Re: [PATCH 1/2] Use sysdeps/posix/dl-fileid.h as the generic and only implementation

["H.J. Lu" <hjl.tools@gmail.com>]

On Fri, Nov 5, 2021 at 7:02 AM Florian Weimer via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> ---
>  sysdeps/generic/dl-fileid.h | 30 ++++++++++++----------
>  sysdeps/posix/dl-fileid.h   | 50 -------------------------------------
>  2 files changed, 17 insertions(+), 63 deletions(-)
>  delete mode 100644 sysdeps/posix/dl-fileid.h
>
> diff --git a/sysdeps/generic/dl-fileid.h b/sysdeps/generic/dl-fileid.h
> index fb1e1c788b..bf437f3d71 100644
> --- a/sysdeps/generic/dl-fileid.h
> +++ b/sysdeps/generic/dl-fileid.h
> @@ -1,4 +1,4 @@
> -/* File identity for the dynamic linker.  Stub version.
> +/* File identity for the dynamic linker.  Generic POSIX.1 version.
>     Copyright (C) 2015-2021 Free Software Foundation, Inc.
>     This file is part of the GNU C Library.
>
> @@ -17,30 +17,34 @@
>     <https://www.gnu.org/licenses/>.  */
>
>  #include <stdbool.h>
> +#include <sys/stat.h>
>
> -/* This type stores whatever information is fetched by _dl_get_file_id
> -   and compared by _dl_file_id_match_p.  */
> +/* For POSIX.1 systems, the pair of st_dev and st_ino constitute
> +   a unique identifier for a file.  */
>  struct r_file_id
>    {
> -    /* In the stub version, we don't record anything at all.  */
> +    dev_t dev;
> +    ino64_t ino;
>    };
>
>  /* Sample FD to fill in *ID.  Returns true on success.
>     On error, returns false, with errno set.  */
>  static inline bool
> -_dl_get_file_id (int fd __attribute__ ((unused)),
> -                struct r_file_id *id __attribute__ ((unused)))
> +_dl_get_file_id (int fd, struct r_file_id *id)
>  {
> +  struct __stat64_t64 st;
> +
> +  if (__glibc_unlikely (__fstat64_time64 (fd, &st) < 0))
> +    return false;
> +
> +  id->dev = st.st_dev;
> +  id->ino = st.st_ino;
>    return true;
>  }
>
> -/* Compare two results from _dl_get_file_id for equality.
> -   It's crucial that this never return false-positive matches.
> -   It's ideal that it never return false-negative mismatches either,
> -   but lack of matches is survivable.  */
> +/* Compare two results from _dl_get_file_id for equality.  */
>  static inline bool
> -_dl_file_id_match_p (const struct r_file_id *a __attribute__ ((unused)),
> -                    const struct r_file_id *b __attribute__ ((unused)))
> +_dl_file_id_match_p (const struct r_file_id *a, const struct r_file_id *b)
>  {
> -  return false;
> +  return a->dev == b->dev && a->ino == b->ino;
>  }
> diff --git a/sysdeps/posix/dl-fileid.h b/sysdeps/posix/dl-fileid.h
> deleted file mode 100644
> index bf437f3d71..0000000000
> --- a/sysdeps/posix/dl-fileid.h
> +++ /dev/null
> @@ -1,50 +0,0 @@
> -/* File identity for the dynamic linker.  Generic POSIX.1 version.
> -   Copyright (C) 2015-2021 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#include <stdbool.h>
> -#include <sys/stat.h>
> -
> -/* For POSIX.1 systems, the pair of st_dev and st_ino constitute
> -   a unique identifier for a file.  */
> -struct r_file_id
> -  {
> -    dev_t dev;
> -    ino64_t ino;
> -  };
> -
> -/* Sample FD to fill in *ID.  Returns true on success.
> -   On error, returns false, with errno set.  */
> -static inline bool
> -_dl_get_file_id (int fd, struct r_file_id *id)
> -{
> -  struct __stat64_t64 st;
> -
> -  if (__glibc_unlikely (__fstat64_time64 (fd, &st) < 0))
> -    return false;
> -
> -  id->dev = st.st_dev;
> -  id->ino = st.st_ino;
> -  return true;
> -}
> -
> -/* Compare two results from _dl_get_file_id for equality.  */
> -static inline bool
> -_dl_file_id_match_p (const struct r_file_id *a, const struct r_file_id *b)
> -{
> -  return a->dev == b->dev && a->ino == b->ino;
> -}
> --
> 2.33.1
>
>

Please submit the v2 patch with the updated cover letter to indicate
that this patch set doesn't fix any bug, but is a cleanup.

Thanks.

-- 
H.J.