Re: [PATCH 24/31] archive-tar: make hash size independent

> Am 12.02.2019 um 08:20 schrieb René Scharfe:
> > That command currently prints the pax comment in tar archives if it
> > looks like a SHA1 hash based on its length.  It should continue to do
> > so, and _also_ show longer hashes.  Your change makes it _only_ show
> > those longer hashes.
> >
> > So it could check for all known valid hash lengths in turn, or accept
> > any payload length between 40 and the_hash_algo->hexsz, or loosen up
> > totally and show comments of any length.
> 
> How about the following patch, as a preparation?
> 
> -- >8 --
> From: Rene Scharfe <l.s.r@web.de>
> Subject: [PATCH] get-tar-commit-id: parse comment record
> 
> Parse pax comment records properly and get rid of magic numbers for
> acceptable comment length.  This simplifies a later change to handle
> longer hashes.
> 
> Signed-off-by: Rene Scharfe <l.s.r@web.de>
> ---
>  builtin/get-tar-commit-id.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/builtin/get-tar-commit-id.c b/builtin/get-tar-commit-id.c
> index 2706fcfaf2..312e44ed05 100644
> --- a/builtin/get-tar-commit-id.c
> +++ b/builtin/get-tar-commit-id.c
> @@ -21,6 +21,8 @@ int cmd_get_tar_commit_id(int argc, const char **argv, const char *prefix)
>  	char *content = buffer + RECORDSIZE;
>  	const char *comment;
>  	ssize_t n;
> +	long len;
> +	char *end;
> 
>  	if (argc != 1)
>  		usage(builtin_get_tar_commit_id_usage);
> @@ -32,10 +34,17 @@ int cmd_get_tar_commit_id(int argc, const char **argv, const char *prefix)
>  		die_errno("git get-tar-commit-id: EOF before reading tar header");
>  	if (header->typeflag[0] != 'g')
>  		return 1;
> -	if (!skip_prefix(content, "52 comment=", &comment))
> +
> +	len = strtol(content, &end, 10);
> +	if (errno == ERANGE || end == content || len < 0)
> +		return 1;
> +	if (!skip_prefix(end, " comment=", &comment))
> +		return 1;
> +	len -= comment - content;
> +	if (len != GIT_SHA1_HEXSZ + 1)
>  		return 1;