[PATCH] Always check lockf64 return value

[Florian Weimer]

* H. J. Lu:

> diff --git a/locale/programs/locarchive.c b/locale/programs/locarchive.c
> index 2c19f4fd29..ad025a819b 100644
> --- a/locale/programs/locarchive.c
> +++ b/locale/programs/locarchive.c
> @@ -638,7 +638,8 @@ open_archive (struct locarhandle *ah, bool readonly)
>  	  || st.st_dev != st2.st_dev
>  	  || st.st_ino != st2.st_ino)
>  	{
> -	  (void) lockf64 (fd, F_ULOCK, sizeof (struct locarhead));
> +	  if (lockf64 (fd, F_ULOCK, sizeof (struct locarhead)) != 0)
> +	    error (EXIT_FAILURE, errno, _("cannot unlock archive header"));
>  	  close (fd);
>  	  continue;
>  	}
> @@ -650,14 +651,17 @@ open_archive (struct locarhandle *ah, bool readonly)
>    /* Read the header.  */
>    if (TEMP_FAILURE_RETRY (read (fd, &head, sizeof (head))) != sizeof (head))
>      {
> -      (void) lockf64 (fd, F_ULOCK, sizeof (struct locarhead));
> -      error (EXIT_FAILURE, errno, _("cannot read archive header"));
> +      int errval = errno;
> +      if (lockf64 (fd, F_ULOCK, sizeof (struct locarhead)) != 0)
> +	error (EXIT_FAILURE, errno, _("cannot unlock archive header"));
> +      error (EXIT_FAILURE, errval, _("cannot read archive header"));
>      }
>  
>    /* Check the magic value */
>    if (GET (head.magic) != AR_MAGIC)
>      {
> -      (void) lockf64 (fd, F_ULOCK, sizeof (struct locarhead));
> +      if (lockf64 (fd, F_ULOCK, sizeof (struct locarhead)) != 0)
> +	error (EXIT_FAILURE, errno, _("cannot unlock archive header"));
>        error (EXIT_FAILURE, 0, _("bad magic value in archive header"));
>      }
>  
> @@ -676,8 +680,10 @@ open_archive (struct locarhandle *ah, bool readonly)
>  		     MAP_SHARED | xflags, fd, 0);
>    if (ah->addr == MAP_FAILED)
>      {
> -      (void) lockf64 (fd, F_ULOCK, sizeof (struct locarhead));
> -      error (EXIT_FAILURE, errno, _("cannot map archive header"));
> +      int errval = errno;
> +      if (lockf64 (fd, F_ULOCK, sizeof (struct locarhead)) != 0)
> +	error (EXIT_FAILURE, errno, _("cannot unlock archive header"));
> +      error (EXIT_FAILURE, errval, _("cannot map archive header"));
>      }
>    ah->reserved = reserved;
>    ah->mmap_base = mmap_base;

Given Sam's comment about unlock ranges, I think this is okay.

Reviewed-by: Florian Weimer <fweimer@redhat.com>

(We'll see soon enough if the new error triggers in practice because the
file pointer is unexpected at this point.)

Thanks,
Florian