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>

1 files changed, 39 insertions, 26 deletions

diff --git a/sysdeps/unix/sysv/linux/fxstatat64.c b/sysdeps/unix/sysv/linux/fxstatat64.c
index e24b456604..ac33ab4fc9 100644
--- a/sysdeps/unix/sysv/linux/fxstatat64.c
+++ b/sysdeps/unix/sysv/linux/fxstatat64.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 2005-2020 Free Software Foundation, Inc.
+/* fxstatat64 used on fstatat64, Linux implementation.
+   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
@@ -15,41 +16,53 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
-#include <fcntl.h>
-#include <stddef.h>
-#include <stdio.h>
-#include <string.h>
+#define __fxstatat __redirect___fxstatat
 #include <sys/stat.h>
+#undef __fxstatat
+#include <fcntl.h>
 #include <kernel_stat.h>
-
 #include <sysdep.h>
-#include <sys/syscall.h>
-
+#include <xstatconv.h>
 #include <statx_cp.h>
 
-/* Get information about the file NAME in BUF.  */
+/* Get information about the file FD in BUF.  */
 
 int
 __fxstatat64 (int vers, int fd, const char *file, struct stat64 *st, int flag)
 {
-  if (__glibc_unlikely (vers != _STAT_VER_LINUX))
-    return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
-
-  int result;
-
-#ifdef __NR_fstatat64
-  result = INTERNAL_SYSCALL_CALL (fstatat64, fd, file, st, flag);
+#if XSTAT_IS_XSTAT64
+# ifdef __NR_newfstatat
+  /* 64-bit kABI, e.g. aarch64, ia64, powerpc64*, s390x, riscv64, and
+     x86_64.  */
+  if (vers == _STAT_VER_KERNEL || vers == _STAT_VER_LINUX)
+    return INLINE_SYSCALL_CALL (newfstatat, fd, file, st, flag);
+# elif defined __NR_fstatat64
+  /* 64-bit kABI outlier, e.g. sparc64.  */
+  struct stat64 st64;
+  int r = INLINE_SYSCALL_CALL (fstatat64, fd, file, &st64, flag);
+  return r ?: __xstat32_conv (vers, &st64, (struct stat *) st);
+# else
+  /* New 32-bit kABIs with only 64-bit time_t support, e.g. arc, riscv32.  */
+  if (vers == _STAT_VER_KERNEL)
+    {
+      struct statx tmp;
+      int r = INLINE_SYSCALL_CALL (statx, fd, file, AT_NO_AUTOMOUNT | flag,
+				   STATX_BASIC_STATS, &tmp);
+      if (r == 0)
+	__cp_stat64_statx (st, &tmp);
+      return r;
+    }
+# endif
 #else
-  struct statx tmp;
-
-  result = INTERNAL_SYSCALL_CALL (statx, fd, file, AT_NO_AUTOMOUNT | flag,
-				  STATX_BASIC_STATS, &tmp);
-  if (result == 0)
-    __cp_stat64_statx (st, &tmp);
+  /* All kABIs with non-LFS support, e.g. arm, csky, i386, hppa, m68k,
+     microblaze, mips32, nios2, sh, powerpc32, and sparc32.  */
+  if (vers == _STAT_VER_LINUX)
+    return INLINE_SYSCALL_CALL (fstatat64, fd, file, st, flag);
 #endif
-  if (!__glibc_likely (INTERNAL_SYSCALL_ERROR_P (result)))
-    return 0;
-  return INLINE_SYSCALL_ERROR_RETURN_VALUE (INTERNAL_SYSCALL_ERRNO (result));
+  return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
 }
 libc_hidden_def (__fxstatat64)
+#if XSTAT_IS_XSTAT64 && IS_IN(libc)
+strong_alias (__fxstatat64, __fxstatat);
+hidden_ver (__fxstatat64, __fxstatat)
+#endif