sysdeps/unix/sysv/linux/i386/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, 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   if (__builtin_expect (flag & ~AT_SYMLINK_NOFOLLOW, 0))
  52     {
  53       __set_errno (EINVAL);
  54       return -1;
  55     }
  56
  57   char *buf = NULL;
  58
  59   if (fd != AT_FDCWD && file[0] != '/')
  60     {
  61       size_t filelen = strlen (file);
  62       static const char procfd[] = "/proc/self/fd/%d/%s";
  63       /* Buffer for the path name we are going to use.  It consists of
  64          - the string /proc/self/fd/
  65          - the file descriptor number
  66          - the file name provided.
  67          The final NUL is included in the sizeof.   A bit of overhead
  68          due to the format elements compensates for possible negative
  69          numbers.  */
  70       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  71       buf = alloca (buflen);
  72
  73       __snprintf (buf, buflen, procfd, fd, file);
  74       file = buf;
  75     }
  76
  77 #if __ASSUME_STAT64_SYSCALL == 0
  78   struct kernel_stat kst;
  79 #endif
  80   int result;
  81   INTERNAL_SYSCALL_DECL (err);
  82
  83   if (vers == _STAT_VER_KERNEL)
  84     {
  85       if (flag & AT_SYMLINK_NOFOLLOW)
  86         result = INTERNAL_SYSCALL (lstat, err, 2, CHECK_STRING (file),
  87                                    CHECK_1 ((struct kernel_stat *) st));
  88       else
  89         result = INTERNAL_SYSCALL (stat, err, 2, CHECK_STRING (file),
  90                                    CHECK_1 ((struct kernel_stat *) st));
  91       goto out;
  92     }
  93
  94 #if __ASSUME_STAT64_SYSCALL > 0
  95   struct stat64 st64;
  96
  97   if (flag & AT_SYMLINK_NOFOLLOW)
  98     result = INTERNAL_SYSCALL (lstat64, err, 2, CHECK_STRING (file),
  99                                __ptrvalue (&st64));
 100   else
 101     result = INTERNAL_SYSCALL (stat64, err, 2, CHECK_STRING (file),
 102                                __ptrvalue (&st64));
 103   if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 104     return __xstat32_conv (vers, &st64, st);
 105 #else
 106 # if defined __NR_stat64
 107   /* To support 32 bit UIDs, we have to use stat64.  The normal stat
 108      call only returns 16 bit UIDs.  */
 109   if (! __have_no_stat64)
 110     {
 111       struct stat64 st64;
 112
 113       if (flag & AT_SYMLINK_NOFOLLOW)
 114         result = INTERNAL_SYSCALL (lstat64, err, 2, CHECK_STRING (file),
 115                                    __ptrvalue (&st64));
 116       else
 117         result = INTERNAL_SYSCALL (stat64, err, 2, CHECK_STRING (file),
 118                                    __ptrvalue (&st64));
 119
 120       if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 121         result = __xstat32_conv (vers, &st64, st);
 122
 123       if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1)
 124           || INTERNAL_SYSCALL_ERRNO (result, err) != ENOSYS)
 125         goto out;
 126
 127       __have_no_stat64 = 1;
 128     }
 129 # endif
 130   if (flag & AT_SYMLINK_NOFOLLOW)
 131     result = INTERNAL_SYSCALL (lstat, err, 2, CHECK_STRING (file),
 132                                __ptrvalue (&kst));
 133   else
 134     result = INTERNAL_SYSCALL (stat, err, 2, CHECK_STRING (file),
 135                                __ptrvalue (&kst));
 136   if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 137     return __xstat_conv (vers, &kst, st);
 138 #endif  /* __ASSUME_STAT64_SYSCALL  */
 139
 140  out:
 141   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
 142     {
 143       __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
 144       result = -1;
 145     }
 146
 147   return result;
 148 }
 149 #ifdef XSTAT_IS_XSTAT64
 150 # undef __fxstatat64
 151 strong_alias (__fxstatat, __fxstatat64);
 152 #endif