From: Junio C Hamano <gitster@pobox.com>
Date: Fri, 21 May 2010 11:02:19 +0000 (-0700)
Subject: Merge branch 'js/maint-receive-pack-symref-alias'
X-Git-Tag: v1.7.2-rc0~117
X-Git-Url: https://git.tokkee.org/?a=commitdiff_plain;h=9215f76fb6d938ae93889f46f27cff22723fe0e4;p=git.git

Merge branch 'js/maint-receive-pack-symref-alias'

* js/maint-receive-pack-symref-alias:
  t5516-fetch-push.sh: style cleanup
  receive-pack: detect aliased updates which can occur with symrefs
  receive-pack: switch global variable 'commands' to a parameter

Conflicts:
	t/t5516-fetch-push.sh
---

9215f76fb6d938ae93889f46f27cff22723fe0e4
diff --cc builtin/receive-pack.c
index 0559fcc87,000000000..bb34757d2
mode 100644,000000..100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@@ -1,800 -1,0 +1,854 @@@
 +#include "cache.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 "transport.h"
++#include "string-list.h"
 +
 +static const char receive_pack_usage[] = "git receive-pack <git-dir>";
 +
 +enum deny_action {
 +	DENY_UNCONFIGURED,
 +	DENY_IGNORE,
 +	DENY_WARN,
 +	DENY_REFUSE,
 +};
 +
 +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;
 +static int receive_unpack_limit = -1;
 +static int transfer_unpack_limit = -1;
 +static int unpack_limit = 100;
 +static int report_status;
 +static int use_sideband;
 +static int prefer_ofs_delta = 1;
 +static int auto_update_server_info;
 +static int auto_gc = 1;
 +static const char *head_name;
 +static int sent_capabilities;
 +
 +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 (git_config_bool(var, value))
 +		return DENY_REFUSE;
 +	return DENY_IGNORE;
 +}
 +
 +static int receive_pack_config(const char *var, const char *value, void *cb)
 +{
 +	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.fsckobjects") == 0) {
 +		receive_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;
 +	}
 +
 +	return git_default_config(var, value, cb);
 +}
 +
 +static int show_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 +{
 +	if (sent_capabilities)
 +		packet_write(1, "%s %s\n", sha1_to_hex(sha1), path);
 +	else
 +		packet_write(1, "%s %s%c%s%s\n",
 +			     sha1_to_hex(sha1), path, 0,
 +			     " report-status delete-refs side-band-64k",
 +			     prefer_ofs_delta ? " ofs-delta" : "");
 +	sent_capabilities = 1;
 +	return 0;
 +}
 +
 +static void write_head_info(void)
 +{
 +	for_each_ref(show_ref, NULL);
 +	if (!sent_capabilities)
 +		show_ref("capabilities^{}", null_sha1, 0, NULL);
 +
 +}
 +
 +struct command {
 +	struct command *next;
 +	const char *error_string;
++	unsigned int skip_update;
 +	unsigned char old_sha1[20];
 +	unsigned char new_sha1[20];
 +	char ref_name[FLEX_ARRAY]; /* more */
 +};
 +
- static struct command *commands;
- 
 +static const char pre_receive_hook[] = "hooks/pre-receive";
 +static const char post_receive_hook[] = "hooks/post-receive";
 +
 +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 = strlen(prefix);
 +	char msg[4096];
 +
 +	strncpy(msg, prefix, sz);
 +	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];
 +	while (1) {
 +		ssize_t sz = xread(in, data, sizeof(data));
 +		if (sz <= 0)
 +			break;
 +		send_sideband(1, 2, data, sz, use_sideband);
 +	}
 +	close(in);
 +	return 0;
 +}
 +
- static int run_receive_hook(const char *hook_name)
++static int run_receive_hook(struct command *commands, const char *hook_name)
 +{
 +	static char buf[sizeof(commands->old_sha1) * 2 + PATH_MAX + 4];
 +	struct command *cmd;
 +	struct child_process proc;
 +	struct async muxer;
 +	const char *argv[2];
 +	int have_input = 0, code;
 +
 +	for (cmd = commands; !have_input && cmd; cmd = cmd->next) {
 +		if (!cmd->error_string)
 +			have_input = 1;
 +	}
 +
 +	if (!have_input || access(hook_name, X_OK) < 0)
 +		return 0;
 +
 +	argv[0] = hook_name;
 +	argv[1] = NULL;
 +
 +	memset(&proc, 0, sizeof(proc));
 +	proc.argv = argv;
 +	proc.in = -1;
 +	proc.stdout_to_stderr = 1;
 +
 +	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;
 +	}
 +
 +	code = start_command(&proc);
 +	if (code) {
 +		if (use_sideband)
 +			finish_async(&muxer);
 +		return code;
 +	}
 +
 +	for (cmd = commands; cmd; cmd = cmd->next) {
 +		if (!cmd->error_string) {
 +			size_t n = snprintf(buf, sizeof(buf), "%s %s %s\n",
 +				sha1_to_hex(cmd->old_sha1),
 +				sha1_to_hex(cmd->new_sha1),
 +				cmd->ref_name);
 +			if (write_in_full(proc.in, buf, n) != n)
 +				break;
 +		}
 +	}
 +	close(proc.in);
 +	if (use_sideband)
 +		finish_async(&muxer);
 +	return finish_command(&proc);
 +}
 +
 +static int run_update_hook(struct command *cmd)
 +{
 +	static const char update_hook[] = "hooks/update";
 +	const char *argv[5];
 +	struct child_process proc;
 +	int code;
 +
 +	if (access(update_hook, X_OK) < 0)
 +		return 0;
 +
 +	argv[0] = update_hook;
 +	argv[1] = cmd->ref_name;
 +	argv[2] = sha1_to_hex(cmd->old_sha1);
 +	argv[3] = sha1_to_hex(cmd->new_sha1);
 +	argv[4] = NULL;
 +
 +	memset(&proc, 0, sizeof(proc));
 +	proc.no_stdin = 1;
 +	proc.stdout_to_stderr = 1;
 +	proc.err = use_sideband ? -1 : 0;
 +	proc.argv = argv;
 +
 +	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[] = {
 +	"By default, updating the current branch in a non-bare repository",
 +	"is denied, because it will make the index and work tree inconsistent",
 +	"with what you pushed, and will require 'git reset --hard' to match",
 +	"the work tree to HEAD.",
 +	"",
 +	"You can set 'receive.denyCurrentBranch' configuration variable to",
 +	"'ignore' or 'warn' in the remote repository to allow pushing into",
 +	"its current branch; however, this is not recommended unless you",
 +	"arranged to update its work tree to match what you pushed in some",
 +	"other way.",
 +	"",
 +	"To squelch this message and still keep the default behaviour, set",
 +	"'receive.denyCurrentBranch' configuration variable to 'refuse'."
 +};
 +
 +static void refuse_unconfigured_deny(void)
 +{
 +	int i;
 +	for (i = 0; i < ARRAY_SIZE(refuse_unconfigured_deny_msg); i++)
 +		rp_error("%s", refuse_unconfigured_deny_msg[i]);
 +}
 +
 +static char *refuse_unconfigured_deny_delete_current_msg[] = {
 +	"By default, deleting the current branch is denied, because the next",
 +	"'git clone' won't result in any file checked out, causing confusion.",
 +	"",
 +	"You can set 'receive.denyDeleteCurrent' configuration variable to",
 +	"'warn' or 'ignore' in the remote repository to allow deleting the",
 +	"current branch, with or without a warning message.",
 +	"",
 +	"To squelch this message, you can set it to 'refuse'."
 +};
 +
 +static void refuse_unconfigured_deny_delete_current(void)
 +{
 +	int i;
 +	for (i = 0;
 +	     i < ARRAY_SIZE(refuse_unconfigured_deny_delete_current_msg);
 +	     i++)
 +		rp_error("%s", refuse_unconfigured_deny_delete_current_msg[i]);
 +}
 +
 +static const char *update(struct command *cmd)
 +{
 +	const char *name = cmd->ref_name;
 +	unsigned char *old_sha1 = cmd->old_sha1;
 +	unsigned char *new_sha1 = cmd->new_sha1;
 +	struct ref_lock *lock;
 +
 +	/* only refs/... are allowed */
 +	if (prefixcmp(name, "refs/") || check_ref_format(name + 5)) {
 +		rp_error("refusing to create funny ref '%s' remotely", name);
 +		return "funny refname";
 +	}
 +
 +	if (is_ref_checked_out(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";
 +		}
 +	}
 +
 +	if (!is_null_sha1(new_sha1) && !has_sha1_file(new_sha1)) {
 +		error("unpack should have generated %s, "
 +		      "but I can't find it!", sha1_to_hex(new_sha1));
 +		return "bad pack";
 +	}
 +
 +	if (!is_null_sha1(old_sha1) && is_null_sha1(new_sha1)) {
 +		if (deny_deletes && !prefixcmp(name, "refs/heads/")) {
 +			rp_error("denying ref deletion for %s", name);
 +			return "deletion prohibited";
 +		}
 +
 +		if (!strcmp(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:
 +				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";
 +			}
 +		}
 +	}
 +
 +	if (deny_non_fast_forwards && !is_null_sha1(new_sha1) &&
 +	    !is_null_sha1(old_sha1) &&
 +	    !prefixcmp(name, "refs/heads/")) {
 +		struct object *old_object, *new_object;
 +		struct commit *old_commit, *new_commit;
 +		struct commit_list *bases, *ent;
 +
 +		old_object = parse_object(old_sha1);
 +		new_object = parse_object(new_sha1);
 +
 +		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;
 +		bases = get_merge_bases(old_commit, new_commit, 1);
 +		for (ent = bases; ent; ent = ent->next)
 +			if (!hashcmp(old_sha1, ent->item->object.sha1))
 +				break;
 +		free_commit_list(bases);
 +		if (!ent) {
 +			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 (is_null_sha1(new_sha1)) {
 +		if (!parse_object(old_sha1)) {
 +			rp_warning("Allowing deletion of corrupt ref.");
 +			old_sha1 = NULL;
 +		}
 +		if (delete_ref(name, old_sha1, 0)) {
 +			rp_error("failed to delete %s", name);
 +			return "failed to delete";
 +		}
 +		return NULL; /* good */
 +	}
 +	else {
 +		lock = lock_any_ref_for_update(name, old_sha1, 0);
 +		if (!lock) {
 +			rp_error("failed to lock %s", name);
 +			return "failed to lock";
 +		}
 +		if (write_ref_sha1(lock, new_sha1, "push")) {
 +			return "failed to write"; /* error() already called */
 +		}
 +		return NULL; /* good */
 +	}
 +}
 +
 +static char update_post_hook[] = "hooks/post-update";
 +
- static void run_update_post_hook(struct command *cmd)
++static void run_update_post_hook(struct command *commands)
 +{
- 	struct command *cmd_p;
++	struct command *cmd;
 +	int argc;
 +	const char **argv;
 +	struct child_process proc;
 +
- 	for (argc = 0, cmd_p = cmd; cmd_p; cmd_p = cmd_p->next) {
- 		if (cmd_p->error_string)
++	for (argc = 0, cmd = commands; cmd; cmd = cmd->next) {
++		if (cmd->error_string)
 +			continue;
 +		argc++;
 +	}
 +	if (!argc || access(update_post_hook, X_OK) < 0)
 +		return;
 +	argv = xmalloc(sizeof(*argv) * (2 + argc));
 +	argv[0] = update_post_hook;
 +
- 	for (argc = 1, cmd_p = cmd; cmd_p; cmd_p = cmd_p->next) {
++	for (argc = 1, cmd = commands; cmd; cmd = cmd->next) {
 +		char *p;
- 		if (cmd_p->error_string)
++		if (cmd->error_string)
 +			continue;
- 		p = xmalloc(strlen(cmd_p->ref_name) + 1);
- 		strcpy(p, cmd_p->ref_name);
++		p = xmalloc(strlen(cmd->ref_name) + 1);
++		strcpy(p, cmd->ref_name);
 +		argv[argc] = p;
 +		argc++;
 +	}
 +	argv[argc] = NULL;
 +
 +	memset(&proc, 0, sizeof(proc));
 +	proc.no_stdin = 1;
 +	proc.stdout_to_stderr = 1;
 +	proc.err = use_sideband ? -1 : 0;
 +	proc.argv = argv;
 +
 +	if (!start_command(&proc)) {
 +		if (use_sideband)
 +			copy_to_sideband(proc.err, -1, NULL);
 +		finish_command(&proc);
 +	}
 +}
 +
- static void execute_commands(const char *unpacker_error)
++static void check_aliased_update(struct command *cmd, struct string_list *list)
++{
++	struct string_list_item *item;
++	struct command *dst_cmd;
++	unsigned char sha1[20];
++	char cmd_oldh[41], cmd_newh[41], dst_oldh[41], dst_newh[41];
++	int flag;
++
++	const char *dst_name = resolve_ref(cmd->ref_name, sha1, 0, &flag);
++
++	if (!(flag & REF_ISSYMREF))
++		return;
++
++	if ((item = string_list_lookup(dst_name, list)) == NULL)
++		return;
++
++	cmd->skip_update = 1;
++
++	dst_cmd = (struct command *) item->util;
++
++	if (!hashcmp(cmd->old_sha1, dst_cmd->old_sha1) &&
++	    !hashcmp(cmd->new_sha1, dst_cmd->new_sha1))
++		return;
++
++	dst_cmd->skip_update = 1;
++
++	strcpy(cmd_oldh, find_unique_abbrev(cmd->old_sha1, DEFAULT_ABBREV));
++	strcat(cmd_newh, find_unique_abbrev(cmd->new_sha1, DEFAULT_ABBREV));
++	strcpy(dst_oldh, find_unique_abbrev(dst_cmd->old_sha1, DEFAULT_ABBREV));
++	strcat(dst_newh, find_unique_abbrev(dst_cmd->new_sha1, DEFAULT_ABBREV));
++	rp_error("refusing inconsistent update between symref '%s' (%s..%s) and"
++		 " its target '%s' (%s..%s)",
++		 cmd->ref_name, cmd_oldh, cmd_newh,
++		 dst_cmd->ref_name, dst_oldh, dst_newh);
++
++	cmd->error_string = dst_cmd->error_string =
++		"inconsistent aliased update";
++}
++
++static void check_aliased_updates(struct command *commands)
++{
++	struct command *cmd;
++	struct string_list ref_list = { NULL, 0, 0, 0 };
++
++	for (cmd = commands; cmd; cmd = cmd->next) {
++		struct string_list_item *item =
++			string_list_append(cmd->ref_name, &ref_list);
++		item->util = (void *)cmd;
++	}
++	sort_string_list(&ref_list);
++
++	for (cmd = commands; cmd; cmd = cmd->next)
++		check_aliased_update(cmd, &ref_list);
++
++	string_list_clear(&ref_list, 0);
++}
++
++static void execute_commands(struct command *commands, const char *unpacker_error)
 +{
- 	struct command *cmd = commands;
++	struct command *cmd;
 +	unsigned char sha1[20];
 +
 +	if (unpacker_error) {
- 		while (cmd) {
++		for (cmd = commands; cmd; cmd = cmd->next)
 +			cmd->error_string = "n/a (unpacker error)";
- 			cmd = cmd->next;
- 		}
 +		return;
 +	}
 +
- 	if (run_receive_hook(pre_receive_hook)) {
- 		while (cmd) {
++	if (run_receive_hook(commands, pre_receive_hook)) {
++		for (cmd = commands; cmd; cmd = cmd->next)
 +			cmd->error_string = "pre-receive hook declined";
- 			cmd = cmd->next;
- 		}
 +		return;
 +	}
 +
++	check_aliased_updates(commands);
++
 +	head_name = resolve_ref("HEAD", sha1, 0, NULL);
 +
- 	while (cmd) {
- 		cmd->error_string = update(cmd);
- 		cmd = cmd->next;
- 	}
++	for (cmd = commands; cmd; cmd = cmd->next)
++		if (!cmd->skip_update)
++			cmd->error_string = update(cmd);
 +}
 +
- static void read_head_info(void)
++static struct command *read_head_info(void)
 +{
++	struct command *commands = NULL;
 +	struct command **p = &commands;
 +	for (;;) {
 +		static char line[1000];
 +		unsigned char old_sha1[20], new_sha1[20];
 +		struct command *cmd;
 +		char *refname;
 +		int len, reflen;
 +
 +		len = packet_read_line(0, line, sizeof(line));
 +		if (!len)
 +			break;
 +		if (line[len-1] == '\n')
 +			line[--len] = 0;
 +		if (len < 83 ||
 +		    line[40] != ' ' ||
 +		    line[81] != ' ' ||
 +		    get_sha1_hex(line, old_sha1) ||
 +		    get_sha1_hex(line + 41, new_sha1))
 +			die("protocol error: expected old/new/ref, got '%s'",
 +			    line);
 +
 +		refname = line + 82;
 +		reflen = strlen(refname);
 +		if (reflen + 82 < len) {
 +			if (strstr(refname + reflen + 1, "report-status"))
 +				report_status = 1;
 +			if (strstr(refname + reflen + 1, "side-band-64k"))
 +				use_sideband = LARGE_PACKET_MAX;
 +		}
- 		cmd = xmalloc(sizeof(struct command) + len - 80);
++		cmd = xcalloc(1, sizeof(struct command) + len - 80);
 +		hashcpy(cmd->old_sha1, old_sha1);
 +		hashcpy(cmd->new_sha1, new_sha1);
 +		memcpy(cmd->ref_name, line + 82, len - 81);
- 		cmd->error_string = NULL;
- 		cmd->next = NULL;
 +		*p = cmd;
 +		p = &cmd->next;
 +	}
++	return commands;
 +}
 +
 +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 const char *unpack(void)
 +{
 +	struct pack_header hdr;
 +	const char *hdr_err;
 +	char hdr_arg[38];
 +
 +	hdr_err = parse_pack_header(&hdr);
 +	if (hdr_err)
 +		return hdr_err;
 +	snprintf(hdr_arg, sizeof(hdr_arg),
 +			"--pack_header=%"PRIu32",%"PRIu32,
 +			ntohl(hdr.hdr_version), ntohl(hdr.hdr_entries));
 +
 +	if (ntohl(hdr.hdr_entries) < unpack_limit) {
 +		int code, i = 0;
 +		const char *unpacker[4];
 +		unpacker[i++] = "unpack-objects";
 +		if (receive_fsck_objects)
 +			unpacker[i++] = "--strict";
 +		unpacker[i++] = hdr_arg;
 +		unpacker[i++] = NULL;
 +		code = run_command_v_opt(unpacker, RUN_GIT_CMD);
 +		if (!code)
 +			return NULL;
 +		return "unpack-objects abnormal exit";
 +	} else {
 +		const char *keeper[7];
 +		int s, status, i = 0;
 +		char keep_arg[256];
 +		struct child_process ip;
 +
 +		s = sprintf(keep_arg, "--keep=receive-pack %"PRIuMAX" on ", (uintmax_t) getpid());
 +		if (gethostname(keep_arg + s, sizeof(keep_arg) - s))
 +			strcpy(keep_arg + s, "localhost");
 +
 +		keeper[i++] = "index-pack";
 +		keeper[i++] = "--stdin";
 +		if (receive_fsck_objects)
 +			keeper[i++] = "--strict";
 +		keeper[i++] = "--fix-thin";
 +		keeper[i++] = hdr_arg;
 +		keeper[i++] = keep_arg;
 +		keeper[i++] = NULL;
 +		memset(&ip, 0, sizeof(ip));
 +		ip.argv = keeper;
 +		ip.out = -1;
 +		ip.git_cmd = 1;
 +		status = start_command(&ip);
 +		if (status) {
 +			return "index-pack fork failed";
 +		}
 +		pack_lockfile = index_pack_lockfile(ip.out);
 +		close(ip.out);
 +		status = finish_command(&ip);
 +		if (!status) {
 +			reprepare_packed_git();
 +			return NULL;
 +		}
 +		return "index-pack abnormal exit";
 +	}
 +}
 +
- static void report(const char *unpack_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
 +		safe_write(1, buf.buf, buf.len);
 +	strbuf_release(&buf);
 +}
 +
- static int delete_only(struct command *cmd)
++static int delete_only(struct command *commands)
 +{
- 	while (cmd) {
++	struct command *cmd;
++	for (cmd = commands; cmd; cmd = cmd->next) {
 +		if (!is_null_sha1(cmd->new_sha1))
 +			return 0;
- 		cmd = cmd->next;
 +	}
 +	return 1;
 +}
 +
 +static int add_refs_from_alternate(struct alternate_object_database *e, void *unused)
 +{
 +	char *other;
 +	size_t len;
 +	struct remote *remote;
 +	struct transport *transport;
 +	const struct ref *extra;
 +
 +	e->name[-1] = '\0';
 +	other = xstrdup(make_absolute_path(e->base));
 +	e->name[-1] = '/';
 +	len = strlen(other);
 +
 +	while (other[len-1] == '/')
 +		other[--len] = '\0';
 +	if (len < 8 || memcmp(other + len - 8, "/objects", 8))
 +		return 0;
 +	/* Is this a git repository with refs? */
 +	memcpy(other + len - 8, "/refs", 6);
 +	if (!is_directory(other))
 +		return 0;
 +	other[len - 8] = '\0';
 +	remote = remote_get(other);
 +	transport = transport_get(remote, other);
 +	for (extra = transport_get_remote_refs(transport);
 +	     extra;
 +	     extra = extra->next) {
 +		add_extra_ref(".have", extra->old_sha1, 0);
 +	}
 +	transport_disconnect(transport);
 +	free(other);
 +	return 0;
 +}
 +
 +static void add_alternate_refs(void)
 +{
 +	foreach_alt_odb(add_refs_from_alternate, NULL);
 +}
 +
 +int cmd_receive_pack(int argc, const char **argv, const char *prefix)
 +{
 +	int advertise_refs = 0;
 +	int stateless_rpc = 0;
 +	int i;
 +	char *dir = NULL;
++	struct command *commands;
 +
 +	argv++;
 +	for (i = 1; i < argc; i++) {
 +		const char *arg = *argv++;
 +
 +		if (*arg == '-') {
 +			if (!strcmp(arg, "--advertise-refs")) {
 +				advertise_refs = 1;
 +				continue;
 +			}
 +			if (!strcmp(arg, "--stateless-rpc")) {
 +				stateless_rpc = 1;
 +				continue;
 +			}
 +
 +			usage(receive_pack_usage);
 +		}
 +		if (dir)
 +			usage(receive_pack_usage);
 +		dir = xstrdup(arg);
 +	}
 +	if (!dir)
 +		usage(receive_pack_usage);
 +
 +	setup_path();
 +
 +	if (!enter_repo(dir, 0))
 +		die("'%s' does not appear to be a git repository", dir);
 +
 +	if (is_repository_shallow())
 +		die("attempt to push into a shallow repository");
 +
 +	git_config(receive_pack_config, NULL);
 +
 +	if (0 <= transfer_unpack_limit)
 +		unpack_limit = transfer_unpack_limit;
 +	else if (0 <= receive_unpack_limit)
 +		unpack_limit = receive_unpack_limit;
 +
 +	if (advertise_refs || !stateless_rpc) {
 +		add_alternate_refs();
 +		write_head_info();
 +		clear_extra_refs();
 +
 +		/* EOF */
 +		packet_flush(1);
 +	}
 +	if (advertise_refs)
 +		return 0;
 +
- 	read_head_info();
- 	if (commands) {
++	if ((commands = read_head_info()) != NULL) {
 +		const char *unpack_status = NULL;
 +
 +		if (!delete_only(commands))
 +			unpack_status = unpack();
- 		execute_commands(unpack_status);
++		execute_commands(commands, unpack_status);
 +		if (pack_lockfile)
 +			unlink_or_warn(pack_lockfile);
 +		if (report_status)
- 			report(unpack_status);
- 		run_receive_hook(post_receive_hook);
++			report(commands, unpack_status);
++		run_receive_hook(commands, post_receive_hook);
 +		run_update_post_hook(commands);
 +		if (auto_gc) {
 +			const char *argv_gc_auto[] = {
 +				"gc", "--auto", "--quiet", NULL,
 +			};
 +			run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 +		}
 +		if (auto_update_server_info)
 +			update_server_info(0);
 +	}
 +	if (use_sideband)
 +		packet_flush(1);
 +	return 0;
 +}
diff --cc t/t5516-fetch-push.sh
index 6a37a4d99,f0813e0d0..b11da79c9
--- a/t/t5516-fetch-push.sh
+++ b/t/t5516-fetch-push.sh
@@@ -528,9 -538,10 +538,10 @@@ test_expect_success 'push does not upda
  	mk_test heads/master &&
  	mk_child child &&
  	mkdir testrepo/.git/hooks &&
 -	echo exit 1 >testrepo/.git/hooks/pre-receive &&
 +	echo "#!/no/frobnication/today" >testrepo/.git/hooks/pre-receive &&
  	chmod +x testrepo/.git/hooks/pre-receive &&
- 	(cd child &&
+ 	(
+ 		cd child &&
  		git pull .. master
  		test_must_fail git push &&
  		test $(git rev-parse master) != \
@@@ -660,54 -683,53 +683,103 @@@ test_expect_success 'push with branche
  	git checkout master
  '
  
+ test_expect_success 'push into aliased refs (consistent)' '
+ 	mk_test heads/master &&
+ 	mk_child child1 &&
+ 	mk_child child2 &&
+ 	(
+ 		cd child1 &&
+ 		git branch foo &&
+ 		git symbolic-ref refs/heads/bar refs/heads/foo
+ 		git config receive.denyCurrentBranch false
+ 	) &&
+ 	(
+ 		cd child2 &&
+ 		>path2 &&
+ 		git add path2 &&
+ 		test_tick &&
+ 		git commit -a -m child2 &&
+ 		git branch foo &&
+ 		git branch bar &&
+ 		git push ../child1 foo bar
+ 	)
+ '
+ 
+ test_expect_success 'push into aliased refs (inconsistent)' '
+ 	mk_test heads/master &&
+ 	mk_child child1 &&
+ 	mk_child child2 &&
+ 	(
+ 		cd child1 &&
+ 		git branch foo &&
+ 		git symbolic-ref refs/heads/bar refs/heads/foo
+ 		git config receive.denyCurrentBranch false
+ 	) &&
+ 	(
+ 		cd child2 &&
+ 		>path2 &&
+ 		git add path2 &&
+ 		test_tick &&
+ 		git commit -a -m child2 &&
+ 		git branch foo &&
+ 		>path3 &&
+ 		git add path3 &&
+ 		test_tick &&
+ 		git commit -a -m child2 &&
+ 		git branch bar &&
+ 		test_must_fail git push ../child1 foo bar 2>stderr &&
+ 		grep "refusing inconsistent update" stderr
+ 	)
+ '
+ 
 +test_expect_success 'push --porcelain' '
 +	mk_empty &&
 +	echo >.git/foo  "To testrepo" &&
 +	echo >>.git/foo "*	refs/heads/master:refs/remotes/origin/master	[new branch]"  &&
 +	echo >>.git/foo "Done" &&
 +	git push >.git/bar --porcelain  testrepo refs/heads/master:refs/remotes/origin/master &&
 +	(
 +		cd testrepo &&
 +		r=$(git show-ref -s --verify refs/remotes/origin/master) &&
 +		test "z$r" = "z$the_commit" &&
 +		test 1 = $(git for-each-ref refs/remotes/origin | wc -l)
 +	) &&
 +	test_cmp .git/foo .git/bar
 +'
 +
 +test_expect_success 'push --porcelain bad url' '
 +	mk_empty &&
 +	test_must_fail git push >.git/bar --porcelain asdfasdfasd refs/heads/master:refs/remotes/origin/master &&
 +	test_must_fail grep -q Done .git/bar
 +'
 +
 +test_expect_success 'push --porcelain rejected' '
 +	mk_empty &&
 +	git push testrepo refs/heads/master:refs/remotes/origin/master &&
 +	(cd testrepo &&
 +		git reset --hard origin/master^
 +		git config receive.denyCurrentBranch true) &&
 +
 +	echo >.git/foo  "To testrepo"  &&
 +	echo >>.git/foo "!	refs/heads/master:refs/heads/master	[remote rejected] (branch is currently checked out)" &&
 +
 +	test_must_fail git push >.git/bar --porcelain  testrepo refs/heads/master:refs/heads/master &&
 +	test_cmp .git/foo .git/bar
 +'
 +
 +test_expect_success 'push --porcelain --dry-run rejected' '
 +	mk_empty &&
 +	git push testrepo refs/heads/master:refs/remotes/origin/master &&
 +	(cd testrepo &&
 +		git reset --hard origin/master
 +		git config receive.denyCurrentBranch true) &&
 +
 +	echo >.git/foo  "To testrepo"  &&
 +	echo >>.git/foo "!	refs/heads/master^:refs/heads/master	[rejected] (non-fast-forward)" &&
 +	echo >>.git/foo "Done" &&
 +
 +	test_must_fail git push >.git/bar --porcelain  --dry-run testrepo refs/heads/master^:refs/heads/master &&
 +	test_cmp .git/foo .git/bar
 +'
 +
  test_done