From: Phillip Wood <phillip.wood123@gmail.com>
Date: Fri, 09 Dec 2022 19:33:37 GMT
Subject: Re: [PATCH 1/1] cat-file: quote-format name in error when using -z
Message-ID: <93d61412-3786-b2b3-3fe8-4574336b08fb@dunelm.org.uk>
In-Reply-To: <20221209150048.2400648-2-toon@iotcl.com>

Hi Toon

On 09/12/2022 15:00, Toon Claes wrote:
> Since it's supported to have NUL-delimited input, introduced in
> db9d67f2e9 (builtin/cat-file.c: support NUL-delimited input with `-z`,
> 2022-07-22), it's possible to pass paths that contain newlines. This
> works great when the object is found, but when it's not, the input path
> is returned in the error message. Because this can contain newlines, the
> error message might get spread over multiple lines, making it harder to
> machine-parse this error message.
> 
> With this change, the input is quote-formatted in the error message, if
> needed. This ensures the error message is always on a single line and
> makes parsing the error more straightforward.

Thanks for working on this. I'd previously suggested NUL terminating the 
output of "git cat-file -z" to avoid this problem [1] but quoting the 
object name is a better solution. The implementation looks good, thanks 
for adding a test - are you sure we need the FUNNYNAMES guard on the 
test even though it isn't creating files with funny names?

Best Wishes

Phillip

[1] 
https://lore.kernel.org/git/66b71194-ad0e-18d0-e43b-71e5c47ba111@gmail.com/

> Signed-off-by: Toon Claes <toon@iotcl.com>
> ---
>   builtin/cat-file.c  | 10 ++++++++++
>   t/t1006-cat-file.sh |  8 ++++++++
>   2 files changed, 18 insertions(+)
> 
> diff --git a/builtin/cat-file.c b/builtin/cat-file.c
> index b3be58b1fb..67dd81238d 100644
> --- a/builtin/cat-file.c
> +++ b/builtin/cat-file.c
> @@ -14,6 +14,7 @@
>   #include "tree-walk.h"
>   #include "oid-array.h"
>   #include "packfile.h"
> +#include "quote.h"
>   #include "object-store.h"
>   #include "promisor-remote.h"
>   #include "mailmap.h"
> @@ -475,6 +476,13 @@ static void batch_one_object(const char *obj_name,
>   	result = get_oid_with_context(the_repository, obj_name,
>   				      flags, &data->oid, &ctx);
>   	if (result != FOUND) {
> +		struct strbuf quoted = STRBUF_INIT;
> +
> +		if (opt->nul_terminated) {
> +			quote_c_style(obj_name, &quoted, NULL, 0);
> +			obj_name = quoted.buf;
> +		}
> +
>   		switch (result) {
>   		case MISSING_OBJECT:
>   			printf("%s missing\n", obj_name);
> @@ -499,6 +507,8 @@ static void batch_one_object(const char *obj_name,
>   			       result);
>   			break;
>   		}
> +
> +		strbuf_release(&quoted);
>   		fflush(stdout);
>   		return;
>   	}
> diff --git a/t/t1006-cat-file.sh b/t/t1006-cat-file.sh
> index 23b8942edb..232bfd1723 100755
> --- a/t/t1006-cat-file.sh
> +++ b/t/t1006-cat-file.sh
> @@ -447,6 +447,14 @@ test_expect_success FUNNYNAMES '--batch-check, -z with newline in input' '
>   	test_cmp expect actual
>   '
> 
> +test_expect_success FUNNYNAMES '--batch-check, -z with newline in non-existent named object' '
> +	printf "HEAD:newline${LF}embedded" >in &&
> +	git cat-file --batch-check -z <in >actual &&
> +
> +	printf "\"HEAD:newline\\\\nembedded\" missing\n" >expect &&
> +	test_cmp expect actual
> +'
> +
>   batch_command_multiple_info="info $hello_sha1
>   info $tree_sha1
>   info $commit_sha1
> --
> 2.39.0.rc0.57