Subject: Re: [PATCH v3] upload-pack: send shallow info over stdin to pack-objects

From: Junio C Hamano <[email-masked]>
Date: Thu, 06 Mar 2014 10:37:24 -0800

Nguyễn Thái Ngọc Duy  <[email-masked]> writes:

> From: Duy Nguyen <[email-masked]>
>
> Before cdab485 (upload-pack: delegate rev walking in shallow fetch to
> pack-objects - 2013-08-16) upload-pack does not write to the source
> repository. cdab485 starts to write $GIT_DIR/shallow_XXXXXX if it's a
> shallow fetch, so the source repo must be writable.
>
> git:// servers do not need write access to repos and usually don't
> have it, which means cdab485 breaks shallow clone over git://
>
> Instead of using a temporary file as the media for shallow points, we
> can send them over stdin to pack-objects as well. Prepend shallow
> SHA-1 with --shallow so pack-objects knows what is
> what.
>
> read_object_list_from_stdin() does not accept --shallow lines because
> upload-pack never uses that code. When upload-pack does, then it can
> learn about --shallow lines.
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <[email-masked]>
> ---
>  OK new approach, stop creating shallow_XXXXXX in upload-pack.

Thanks.

I like what I see in this patch, but I wonder if we can essentially
revert that "temporary shallow file" patch and replace it with the
same (or a similar) mechanism uniformly?

On the receive-pack side, the comment at the bottom of
preprare_shallow_update() makes it clear that, if we wanted to use
hooks, we cannot avoid having the proposed new shallow-file in a
temporary file, which is unfortunate.  Do we have a similar issue on
hooks on the upload-pack side?

>  builtin/pack-objects.c   |  7 +++++++
>  shallow.c                |  2 ++
>  t/t5537-fetch-shallow.sh | 13 +++++++++++++
>  upload-pack.c            | 21 ++++++++++++---------
>  4 files changed, 34 insertions(+), 9 deletions(-)

Nothing for Documentation/ anywhere?

> diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
> index c733379..79e848e 100644
> --- a/builtin/pack-objects.c
> +++ b/builtin/pack-objects.c
> @@ -2467,6 +2467,13 @@ static void get_object_list(int ac, const char **av)
>  				write_bitmap_index = 0;
>  				continue;
>  			}
> +			if (starts_with(line, "--shallow ")) {
> +				unsigned char sha1[20];
> +				if (get_sha1_hex(line + 10, sha1))
> +					die("not an SHA-1 '%s'", line + 10);
> +				register_shallow(sha1);
> +				continue;
> +			}
>  			die("not a rev '%s'", line);
>  		}
>  		if (handle_revision_arg(line, &revs, flags, REVARG_CANNOT_BE_FILENAME))
> diff --git a/shallow.c b/shallow.c
> index bbc98b5..41ff4a0 100644
> --- a/shallow.c
> +++ b/shallow.c
> @@ -33,6 +33,8 @@ int register_shallow(const unsigned char *sha1)
>  	graft->nr_parent = -1;
>  	if (commit && commit->object.parsed)
>  		commit->parents = NULL;
> +	if (is_shallow == -1)
> +		is_shallow = 1;
>  	return register_commit_graft(graft, 0);
>  }
>  
> diff --git a/t/t5537-fetch-shallow.sh b/t/t5537-fetch-shallow.sh
> index 3ae9092..a980574 100755
> --- a/t/t5537-fetch-shallow.sh
> +++ b/t/t5537-fetch-shallow.sh
> @@ -173,4 +173,17 @@ EOF
>  	)
>  '
>  
> +test_expect_success POSIXPERM,SANITY 'shallow fetch from a read-only repo' '
> +	cp -R .git read-only.git &&
> +	find read-only.git -print | xargs chmod -w &&
> +	test_when_finished "find read-only.git -type d -print | xargs chmod +w" &&
> +	git clone --no-local --depth=2 read-only.git from-read-only &&
> +	git --git-dir=from-read-only/.git log --format=%s >actual &&
> +	cat >expect <<EOF &&
> +add-1-back
> +4
> +EOF
> +	test_cmp expect actual
> +'
> +
>  test_done
> diff --git a/upload-pack.c b/upload-pack.c
> index 0c44f6b..a5c50e4 100644
> --- a/upload-pack.c
> +++ b/upload-pack.c
> @@ -70,6 +70,14 @@ static ssize_t send_client_data(int fd, const char *data, ssize_t sz)
>  	return sz;
>  }
>  
> +static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
> +{
> +	FILE *fp = cb_data;
> +	if (graft->nr_parent == -1)
> +		fprintf(fp, "--shallow %s\n", sha1_to_hex(graft->sha1));
> +	return 0;
> +}
> +
>  static void create_pack_file(void)
>  {
>  	struct child_process pack_objects;
> @@ -81,12 +89,10 @@ static void create_pack_file(void)
>  	const char *argv[12];
>  	int i, arg = 0;
>  	FILE *pipe_fd;
> -	char *shallow_file = NULL;
>  
>  	if (shallow_nr) {
> -		shallow_file = setup_temporary_shallow(NULL);
>  		argv[arg++] = "--shallow-file";
> -		argv[arg++] = shallow_file;
> +		argv[arg++] = "";
>  	}
>  	argv[arg++] = "pack-objects";
>  	argv[arg++] = "--revs";
> @@ -114,6 +120,9 @@ static void create_pack_file(void)
>  
>  	pipe_fd = xfdopen(pack_objects.in, "w");
>  
> +	if (shallow_nr)
> +		for_each_commit_graft(write_one_shallow, pipe_fd);
> +
>  	for (i = 0; i < want_obj.nr; i++)
>  		fprintf(pipe_fd, "%s\n",
>  			sha1_to_hex(want_obj.objects[i].item->sha1));
> @@ -242,12 +251,6 @@ static void create_pack_file(void)
>  		error("git upload-pack: git-pack-objects died with error.");
>  		goto fail;
>  	}
> -	if (shallow_file) {
> -		if (*shallow_file)
> -			unlink(shallow_file);
> -		free(shallow_file);
> -	}
> -
>  	/* flush the data */
>  	if (0 <= buffered) {
>  		data[0] = buffered;