
+		goto failure;
+	}
+
+	for (cmd = commands; cmd; cmd = cmd->next) {
+		if (!should_process_cmd(cmd))
+			continue;
+
+		cmd->error_string = update(cmd, si);
+
+		if (cmd->error_string)
+			goto failure;
+	}
+
+	if (ref_transaction_commit(transaction, &err)) {
+		rp_error("%s", err.buf);
+		reported_error = "atomic transaction failed";
+		goto failure;
+	}
+	goto cleanup;
+
+failure:
+	for (cmd = commands; cmd; cmd = cmd->next)
+		if (!cmd->error_string)
+			cmd->error_string = reported_error;
+
+cleanup:
+	ref_transaction_free(transaction);
+	strbuf_release(&err);
+}
+
+static void execute_commands(struct command *commands,
+			     const char *unpacker_error,
+			     struct shallow_info *si,
+			     const struct string_list *push_options)
+{
+	struct check_connected_options opt = CHECK_CONNECTED_INIT;
+	struct command *cmd;
+	struct iterate_data data;
+	struct async muxer;
+	int err_fd = 0;
+
+	if (unpacker_error) {
+		for (cmd = commands; cmd; cmd = cmd->next)
+			cmd->error_string = "unpacker error";
+		return;
+	}
+
+	if (use_sideband) {
+		memset(&muxer, 0, sizeof(muxer));
+		muxer.proc = copy_to_sideband;
+		muxer.in = -1;
+		if (!start_async(&muxer))
+			err_fd = muxer.in;
+		/* ...else, continue without relaying sideband */
+	}
+
+	data.cmds = commands;
+	data.si = si;
+	opt.err_fd = err_fd;
+	opt.progress = err_fd && !quiet;
+	opt.env = tmp_objdir_env(tmp_objdir);
+	if (check_connected(iterate_receive_command_list, &data, &opt))
+		set_connectivity_errors(commands, si);
+
+	if (use_sideband)
+		finish_async(&muxer);
+
+	reject_updates_to_hidden(commands);
+
+	if (run_receive_hook(commands, "pre-receive", 0, push_options)) {
+		for (cmd = commands; cmd; cmd = cmd->next) {
+			if (!cmd->error_string)
+				cmd->error_string = "pre-receive hook declined";
+		}
+		return;
+	}
+
+	/*
+	 * Now we'll start writing out refs, which means the objects need
+	 * to be in their final positions so that other processes can see them.
+	 */
+	if (tmp_objdir_migrate(tmp_objdir) < 0) {
+		for (cmd = commands; cmd; cmd = cmd->next) {
+			if (!cmd->error_string)
+				cmd->error_string = "unable to migrate objects to permanent storage";
+		}
+		return;
+	}
+	tmp_objdir = NULL;
+
+	check_aliased_updates(commands);
+
+	free(head_name_to_free);
+	head_name = head_name_to_free = resolve_refdup("HEAD", 0, NULL, NULL);
+
+	if (use_atomic)
+		execute_commands_atomic(commands, si);
+	else
+		execute_commands_non_atomic(commands, si);
+
+	if (shallow_update)
+		warn_if_skipped_connectivity_check(commands, si);
+}
+
+static struct command **queue_command(struct command **tail,
+				      const char *line,
+				      int linelen)
+{
+	struct object_id old_oid, new_oid;
+	struct command *cmd;
+	const char *refname;
+	int reflen;
+	const char *p;
+
+	if (parse_oid_hex(line, &old_oid, &p) ||
+	    *p++ != ' ' ||
+	    parse_oid_hex(p, &new_oid, &p) ||
+	    *p++ != ' ')
+		die("protocol error: expected old/new/ref, got '%s'", line);
+
+	refname = p;
+	reflen = linelen - (p - line);
+	FLEX_ALLOC_MEM(cmd, ref_name, refname, reflen);
+	oidcpy(&cmd->old_oid, &old_oid);
+	oidcpy(&cmd->new_oid, &new_oid);
+	*tail = cmd;
+	return &cmd->next;
+}
+
+static void queue_commands_from_cert(struct command **tail,
+				     struct strbuf *push_cert)
+{
+	const char *boc, *eoc;
+
+	if (*tail)
+		die("protocol error: got both push certificate and unsigned commands");
+
+	boc = strstr(push_cert->buf, "\n\n");
+	if (!boc)
+		die("malformed push certificate %.*s", 100, push_cert->buf);
+	else
+		boc += 2;
+	eoc = push_cert->buf + parse_signature(push_cert->buf, push_cert->len);
+
+	while (boc < eoc) {
+		const char *eol = memchr(boc, '\n', eoc - boc);
+		tail = queue_command(tail, boc, eol ? eol - boc : eoc - boc);
+		boc = eol ? eol + 1 : eoc;
+	}
+}
+
+static struct command *read_head_info(struct packet_reader *reader,
+				      struct oid_array *shallow)
+{
+	struct command *commands = NULL;
+	struct command **p = &commands;
+	for (;;) {
+		int linelen;
+
+		if (packet_reader_read(reader) != PACKET_READ_NORMAL)
+			break;
+
+		if (reader->pktlen > 8 && starts_with(reader->line, "shallow ")) {
+			struct object_id oid;
+			if (get_oid_hex(reader->line + 8, &oid))
+				die("protocol error: expected shallow sha, got '%s'",
+				    reader->line + 8);
+			oid_array_append(shallow, &oid);
+			continue;
+		}
+
+		linelen = strlen(reader->line);
+		if (linelen < reader->pktlen) {
+			const char *feature_list = reader->line + linelen + 1;
+			if (parse_feature_request(feature_list, "report-status"))
+				report_status = 1;
+			if (parse_feature_request(feature_list, "side-band-64k"))
+				use_sideband = LARGE_PACKET_MAX;
+			if (parse_feature_request(feature_list, "quiet"))
+				quiet = 1;
+			if (advertise_atomic_push
+			    && parse_feature_request(feature_list, "atomic"))
+				use_atomic = 1;
+			if (advertise_push_options
+			    && parse_feature_request(feature_list, "push-options"))
+				use_push_options = 1;
+		}
+
+		if (!strcmp(reader->line, "push-cert")) {
+			int true_flush = 0;
+			int saved_options = reader->options;
+			reader->options &= ~PACKET_READ_CHOMP_NEWLINE;
+
+			for (;;) {
+				packet_reader_read(reader);
+				if (reader->status == PACKET_READ_FLUSH) {
+					true_flush = 1;
+					break;
+				}
+				if (reader->status != PACKET_READ_NORMAL) {
+					die("protocol error: got an unexpected packet");
+				}
+				if (!strcmp(reader->line, "push-cert-end\n"))
+					break; /* end of cert */
+				strbuf_addstr(&push_cert, reader->line);
+			}
+			reader->options = saved_options;
+
+			if (true_flush)
+				break;
+			continue;
+		}
+
+		p = queue_command(p, reader->line, linelen);
+	}
+
+	if (push_cert.len)
+		queue_commands_from_cert(p, &push_cert);
+
+	return commands;
+}
+
+static void read_push_options(struct packet_reader *reader,
+			      struct string_list *options)
+{
+	while (1) {
+		if (packet_reader_read(reader) != PACKET_READ_NORMAL)
+			break;
+
+		string_list_append(options, reader->line);
+	}
+}
+
+static const char *parse_pack_header(struct pack_header *hdr)
+{
+	switch (read_pack_header(0, hdr)) {
+	case PH_ERROR_EOF:
+		return "eof before pack header was fully read";
+
+	case PH_ERROR_PACK_SIGNATURE:
+		return "protocol error (pack signature mismatch detected)";
+
+	case PH_ERROR_PROTOCOL:
+		return "protocol error (pack version unsupported)";
+
+	default:
+		return "unknown error in parse_pack_header";
+
+	case 0:
+		return NULL;
+	}
+}
+
+static const char *pack_lockfile;
+
+static void push_header_arg(struct argv_array *args, struct pack_header *hdr)
+{
+	argv_array_pushf(args, "--pack_header=%"PRIu32",%"PRIu32,
+			ntohl(hdr->hdr_version), ntohl(hdr->hdr_entries));
+}
+
+static const char *unpack(int err_fd, struct shallow_info *si)
+{
+	struct pack_header hdr;
+	const char *hdr_err;
+	int status;
+	struct child_process child = CHILD_PROCESS_INIT;
+	int fsck_objects = (receive_fsck_objects >= 0
+			    ? receive_fsck_objects
+			    : transfer_fsck_objects >= 0
+			    ? transfer_fsck_objects
+			    : 0);
+
+	hdr_err = parse_pack_header(&hdr);
+	if (hdr_err) {
+		if (err_fd > 0)
+			close(err_fd);
+		return hdr_err;
+	}
+
+	if (si->nr_ours || si->nr_theirs) {
+		alt_shallow_file = setup_temporary_shallow(si->shallow);
+		argv_array_push(&child.args, "--shallow-file");
+		argv_array_push(&child.args, alt_shallow_file);
+	}
+
+	tmp_objdir = tmp_objdir_create();
+	if (!tmp_objdir) {
+		if (err_fd > 0)
+			close(err_fd);
+		return "unable to create temporary object directory";
+	}
+	child.env = tmp_objdir_env(tmp_objdir);
+
+	/*
+	 * Normally we just pass the tmp_objdir environment to the child
+	 * processes that do the heavy lifting, but we may need to see these
+	 * objects ourselves to set up shallow information.
+	 */
+	tmp_objdir_add_as_alternate(tmp_objdir);
+
+	if (ntohl(hdr.hdr_entries) < unpack_limit) {
+		argv_array_push(&child.args, "unpack-objects");
+		push_header_arg(&child.args, &hdr);
+		if (quiet)
+			argv_array_push(&child.args, "-q");
+		if (fsck_objects)
+			argv_array_pushf(&child.args, "--strict%s",
+				fsck_msg_types.buf);
+		if (max_input_size)
+			argv_array_pushf(&child.args, "--max-input-size=%"PRIuMAX,
+				(uintmax_t)max_input_size);
+		child.no_stdout = 1;
+		child.err = err_fd;
+		child.git_cmd = 1;
+		status = run_command(&child);
+		if (status)
+			return "unpack-objects abnormal exit";
+	} else {
+		char hostname[HOST_NAME_MAX + 1];
+
+		argv_array_pushl(&child.args, "index-pack", "--stdin", NULL);
+		push_header_arg(&child.args, &hdr);
+
+		if (xgethostname(hostname, sizeof(hostname)))
+			xsnprintf(hostname, sizeof(hostname), "localhost");
+		argv_array_pushf(&child.args,
+				 "--keep=receive-pack %"PRIuMAX" on %s",
+				 (uintmax_t)getpid(),
+				 hostname);
+
+		if (!quiet && err_fd)
+			argv_array_push(&child.args, "--show-resolving-progress");
+		if (use_sideband)
+			argv_array_push(&child.args, "--report-end-of-input");
+		if (fsck_objects)
+			argv_array_pushf(&child.args, "--strict%s",
+				fsck_msg_types.buf);
+		if (!reject_thin)
+			argv_array_push(&child.args, "--fix-thin");
+		if (max_input_size)
+			argv_array_pushf(&child.args, "--max-input-size=%"PRIuMAX,
+				(uintmax_t)max_input_size);
+		child.out = -1;
+		child.err = err_fd;
+		child.git_cmd = 1;
+		status = start_command(&child);
+		if (status)
+			return "index-pack fork failed";
+		pack_lockfile = index_pack_lockfile(child.out);
+		close(child.out);
+		status = finish_command(&child);
+		if (status)
+			return "index-pack abnormal exit";
+		reprepare_packed_git(the_repository);
+	}
+	return NULL;
+}
+
+static const char *unpack_with_sideband(struct shallow_info *si)
+{
+	struct async muxer;
+	const char *ret;
+
+	if (!use_sideband)
+		return unpack(0, si);
+
+	use_keepalive = KEEPALIVE_AFTER_NUL;
+	memset(&muxer, 0, sizeof(muxer));
+	muxer.proc = copy_to_sideband;
+	muxer.in = -1;
+	if (start_async(&muxer))
+		return NULL;
+
+	ret = unpack(muxer.in, si);
+
+	finish_async(&muxer);
+	return ret;
+}
+
+static void prepare_shallow_update(struct shallow_info *si)
+{
+	int i, j, k, bitmap_size = DIV_ROUND_UP(si->ref->nr, 32);
+
+	ALLOC_ARRAY(si->used_shallow, si->shallow->nr);
+	assign_shallow_commits_to_refs(si, si->used_shallow, NULL);
+
+	si->need_reachability_test =
+		xcalloc(si->shallow->nr, sizeof(*si->need_reachability_test));
+	si->reachable =
+		xcalloc(si->shallow->nr, sizeof(*si->reachable));
+	si->shallow_ref = xcalloc(si->ref->nr, sizeof(*si->shallow_ref));
+
+	for (i = 0; i < si->nr_ours; i++)
+		si->need_reachability_test[si->ours[i]] = 1;
+
+	for (i = 0; i < si->shallow->nr; i++) {
+		if (!si->used_shallow[i])
+			continue;
+		for (j = 0; j < bitmap_size; j++) {
+			if (!si->used_shallow[i][j])
+				continue;
+			si->need_reachability_test[i]++;
+			for (k = 0; k < 32; k++)
+				if (si->used_shallow[i][j] & (1U << k))
+					si->shallow_ref[j * 32 + k]++;
+		}
+
+		/*
+		 * true for those associated with some refs and belong
+		 * in "ours" list aka "step 7 not done yet"
+		 */
+		si->need_reachability_test[i] =
+			si->need_reachability_test[i] > 1;
+	}
+
+	/*
+	 * keep hooks happy by forcing a temporary shallow file via
+	 * env variable because we can't add --shallow-file to every
+	 * command. check_connected() will be done with
+	 * true .git/shallow though.
+	 */
+	setenv(GIT_SHALLOW_FILE_ENVIRONMENT, alt_shallow_file, 1);
+}
+
+static void update_shallow_info(struct command *commands,
+				struct shallow_info *si,
+				struct oid_array *ref)
+{
+	struct command *cmd;
+	int *ref_status;
+	remove_nonexistent_theirs_shallow(si);
+	if (!si->nr_ours && !si->nr_theirs) {
+		shallow_update = 0;
+		return;
+	}
+
+	for (cmd = commands; cmd; cmd = cmd->next) {
+		if (is_null_oid(&cmd->new_oid))
+			continue;
+		oid_array_append(ref, &cmd->new_oid);
+		cmd->index = ref->nr - 1;
+	}
+	si->ref = ref;
+
+	if (shallow_update) {
+		prepare_shallow_update(si);
+		return;
+	}
+
+	ALLOC_ARRAY(ref_status, ref->nr);
+	assign_shallow_commits_to_refs(si, NULL, ref_status);
+	for (cmd = commands; cmd; cmd = cmd->next) {
+		if (is_null_oid(&cmd->new_oid))
+			continue;
+		if (ref_status[cmd->index]) {
+			cmd->error_string = "shallow update not allowed";
+			cmd->skip_update = 1;
+		}
+	}
+	free(ref_status);
+}
+
+static void report(struct command *commands, const char *unpack_status)
+{
+	struct command *cmd;
+	struct strbuf buf = STRBUF_INIT;
+
+	packet_buf_write(&buf, "unpack %s\n",
+			 unpack_status ? unpack_status : "ok");
+	for (cmd = commands; cmd; cmd = cmd->next) {
+		if (!cmd->error_string)
+			packet_buf_write(&buf, "ok %s\n",
+					 cmd->ref_name);
+		else
+			packet_buf_write(&buf, "ng %s %s\n",
+					 cmd->ref_name, cmd->error_string);
+	}
+	packet_buf_flush(&buf);
+
+	if (use_sideband)
+		send_sideband(1, 1, buf.buf, buf.len, use_sideband);
+	else
+		write_or_die(1, buf.buf, buf.len);
+	strbuf_release(&buf);
+}
+
+static int delete_only(struct command *commands)
+{
+	struct command *cmd;
+	for (cmd = commands; cmd; cmd = cmd->next) {
+		if (!is_null_oid(&cmd->new_oid))
+			return 0;
+	}
+	return 1;
+}
+
+int cmd_receive_pack(int argc, const char **argv, const char *prefix)
+{
+	int advertise_refs = 0;
+	struct command *commands;
+	struct oid_array shallow = OID_ARRAY_INIT;
+	struct oid_array ref = OID_ARRAY_INIT;
+	struct shallow_info si;
+	struct packet_reader reader;
+
+	struct option options[] = {
+		OPT__QUIET(&quiet, N_("quiet")),
+		OPT_HIDDEN_BOOL(0, "stateless-rpc", &stateless_rpc, NULL),
+		OPT_HIDDEN_BOOL(0, "advertise-refs", &advertise_refs, NULL),
+		OPT_HIDDEN_BOOL(0, "reject-thin-pack-for-testing", &reject_thin, NULL),
+		OPT_END()
+	};
+
+	packet_trace_identity("receive-pack");
+
+	argc = parse_options(argc, argv, prefix, options, receive_pack_usage, 0);
+
+	if (argc > 1)
+		usage_msg_opt(_("Too many arguments."), receive_pack_usage, options);
+	if (argc == 0)
+		usage_msg_opt(_("You must specify a directory."), receive_pack_usage, options);
+
+	service_dir = argv[0];
+
+	setup_path();
+
+	if (!enter_repo(service_dir, 0))
+		die("'%s' does not appear to be a git repository", service_dir);
+
+	git_config(receive_pack_config, NULL);
+	if (cert_nonce_seed)
+		push_cert_nonce = prepare_push_cert_nonce(service_dir, time(NULL));
+
+	if (0 <= transfer_unpack_limit)
+		unpack_limit = transfer_unpack_limit;
+	else if (0 <= receive_unpack_limit)
+		unpack_limit = receive_unpack_limit;
+
+	switch (determine_protocol_version_server()) {
+	case protocol_v2:
+		/*
+		 * push support for protocol v2 has not been implemented yet,
+		 * so ignore the request to use v2 and fallback to using v0.
+		 */
+		break;
+	case protocol_v1:
+		/*
+		 * v1 is just the original protocol with a version string,
+		 * so just fall through after writing the version string.
+		 */
+		if (advertise_refs || !stateless_rpc)
+			packet_write_fmt(1, "version 1\n");
+
+		/* fallthrough */
+	case protocol_v0:
+		break;
+	case protocol_unknown_version:
+		BUG("unknown protocol version");
+	}
+
+	if (advertise_refs || !stateless_rpc) {
+		write_head_info();
+	}
+	if (advertise_refs)
+		return 0;
+
+	packet_reader_init(&reader, 0, NULL, 0,
+			   PACKET_READ_CHOMP_NEWLINE |
+			   PACKET_READ_DIE_ON_ERR_PACKET);
+
+	if ((commands = read_head_info(&reader, &shallow)) != NULL) {
+		const char *unpack_status = NULL;
+		struct string_list push_options = STRING_LIST_INIT_DUP;
+
+		if (use_push_options)
+			read_push_options(&reader, &push_options);
+		if (!check_cert_push_options(&push_options)) {
+			struct command *cmd;
+			for (cmd = commands; cmd; cmd = cmd->next)
+				cmd->error_string = "inconsistent push options";
+		}
+
+		prepare_shallow_info(&si, &shallow);
+		if (!si.nr_ours && !si.nr_theirs)
+			shallow_update = 0;
+		if (!delete_only(commands)) {
+			unpack_status = unpack_with_sideband(&si);
+			update_shallow_info(commands, &si, &ref);
+		}
+		use_keepalive = KEEPALIVE_ALWAYS;
+		execute_commands(commands, unpack_status, &si,
+				 &push_options);
+		if (pack_lockfile)
+			unlink_or_warn(pack_lockfile);
+		if (report_status)
+			report(commands, unpack_status);
+		run_receive_hook(commands, "post-receive", 1,
+				 &push_options);
+		run_update_post_hook(commands);
+		string_list_clear(&push_options, 0);
+		if (auto_gc) {
+			const char *argv_gc_auto[] = {
+				"gc", "--auto", "--quiet", NULL,
+			};
+			struct child_process proc = CHILD_PROCESS_INIT;
+
+			proc.no_stdin = 1;
+			proc.stdout_to_stderr = 1;
+			proc.err = use_sideband ? -1 : 0;
+			proc.git_cmd = 1;
+			proc.argv = argv_gc_auto;
+
+			close_object_store(the_repository->objects);
+			if (!start_command(&proc)) {
+				if (use_sideband)
+					copy_to_sideband(proc.err, -1, NULL);
+				finish_command(&proc);
+			}
+		}
+		if (auto_update_server_info)
+			update_server_info(0);
+		clear_shallow_info(&si);
+	}
+	if (use_sideband)
+		packet_flush(1);
+	oid_array_clear(&shallow);
+	oid_array_clear(&ref);
+	free((void *)push_cert_nonce);
+	return 0;
+}