sysdeps/unix/sysv/linux/fxstatat.c

   1 /* Copyright (C) 2005, 2006 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, if fxstatat == fxstatat64 we must get rid of the prototype or gcc
  20    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 <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 <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   if (flag & ~AT_SYMLINK_NOFOLLOW)
  41     {
  42       __set_errno (EINVAL);
  43       return -1;
  44     }
  45
  46   char *buf = NULL;
  47
  48   if (fd != AT_FDCWD && file[0] != '/')
  49     {
  50       size_t filelen = strlen (file);
  51       static const char procfd[] = "/proc/self/fd/%d/%s";
  52       /* Buffer for the path name we are going to use.  It consists of
  53          - the string /proc/self/fd/
  54          - the file descriptor number
  55          - the file name provided.
  56          The final NUL is included in the sizeof.   A bit of overhead
  57          due to the format elements compensates for possible negative
  58          numbers.  */
  59       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  60       buf = alloca (buflen);
  61
  62       __snprintf (buf, buflen, procfd, fd, file);
  63       file = buf;
  64     }
  65
  66   int result;
  67   INTERNAL_SYSCALL_DECL (err);
  68
  69   if (vers == _STAT_VER_KERNEL)
  70     {
  71       if (flag & AT_SYMLINK_NOFOLLOW)
  72         result = INTERNAL_SYSCALL (lstat, err, 2, CHECK_STRING (file),
  73                                    CHECK_1 ((struct kernel_stat *) st));
  74       else
  75         result = INTERNAL_SYSCALL (stat, err, 2, CHECK_STRING (file),
  76                                    CHECK_1 ((struct kernel_stat *) st));
  77
  78       if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
  79         return result;
  80     }
  81 #ifdef STAT_IS_KERNEL_STAT
  82   else
  83     {
  84       __set_errno (EINVAL);
  85       return -1;
  86     }
  87 #else
  88   struct kernel_stat kst;
  89
  90   if (flag & AT_SYMLINK_NOFOLLOW)
  91     result = INTERNAL_SYSCALL (lstat, err, 2, CHECK_STRING (file),
  92                                __ptrvalue (&kst));
  93   else
  94     result = INTERNAL_SYSCALL (stat, err, 2, CHECK_STRING (file),
  95                                __ptrvalue (&kst));
  96
  97   if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
  98     return __xstat_conv (vers, &kst, st);
  99 #endif
 100
 101   __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
 102
 103   return -1;
 104 }
 105 #ifdef XSTAT_IS_XSTAT64
 106 # undef __fxstatat64
 107 strong_alias (__fxstatat, __fxstatat64);
 108 #endif