sysdeps/unix/sysv/linux/sh/fchownat.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 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <stdio.h>
  22 #include <unistd.h>
  23 #include <string.h>
  24
  25 #include <sysdep.h>
  26 #include <sys/syscall.h>
  27 #include <bp-checks.h>
  28
  29 #include <linux/posix_types.h>
  30 #include <kernel-features.h>
  31
  32 #ifdef __NR_chown32
  33 # if __ASSUME_32BITUIDS == 0
  34 /* This variable is shared with all files that need to check for 32bit
  35    uids.  */
  36 extern int __libc_missing_32bit_uids;
  37 # endif
  38 #endif /* __NR_chown32 */
  39
  40 int
  41 fchownat (int fd, const char *file, uid_t owner, gid_t group, int flag)
  42 {
  43   if (flag & ~AT_SYMLINK_NOFOLLOW)
  44     {
  45       __set_errno (EINVAL);
  46       return -1;
  47     }
  48
  49   char *buf = NULL;
  50
  51   if (fd != AT_FDCWD && file[0] != '/')
  52     {
  53       size_t filelen = strlen (file);
  54       static const char procfd[] = "/proc/self/fd/%d/%s";
  55       /* Buffer for the path name we are going to use.  It consists of
  56          - the string /proc/self/fd/
  57          - the file descriptor number
  58          - the file name provided.
  59          The final NUL is included in the sizeof.   A bit of overhead
  60          due to the format elements compensates for possible negative
  61          numbers.  */
  62       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  63       buf = alloca (buflen);
  64
  65       __snprintf (buf, buflen, procfd, fd, file);
  66       file = buf;
  67     }
  68
  69   int result;
  70   INTERNAL_SYSCALL_DECL (err);
  71
  72 #if __ASSUME_32BITUIDS > 0
  73   if (flag & AT_SYMLINK_NOFOLLOW)
  74     result = INTERNAL_SYSCALL (lchown32, err, 3, CHECK_STRING (file), owner,
  75                                group);
  76   else
  77     result = INTERNAL_SYSCALL (chown32, err, 3, CHECK_STRING (file), owner,
  78                                group);
  79 #else
  80 # ifdef __NR_chown32
  81   if (__libc_missing_32bit_uids <= 0)
  82     {
  83       if (flag & AT_SYMLINK_NOFOLLOW)
  84         result = INTERNAL_SYSCALL (lchown32, err, 3, CHECK_STRING (file),
  85                                    owner, group);
  86       else
  87         result = INTERNAL_SYSCALL (chown32, err, 3, CHECK_STRING (file), owner,
  88                                    group);
  89
  90       if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
  91         return result;
  92       if (INTERNAL_SYSCALL_ERRNO (result, err) != ENOSYS)
  93         goto fail;
  94
  95       __libc_missing_32bit_uids = 1;
  96     }
  97 # endif /* __NR_chown32 */
  98
  99   if (((owner + 1) > (gid_t) ((__kernel_uid_t) -1U))
 100       || ((group + 1) > (gid_t) ((__kernel_gid_t) -1U)))
 101     {
 102       __set_errno (EINVAL);
 103       return -1;
 104     }
 105
 106   if (flag & AT_SYMLINK_NOFOLLOW)
 107     result = INTERNAL_SYSCALL (lchown, err, 3, CHECK_STRING (file), owner,
 108                                group);
 109   else
 110     result = INTERNAL_SYSCALL (chown, err, 3, CHECK_STRING (file), owner,
 111                                group);
 112 #endif
 113
 114   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
 115     {
 116     fail:
 117       __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
 118       result = -1;
 119     }
 120
 121   return result;
 122 }