[PATCH 3/3] fetch: verify we have everything we need before updating our ref

From

Junio C Hamano <gitster@pobox.com>

Date

Sep 1, 2011, 22:43 UTC

Message-ID

<1314917015-3587-4-git-send-email-gitster@pobox.com>

In-Reply-To

<1314917015-3587-1-git-send-email-gitster@pobox.com>

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/fetch.c |  119 +++++++++++++++++++++++++++++--------------------------
 1 files changed, 63 insertions(+), 56 deletions(-)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index f9c41da..bdb03ff 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -345,6 +345,64 @@ static int update_local_ref(struct ref *ref,
 	}
 }
 
+/*
+ * The ref_map records the tips of the refs we are fetching. If
+ *
+ *  $ git rev-list --verify-objects --stdin --not --all
+ *
+ * (feeding all the refs in ref_map on its standard input) does not
+ * error out, that means everything reachable from these updated refs
+ * locally exists and is connected to some of our existing refs.
+ *
+ * Returns 0 if everything is connected, non-zero otherwise.
+ */
+static int check_everything_connected(struct ref *ref_map, int quiet)
+{
+	struct child_process rev_list;
+	const char *argv[] = {"rev-list", "--verify-objects",
+			      "--stdin", "--not", "--all", NULL, NULL};
+	char commit[41];
+	struct ref *ref;
+	int err = 0;
+
+	if (!ref_map)
+		return 0;
+
+	if (quiet)
+		argv[5] = "--quiet";
+
+	memset(&rev_list, 0, sizeof(rev_list));
+	rev_list.argv = argv;
+	rev_list.git_cmd = 1;
+	rev_list.in = -1;
+	rev_list.no_stdout = 1;
+	rev_list.no_stderr = quiet;
+	if (start_command(&rev_list))
+		return error(_("Could not run 'git rev-list'"));
+
+	sigchain_push(SIGPIPE, SIG_IGN);
+
+	memcpy(commit + 40, "\n", 2);
+	for (ref = ref_map; ref; ref = ref->next) {
+		memcpy(commit, sha1_to_hex(ref->old_sha1), 40);
+		if (write_in_full(rev_list.in, commit, 41) < 0) {
+			if (errno != EPIPE && errno != EINVAL)
+				error(_("failed write to rev-list: %s"),
+				      strerror(errno));
+			err = -1;
+			break;
+		}
+	}
+	if (close(rev_list.in)) {
+		error(_("failed to close rev-list's stdin: %s"), strerror(errno));
+		err = -1;
+	}
+
+	sigchain_pop(SIGPIPE);
+
+	return finish_command(&rev_list) || err;
+}
+
 static int store_updated_refs(const char *raw_url, const char *remote_name,
 		struct ref *ref_map)
 {
@@ -364,6 +422,10 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
 		url = transport_anonymize_url(raw_url);
 	else
 		url = xstrdup("foreign");
+
+	if (check_everything_connected(ref_map, 0))
+		return error(_("%s did not send all necessary objects\n"), url);
+
 	for (rm = ref_map; rm; rm = rm->next) {
 		struct ref *ref = NULL;
 
@@ -457,24 +519,9 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
  * We would want to bypass the object transfer altogether if
  * everything we are going to fetch already exists and is connected
  * locally.
- *
- * The refs we are going to fetch are in ref_map.  If running
- *
- *  $ git rev-list --objects --stdin --not --all
- *
- * (feeding all the refs in ref_map on its standard input)
- * does not error out, that means everything reachable from the
- * refs we are going to fetch exists and is connected to some of
- * our existing refs.
  */
 static int quickfetch(struct ref *ref_map)
 {
-	struct child_process revlist;
-	struct ref *ref;
-	int err;
-	const char *argv[] = {"rev-list",
-		"--quiet", "--objects", "--stdin", "--not", "--all", NULL};
-
 	/*
 	 * If we are deepening a shallow clone we already have these
 	 * objects reachable.  Running rev-list here will return with
@@ -484,47 +531,7 @@ static int quickfetch(struct ref *ref_map)
 	 */
 	if (depth)
 		return -1;
-
-	if (!ref_map)
-		return 0;
-
-	memset(&revlist, 0, sizeof(revlist));
-	revlist.argv = argv;
-	revlist.git_cmd = 1;
-	revlist.no_stdout = 1;
-	revlist.no_stderr = 1;
-	revlist.in = -1;
-
-	err = start_command(&revlist);
-	if (err) {
-		error(_("could not run rev-list"));
-		return err;
-	}
-
-	/*
-	 * If rev-list --stdin encounters an unknown commit, it terminates,
-	 * which will cause SIGPIPE in the write loop below.
-	 */
-	sigchain_push(SIGPIPE, SIG_IGN);
-
-	for (ref = ref_map; ref; ref = ref->next) {
-		if (write_in_full(revlist.in, sha1_to_hex(ref->old_sha1), 40) < 0 ||
-		    write_str_in_full(revlist.in, "\n") < 0) {
-			if (errno != EPIPE && errno != EINVAL)
-				error(_("failed write to rev-list: %s"), strerror(errno));
-			err = -1;
-			break;
-		}
-	}
-
-	if (close(revlist.in)) {
-		error(_("failed to close rev-list's stdin: %s"), strerror(errno));
-		err = -1;
-	}
-
-	sigchain_pop(SIGPIPE);
-
-	return finish_command(&revlist) || err;
+	return check_everything_connected(ref_map, 1);
 }
 
 static int fetch_refs(struct transport *transport, struct ref *ref_map)

-- 
1.7.7.rc0.72.g4b5ea