Re: [PATCH v2 4/5] replace snprintf with odb_pack_name()

> In several places we write the name of the pack filename
> into a fixed-size buffer using snprintf(), but do not check
> the return value.  As a result, a very long object directory
> could cause us to quietly truncate the pack filename
> (potentially leading to a corrupted repository, as a newly
> written packfile could be missing its .pack extension).
> 
> We can use odb_pack_name() to do this with a strbuf (and
> shorten the code, as well).
> 
> Signed-off-by: Jeff King <peff@peff.net>
> ---
>  builtin/index-pack.c | 27 +++++++++++----------------
>  fast-import.c        | 28 +++++++++++++---------------
>  2 files changed, 24 insertions(+), 31 deletions(-)
> 

> diff --git a/fast-import.c b/fast-import.c
> index dad697653..41a539f97 100644
> --- a/fast-import.c
> +++ b/fast-import.c
> @@ -940,43 +940,40 @@ static const char *create_index(void)
>  
>  static char *keep_pack(const char *curr_index_name)
>  {
> -	static char name[PATH_MAX];
>  	static const char *keep_msg = "fast-import";
> +	struct strbuf name = STRBUF_INIT;
>  	int keep_fd;
>  
> -	snprintf(name, sizeof(name), "%s/pack/pack-%s.keep",
> -		 get_object_directory(), sha1_to_hex(pack_data->sha1));
> -	keep_fd = odb_pack_keep(name);
> +	odb_pack_name(&name, pack_data->sha1, "keep");
> +	keep_fd = odb_pack_keep(name.buf);
>  	if (keep_fd < 0)
>  		die_errno("cannot create keep file");
>  	write_or_die(keep_fd, keep_msg, strlen(keep_msg));
>  	if (close(keep_fd))
>  		die_errno("failed to write keep file");
>  
> -	snprintf(name, sizeof(name), "%s/pack/pack-%s.pack",
> -		 get_object_directory(), sha1_to_hex(pack_data->sha1));
> -	if (finalize_object_file(pack_data->pack_name, name))
> +	odb_pack_name(&name, pack_data->sha1, "pack");
> +	if (finalize_object_file(pack_data->pack_name, name.buf))
>  		die("cannot store pack file");
>  
> -	snprintf(name, sizeof(name), "%s/pack/pack-%s.idx",
> -		 get_object_directory(), sha1_to_hex(pack_data->sha1));
> -	if (finalize_object_file(curr_index_name, name))
> +	odb_pack_name(&name, pack_data->sha1, "idx");
> +	if (finalize_object_file(curr_index_name, name.buf))
>  		die("cannot store index file");
>  	free((void *)curr_index_name);
> -	return name;
> +	return strbuf_detach(&name, NULL);

>  }
>  
>  static void unkeep_all_packs(void)
>  {
> -	static char name[PATH_MAX];
> +	struct strbuf name = STRBUF_INIT;
>  	int k;
>  
>  	for (k = 0; k < pack_id; k++) {
>  		struct packed_git *p = all_packs[k];
> -		snprintf(name, sizeof(name), "%s/pack/pack-%s.keep",
> -			 get_object_directory(), sha1_to_hex(p->sha1));
> -		unlink_or_warn(name);
> +		odb_pack_name(&name, p->sha1, "keep");
> +		unlink_or_warn(name.buf);
>  	}
> +	strbuf_release(&name);
>  }
>  
>  static int loosen_small_pack(const struct packed_git *p)
> @@ -1035,6 +1032,7 @@ static void end_packfile(void)
>  			die("core git rejected index %s", idx_name);
>  		all_packs[pack_id] = new_p;
>  		install_packed_git(new_p);
> +		free(idx_name);