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

   1 /* Copyright (C) 2005 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 /* Ho hum, since fxstatat == fxstatat64 we must get rid of the
  20    prototype or gcc will complain since they don't strictly match.  */
  21 #define __fxstatat64 __fxstatat64_disable
  22
  23 #include <errno.h>
  24 #include <fcntl.h>
  25 #include <stddef.h>
  26 #include <stdio.h>
  27 #include <string.h>
  28 #include <sys/stat.h>
  29
  30 #include <sysdep.h>
  31 #include <sys/syscall.h>
  32 #include <bp-checks.h>
  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       || (flag & ~AT_SYMLINK_NOFOLLOW) != 0)
  40     {
  41       __set_errno (EINVAL);
  42       return -1;
  43     }
  44
  45   char *buf = NULL;
  46
  47   if (fd != AT_FDCWD && file[0] != '/')
  48     {
  49       size_t filelen = strlen (file);
  50       static const char procfd[] = "/proc/self/fd/%d/%s";
  51       /* Buffer for the path name we are going to use.  It consists of
  52          - the string /proc/self/fd/
  53          - the file descriptor number
  54          - the file name provided.
  55          The final NUL is included in the sizeof.   A bit of overhead
  56          due to the format elements compensates for possible negative
  57          numbers.  */
  58       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  59       buf = alloca (buflen);
  60
  61       __snprintf (buf, buflen, procfd, fd, file);
  62       file = buf;
  63     }
  64
  65   INTERNAL_SYSCALL_DECL (err);
  66   int res;
  67
  68   if (flag & AT_SYMLINK_NOFOLLOW)
  69     res = INTERNAL_SYSCALL (lstat, err, 2, file, CHECK_1 (st));
  70   else
  71     res = INTERNAL_SYSCALL (stat, err, 2, file, CHECK_1 (st));
  72
  73   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (res, err), 0))
  74     {
  75       __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (res, err), fd, buf);
  76       res = -1;
  77     }
  78
  79   return res;
  80 }
  81 #undef __fxstatat64
  82 strong_alias (__fxstatat, __fxstatat64);