sysdeps/unix/sysv/linux/fxstatat.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 /* 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 <kernel-features.h>
  33
  34 #include <xstatconv.h>
  35
  36 /* Get information about the file NAME in BUF.  */
  37 int
  38 __fxstatat (int vers, int fd, const char *file, struct stat *st, int flag)
  39 {
  40   int result;
  41   INTERNAL_SYSCALL_DECL (err);
  42 #ifdef STAT_IS_KERNEL_STAT
  43 # define kst (*st)
  44 #else
  45   struct kernel_stat kst;
  46 #endif
  47
  48 #ifdef __NR_newfstatat
  49 # ifndef __ASSUME_ATFCTS
  50   if (__have_atfcts >= 0)
  51 # endif
  52     {
  53       result = INTERNAL_SYSCALL (newfstatat, err, 4, fd, file, &kst, flag);
  54 # ifndef __ASSUME_ATFCTS
  55       if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 1)
  56           && INTERNAL_SYSCALL_ERRNO (result, err) == ENOSYS)
  57         __have_atfcts = -1;
  58       else
  59 # endif
  60         if (!__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 1))
  61           {
  62 #ifdef STAT_IS_KERNEL_STAT
  63             return 0;
  64 #else
  65             return __xstat_conv (vers, &kst, st);
  66 #endif
  67           }
  68         else
  69           {
  70             __set_errno (INTERNAL_SYSCALL_ERRNO (result, err));
  71             return -1;
  72           }
  73     }
  74 #endif
  75
  76   if (flag & ~AT_SYMLINK_NOFOLLOW)
  77     {
  78       __set_errno (EINVAL);
  79       return -1;
  80     }
  81
  82   char *buf = NULL;
  83
  84   if (fd != AT_FDCWD && file[0] != '/')
  85     {
  86       size_t filelen = strlen (file);
  87       if (__builtin_expect (filelen == 0, 0))
  88         {
  89           __set_errno (ENOENT);
  90           return -1;
  91         }
  92
  93       static const char procfd[] = "/proc/self/fd/%d/%s";
  94       /* Buffer for the path name we are going to use.  It consists of
  95          - the string /proc/self/fd/
  96          - the file descriptor number
  97          - the file name provided.
  98          The final NUL is included in the sizeof.   A bit of overhead
  99          due to the format elements compensates for possible negative
 100          numbers.  */
 101       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
 102       buf = alloca (buflen);
 103
 104       __snprintf (buf, buflen, procfd, fd, file);
 105       file = buf;
 106     }
 107
 108   if (vers == _STAT_VER_KERNEL)
 109     {
 110       if (flag & AT_SYMLINK_NOFOLLOW)
 111         result = INTERNAL_SYSCALL (lstat, err, 2, file,
 112                                    (struct kernel_stat *) st);
 113       else
 114         result = INTERNAL_SYSCALL (stat, err, 2, file,
 115                                    (struct kernel_stat *) st);
 116
 117       if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 118         return result;
 119     }
 120 #ifdef STAT_IS_KERNEL_STAT
 121   else
 122     {
 123       __set_errno (EINVAL);
 124       return -1;
 125     }
 126 #else
 127   if (flag & AT_SYMLINK_NOFOLLOW)
 128     result = INTERNAL_SYSCALL (lstat, err, 2, file, &kst);
 129   else
 130     result = INTERNAL_SYSCALL (stat, err, 2, file, &kst);
 131
 132   if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 133     return __xstat_conv (vers, &kst, st);
 134 #endif
 135
 136   __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
 137
 138   return -1;
 139 }
 140 libc_hidden_def (__fxstatat)
 141 #ifdef XSTAT_IS_XSTAT64
 142 # undef __fxstatat64
 143 strong_alias (__fxstatat, __fxstatat64);
 144 libc_hidden_def (__fxstatat64)
 145 #endif