sysdeps/unix/sysv/linux/i386/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 <string.h>
  28 #include <sys/stat.h>
  29 #include <kernel_stat.h>
  30
  31 #include <sysdep.h>
  32 #include <sys/syscall.h>
  33 #include <bp-checks.h>
  34
  35 #include <kernel-features.h>
  36
  37 #include <xstatconv.h>
  38
  39 #ifdef __NR_stat64
  40 # if __ASSUME_STAT64_SYSCALL == 0
  41 /* The variable is shared between all wrappers around *stat64 calls.  */
  42 extern int __have_no_stat64;
  43 # endif
  44 #endif
  45
  46
  47 /* Get information about the file NAME relative to FD in ST.  */
  48 int
  49 __fxstatat (int vers, int fd, const char *file, struct stat *st, int flag)
  50 {
  51   int result;
  52   INTERNAL_SYSCALL_DECL (err);
  53   struct stat64 st64;
  54
  55 #ifdef __NR_fstatat64
  56 # ifndef __ASSUME_ATFCTS
  57   if (__have_atfcts >= 0)
  58 # endif
  59     {
  60       result = INTERNAL_SYSCALL (fstatat64, err, 4, fd, file, &st64, flag);
  61 # ifndef __ASSUME_ATFCTS
  62       if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 1)
  63           && INTERNAL_SYSCALL_ERRNO (result, err) == ENOSYS)
  64         __have_atfcts = -1;
  65       else
  66 # endif
  67         if (!__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 1))
  68           return __xstat32_conv (vers, &st64, st);
  69         else
  70           {
  71             __set_errno (INTERNAL_SYSCALL_ERRNO (result, err));
  72             return -1;
  73           }
  74     }
  75 #endif
  76
  77 #ifndef __ASSUME_ATFCTS
  78   if (__builtin_expect (flag & ~AT_SYMLINK_NOFOLLOW, 0))
  79     {
  80       __set_errno (EINVAL);
  81       return -1;
  82     }
  83
  84   char *buf = NULL;
  85
  86   if (fd != AT_FDCWD && file[0] != '/')
  87     {
  88       size_t filelen = strlen (file);
  89       static const char procfd[] = "/proc/self/fd/%d/%s";
  90       /* Buffer for the path name we are going to use.  It consists of
  91          - the string /proc/self/fd/
  92          - the file descriptor number
  93          - the file name provided.
  94          The final NUL is included in the sizeof.   A bit of overhead
  95          due to the format elements compensates for possible negative
  96          numbers.  */
  97       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  98       buf = alloca (buflen);
  99
 100       __snprintf (buf, buflen, procfd, fd, file);
 101       file = buf;
 102     }
 103
 104 # if __ASSUME_STAT64_SYSCALL == 0
 105   struct kernel_stat kst;
 106 # endif
 107   if (vers == _STAT_VER_KERNEL)
 108     {
 109       if (flag & AT_SYMLINK_NOFOLLOW)
 110         result = INTERNAL_SYSCALL (lstat, err, 2, CHECK_STRING (file),
 111                                    CHECK_1 ((struct kernel_stat *) st));
 112       else
 113         result = INTERNAL_SYSCALL (stat, err, 2, CHECK_STRING (file),
 114                                    CHECK_1 ((struct kernel_stat *) st));
 115       goto out;
 116     }
 117
 118 # if __ASSUME_STAT64_SYSCALL > 0
 119
 120   if (flag & AT_SYMLINK_NOFOLLOW)
 121     result = INTERNAL_SYSCALL (lstat64, err, 2, CHECK_STRING (file),
 122                                __ptrvalue (&st64));
 123   else
 124     result = INTERNAL_SYSCALL (stat64, err, 2, CHECK_STRING (file),
 125                                __ptrvalue (&st64));
 126   if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 127     return __xstat32_conv (vers, &st64, st);
 128 # else
 129 #  if defined __NR_stat64
 130   /* To support 32 bit UIDs, we have to use stat64.  The normal stat
 131      call only returns 16 bit UIDs.  */
 132   if (! __have_no_stat64)
 133     {
 134       if (flag & AT_SYMLINK_NOFOLLOW)
 135         result = INTERNAL_SYSCALL (lstat64, err, 2, CHECK_STRING (file),
 136                                    __ptrvalue (&st64));
 137       else
 138         result = INTERNAL_SYSCALL (stat64, err, 2, CHECK_STRING (file),
 139                                    __ptrvalue (&st64));
 140
 141       if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 142         result = __xstat32_conv (vers, &st64, st);
 143
 144       if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1)
 145           || INTERNAL_SYSCALL_ERRNO (result, err) != ENOSYS)
 146         goto out;
 147
 148       __have_no_stat64 = 1;
 149     }
 150 #  endif
 151   if (flag & AT_SYMLINK_NOFOLLOW)
 152     result = INTERNAL_SYSCALL (lstat, err, 2, CHECK_STRING (file),
 153                                __ptrvalue (&kst));
 154   else
 155     result = INTERNAL_SYSCALL (stat, err, 2, CHECK_STRING (file),
 156                                __ptrvalue (&kst));
 157   if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 158     return __xstat_conv (vers, &kst, st);
 159 # endif  /* __ASSUME_STAT64_SYSCALL  */
 160
 161  out:
 162   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
 163     {
 164       __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
 165       result = -1;
 166     }
 167
 168   return result;
 169 #endif
 170 }
 171 libc_hidden_def (__fxstatat)
 172 #ifdef XSTAT_IS_XSTAT64
 173 # undef __fxstatat64
 174 strong_alias (__fxstatat, __fxstatat64);
 175 libc_hidden_ver (__fxstatat, __fxstatat64)
 176 #endif