sysdeps/unix/sysv/linux/i386/fchownat.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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24
  25 #include <sysdep.h>
  26 #include <sys/syscall.h>
  27 #include <shlib-compat.h>
  28 #include <bp-checks.h>
  29
  30 #include <linux/posix_types.h>
  31 #include <kernel-features.h>
  32
  33
  34 int
  35 fchownat (int fd, const char *file, uid_t owner, gid_t group, int flag)
  36 {
  37   int result;
  38
  39 #ifdef __NR_fchownat
  40 # ifndef __ASSUME_ATFCTS
  41   if (__have_atfcts >= 0)
  42 # endif
  43     {
  44       result = INLINE_SYSCALL (fchownat, 5, fd, file, owner, group, flag);
  45 # ifndef __ASSUME_ATFCTS
  46       if (result == -1 && errno == ENOSYS)
  47         __have_atfcts = -1;
  48       else
  49 # endif
  50         return result;
  51     }
  52 #endif
  53
  54 #ifndef __ASSUME_ATFCTS
  55   if (flag & ~AT_SYMLINK_NOFOLLOW)
  56     {
  57       __set_errno (EINVAL);
  58       return -1;
  59     }
  60
  61   char *buf = NULL;
  62
  63   if (fd != AT_FDCWD && file[0] != '/')
  64     {
  65       size_t filelen = strlen (file);
  66       if (__builtin_expect (filelen == 0, 0))
  67         {
  68           __set_errno (ENOENT);
  69           return -1;
  70         }
  71
  72       static const char procfd[] = "/proc/self/fd/%d/%s";
  73       /* Buffer for the path name we are going to use.  It consists of
  74          - the string /proc/self/fd/
  75          - the file descriptor number
  76          - the file name provided.
  77          The final NUL is included in the sizeof.   A bit of overhead
  78          due to the format elements compensates for possible negative
  79          numbers.  */
  80       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  81       buf = alloca (buflen);
  82
  83       __snprintf (buf, buflen, procfd, fd, file);
  84       file = buf;
  85     }
  86
  87 # if __ASSUME_32BITUIDS > 0
  88   /* This implies __ASSUME_LCHOWN_SYSCALL.  */
  89   INTERNAL_SYSCALL_DECL (err);
  90
  91   if (flag & AT_SYMLINK_NOFOLLOW)
  92     result = INTERNAL_SYSCALL (lchown32, err, 3, CHECK_STRING (file), owner,
  93                                group);
  94   else
  95     result = INTERNAL_SYSCALL (chown32, err, 3, CHECK_STRING (file), owner,
  96                                group);
  97
  98   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
  99     {
 100       __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
 101       return -1;
 102     }
 103 # else
 104   /* Don't inline the rest to avoid unnecessary code duplication.  */
 105   if (flag & AT_SYMLINK_NOFOLLOW)
 106     result = __lchown (file, owner, group);
 107   else
 108     result = __chown (file, owner, group);
 109   if (result < 0)
 110     __atfct_seterrno (errno, fd, buf);
 111 # endif
 112
 113   return result;
 114
 115 #endif
 116 }