sysdeps/unix/sysv/linux/wordsize-64/fxstatat.c

   1 /* Copyright (C) 2005-2013 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 /* Ho hum, since fxstatat == fxstatat64 we must get rid of the
  19    prototype or gcc will complain since they don't strictly match.  */
  20 #define __fxstatat64 __fxstatat64_disable
  21
  22 #include <errno.h>
  23 #include <fcntl.h>
  24 #include <stddef.h>
  25 #include <stdio.h>
  26 #include <string.h>
  27 #include <sys/stat.h>
  28
  29 #include <sysdep.h>
  30 #include <kernel-features.h>
  31 #include <sys/syscall.h>
  32 #include <bp-checks.h>
  33
  34
  35 /* Get information about the file NAME relative to FD in ST.  */
  36 int
  37 __fxstatat (int vers, int fd, const char *file, struct stat *st, int flag)
  38 {
  39   if (vers != _STAT_VER_KERNEL && vers != _STAT_VER_LINUX)
  40     {
  41       __set_errno (EINVAL);
  42       return -1;
  43     }
  44
  45   int res;
  46
  47 #ifdef __NR_newfstatat
  48 # ifndef __ASSUME_ATFCTS
  49   if (__have_atfcts >= 0)
  50 # endif
  51     {
  52       res = INLINE_SYSCALL (newfstatat, 4, fd, file, st, flag);
  53 # ifndef __ASSUME_ATFCTS
  54       if (res == -1 && errno == ENOSYS)
  55         __have_atfcts = -1;
  56       else
  57 # endif
  58         return res;
  59     }
  60 #endif
  61
  62 #ifndef __ASSUME_ATFCTS
  63   if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
  64     {
  65       __set_errno (EINVAL);
  66       return -1;
  67     }
  68
  69   char *buf = NULL;
  70
  71   if (fd != AT_FDCWD && file[0] != '/')
  72     {
  73       size_t filelen = strlen (file);
  74       if (__builtin_expect (filelen == 0, 0))
  75         {
  76           __set_errno (ENOENT);
  77           return -1;
  78         }
  79
  80       static const char procfd[] = "/proc/self/fd/%d/%s";
  81       /* Buffer for the path name we are going to use.  It consists of
  82          - the string /proc/self/fd/
  83          - the file descriptor number
  84          - the file name provided.
  85          The final NUL is included in the sizeof.   A bit of overhead
  86          due to the format elements compensates for possible negative
  87          numbers.  */
  88       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  89       buf = alloca (buflen);
  90
  91       __snprintf (buf, buflen, procfd, fd, file);
  92       file = buf;
  93     }
  94
  95   INTERNAL_SYSCALL_DECL (err);
  96
  97   if (flag & AT_SYMLINK_NOFOLLOW)
  98     res = INTERNAL_SYSCALL (lstat, err, 2, file, CHECK_1 (st));
  99   else
 100     res = INTERNAL_SYSCALL (stat, err, 2, file, CHECK_1 (st));
 101
 102   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (res, err), 0))
 103     {
 104       __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (res, err), fd, buf);
 105       res = -1;
 106     }
 107
 108   return res;
 109 #endif
 110 }
 111 libc_hidden_def (__fxstatat)
 112 #undef __fxstatat64
 113 strong_alias (__fxstatat, __fxstatat64);
 114 strong_alias (__fxstatat64, __GI___fxstatat64)