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

   1 /* chown() compatibility.
   2    Copyright (C) 1998, 2000, 2002, 2003 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 /*
  28   In Linux 2.1.x the chown functions have been changed.  A new function lchown
  29   was introduced.  The new chown now follows symlinks - the old chown and the
  30   new lchown do not follow symlinks.
  31   This file emulates chown() under the old kernels.
  32 */
  33
  34 int
  35 __chown (const char *file, uid_t owner, gid_t group)
  36 {
  37    int err;
  38    int old_errno;
  39    char link[PATH_MAX+2];
  40    char path[2*PATH_MAX+4];
  41    int loopct;
  42    size_t filelen;
  43    static int libc_old_chown = 0 /* -1=old linux, 1=new linux, 0=unknown */;
  44
  45    if (libc_old_chown == 1)
  46      return INLINE_SYSCALL (chown, 3, __ptrvalue (file), owner, group);
  47
  48    old_errno = errno;
  49
  50 #ifdef __NR_lchown
  51    if (libc_old_chown == 0)
  52      {
  53        err = INLINE_SYSCALL (chown, 3, __ptrvalue (file), owner, group);
  54        if (err != -1 || errno != ENOSYS)
  55          {
  56            libc_old_chown = 1;
  57            return err;
  58          }
  59        libc_old_chown = -1;
  60      }
  61 #endif
  62
  63    err = __readlink (file, link, PATH_MAX+1);
  64    if (err == -1)
  65      {
  66        errno = old_errno;
  67        return __lchown(file, owner, group);
  68      }
  69
  70    filelen = strlen (file) + 1;
  71    if (filelen > sizeof(path))
  72      {
  73        errno = ENAMETOOLONG;
  74        return -1;
  75      }
  76    memcpy (path, file, filelen);
  77
  78    /* 'The system has an arbitrary limit...'  In practise, we'll hit
  79       ENAMETOOLONG before this, usually.  */
  80    for (loopct = 0; loopct < 128; loopct++)
  81    {
  82      size_t linklen;
  83
  84      if (err >= PATH_MAX+1)
  85        {
  86          errno = ENAMETOOLONG;
  87          return -1;
  88        }
  89
  90       link[err] = 0;  /* Null-terminate string, just-in-case.  */
  91
  92       linklen = strlen (link) + 1;
  93
  94       if (link[0] == '/')
  95         memcpy (path, link, linklen);
  96       else
  97         {
  98           filelen = strlen (path);
  99
 100           while (filelen > 1 && path[filelen-1] == '/')
 101             filelen--;
 102           while (filelen > 0 && path[filelen-1] != '/')
 103             filelen--;
 104           if (filelen + linklen > sizeof(path))
 105             {
 106               errno = ENAMETOOLONG;
 107               return -1;
 108             }
 109           memcpy (path+filelen, link, linklen);
 110         }
 111
 112       err = __readlink(path, link, PATH_MAX+1);
 113
 114       if (err == -1)
 115       {
 116         errno = old_errno;
 117         return __lchown(path, owner, group);
 118       }
 119    }
 120    errno = ELOOP;
 121    return -1;
 122 }
 123 libc_hidden_def (__chown)
 124
 125 #include <shlib-compat.h>
 126 versioned_symbol (libc, __chown, chown, GLIBC_2_1);