bundle: arguments can be read from stdin

In order to create an incremental bundle, we need to pass many arguments
to let git-bundle ignore some already packed commits.  It will be more
convenient to pass args via stdin.  But the current implementation does
not allow us to do this.

This is because args are parsed twice when creating bundle.  The first
time for parsing args is in `compute_and_write_prerequisites()` by
running `git-rev-list` command to write prerequisites in bundle file,
and stdin is consumed in this step if "--stdin" option is provided for
`git-bundle`.  Later nothing can be read from stdin when running
`setup_revisions()` in `create_bundle()`.

The solution is to parse args once by removing the entire function
`compute_and_write_prerequisites()` and then calling function
`setup_revisions()`.  In order to write prerequisites for bundle, will
call `prepare_revision_walk()` and `traverse_commit_list()`.  But after
calling `prepare_revision_walk()`, the object array `revs.pending` is
left empty, and the following steps could not work properly with the
empty object array (`revs.pending`).  Therefore, make a copy of `revs`
to `revs_copy` for later use right after calling `setup_revisions()`.

The copy of `revs_copy` is not a deep copy, it shares the same objects
with `revs`. The object array of `revs` has been cleared, but objects
themselves are still kept.  Flags of objects may change after calling
`prepare_revision_walk()`, we can use these changed flags without
calling the `git rev-list` command and parsing its output like the
former implementation.

Also add testcases for git bundle in t6020, which read args from stdin.

Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 59 insertions, 50 deletions

diff --git a/bundle.c b/bundle.c
index cb0e5931ac..693d619551 100644
--- a/bundle.c
+++ b/bundle.c
@@ -338,48 +338,6 @@ static int write_pack_data(int bundle_fd, struct rev_info *revs, struct strvec *
 	return 0;
 }
 
-static int compute_and_write_prerequisites(int bundle_fd,
-					   struct rev_info *revs,
-					   int argc, const char **argv)
-{
-	struct child_process rls = CHILD_PROCESS_INIT;
-	struct strbuf buf = STRBUF_INIT;
-	FILE *rls_fout;
-	int i;
-
-	strvec_pushl(&rls.args,
-		     "rev-list", "--boundary", "--pretty=oneline",
-		     NULL);
-	for (i = 1; i < argc; i++)
-		strvec_push(&rls.args, argv[i]);
-	rls.out = -1;
-	rls.git_cmd = 1;
-	if (start_command(&rls))
-		return -1;
-	rls_fout = xfdopen(rls.out, "r");
-	while (strbuf_getwholeline(&buf, rls_fout, '\n') != EOF) {
-		struct object_id oid;
-		if (buf.len > 0 && buf.buf[0] == '-') {
-			write_or_die(bundle_fd, buf.buf, buf.len);
-			if (!get_oid_hex(buf.buf + 1, &oid)) {
-				struct object *object = parse_object_or_die(&oid,
-									    buf.buf);
-				object->flags |= UNINTERESTING;
-				add_pending_object(revs, object, buf.buf);
-			}
-		} else if (!get_oid_hex(buf.buf, &oid)) {
-			struct object *object = parse_object_or_die(&oid,
-								    buf.buf);
-			object->flags |= SHOWN;
-		}
-	}
-	strbuf_release(&buf);
-	fclose(rls_fout);
-	if (finish_command(&rls))
-		return error(_("rev-list died"));
-	return 0;
-}
-
 /*
  * Write out bundle refs based on the tips already
  * parsed into revs.pending. As a side effect, may
@@ -474,6 +432,38 @@ static int write_bundle_refs(int bundle_fd, struct rev_info *revs)
 	return ref_count;
 }
 
+struct bundle_prerequisites_info {
+	struct object_array *pending;
+	int fd;
+};
+
+static void write_bundle_prerequisites(struct commit *commit, void *data)
+{
+	struct bundle_prerequisites_info *bpi = data;
+	struct object *object;
+	struct pretty_print_context ctx = { 0 };
+	struct strbuf buf = STRBUF_INIT;
+
+	if (!(commit->object.flags & BOUNDARY))
+		return;
+	strbuf_addf(&buf, "-%s ", oid_to_hex(&commit->object.oid));
+	write_or_die(bpi->fd, buf.buf, buf.len);
+
+	ctx.fmt = CMIT_FMT_ONELINE;
+	ctx.output_encoding = get_log_output_encoding();
+	strbuf_reset(&buf);
+	pretty_print_commit(&ctx, commit, &buf);
+	strbuf_trim(&buf);
+
+	object = (struct object *)commit;
+	object->flags |= UNINTERESTING;
+	add_object_array_with_path(object, buf.buf, bpi->pending, S_IFINVALID,
+				   NULL);
+	strbuf_addch(&buf, '\n');
+	write_or_die(bpi->fd, buf.buf, buf.len);
+	strbuf_release(&buf);
+}
+
 int create_bundle(struct repository *r, const char *path,
 		  int argc, const char **argv, struct strvec *pack_options, int version)
 {
@@ -481,8 +471,10 @@ int create_bundle(struct repository *r, const char *path,
 	int bundle_fd = -1;
 	int bundle_to_stdout;
 	int ref_count = 0;
-	struct rev_info revs;
+	struct rev_info revs, revs_copy;
 	int min_version = the_hash_algo == &hash_algos[GIT_HASH_SHA1] ? 2 : 3;
+	struct bundle_prerequisites_info bpi;
+	int i;
 
 	bundle_to_stdout = !strcmp(path, "-");
 	if (bundle_to_stdout)
@@ -512,10 +504,6 @@ int create_bundle(struct repository *r, const char *path,
 	save_commit_buffer = 0;
 	repo_init_revisions(r, &revs, NULL);
 
-	/* write prerequisites */
-	if (compute_and_write_prerequisites(bundle_fd, &revs, argc, argv))
-		goto err;
-
 	argc = setup_revisions(argc, argv, &revs, NULL);
 
 	if (argc > 1) {
@@ -523,16 +511,37 @@ int create_bundle(struct repository *r, const char *path,
 		goto err;
 	}
 
-	object_array_remove_duplicates(&revs.pending);
+	/* save revs.pending in revs_copy for later use */
+	memcpy(&revs_copy, &revs, sizeof(revs));
+	revs_copy.pending.nr = 0;
+	revs_copy.pending.alloc = 0;
+	revs_copy.pending.objects = NULL;
+	for (i = 0; i < revs.pending.nr; i++) {
+		struct object_array_entry *e = revs.pending.objects + i;
+		if (e)
+			add_object_array_with_path(e->item, e->name,
+						   &revs_copy.pending,
+						   e->mode, e->path);
+	}
 
-	ref_count = write_bundle_refs(bundle_fd, &revs);
+	/* write prerequisites */
+	revs.boundary = 1;
+	if (prepare_revision_walk(&revs))
+		die("revision walk setup failed");
+	bpi.fd = bundle_fd;
+	bpi.pending = &revs_copy.pending;
+	traverse_commit_list(&revs, write_bundle_prerequisites, NULL, &bpi);
+	object_array_remove_duplicates(&revs_copy.pending);
+
+	/* write bundle refs */
+	ref_count = write_bundle_refs(bundle_fd, &revs_copy);
 	if (!ref_count)
 		die(_("Refusing to create empty bundle."));
 	else if (ref_count < 0)
 		goto err;
 
 	/* write pack */
-	if (write_pack_data(bundle_fd, &revs, pack_options))
+	if (write_pack_data(bundle_fd, &revs_copy, pack_options))
 		goto err;
 
 	if (!bundle_to_stdout) {