sysdeps/unix/sysv/linux/i386/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, if fxstatat == fxstatat64 we must get rid of the prototype or gcc
  19    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 #include <kernel_stat.h>
  29
  30 #include <sysdep.h>
  31 #include <sys/syscall.h>
  32 #include <bp-checks.h>
  33
  34 #include <kernel-features.h>
  35
  36 #include <xstatconv.h>
  37
  38
  39 /* Get information about the file NAME relative to FD in ST.  */
  40 int
  41 __fxstatat (int vers, int fd, const char *file, struct stat *st, int flag)
  42 {
  43   int result;
  44   INTERNAL_SYSCALL_DECL (err);
  45   struct stat64 st64;
  46
  47 #ifdef __NR_fstatat64
  48 # ifndef __ASSUME_ATFCTS
  49   if (__have_atfcts >= 0)
  50 # endif
  51     {
  52       result = INTERNAL_SYSCALL (fstatat64, err, 4, fd, file, &st64, flag);
  53 # ifndef __ASSUME_ATFCTS
  54       if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 1)
  55           && INTERNAL_SYSCALL_ERRNO (result, err) == ENOSYS)
  56         __have_atfcts = -1;
  57       else
  58 # endif
  59         if (!__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 1))
  60           return __xstat32_conv (vers, &st64, st);
  61         else
  62           {
  63             __set_errno (INTERNAL_SYSCALL_ERRNO (result, err));
  64             return -1;
  65           }
  66     }
  67 #endif
  68
  69 #ifndef __ASSUME_ATFCTS
  70   if (__builtin_expect (flag & ~AT_SYMLINK_NOFOLLOW, 0))
  71     {
  72       __set_errno (EINVAL);
  73       return -1;
  74     }
  75
  76   char *buf = NULL;
  77
  78   if (fd != AT_FDCWD && file[0] != '/')
  79     {
  80       size_t filelen = strlen (file);
  81       if (__builtin_expect (filelen == 0, 0))
  82         {
  83           __set_errno (ENOENT);
  84           return -1;
  85         }
  86
  87       static const char procfd[] = "/proc/self/fd/%d/%s";
  88       /* Buffer for the path name we are going to use.  It consists of
  89          - the string /proc/self/fd/
  90          - the file descriptor number
  91          - the file name provided.
  92          The final NUL is included in the sizeof.   A bit of overhead
  93          due to the format elements compensates for possible negative
  94          numbers.  */
  95       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  96       buf = alloca (buflen);
  97
  98       __snprintf (buf, buflen, procfd, fd, file);
  99       file = buf;
 100     }
 101
 102   if (vers == _STAT_VER_KERNEL)
 103     {
 104       if (flag & AT_SYMLINK_NOFOLLOW)
 105         result = INTERNAL_SYSCALL (lstat, err, 2, file,
 106                                    CHECK_1 ((struct kernel_stat *) st));
 107       else
 108         result = INTERNAL_SYSCALL (stat, err, 2, file,
 109                                    CHECK_1 ((struct kernel_stat *) st));
 110       goto out;
 111     }
 112
 113   if (flag & AT_SYMLINK_NOFOLLOW)
 114     result = INTERNAL_SYSCALL (lstat64, err, 2, file, __ptrvalue (&st64));
 115   else
 116     result = INTERNAL_SYSCALL (stat64, err, 2, file, __ptrvalue (&st64));
 117   if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 118     return __xstat32_conv (vers, &st64, st);
 119
 120  out:
 121   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
 122     {
 123       __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
 124       result = -1;
 125     }
 126
 127   return result;
 128 #endif
 129 }
 130 libc_hidden_def (__fxstatat)
 131 #ifdef XSTAT_IS_XSTAT64
 132 # undef __fxstatat64
 133 strong_alias (__fxstatat, __fxstatat64);
 134 libc_hidden_ver (__fxstatat, __fxstatat64)
 135 #endif