upload-pack: Do not choke on too many heads request.

Cloning from a repository with more than 256 refs (heads and tags
included) will choke, because upload-pack has a built-in limit of
feeding not more than MAX_NEEDS (currently 256) heads to underlying
git-rev-list.  This is a problem when cloning a repository with many
tags, like http://www.linux-mips.org/pub/scm/linux.git, which has 290+
tags.

This commit introduces a new flag, --all, to git-rev-list, to include
all refs in the repository.  Updated upload-pack detects requests that
ask more than MAX_NEEDS refs, and sends everything back instead.

We may probably want to tweak the definitions of MAX_NEEDS and
MAX_HAS, but that is a separate topic.

Signed-off-by: Junio C Hamano <junkio@cox.net>

rev-list.c

@@ -1,4 +1,5 @@
 #include "cache.h"
+#include "refs.h"
 #include "tag.h"
 #include "commit.h"
 #include "tree.h"
@@ -489,6 +490,22 @@ static void handle_one_commit(struct commit *com, struct commit_list **lst)
 	commit_list_insert(com, lst);
 }
 
+/* for_each_ref() callback does not allow user data -- Yuck. */
+static struct commit_list **global_lst;
+
+static int include_one_commit(const char *path, const unsigned char *sha1)
+{
+	struct commit *com = get_commit_reference(path, 0);
+	handle_one_commit(com, global_lst);
+	return 0;
+}
+
+static void handle_all(struct commit_list **lst)
+{
+	global_lst = lst;
+	for_each_ref(include_one_commit);
+	global_lst = NULL;
+}
 
 int main(int argc, char **argv)
 {
@@ -542,6 +559,10 @@ int main(int argc, char **argv)
 			bisect_list = 1;
 			continue;
 		}
+		if (!strcmp(arg, "--all")) {
+			handle_all(&list);
+			continue;
+		}
 		if (!strcmp(arg, "--objects")) {
 			tag_objects = 1;
 			tree_objects = 1;

rev-parse.c

@@ -32,6 +32,7 @@ static int revs_count = 0;
 static int is_rev_argument(const char *arg)
 {
 	static const char *rev_args[] = {
+		"--all",
 		"--bisect",
 		"--header",
 		"--max-age=",

upload-pack.c

@@ -30,21 +30,33 @@ static void create_pack_file(void)
 
 	if (!pid) {
 		int i;
-		int args = nr_has + nr_needs + 5;
-		char **argv = xmalloc(args * sizeof(char *));
-		char *buf = xmalloc(args * 45);
-		char **p = argv;
+		int args;
+		char **argv;
+		char *buf;
+		char **p;
+
+		if (MAX_NEEDS <= nr_needs)
+			args = nr_has + 10;
+		else
+			args = nr_has + nr_needs + 5;
+		argv = xmalloc(args * sizeof(char *));
+		buf = xmalloc(args * 45);
+		p = argv;
 
 		dup2(fd[1], 1);
 		close(0);
 		close(fd[0]);
 		close(fd[1]);
 		*p++ = "git-rev-list";
 		*p++ = "--objects";
-		for (i = 0; i < nr_needs; i++) {
-			*p++ = buf;
-			memcpy(buf, sha1_to_hex(needs_sha1[i]), 41);
-			buf += 41;
+		if (MAX_NEEDS <= nr_needs)
+			*p++ = "--all";
+		else {
+			for (i = 0; i < nr_needs; i++) {
+				*p++ = buf;
+				memcpy(buf, sha1_to_hex(needs_sha1[i]), 41);
+				buf += 41;
+			}
 		}
 		for (i = 0; i < nr_has; i++) {
 			*p++ = buf;
@@ -129,18 +141,24 @@ static int receive_needs(void)
 
 	needs = 0;
 	for (;;) {
+		unsigned char dummy[20], *sha1_buf;
 		len = packet_read_line(0, line, sizeof(line));
 		if (!len)
 			return needs;
 
-		/*
-		 * This is purely theoretical right now: git-fetch-pack only
-		 * ever asks for a single HEAD
-		 */
-		if (needs >= MAX_NEEDS)
-			die("I'm only doing a max of %d requests", MAX_NEEDS);
-		if (strncmp("want ", line, 5) || get_sha1_hex(line+5, needs_sha1[needs]))
-			die("git-upload-pack: protocol error, expected to get sha, not '%s'", line);
+		sha1_buf = dummy;
+		if (needs == MAX_NEEDS) {
+			fprintf(stderr,
+				"warning: supporting only a max of %d requests. "
+				"sending everything instead.\n",
+				MAX_NEEDS);
+		}
+		else if (needs < MAX_NEEDS)
+			sha1_buf = needs_sha1[needs];
+
+		if (strncmp("want ", line, 5) || get_sha1_hex(line+5, sha1_buf))
+			die("git-upload-pack: protocol error, "
+			    "expected to get sha, not '%s'", line);
 		needs++;
 	}
 }