Shift object enumeration out of upload-pack

Offload object enumeration in upload-pack to pack-objects, but fall
back on internal revision walker for shallow interaction.   Aside from
architecturally making more sense, this also leaves the door open for
pack-objects to employ a revision cache mechanism.  Test t5530 updated
in order to explicitly check both enumeration methods.

Signed-off-by: Nick Edelen <sirnot@gmail.com>
Acked-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t5530-upload-pack-error.sh

@@ -30,11 +30,12 @@ test_expect_success 'fsck fails' '
 	test_must_fail git fsck
 '
 
-test_expect_success 'upload-pack fails due to error in pack-objects' '
+test_expect_success 'upload-pack fails due to error in pack-objects packing' '
 
 	! echo "0032want $(git rev-parse HEAD)
 00000009done
 0000" | git upload-pack . > /dev/null 2> output.err &&
+	grep "unable to read" output.err &&
 	grep "pack-objects died" output.err
 '
 
@@ -51,11 +52,20 @@ test_expect_success 'fsck fails' '
 test_expect_success 'upload-pack fails due to error in rev-list' '
 
 	! echo "0032want $(git rev-parse HEAD)
-00000009done
+0034shallow $(git rev-parse HEAD^)00000009done
 0000" | git upload-pack . > /dev/null 2> output.err &&
 	grep "waitpid (async) failed" output.err
 '
 
+test_expect_success 'upload-pack fails due to error in pack-objects enumeration' '
+
+	! echo "0032want $(git rev-parse HEAD)
+00000009done
+0000" | git upload-pack . > /dev/null 2> output.err &&
+	grep "bad tree object" output.err &&
+	grep "pack-objects died" output.err
+'
+
 test_expect_success 'create empty repository' '
 
 	mkdir foo &&

upload-pack.c

@@ -29,6 +29,7 @@ static unsigned long oldest_have;
 static int multi_ack, nr_our_refs;
 static int use_thin_pack, use_ofs_delta, use_include_tag;
 static int no_progress;
+static int shallow_nr;
 static struct object_array have_obj;
 static struct object_array want_obj;
 static unsigned int timeout;
@@ -107,8 +108,6 @@ static int do_rev_list(int fd, void *create_full_pack)
 	struct rev_info revs;
 
 	pack_pipe = fdopen(fd, "w");
-	if (create_full_pack)
-		use_thin_pack = 0; /* no point doing it */
 	init_revisions(&revs, NULL);
 	revs.tag_objects = 1;
 	revs.tree_objects = 1;
@@ -155,13 +154,21 @@ static void create_pack_file(void)
 	const char *argv[10];
 	int arg = 0;
 
+	if (shallow_nr) {
 		rev_list.proc = do_rev_list;
-	/* .data is just a boolean: any non-NULL value will do */
-	rev_list.data = create_full_pack ? &rev_list : NULL;
+		rev_list.data = 0;
 		if (start_async(&rev_list))
 			die("git upload-pack: unable to fork git-rev-list");
-
 		argv[arg++] = "pack-objects";
+	} else {
+		argv[arg++] = "pack-objects";
+		argv[arg++] = "--revs";
+		if (create_full_pack)
+			argv[arg++] = "--all";
+		else if (use_thin_pack)
+			argv[arg++] = "--thin";
+	}
+
 	argv[arg++] = "--stdout";
 	if (!no_progress)
 		argv[arg++] = "--progress";
@@ -172,7 +179,7 @@ static void create_pack_file(void)
 	argv[arg++] = NULL;
 
 	memset(&pack_objects, 0, sizeof(pack_objects));
-	pack_objects.in = rev_list.out;	/* start_command closes it */
+	pack_objects.in = shallow_nr ? rev_list.out : -1;
 	pack_objects.out = -1;
 	pack_objects.err = -1;
 	pack_objects.git_cmd = 1;
@@ -181,6 +188,24 @@ static void create_pack_file(void)
 	if (start_command(&pack_objects))
 		die("git upload-pack: unable to fork git-pack-objects");
 
+	/* pass on revisions we (don't) want */
+	if (!shallow_nr) {
+		FILE *pipe_fd = fdopen(pack_objects.in, "w");
+		if (!create_full_pack) {
+			int i;
+			for (i = 0; i < want_obj.nr; i++)
+				fprintf(pipe_fd, "%s\n", sha1_to_hex(want_obj.objects[i].item->sha1));
+			fprintf(pipe_fd, "--not\n");
+			for (i = 0; i < have_obj.nr; i++)
+				fprintf(pipe_fd, "%s\n", sha1_to_hex(have_obj.objects[i].item->sha1));
+		}
+
+		fprintf(pipe_fd, "\n");
+		fflush(pipe_fd);
+		fclose(pipe_fd);
+	}
+
+
 	/* We read from pack_objects.err to capture stderr output for
 	 * progress bar, and pack_objects.out to capture the pack data.
 	 */
@@ -276,7 +301,7 @@ static void create_pack_file(void)
 		error("git upload-pack: git-pack-objects died with error.");
 		goto fail;
 	}
-	if (finish_async(&rev_list))
+	if (shallow_nr && finish_async(&rev_list))
 		goto fail;	/* error was already reported */
 
 	/* flush the data */
@@ -451,6 +476,7 @@ static void receive_needs(void)
 	static char line[1000];
 	int len, depth = 0;
 
+	shallow_nr = 0;
 	if (debug_fd)
 		write_in_full(debug_fd, "#S\n", 3);
 	for (;;) {
@@ -534,6 +560,7 @@ static void receive_needs(void)
 				packet_write(1, "shallow %s",
 						sha1_to_hex(object->sha1));
 				register_shallow(object->sha1);
+				shallow_nr++;
 			}
 			result = result->next;
 		}
@@ -567,6 +594,8 @@ static void receive_needs(void)
 			for (i = 0; i < shallows.nr; i++)
 				register_shallow(shallows.objects[i].item->sha1);
 		}
+
+	shallow_nr += shallows.nr;
 	free(shallows.objects);
 }