replace: use argv_array in export_object

This is a little more verbose, but will make it easier to
make parts of our command-line conditional (without
resorting to magic numbers or lots of NULLs to get an
appropriately sized argv array).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/replace.c b/builtin/replace.c
index eb1d2ec..2584170 100644 (file)
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -193,15 +193,17 @@ static int replace_object(const char *object_ref, const char *replace_ref, int f
  */
 static void export_object(const unsigned char *sha1, const char *filename)
 {
-       const char *argv[] = { "--no-replace-objects", "cat-file", "-p", NULL, NULL };
-       struct child_process cmd = { argv };
+       struct child_process cmd = { NULL };
        int fd;
 
        fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
        if (fd < 0)
                die_errno("unable to open %s for writing", filename);
 
-       argv[3] = sha1_to_hex(sha1);
+       argv_array_push(&cmd.args, "--no-replace-objects");
+       argv_array_push(&cmd.args, "cat-file");
+       argv_array_push(&cmd.args, "-p");
+       argv_array_push(&cmd.args, sha1_to_hex(sha1));
        cmd.git_cmd = 1;
        cmd.out = fd;