Re: [PATCH] config.c: handle error case for fstat() calls

[Duy Nguyen]

On Mon, Dec 19, 2016 at 10:14:27AM -0800, Junio C Hamano wrote:
> Shouldn't the error-return path in the second hunk rollback the
> lockfile to clean after itself?  The existing "Oh, we cannot chmod
> to match the original" check that comes immediately after shares the
> same issue, so this is not a new problem, but making an existing one
> worse.

OK. How about two more patches on top (or bottom, does not matter)?
The second one should fix this. The first is sort of "good to do".

[PATCH 1/2] config.c: rename label unlock_and_out
[PATCH 2/2] config.c: handle lock file in error case in git_config_rename_...
--
Duy

Re: [PATCH] config.c: handle error case for fstat() calls

[Junio C Hamano]

Nguyễn Thái Ngọc Duy   writes:

> Signed-off-by: Nguyễn Thái Ngọc Duy 
> ---
>  Will this fix the problem I'm replying to? I don't know. I found this
>  while checking the code and it should be fixed regardless.

Yeah, from a cursory read, it is a step in the right direction to
check the return value of fstat().  

Shouldn't the error-return path in the second hunk rollback the
lockfile to clean after itself?  The existing "Oh, we cannot chmod
to match the original" check that comes immediately after shares the
same issue, so this is not a new problem, but making an existing one
worse.

>  config.c | 12 ++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/config.c b/config.c
> index 83fdecb..4973256 100644
> --- a/config.c
> +++ b/config.c
> @@ -2194,7 +2194,12 @@ int git_config_set_multivar_in_file_gently(const char 
> *config_filename,
>   goto out_free;
>   }
>  
> - fstat(in_fd, &st);
> + if (fstat(in_fd, &st) == -1) {
> + error_errno(_("fstat on %s failed"), config_filename);
> + ret = CONFIG_INVALID_FILE;
> + goto out_free;
> + }
> +
>   contents_sz = xsize_t(st.st_size);
>   contents = xmmap_gently(NULL, contents_sz, PROT_READ,
>   MAP_PRIVATE, in_fd, 0);
> @@ -2414,7 +2419,10 @@ int git_config_rename_section_in_file(const char 
> *config_filename,
>   goto unlock_and_out;
>   }
>  
> - fstat(fileno(config_file), &st);
> + if (fstat(fileno(config_file), &st) == -1) {
> + ret = error_errno(_("fstat on %s failed"), config_filename);
> + goto out;
> + }
>  
>   if (chmod(get_lock_file_path(lock), st.st_mode & 0) < 0) {
>   ret = error_errno("chmod on %s failed",