linux: Disentangle fstatat from fxstatat

It implements all the required syscall for the all Linux kABIS on
fstatat{64} instead of calling fxstatat{64}.

On non-LFS implementation, it handles 3 cases:

  1. New kABIs which uses generic pre 64-bit time Linux ABI (csky and
     nios): it issues __NR_fstat64 plus handle the overflow on st_ino,
     st_size, or st_blocks.

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

  3. 64-bit kABI outliers (mips64 and mips64-n32): it issues
     __NR_newfstatat and convert the result to struct stat.

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.

    1.2. 64-bit kABI outlier (alpha): it issues __NR_fstatat64.

    1.3. 64-bit kABI outlier where struct stat64 does not match kernel
         one (sparc64): it issues __NR_fstatat64 and convert the result
         to struct stat64.

    1.4. 32-bit kABI with default 64-bit time_t (arc, riscv32): it
         issues __NR_statx and convert the result to struct stat64.

  2. Old ABIs with XSTAT_IS_XSTAT64 being 0:

    2.1. All kABIs with non-LFS support (arm, csky, i386, hppa, m68k,
         microblaze, nios2, sh, powerpc32, and sparc32): it issues
         __NR_fstatat64.

    2.2. 64-bit kABI outliers (mips64 and mips64-n32): it issues
         __NR_newfstatat and convert the result to struct stat64.

It allows to remove all the hidden definitions from the {f,l}xstat{64}
(some are still kept because Hurd requires it).

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, 53 insertions, 1 deletions

diff --git a/sysdeps/unix/sysv/linux/fstatat.c b/sysdeps/unix/sysv/linux/fstatat.c
index 457496605c..c7fcfaf277 100644
--- a/sysdeps/unix/sysv/linux/fstatat.c
+++ b/sysdeps/unix/sysv/linux/fstatat.c
@@ -18,12 +18,64 @@
 
 #include <sys/stat.h>
 #include <kernel_stat.h>
+#include <sysdep.h>
 
 #if !XSTAT_IS_XSTAT64
+# include <kstat_cp.h>
+
 int
 __fstatat (int fd, const char *file, struct stat *buf, int flag)
 {
-  return __fxstatat (_STAT_VER, fd, file, buf, flag);
+# if STAT_IS_KERNEL_STAT
+  /* New kABIs which uses generic pre 64-bit time Linux ABI, e.g.
+     csky, nios2  */
+  int r = INLINE_SYSCALL_CALL (fstatat64, fd, file, buf, flag);
+  if (r == 0 && (buf->__st_ino_pad != 0
+		 || buf->__st_size_pad != 0
+		 || buf->__st_blocks_pad != 0))
+    return INLINE_SYSCALL_ERROR_RETURN_VALUE (EOVERFLOW);
+  return r;
+# else
+#  ifdef __NR_fstatat64
+  /* Old KABIs with old non-LFS support, e.g. arm, i386, hppa, m68k, mips32,
+     microblaze, s390, sh, powerpc, and sparc.  */
+  struct stat64 st64;
+  int r = INLINE_SYSCALL_CALL (fstatat64, fd, file, &st64, flag);
+  if (r == 0)
+    {
+      if (! in_ino_t_range (st64.st_ino)
+	  || ! in_off_t_range (st64.st_size)
+	  || ! in_blkcnt_t_range (st64.st_blocks))
+	return INLINE_SYSCALL_ERROR_RETURN_VALUE (EOVERFLOW);
+
+      /* Clear internal pad and reserved fields.  */
+      memset (buf, 0, sizeof (*buf));
+
+      buf->st_dev = st64.st_dev,
+      buf->st_ino = st64.st_ino;
+      buf->st_mode = st64.st_mode;
+      buf->st_nlink = st64.st_nlink;
+      buf->st_uid = st64.st_uid;
+      buf->st_gid = st64.st_gid;
+      buf->st_rdev = st64.st_rdev;
+      buf->st_size = st64.st_size;
+      buf->st_blksize = st64.st_blksize;
+      buf->st_blocks  = st64.st_blocks;
+      buf->st_atim.tv_sec = st64.st_atim.tv_sec;
+      buf->st_atim.tv_nsec = st64.st_atim.tv_nsec;
+      buf->st_mtim.tv_sec = st64.st_mtim.tv_sec;
+      buf->st_mtim.tv_nsec = st64.st_mtim.tv_nsec;
+      buf->st_ctim.tv_sec = st64.st_ctim.tv_sec;
+      buf->st_ctim.tv_nsec = st64.st_ctim.tv_nsec;
+    }
+  return r;
+#  else
+  /* 64-bit kabi outlier, e.g. mips64 and mips64-n32.  */
+  struct kernel_stat kst;
+  int r = INLINE_SYSCALL_CALL (newfstatat, fd, file, &kst, flag);
+  return r ?: __cp_kstat_stat (&kst, buf);
+#  endif /* __nr_fstatat64  */
+# endif /* STAT_IS_KERNEL_STAT  */
 }
 
 weak_alias (__fstatat, fstatat)