sysdeps/unix/sysv/linux/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 #include <kernel-features.h>
  34
  35 #include <xstatconv.h>
  36
  37 /* Get information about the file NAME in BUF.  */
  38 int
  39 __fxstatat (int vers, int fd, const char *file, struct stat *st, int flag)
  40 {
  41   int result;
  42   INTERNAL_SYSCALL_DECL (err);
  43 #ifdef STAT_IS_KERNEL_STAT
  44 # define kst (*st)
  45 #else
  46   struct kernel_stat kst;
  47 #endif
  48
  49 #ifdef __NR_newfstatat
  50 # ifndef __ASSUME_ATFCTS
  51   if (__have_atfcts >= 0)
  52 # endif
  53     {
  54       result = INTERNAL_SYSCALL (newfstatat, err, 4, fd, file, &kst, flag);
  55 # ifndef __ASSUME_ATFCTS
  56       if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 1)
  57           && INTERNAL_SYSCALL_ERRNO (result, err) == ENOSYS)
  58         __have_atfcts = -1;
  59       else
  60 # endif
  61         if (!__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 1))
  62           {
  63 #ifdef STAT_IS_KERNEL_STAT
  64             return 0;
  65 #else
  66             return __xstat_conv (vers, &kst, st);
  67 #endif
  68           }
  69         else
  70           {
  71             __set_errno (INTERNAL_SYSCALL_ERRNO (result, err));
  72             return -1;
  73           }
  74     }
  75 #endif
  76
  77   if (flag & ~AT_SYMLINK_NOFOLLOW)
  78     {
  79       __set_errno (EINVAL);
  80       return -1;
  81     }
  82
  83   char *buf = NULL;
  84
  85   if (fd != AT_FDCWD && file[0] != '/')
  86     {
  87       size_t filelen = strlen (file);
  88       if (__builtin_expect (filelen == 0, 0))
  89         {
  90           __set_errno (ENOENT);
  91           return -1;
  92         }
  93
  94       static const char procfd[] = "/proc/self/fd/%d/%s";
  95       /* Buffer for the path name we are going to use.  It consists of
  96          - the string /proc/self/fd/
  97          - the file descriptor number
  98          - the file name provided.
  99          The final NUL is included in the sizeof.   A bit of overhead
 100          due to the format elements compensates for possible negative
 101          numbers.  */
 102       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
 103       buf = alloca (buflen);
 104
 105       __snprintf (buf, buflen, procfd, fd, file);
 106       file = buf;
 107     }
 108
 109   if (vers == _STAT_VER_KERNEL)
 110     {
 111       if (flag & AT_SYMLINK_NOFOLLOW)
 112         result = INTERNAL_SYSCALL (lstat, err, 2, CHECK_STRING (file),
 113                                    CHECK_1 ((struct kernel_stat *) st));
 114       else
 115         result = INTERNAL_SYSCALL (stat, err, 2, CHECK_STRING (file),
 116                                    CHECK_1 ((struct kernel_stat *) st));
 117
 118       if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 119         return result;
 120     }
 121 #ifdef STAT_IS_KERNEL_STAT
 122   else
 123     {
 124       __set_errno (EINVAL);
 125       return -1;
 126     }
 127 #else
 128   if (flag & AT_SYMLINK_NOFOLLOW)
 129     result = INTERNAL_SYSCALL (lstat, err, 2, CHECK_STRING (file),
 130                                __ptrvalue (&kst));
 131   else
 132     result = INTERNAL_SYSCALL (stat, err, 2, CHECK_STRING (file),
 133                                __ptrvalue (&kst));
 134
 135   if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 136     return __xstat_conv (vers, &kst, st);
 137 #endif
 138
 139   __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
 140
 141   return -1;
 142 }
 143 libc_hidden_def (__fxstatat)
 144 #ifdef XSTAT_IS_XSTAT64
 145 # undef __fxstatat64
 146 strong_alias (__fxstatat, __fxstatat64);
 147 libc_hidden_def (__fxstatat64)
 148 #endif