patchmingw: do not set errno to 0 on success

> Currently do_lstat always sets errno to 0 on success. This incorrectly
> overwrites previous errors.
>
> Fetch the error-code into a temporary variable instead, and assign that
> to errno on failure.
>
> Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
> ---
>
> A bug I found while hunting down another regression. maint-worthy, perhaps?

>
>  compat/mingw.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/compat/mingw.c b/compat/mingw.c
> index f2d9e1f..b98e600 100644
> --- a/compat/mingw.c
> +++ b/compat/mingw.c
> @@ -195,9 +195,10 @@ static inline time_t filetime_to_time_t(const FILETIME *ft)
>   */
>  static int do_lstat(const char *file_name, struct stat *buf)
>  {
> +	int err;
>  	WIN32_FILE_ATTRIBUTE_DATA fdata;
>  
> -	if (!(errno = get_file_attr(file_name, &fdata))) {
> +	if (!(err = get_file_attr(file_name, &fdata))) {
>  		buf->st_ino = 0;
>  		buf->st_gid = 0;
>  		buf->st_uid = 0;
> @@ -211,6 +212,7 @@ static int do_lstat(const char *file_name, struct stat *buf)
>  		buf->st_ctime = filetime_to_time_t(&(fdata.ftCreationTime));
>  		return 0;
>  	}
> +	errno = err;
>  	return -1;
>  }
>  
> -- 
> 1.7.3.2

> Erik Faye-Lund <kusmabite@gmail.com> writes:
>
>> Currently do_lstat always sets errno to 0 on success. This incorrectly
>> overwrites previous errors.
>>
>> Fetch the error-code into a temporary variable instead, and assign that
>> to errno on failure.
>>
>> Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
>> ---
>>
>> A bug I found while hunting down another regression. maint-worthy, perhaps?
>
> I would say so, as long as the error return from get_file_attr() is
> trustworthy.