sysdeps/unix/sysv/linux/i386/fxstatat.c

   1 /* Copyright (C) 2005, 2006, 2009 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
  34 #include <kernel-features.h>
  35
  36 #include <xstatconv.h>
  37
  38 #ifdef __NR_stat64
  39 # if __ASSUME_STAT64_SYSCALL == 0
  40 /* The variable is shared between all wrappers around *stat64 calls.  */
  41 extern int __have_no_stat64;
  42 # endif
  43 #endif
  44
  45
  46 /* Get information about the file NAME relative to FD in ST.  */
  47 int
  48 __fxstatat (int vers, int fd, const char *file, struct stat *st, int flag)
  49 {
  50   int result;
  51   INTERNAL_SYSCALL_DECL (err);
  52   struct stat64 st64;
  53
  54 #ifdef __NR_fstatat64
  55 # ifndef __ASSUME_ATFCTS
  56   if (__have_atfcts >= 0)
  57 # endif
  58     {
  59       result = INTERNAL_SYSCALL (fstatat64, err, 4, fd, file, &st64, flag);
  60 # ifndef __ASSUME_ATFCTS
  61       if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 1)
  62           && INTERNAL_SYSCALL_ERRNO (result, err) == ENOSYS)
  63         __have_atfcts = -1;
  64       else
  65 # endif
  66         if (!__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 1))
  67           return __xstat32_conv (vers, &st64, st);
  68         else
  69           {
  70             __set_errno (INTERNAL_SYSCALL_ERRNO (result, err));
  71             return -1;
  72           }
  73     }
  74 #endif
  75
  76 #ifndef __ASSUME_ATFCTS
  77   if (__builtin_expect (flag & ~AT_SYMLINK_NOFOLLOW, 0))
  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 __ASSUME_STAT64_SYSCALL == 0
 110   struct kernel_stat kst;
 111 # endif
 112   if (vers == _STAT_VER_KERNEL)
 113     {
 114       if (flag & AT_SYMLINK_NOFOLLOW)
 115         result = INTERNAL_SYSCALL (lstat, err, 2, CHECK_STRING (file),
 116                                    CHECK_1 ((struct kernel_stat *) st));
 117       else
 118         result = INTERNAL_SYSCALL (stat, err, 2, CHECK_STRING (file),
 119                                    CHECK_1 ((struct kernel_stat *) st));
 120       goto out;
 121     }
 122
 123 # if __ASSUME_STAT64_SYSCALL > 0
 124
 125   if (flag & AT_SYMLINK_NOFOLLOW)
 126     result = INTERNAL_SYSCALL (lstat64, err, 2, CHECK_STRING (file),
 127                                __ptrvalue (&st64));
 128   else
 129     result = INTERNAL_SYSCALL (stat64, err, 2, CHECK_STRING (file),
 130                                __ptrvalue (&st64));
 131   if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 132     return __xstat32_conv (vers, &st64, st);
 133 # else
 134 #  if defined __NR_stat64
 135   /* To support 32 bit UIDs, we have to use stat64.  The normal stat
 136      call only returns 16 bit UIDs.  */
 137   if (! __have_no_stat64)
 138     {
 139       if (flag & AT_SYMLINK_NOFOLLOW)
 140         result = INTERNAL_SYSCALL (lstat64, err, 2, CHECK_STRING (file),
 141                                    __ptrvalue (&st64));
 142       else
 143         result = INTERNAL_SYSCALL (stat64, err, 2, CHECK_STRING (file),
 144                                    __ptrvalue (&st64));
 145
 146       if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 147         result = __xstat32_conv (vers, &st64, st);
 148
 149       if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1)
 150           || INTERNAL_SYSCALL_ERRNO (result, err) != ENOSYS)
 151         goto out;
 152
 153       __have_no_stat64 = 1;
 154     }
 155 #  endif
 156   if (flag & AT_SYMLINK_NOFOLLOW)
 157     result = INTERNAL_SYSCALL (lstat, err, 2, CHECK_STRING (file),
 158                                __ptrvalue (&kst));
 159   else
 160     result = INTERNAL_SYSCALL (stat, err, 2, CHECK_STRING (file),
 161                                __ptrvalue (&kst));
 162   if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 163     return __xstat_conv (vers, &kst, st);
 164 # endif  /* __ASSUME_STAT64_SYSCALL  */
 165
 166  out:
 167   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
 168     {
 169       __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
 170       result = -1;
 171     }
 172
 173   return result;
 174 #endif
 175 }
 176 libc_hidden_def (__fxstatat)
 177 #ifdef XSTAT_IS_XSTAT64
 178 # undef __fxstatat64
 179 strong_alias (__fxstatat, __fxstatat64);
 180 libc_hidden_ver (__fxstatat, __fxstatat64)
 181 #endif