sysdeps/unix/sysv/linux/i386/chown.c

   1 /* Copyright (C) 1998,1999,2000,2002,2003,2004,2006
   2         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 <unistd.h>
  22
  23 #include <sysdep.h>
  24 #include <sys/syscall.h>
  25 #include <shlib-compat.h>
  26 #include <bp-checks.h>
  27
  28 #include <linux/posix_types.h>
  29 #include <kernel-features.h>
  30
  31 /*
  32   In Linux 2.1.x the chown functions have been changed.  A new function lchown
  33   was introduced.  The new chown now follows symlinks - the old chown and the
  34   new lchown do not follow symlinks.
  35   The new lchown function has the same number as the old chown had and the
  36   new chown has a new number.  When compiling with headers from Linux > 2.1.8x
  37   it's impossible to run this libc with older kernels.  In these cases libc
  38   has therefore to route calls to chown to the old chown function.
  39 */
  40
  41 extern int __chown_is_lchown (const char *__file, uid_t __owner,
  42                               gid_t __group);
  43 extern int __real_chown (const char *__file, uid_t __owner, gid_t __group);
  44
  45
  46 #if defined __NR_lchown || __ASSUME_LCHOWN_SYSCALL > 0
  47 /* Running under Linux > 2.1.80.  */
  48
  49 # ifdef __NR_chown32
  50 #  if __ASSUME_32BITUIDS == 0
  51 /* This variable is shared with all files that need to check for 32bit
  52    uids.  */
  53 extern int __libc_missing_32bit_uids;
  54 #  endif
  55 # endif /* __NR_chown32 */
  56
  57 int
  58 __real_chown (const char *file, uid_t owner, gid_t group)
  59 {
  60 # if __ASSUME_LCHOWN_SYSCALL == 0
  61   static int __libc_old_chown;
  62   int result;
  63
  64   if (!__libc_old_chown)
  65     {
  66       int saved_errno = errno;
  67 #  ifdef __NR_chown32
  68       if (__libc_missing_32bit_uids <= 0)
  69         {
  70           int result;
  71           int saved_errno = errno;
  72
  73           result = INLINE_SYSCALL (chown32, 3, CHECK_STRING (file), owner, group);
  74           if (result == 0 || errno != ENOSYS)
  75             return result;
  76
  77           __set_errno (saved_errno);
  78           __libc_missing_32bit_uids = 1;
  79         }
  80 #  endif /* __NR_chown32 */
  81       if (((owner + 1) > (uid_t) ((__kernel_uid_t) -1U))
  82           || ((group + 1) > (gid_t) ((__kernel_gid_t) -1U)))
  83         {
  84           __set_errno (EINVAL);
  85           return -1;
  86         }
  87
  88       result = INLINE_SYSCALL (chown, 3, CHECK_STRING (file), owner, group);
  89
  90       if (result >= 0 || errno != ENOSYS)
  91         return result;
  92
  93       __set_errno (saved_errno);
  94       __libc_old_chown = 1;
  95     }
  96
  97   return __lchown (file, owner, group);
  98 # elif __ASSUME_32BITUIDS
  99   /* This implies __ASSUME_LCHOWN_SYSCALL.  */
 100   return INLINE_SYSCALL (chown32, 3, CHECK_STRING (file), owner, group);
 101 # else
 102   /* !__ASSUME_32BITUIDS && ASSUME_LCHOWN_SYSCALL  */
 103 #  ifdef __NR_chown32
 104   if (__libc_missing_32bit_uids <= 0)
 105     {
 106       int result;
 107       int saved_errno = errno;
 108
 109       result = INLINE_SYSCALL (chown32, 3, CHECK_STRING (file), owner, group);
 110       if (result == 0 || errno != ENOSYS)
 111         return result;
 112
 113       __set_errno (saved_errno);
 114       __libc_missing_32bit_uids = 1;
 115     }
 116 #  endif /* __NR_chown32 */
 117   if (((owner + 1) > (uid_t) ((__kernel_uid_t) -1U))
 118       || ((group + 1) > (gid_t) ((__kernel_gid_t) -1U)))
 119     {
 120       __set_errno (EINVAL);
 121       return -1;
 122     }
 123
 124   return INLINE_SYSCALL (chown, 3, CHECK_STRING (file), owner, group);
 125 # endif
 126 }
 127 #endif
 128
 129
 130 #if !defined __NR_lchown && __ASSUME_LCHOWN_SYSCALL == 0
 131 /* Compiling under older kernels.  */
 132 int
 133 __chown_is_lchown (const char *file, uid_t owner, gid_t group)
 134 {
 135   return INLINE_SYSCALL (chown, 3, CHECK_STRING (file), owner, group);
 136 }
 137 #elif SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1)
 138 /* Compiling for compatibiity.  */
 139 int
 140 attribute_compat_text_section
 141 __chown_is_lchown (const char *file, uid_t owner, gid_t group)
 142 {
 143   return __lchown (file, owner, group);
 144 }
 145 #endif
 146
 147 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1)
 148 compat_symbol (libc, __chown_is_lchown, chown, GLIBC_2_0);
 149 #endif
 150
 151 #ifdef __NR_lchown
 152 versioned_symbol (libc, __real_chown, chown, GLIBC_2_1);
 153 strong_alias (__real_chown, __chown)
 154 #else
 155 strong_alias (__chown_is_lchown, __chown_is_lchown21)
 156 versioned_symbol (libc, __chown_is_lchown21, chown, GLIBC_2_1);
 157 strong_alias (__chown_is_lchown, __chown)
 158 #endif
 159 libc_hidden_def (__chown)