sysdeps/unix/sysv/linux/powerpc/chown.c

   1 /* chown() compatibility.
   2    Copyright (C) 1998, 2000, 2002, 2003, 2005 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <limits.h>
  24 #include <sysdep.h>
  25 #include <stdlib.h>
  26
  27 #include <kernel-features.h>
  28
  29 /*
  30   In Linux 2.1.x the chown functions have been changed.  A new function lchown
  31   was introduced.  The new chown now follows symlinks - the old chown and the
  32   new lchown do not follow symlinks.
  33   This file emulates chown() under the old kernels.
  34 */
  35
  36 int
  37 __chown (const char *file, uid_t owner, gid_t group)
  38 {
  39 #if __ASSUME_LCHOWN_SYSCALL
  40   return INLINE_SYSCALL (chown, 3, file, owner, group);
  41 #else
  42   int err;
  43   int old_errno;
  44   char link[PATH_MAX + 2];
  45   char path[2 * PATH_MAX + 4];
  46   int loopct;
  47   size_t filelen;
  48   static int libc_old_chown = 0 /* -1=old linux, 1=new linux, 0=unknown */;
  49
  50   if (libc_old_chown == 1)
  51     return INLINE_SYSCALL (chown, 3, __ptrvalue (file), owner, group);
  52
  53   old_errno = errno;
  54
  55 # ifdef __NR_lchown
  56   if (libc_old_chown == 0)
  57     {
  58       err = INLINE_SYSCALL (chown, 3, __ptrvalue (file), owner, group);
  59       if (err != -1 || errno != ENOSYS)
  60         {
  61           libc_old_chown = 1;
  62           return err;
  63         }
  64       libc_old_chown = -1;
  65     }
  66 # endif
  67
  68   err = __readlink (file, link, PATH_MAX + 1);
  69   if (err == -1)
  70     {
  71       __set_errno (old_errno);
  72       return __lchown (file, owner, group);
  73     }
  74
  75   filelen = strlen (file) + 1;
  76   if (filelen > sizeof (path))
  77     {
  78       __set_errno (ENAMETOOLONG);
  79       return -1;
  80     }
  81   memcpy (path, file, filelen);
  82
  83   /* 'The system has an arbitrary limit...'  In practise, we'll hit
  84      ENAMETOOLONG before this, usually.  */
  85   for (loopct = 0; loopct < 128; ++loopct)
  86     {
  87       size_t linklen;
  88
  89       if (err >= PATH_MAX + 1)
  90         {
  91           __set_errno (ENAMETOOLONG);
  92           return -1;
  93         }
  94
  95       link[err] = 0;  /* Null-terminate string, just-in-case.  */
  96
  97       linklen = strlen (link) + 1;
  98
  99       if (link[0] == '/')
 100         memcpy (path, link, linklen);
 101       else
 102         {
 103           filelen = strlen (path);
 104
 105           while (filelen > 1 && path[filelen - 1] == '/')
 106             --filelen;
 107           while (filelen > 0 && path[filelen - 1] != '/')
 108             --filelen;
 109           if (filelen + linklen > sizeof (path))
 110             {
 111               errno = ENAMETOOLONG;
 112               return -1;
 113             }
 114           memcpy (path + filelen, link, linklen);
 115         }
 116
 117       err = __readlink (path, link, PATH_MAX + 1);
 118
 119       if (err == -1)
 120         {
 121           __set_errno (old_errno);
 122           return __lchown (path, owner, group);
 123         }
 124     }
 125   __set_errno (ELOOP);
 126   return -1;
 127 #endif
 128 }
 129 libc_hidden_def (__chown)
 130
 131 #include <shlib-compat.h>
 132 versioned_symbol (libc, __chown, chown, GLIBC_2_1);