patch, 2 partsTeach rev-list an option to read revs from the standard input.

Documentation/git-rev-list.txt, builtin-rev-list.c

diff --git a/Documentation/git-rev-list.txt b/Documentation/git-rev-list.txt
index 3c4c2fb..28966ad 100644
--- a/Documentation/git-rev-list.txt
+++ b/Documentation/git-rev-list.txt
@@ -17,6 +17,7 @@ SYNOPSIS
 	     [ \--remove-empty ]
 	     [ \--not ]
 	     [ \--all ]
+	     [ \--stdin ]
 	     [ \--topo-order ]
 	     [ \--parents ]
 	     [ [\--objects | \--objects-edge] [ \--unpacked ] ]
@@ -171,6 +172,11 @@ limiting may be applied.
 	Pretend as if all the refs in `$GIT_DIR/refs/` are listed on the
 	command line as '<commit>'.
 
+--stdin::
+
+	In addition to the '<commit>' listed on the command
+	line, read them from the standard input.
+
 --merge::
 
 	After a failed merge, show refs that touch files having a
diff --git a/builtin-rev-list.c b/builtin-rev-list.c
index 8437454..8fe8afb 100644
--- a/builtin-rev-list.c
+++ b/builtin-rev-list.c
@@ -23,6 +23,7 @@ static const char rev_list_usage[] =
 "    --no-merges\n"
 "    --remove-empty\n"
 "    --all\n"
+"    --stdin\n"
 "  ordering output:\n"
 "    --topo-order\n"
 "    --date-order\n"
@@ -304,10 +305,28 @@ static void mark_edges_uninteresting(str
 	}
 }
 
+static void read_revisions_from_stdin(struct rev_info *revs)
+{
+	char line[1000];
+
+	while (fgets(line, sizeof(line), stdin) != NULL) {
+		int len = strlen(line);
+		if (line[len - 1] == '\n')
+			line[--len] = 0;
+		if (!len)
+			break;
+		if (line[0] == '-')
+			die("options not supported in --stdin mode");
+		if (handle_revision_arg(line, revs, 0, 1))
+			die("bad revision '%s'", line);
+	}
+}
+
 int cmd_rev_list(int argc, const char **argv, const char *prefix)
 {
 	struct commit_list *list;
 	int i;
+	int read_from_stdin = 0;
 
 	init_revisions(&revs, prefix);
 	revs.abbrev = 0;
@@ -329,6 +348,12 @@ int cmd_rev_list(int argc, const char **
 			bisect_list = 1;
 			continue;
 		}
+		if (!strcmp(arg, "--stdin")) {
+			if (read_from_stdin++)
+				die("--stdin given twice?");
+			read_revisions_from_stdin(&revs);
+			continue;
+		}
 		usage(rev_list_usage);
 
 	}

diff --git a/send-pack.c b/send-pack.c
index ac4501d..b403ee9 100644
--- a/send-pack.c
+++ b/send-pack.c
@@ -38,9 +38,8 @@ static void exec_pack_objects(void)
 
 static void exec_rev_list(struct ref *refs)
 {
-	struct ref *ref;
-	static const char *args[1000];
-	int i = 0, j;
+	static const char *args[4];
+	int i = 0;
 
 	args[i++] = "rev-list";	/* 0 */
 	if (use_thin_pack)	/* 1 */
@@ -48,43 +47,29 @@ static void exec_rev_list(struct ref *re
 	else
 		args[i++] = "--objects";
 
-	/* First send the ones we care about most */
-	for (ref = refs; ref; ref = ref->next) {
-		if (900 < i)
-			die("git-rev-list environment overflow");
-		if (!is_zero_sha1(ref->new_sha1)) {
-			char *buf = xmalloc(100);
-			args[i++] = buf;
-			snprintf(buf, 50, "%s", sha1_to_hex(ref->new_sha1));
-			buf += 50;
-			if (!is_zero_sha1(ref->old_sha1) &&
-			    has_sha1_file(ref->old_sha1)) {
-				args[i++] = buf;
-				snprintf(buf, 50, "^%s",
-					 sha1_to_hex(ref->old_sha1));
-			}
-		}
-	}
+	args[i++] = "--stdin";
 
-	/* Then a handful of the remainder
-	 * NEEDSWORK: we would be better off if used the newer ones first.
-	 */
-	for (ref = refs, j = i + 16;
-	     i < 900 && i < j && ref;
-	     ref = ref->next) {
-		if (is_zero_sha1(ref->new_sha1) &&
-		    !is_zero_sha1(ref->old_sha1) &&
-		    has_sha1_file(ref->old_sha1)) {
-			char *buf = xmalloc(42);
-			args[i++] = buf;
-			snprintf(buf, 42, "^%s", sha1_to_hex(ref->old_sha1));
-		}
-	}
 	args[i] = NULL;
 	execv_git_cmd(args);
 	die("git-rev-list exec failed (%s)", strerror(errno));
 }
 
+static void builtin_rev_list_generate(struct ref *refs)
+{
+	while (refs) {
+		if (!is_zero_sha1(refs->old_sha1) &&
+		    has_sha1_file(refs->old_sha1)) {
+			printf("^%s\n", sha1_to_hex(refs->old_sha1));
+		}
+		if (!is_zero_sha1(refs->new_sha1)) {
+			printf("%s\n", sha1_to_hex(refs->new_sha1));
+		}
+		refs = refs->next;
+	}
+
+	exit(0);
+}
+
 static void rev_list(int fd, struct ref *refs)
 {
 	int pipe_fd[2];
@@ -111,13 +96,38 @@ static void rev_list(int fd, struct ref 
 	exec_rev_list(refs);
 }
 
+static void rev_list_generate(int fd, struct ref *refs)
+{
+	int pipe_fd[2];
+	pid_t rev_list_generate_pid;
+
+	if (pipe(pipe_fd) < 0)
+		die("rev-list-generate setup: pipe failed");
+	rev_list_generate_pid = fork();
+	if (!rev_list_generate_pid) {
+		dup2(pipe_fd[0], 0);
+		dup2(fd, 1);
+		close(pipe_fd[0]);
+		close(pipe_fd[1]);
+		close(fd);
+		rev_list(fd, refs);
+		die("rev-list setup failed");
+	}
+	if (rev_list_generate_pid < 0)
+		die("rev-list-generate fork failed");
+	dup2(pipe_fd[1], 1);
+	close(pipe_fd[0]);
+	close(pipe_fd[1]);
+	close(fd);
+	builtin_rev_list_generate(refs);
+}
 static void pack_objects(int fd, struct ref *refs)
 {
 	pid_t rev_list_pid;
 
 	rev_list_pid = fork();
 	if (!rev_list_pid) {
-		rev_list(fd, refs);
+		rev_list_generate(fd, refs);
 		die("rev-list setup failed");
 	}
 	if (rev_list_pid < 0)