sysdeps/unix/sysv/linux/fxstatat64.c

   1 /* Copyright (C) 2005-2014 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <fcntl.h>
  20 #include <stddef.h>
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <sys/stat.h>
  24 #include <kernel_stat.h>
  25
  26 #include <sysdep.h>
  27 #include <sys/syscall.h>
  28
  29 #include <kernel-features.h>
  30
  31 /* Get information about the file NAME in BUF.  */
  32
  33 int
  34 __fxstatat64 (int vers, int fd, const char *file, struct stat64 *st, int flag)
  35 {
  36   if (__builtin_expect (vers != _STAT_VER_LINUX, 0))
  37     {
  38       __set_errno (EINVAL);
  39       return -1;
  40     }
  41
  42   int result;
  43   INTERNAL_SYSCALL_DECL (err);
  44
  45 #ifdef __NR_fstatat64
  46 # ifndef __ASSUME_ATFCTS
  47   if (__have_atfcts >= 0)
  48 # endif
  49     {
  50       result = INTERNAL_SYSCALL (fstatat64, err, 4, fd, file, st, flag);
  51 # ifndef __ASSUME_ATFCTS
  52       if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 1)
  53           && INTERNAL_SYSCALL_ERRNO (result, err) == ENOSYS)
  54         __have_atfcts = -1;
  55       else
  56 # endif
  57         if (!__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 1))
  58           return 0;
  59         else
  60           {
  61             __set_errno (INTERNAL_SYSCALL_ERRNO (result, err));
  62             return -1;
  63           }
  64     }
  65 #endif
  66
  67 #ifndef __ASSUME_ATFCTS
  68   if (flag & ~AT_SYMLINK_NOFOLLOW)
  69     {
  70       __set_errno (EINVAL);
  71       return -1;
  72     }
  73
  74   char *buf = NULL;
  75
  76   if (fd != AT_FDCWD && file[0] != '/')
  77     {
  78       size_t filelen = strlen (file);
  79       if (__builtin_expect (filelen == 0, 0))
  80         {
  81           __set_errno (ENOENT);
  82           return -1;
  83         }
  84
  85       static const char procfd[] = "/proc/self/fd/%d/%s";
  86       /* Buffer for the path name we are going to use.  It consists of
  87          - the string /proc/self/fd/
  88          - the file descriptor number
  89          - the file name provided.
  90          The final NUL is included in the sizeof.   A bit of overhead
  91          due to the format elements compensates for possible negative
  92          numbers.  */
  93       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  94       buf = alloca (buflen);
  95
  96       __snprintf (buf, buflen, procfd, fd, file);
  97       file = buf;
  98     }
  99
 100   if (flag & AT_SYMLINK_NOFOLLOW)
 101     result = INTERNAL_SYSCALL (lstat64, err, 2, file, st);
 102   else
 103     result = INTERNAL_SYSCALL (stat64, err, 2, file, st);
 104   if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 105     {
 106 # if defined _HAVE_STAT64___ST_INO && __ASSUME_ST_INO_64_BIT == 0
 107       if (st->__st_ino != (__ino_t) st->st_ino)
 108         st->st_ino = st->__st_ino;
 109 # endif
 110       return result;
 111     }
 112   __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
 113
 114   return -1;
 115 #endif
 116 }
 117 libc_hidden_def (__fxstatat64)