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

2 files changed, 186 insertions, 60 deletions

diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 0559fcc871..bb34757d27 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -9,6 +9,7 @@
 #include "object.h"
 #include "remote.h"
 #include "transport.h"
+#include "string-list.h"
 
 static const char receive_pack_usage[] = "git receive-pack <git-dir>";
 
@@ -129,13 +130,12 @@ static void write_head_info(void)
 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";
 
@@ -188,7 +188,7 @@ static int copy_to_sideband(int in, int out, void *arg)
 	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;
@@ -447,15 +447,15 @@ static const char *update(struct command *cmd)
 
 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++;
 	}
@@ -464,12 +464,12 @@ static void run_update_post_hook(struct command *cmd)
 	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++;
 	}
@@ -488,37 +488,92 @@ static void run_update_post_hook(struct command *cmd)
 	}
 }
 
-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];
@@ -548,15 +603,14 @@ static void read_head_info(void)
 			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)
@@ -643,7 +697,7 @@ static const char *unpack(void)
 	}
 }
 
-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;
@@ -667,12 +721,12 @@ static void report(const char *unpack_status)
 	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;
 }
@@ -722,6 +776,7 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
 	int stateless_rpc = 0;
 	int i;
 	char *dir = NULL;
+	struct command *commands;
 
 	argv++;
 	for (i = 1; i < argc; i++) {
@@ -772,18 +827,17 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
 	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[] = {
diff --git a/t/t5516-fetch-push.sh b/t/t5516-fetch-push.sh
index 6a37a4d993..b11da79c9c 100755
--- a/t/t5516-fetch-push.sh
+++ b/t/t5516-fetch-push.sh
@@ -64,13 +64,13 @@ check_push_result () {
 
 test_expect_success setup '
 
-	: >path1 &&
+	>path1 &&
 	git add path1 &&
 	test_tick &&
 	git commit -a -m repo &&
 	the_first_commit=$(git show-ref -s --verify refs/heads/master) &&
 
-	: >path2 &&
+	>path2 &&
 	git add path2 &&
 	test_tick &&
 	git commit -a -m second &&
@@ -483,8 +483,10 @@ git config --remove-section remote.there
 test_expect_success 'push with dry-run' '
 
 	mk_test heads/master &&
-	(cd testrepo &&
-	 old_commit=$(git show-ref -s --verify refs/heads/master)) &&
+	(
+		cd testrepo &&
+		old_commit=$(git show-ref -s --verify refs/heads/master)
+	) &&
 	git push --dry-run testrepo &&
 	check_push_result $old_commit heads/master
 '
@@ -493,10 +495,13 @@ test_expect_success 'push updates local refs' '
 
 	mk_test heads/master &&
 	mk_child child &&
-	(cd child &&
+	(
+		cd child &&
 		git pull .. master &&
 		git push &&
-	test $(git rev-parse master) = $(git rev-parse remotes/origin/master))
+		test $(git rev-parse master) = \
+			$(git rev-parse remotes/origin/master)
+	)
 
 '
 
@@ -506,10 +511,13 @@ test_expect_success 'push updates up-to-date local refs' '
 	mk_child child1 &&
 	mk_child child2 &&
 	(cd child1 && git pull .. master && git push) &&
-	(cd child2 &&
+	(
+		cd child2 &&
 		git pull ../child1 master &&
 		git push &&
-	test $(git rev-parse master) = $(git rev-parse remotes/origin/master))
+		test $(git rev-parse master) = \
+			$(git rev-parse remotes/origin/master)
+	)
 
 '
 
@@ -517,9 +525,11 @@ test_expect_success 'push preserves up-to-date packed refs' '
 
 	mk_test heads/master &&
 	mk_child child &&
-	(cd child &&
+	(
+		cd child &&
 		git push &&
-	! test -f .git/refs/remotes/origin/master)
+		! test -f .git/refs/remotes/origin/master
+	)
 
 '
 
@@ -530,11 +540,13 @@ test_expect_success 'push does not update local refs on failure' '
 	mkdir testrepo/.git/hooks &&
 	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) != \
-			$(git rev-parse remotes/origin/master))
+			$(git rev-parse remotes/origin/master)
+	)
 
 '
 
@@ -575,34 +587,41 @@ test_expect_success 'push --delete refuses src:dest refspecs' '
 
 test_expect_success 'warn on push to HEAD of non-bare repository' '
 	mk_test heads/master
-	(cd testrepo &&
+	(
+		cd testrepo &&
 		git checkout master &&
-		git config receive.denyCurrentBranch warn) &&
+		git config receive.denyCurrentBranch warn
+	) &&
 	git push testrepo master 2>stderr &&
 	grep "warning: updating the current branch" stderr
 '
 
 test_expect_success 'deny push to HEAD of non-bare repository' '
 	mk_test heads/master
-	(cd testrepo &&
+	(
+		cd testrepo &&
 		git checkout master &&
-		git config receive.denyCurrentBranch true) &&
+		git config receive.denyCurrentBranch true
+	) &&
 	test_must_fail git push testrepo master
 '
 
 test_expect_success 'allow push to HEAD of bare repository (bare)' '
 	mk_test heads/master
-	(cd testrepo &&
+	(
+		cd testrepo &&
 		git checkout master &&
 		git config receive.denyCurrentBranch true &&
-		git config core.bare true) &&
+		git config core.bare true
+	) &&
 	git push testrepo master 2>stderr &&
 	! grep "warning: updating the current branch" stderr
 '
 
 test_expect_success 'allow push to HEAD of non-bare repository (config)' '
 	mk_test heads/master
-	(cd testrepo &&
+	(
+		cd testrepo &&
 		git checkout master &&
 		git config receive.denyCurrentBranch false
 	) &&
@@ -615,7 +634,8 @@ test_expect_success 'fetch with branches' '
 	git branch second $the_first_commit &&
 	git checkout second &&
 	echo ".." > testrepo/.git/branches/branch1 &&
-	(cd testrepo &&
+	(
+		cd testrepo &&
 		git fetch branch1 &&
 		r=$(git show-ref -s --verify refs/heads/branch1) &&
 		test "z$r" = "z$the_commit" &&
@@ -627,7 +647,8 @@ test_expect_success 'fetch with branches' '
 test_expect_success 'fetch with branches containing #' '
 	mk_empty &&
 	echo "..#second" > testrepo/.git/branches/branch2 &&
-	(cd testrepo &&
+	(
+		cd testrepo &&
 		git fetch branch2 &&
 		r=$(git show-ref -s --verify refs/heads/branch2) &&
 		test "z$r" = "z$the_first_commit" &&
@@ -641,7 +662,8 @@ test_expect_success 'push with branches' '
 	git checkout second &&
 	echo "testrepo" > .git/branches/branch1 &&
 	git push branch1 &&
-	(cd testrepo &&
+	(
+		cd testrepo &&
 		r=$(git show-ref -s --verify refs/heads/master) &&
 		test "z$r" = "z$the_first_commit" &&
 		test 1 = $(git for-each-ref refs/heads | wc -l)
@@ -652,7 +674,8 @@ test_expect_success 'push with branches containing #' '
 	mk_empty &&
 	echo "testrepo#branch3" > .git/branches/branch2 &&
 	git push branch2 &&
-	(cd testrepo &&
+	(
+		cd testrepo &&
 		r=$(git show-ref -s --verify refs/heads/branch3) &&
 		test "z$r" = "z$the_first_commit" &&
 		test 1 = $(git for-each-ref refs/heads | wc -l)
@@ -660,6 +683,55 @@ test_expect_success 'push with branches containing #' '
 	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" &&