sysdeps/unix/sysv/linux/s390/s390-32/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 <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   In Linux 2.1.x the chown functions have been changed.  A new function lchown
  35   was introduced.  The new chown now follows symlinks - the old chown and the
  36   new lchown do not follow symlinks.
  37   The new lchown function has the same number as the old chown had and the
  38   new chown has a new number.  When compiling with headers from Linux > 2.1.8x
  39   it's impossible to run this libc with older kernels.  In these cases libc
  40   has therefore to route calls to chown to the old chown function.
  41 */
  42
  43 /* Running under Linux > 2.1.80.  */
  44
  45 #ifdef __NR_chown32
  46 # if __ASSUME_32BITUIDS == 0
  47 /* This variable is shared with all files that need to check for 32bit
  48    uids.  */
  49 extern int __libc_missing_32bit_uids;
  50 # endif
  51 #endif /* __NR_chown32 */
  52
  53 int
  54 fchownat (int fd, const char *file, uid_t owner, gid_t group, int flag)
  55 {
  56   if (flag & ~AT_SYMLINK_NOFOLLOW)
  57     {
  58       __set_errno (EINVAL);
  59       return -1;
  60     }
  61
  62   char *buf = NULL;
  63
  64   if (fd != AT_FDCWD && file[0] != '/')
  65     {
  66       size_t filelen = strlen (file);
  67       static const char procfd[] = "/proc/self/fd/%d/%s";
  68       /* Buffer for the path name we are going to use.  It consists of
  69          - the string /proc/self/fd/
  70          - the file descriptor number
  71          - the file name provided.
  72          The final NUL is included in the sizeof.   A bit of overhead
  73          due to the format elements compensates for possible negative
  74          numbers.  */
  75       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  76       buf = alloca (buflen);
  77
  78       __snprintf (buf, buflen, procfd, fd, file);
  79       file = buf;
  80     }
  81
  82   int result;
  83   INTERNAL_SYSCALL_DECL (err);
  84
  85 #if __ASSUME_32BITUIDS > 0
  86   result = INTERNAL_SYSCALL (chown32, err, 3, CHECK_STRING (file), owner,
  87                              group);
  88 #else
  89   static int __libc_old_chown;
  90
  91 # ifdef __NR_chown32
  92   if (__libc_missing_32bit_uids <= 0)
  93     {
  94       if (flag & AT_SYMLINK_NOFOLLOW)
  95         result = INTERNAL_SYSCALL (lchown32, err, 3, CHECK_STRING (file),
  96                                    owner, group);
  97       else
  98         result = INTERNAL_SYSCALL (chown32, err, 3, CHECK_STRING (file),
  99                                    owner, group);
 100
 101       if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
 102         return result;
 103       if (INTERNAL_SYSCALL_ERRNO (result, err) != ENOSYS)
 104         goto fail;
 105
 106       __libc_missing_32bit_uids = 1;
 107     }
 108 # endif /* __NR_chown32 */
 109   if (((owner + 1) > (uid_t) ((__kernel_uid_t) -1U))
 110       || ((group + 1) > (gid_t) ((__kernel_gid_t) -1U)))
 111     {
 112       __set_errno (EINVAL);
 113       return -1;
 114     }
 115
 116   if (!__libc_old_chown && (flag & AT_SYMLINK_NOFOLLOW) == 0)
 117     {
 118       result = INTERNAL_SYSCALL (chown, err, 3, CHECK_STRING (file), owner,
 119                                  group);
 120
 121       if (!INTERNAL_SYSCALL_ERROR_P (result, err))
 122         return result;
 123       if (INTERNAL_SYSCALL_ERRNO (result, err) != ENOSYS)
 124         goto fail;
 125
 126       __libc_old_chown = 1;
 127     }
 128
 129   result = INTERNAL_SYSCALL (lchown, err, 3, CHECK_STRING (file), owner,
 130                              group);
 131 #endif
 132
 133   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
 134     {
 135     fail:
 136       __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
 137       result = -1;
 138     }
 139
 140   return result;
 141 }