Merge branch 'sp/fetch-fix'

* sp/fetch-fix:
  git-fetch: avoid local fetching from alternate (again)
  rev-list: Introduce --quiet to avoid /dev/null redirects
  run-command: Support sending stderr to /dev/null
  git-fetch: Always fetch tags if the object they reference exists

builtin-fetch.c

@@ -8,10 +8,12 @@
 #include "path-list.h"
 #include "remote.h"
 #include "transport.h"
+#include "run-command.h"
 
 static const char fetch_usage[] = "git-fetch [-a | --append] [--upload-pack <upload-pack>] [-f | --force] [--no-tags] [-t | --tags] [-k | --keep] [-u | --update-head-ok] [--depth <depth>] [-v | --verbose] [<repository> <refspec>...]";
 
 static int append, force, tags, no_tags, update_head_ok, verbose, quiet;
+static const char *depth;
 static char *default_rla = NULL;
 static struct transport *transport;
 
@@ -335,9 +337,72 @@ static void store_updated_refs(const char *url, struct ref *ref_map)
 	fclose(fp);
 }
 
+/*
+ * We would want to bypass the object transfer altogether if
+ * everything we are going to fetch already exists and connected
+ * locally.
+ *
+ * The refs we are going to fetch are in to_fetch (nr_heads in
+ * total).  If running
+ *
+ *  $ git-rev-list --objects to_fetch[0] to_fetch[1] ... --not --all
+ *
+ * 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;
+	char **argv;
+	int i, err;
+
+	/*
+	 * If we are deepening a shallow clone we already have these
+	 * objects reachable.  Running rev-list here will return with
+	 * a good (0) exit status and we'll bypass the fetch that we
+	 * really need to perform.  Claiming failure now will ensure
+	 * we perform the network exchange to deepen our history.
+	 */
+	if (depth)
+		return -1;
+
+	for (i = 0, ref = ref_map; ref; ref = ref->next)
+		i++;
+	if (!i)
+		return 0;
+
+	argv = xmalloc(sizeof(*argv) * (i + 6));
+	i = 0;
+	argv[i++] = xstrdup("rev-list");
+	argv[i++] = xstrdup("--quiet");
+	argv[i++] = xstrdup("--objects");
+	for (ref = ref_map; ref; ref = ref->next)
+		argv[i++] = xstrdup(sha1_to_hex(ref->old_sha1));
+	argv[i++] = xstrdup("--not");
+	argv[i++] = xstrdup("--all");
+	argv[i++] = NULL;
+
+	memset(&revlist, 0, sizeof(revlist));
+	revlist.argv = (const char**)argv;
+	revlist.git_cmd = 1;
+	revlist.no_stdin = 1;
+	revlist.no_stdout = 1;
+	revlist.no_stderr = 1;
+	err = run_command(&revlist);
+
+	for (i = 0; argv[i]; i++)
+		free(argv[i]);
+	free(argv);
+	return err;
+}
+
 static int fetch_refs(struct transport *transport, struct ref *ref_map)
 {
-	int ret = transport_fetch_refs(transport, ref_map);
+	int ret = quickfetch(ref_map);
+	if (ret)
+		ret = transport_fetch_refs(transport, ref_map);
 	if (!ret)
 		store_updated_refs(transport->url, ref_map);
 	transport_unlock_pack(transport);
@@ -389,7 +454,7 @@ static struct ref *find_non_local_tags(struct transport *transport,
 
 		if (!path_list_has_path(&existing_refs, ref_name) &&
 		    !path_list_has_path(&new_refs, ref_name) &&
-		    lookup_object(ref->old_sha1)) {
+		    has_sha1_file(ref->old_sha1)) {
 			path_list_insert(ref_name, &new_refs);
 
 			rm = alloc_ref(strlen(ref_name) + 1);
@@ -473,7 +538,7 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
 	static const char **refs = NULL;
 	int ref_nr = 0;
 	int cmd_len = 0;
-	const char *depth = NULL, *upload_pack = NULL;
+	const char *upload_pack = NULL;
 	int keep = 0;
 
 	for (i = 1; i < argc; i++) {