run-command: support custom fd-set in async

This patch adds the possibility to supply a set of non-0 file
descriptors for async process communication instead of the
default-created pipe.

Additionally, we now support bi-directional communiction with the
async procedure, by giving the async function both read and write
file descriptors.

To retain compatiblity and similar "API feel" with start_command,
we require start_async callers to set .out = -1 to get a readable
file descriptor.  If either of .in or .out is 0, we supply no file
descriptor to the async process.

[sp: Note: Erik started this patch, and a huge bulk of it is
     his work.  All bugs were introduced later by Shawn.]

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/upload-pack.c b/upload-pack.c
index df15181..dc464d7 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -105,12 +105,12 @@ static void show_edge(struct commit *commit)
 	fprintf(pack_pipe, "-%s\n", sha1_to_hex(commit->object.sha1));
 }
 
-static int do_rev_list(int fd, void *create_full_pack)
+static int do_rev_list(int in, int out, void *create_full_pack)
 {
 	int i;
 	struct rev_info revs;
 
-	pack_pipe = xfdopen(fd, "w");
+	pack_pipe = xfdopen(out, "w");
 	init_revisions(&revs, NULL);
 	revs.tag_objects = 1;
 	revs.tree_objects = 1;
@@ -162,8 +162,9 @@ static void create_pack_file(void)
 	int arg = 0;
 
 	if (shallow_nr) {
+		memset(&rev_list, 0, sizeof(rev_list));
 		rev_list.proc = do_rev_list;
-		rev_list.data = 0;
+		rev_list.out = -1;
 		if (start_async(&rev_list))
 			die("git upload-pack: unable to fork git-rev-list");
 		argv[arg++] = "pack-objects";