sysdeps/unix/sysv/linux/wordsize-64/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, 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
  33
  34 /* Get information about the file NAME relative to FD in ST.  */
  35 int
  36 __fxstatat (int vers, int fd, const char *file, struct stat *st, int flag)
  37 {
  38   if (vers != _STAT_VER_KERNEL && vers != _STAT_VER_LINUX)
  39     {
  40       __set_errno (EINVAL);
  41       return -1;
  42     }
  43
  44   int res;
  45
  46 #ifdef __NR_newfstatat
  47 # ifndef __ASSUME_ATFCTS
  48   if (__have_atfcts >= 0)
  49 # endif
  50     {
  51       res = INLINE_SYSCALL (newfstatat, 4, fd, file, st, flag);
  52 # ifndef __ASSUME_ATFCTS
  53       if (res == -1 && errno == ENOSYS)
  54         __have_atfcts = -1;
  55       else
  56 # endif
  57         return res;
  58     }
  59 #endif
  60
  61 #ifndef __ASSUME_ATFCTS
  62   if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
  63     {
  64       __set_errno (EINVAL);
  65       return -1;
  66     }
  67
  68   char *buf = NULL;
  69
  70   if (fd != AT_FDCWD && file[0] != '/')
  71     {
  72       size_t filelen = strlen (file);
  73       if (__builtin_expect (filelen == 0, 0))
  74         {
  75           __set_errno (ENOENT);
  76           return -1;
  77         }
  78
  79       static const char procfd[] = "/proc/self/fd/%d/%s";
  80       /* Buffer for the path name we are going to use.  It consists of
  81          - the string /proc/self/fd/
  82          - the file descriptor number
  83          - the file name provided.
  84          The final NUL is included in the sizeof.   A bit of overhead
  85          due to the format elements compensates for possible negative
  86          numbers.  */
  87       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  88       buf = alloca (buflen);
  89
  90       __snprintf (buf, buflen, procfd, fd, file);
  91       file = buf;
  92     }
  93
  94   INTERNAL_SYSCALL_DECL (err);
  95
  96   if (flag & AT_SYMLINK_NOFOLLOW)
  97     res = INTERNAL_SYSCALL (lstat, err, 2, file, st);
  98   else
  99     res = INTERNAL_SYSCALL (stat, err, 2, file, st);
 100
 101   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (res, err), 0))
 102     {
 103       __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (res, err), fd, buf);
 104       res = -1;
 105     }
 106
 107   return res;
 108 #endif
 109 }
 110 libc_hidden_def (__fxstatat)
 111 #undef __fxstatat64
 112 strong_alias (__fxstatat, __fxstatat64);
 113 strong_alias (__fxstatat64, __GI___fxstatat64)