linux: Consolidate fxstatat{64}

The LFS support is implemented on fxstat64.c, instead of fxstat.c for
64-bit architectures.  The fxstatat.c implements the non-LFS and it is
a no-op for !XSTAT_IS_XSTAT64.

The generic non-LFS implementation handles two cases:

  1. New kABIs which uses generic pre 64-bit time Linux ABI (csky and
     nios): it issues __NR_fstatat64 plus handle the overflow on st_ino,
     st_size, or st_blocks.  It only handles _STAT_VER_KERNEL.

  2. Old kABIs with old non-LFS support (arm, i386, hppa, m68k, mips32,
     microblaze, s390, sh, powerpc, and sparc32).  it issues
     __NR_fstatat64 and convert to non-LFS stat struct based on the
     version.

Also non-LFS mips64 is an outlier and it has its own implementation
since _STAT_VER_LINUX requires a different conversion function (it
uses the kernel_stat as the sysissues argument since its exported ABI
is different than the kernel one for both non-LFS and LFS
implementation).

The generic LFS implementation handles multiple cases:

  1. XSTAT_IS_XSTAT64 being 1:

    1.1. 64-bit kABI (aarch64, ia64, powerpc64*, s390x, riscv64, and
         x86_64): it issues __NR_newfstatat for _STAT_VER_KERNEL or
         _STAT_VER_LINUX.

    1.2. 64-bit kABI outlier (sparc64): it issuess fstatat64 with a
         temporary stat64 and convert to output stat64 based on the
         input version (and using a sparc64 specific __xstat32_conv).

    1.3. New 32-bit kABIs with only 64-bit time_t support (arc and
	 riscv32): it issues __NR_statx and covert to struct stat64.

  2. Old ABIs with XSTAT_IS_XSTAT64 being 0 (arm, csky, i386, hppa, m68k,
     microblaze, mips32, nios2, sh, powerpc32, and sparc32): it issues
     __NR_fstat64.

Also, two special cases requires specific implementations:

  1. alpha: it uses the __NR_fstatat64 syscall instead.

  2. mips64: as for non-LFS implementation its ABIs differ from
     glibc exported one, which requires an specific conversion
     function to handle the kernel_stat.

Checked with a build for all affected ABIs. I also checked on x86_64,
i686, powerpc, powerpc64le, sparcv9, sparc64, s390, and s390x.

Reviewed-by: Lukasz Majewski <lukma@denx.de>

3 files changed, 36 insertions, 53 deletions

diff --git a/sysdeps/unix/sysv/linux/alpha/dl-fxstatat64.c b/sysdeps/unix/sysv/linux/alpha/dl-fxstatat64.c
deleted file mode 100644
index 330b33f7c7..0000000000
--- a/sysdeps/unix/sysv/linux/alpha/dl-fxstatat64.c
+++ /dev/null
@@ -1 +0,0 @@
-#include "fxstatat.c"
diff --git a/sysdeps/unix/sysv/linux/alpha/fxstatat.c b/sysdeps/unix/sysv/linux/alpha/fxstatat.c
deleted file mode 100644
index c5953d250a..0000000000
--- a/sysdeps/unix/sysv/linux/alpha/fxstatat.c
+++ /dev/null
@@ -1,52 +0,0 @@
-/* Copyright (C) 2005-2020 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/>.  */
-
-#define __fxstatat64 __fxstatat64_disable
-
-#include <errno.h>
-#include <fcntl.h>
-#include <stddef.h>
-#include <stdio.h>
-#include <sys/stat.h>
-#include <kernel_stat.h>
-#include <sysdep.h>
-#include <sys/syscall.h>
-#include <xstatconv.h>
-
-#undef __fxstatat64
-
-/* Get information about the file NAME in BUF.  */
-int
-__fxstatat (int vers, int fd, const char *file, struct stat *st, int flag)
-{
-  int result, errno_out;
-
-  /* ??? The __fxstatat entry point is new enough that it must be using
-     vers == _STAT_VER_KERNEL64.  For the benefit of dl-fxstatat64.c, we
-     cannot actually check this, lest the compiler not optimize the rest
-     of the function away.  */
-
-  result = INTERNAL_SYSCALL_CALL (fstatat64, fd, file, st, flag);
-  if (__glibc_likely (!INTERNAL_SYSCALL_ERROR_P (result)))
-    return result;
-  errno_out = INTERNAL_SYSCALL_ERRNO (result);
-  __set_errno (errno_out);
-  return -1;
-}
-libc_hidden_def (__fxstatat)
-strong_alias (__fxstatat, __fxstatat64);
-libc_hidden_ver(__fxstatat, __fxstatat64);
diff --git a/sysdeps/unix/sysv/linux/alpha/fxstatat64.c b/sysdeps/unix/sysv/linux/alpha/fxstatat64.c
new file mode 100644
index 0000000000..f10c1d31e8
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/alpha/fxstatat64.c
@@ -0,0 +1,36 @@
+/* fxstat using old-style Unix stat system call.
+   Copyright (C) 2004-2020 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/>.  */
+
+#define __fxstatat __redirect___fxstatat64
+#include <sys/stat.h>
+#undef __fxstatat
+#include <kernel_stat.h>
+#include <sysdep.h>
+#include <xstatconv.h>
+
+/* Get information about the file NAME in BUF.  */
+int
+__fxstatat64 (int vers, int fd, const char *file, struct stat64 *st, int flag)
+{
+  return INLINE_SYSCALL_CALL (fstatat64, fd, file, st, flag);
+}
+libc_hidden_def (__fxstatat64)
+#if IS_IN(libc)
+strong_alias (__fxstatat64, __fxstatat);
+hidden_ver (__fxstatat64, __fxstatat)
+#endif