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

/* Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <errno.h>
#include <unistd.h>

#include <sysdep.h>
#include <sys/syscall.h>
#include <shlib-compat.h>
#include <bp-checks.h>

#include <linux/posix_types.h>
#include "kernel-features.h"

/*
  In Linux 2.1.x the chown functions have been changed.  A new function lchown
  was introduced.  The new chown now follows symlinks - the old chown and the
  new lchown do not follow symlinks.
  The new lchown function has the same number as the old chown had and the
  new chown has a new number.  When compiling with headers from Linux > 2.1.8x
  it's impossible to run this libc with older kernels.  In these cases libc
  has therefore to route calls to chown to the old chown function.
*/

extern int __syscall_chown (const char *__file,
			    __kernel_uid_t __owner, __kernel_gid_t __group);

extern int __chown_is_lchown (const char *__file, uid_t __owner,
			      gid_t __group);
extern int __real_chown (const char *__file, uid_t __owner, gid_t __group);


#if defined __NR_lchown || __ASSUME_LCHOWN_SYSCALL > 0
/* Running under Linux > 2.1.80.  */

# ifdef __NR_chown32
extern int __syscall_chown32 (const char *__file,
			      __kernel_uid32_t owner, __kernel_gid32_t group);
#  if __ASSUME_32BITUIDS == 0
/* This variable is shared with all files that need to check for 32bit
   uids.  */
extern int __libc_missing_32bit_uids;
#  endif
# endif /* __NR_chown32 */

int
__real_chown (const char *file, uid_t owner, gid_t group)
{
# if __ASSUME_LCHOWN_SYSCALL == 0
  static int __libc_old_chown;
  int result;

  if (!__libc_old_chown)
    {
      int saved_errno = errno;
#  ifdef __NR_chown32
      if (__libc_missing_32bit_uids <= 0)
	{
	  int result;
	  int saved_errno = errno;

	  result = INLINE_SYSCALL (chown32, 3, CHECK_STRING (file), owner, group);
	  if (result == 0 || errno != ENOSYS)
	    return result;

	  __set_errno (saved_errno);
	  __libc_missing_32bit_uids = 1;
	}
#  endif /* __NR_chown32 */
      if (((owner + 1) > (uid_t) ((__kernel_uid_t) -1U))
	  || ((group + 1) > (gid_t) ((__kernel_gid_t) -1U)))
	{
	  __set_errno (EINVAL);
	  return -1;
	}

      result = INLINE_SYSCALL (chown, 3, CHECK_STRING (file), owner, group);

      if (result >= 0 || errno != ENOSYS)
	return result;

      __set_errno (saved_errno);
      __libc_old_chown = 1;
    }

  return __lchown (file, owner, group);
# elif __ASSUME_32BITUIDS
  /* This implies __ASSUME_LCHOWN_SYSCALL.  */
  return INLINE_SYSCALL (chown32, 3, CHECK_STRING (file), owner, group);
# else
  /* !__ASSUME_32BITUIDS && ASSUME_LCHOWN_SYSCALL  */
#  ifdef __NR_chown32
  if (__libc_missing_32bit_uids <= 0)
    {
      int result;
      int saved_errno = errno;

      result = INLINE_SYSCALL (chown32, 3, CHECK_STRING (file), owner, group);
      if (result == 0 || errno != ENOSYS)
	return result;

      __set_errno (saved_errno);
      __libc_missing_32bit_uids = 1;
    }
#  endif /* __NR_chown32 */
  if (((owner + 1) > (uid_t) ((__kernel_uid_t) -1U))
      || ((group + 1) > (gid_t) ((__kernel_gid_t) -1U)))
    {
      __set_errno (EINVAL);
      return -1;
    }

  return INLINE_SYSCALL (chown, 3, CHECK_STRING (file), owner, group);
# endif
}
#endif


#if !defined __NR_lchown && __ASSUME_LCHOWN_SYSCALL == 0
/* Compiling under older kernels.  */
int
__chown_is_lchown (const char *file, uid_t owner, gid_t group)
{
  return INLINE_SYSCALL (chown, 3, CHECK_STRING (file), owner, group);
}
#elif SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1)
/* Compiling for compatibiity.  */
int
__chown_is_lchown (const char *file, uid_t owner, gid_t group)
{
  return __lchown (file, owner, group);
}
#endif

#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1)
strong_alias (__chown_is_lchown, _chown_is_lchown)
compat_symbol (libc, __chown_is_lchown, __chown, GLIBC_2_0);
compat_symbol (libc, _chown_is_lchown, chown, GLIBC_2_0);
#endif

#ifdef __NR_lchown
strong_alias (__real_chown, _real_chown)
versioned_symbol (libc, __real_chown, __chown, GLIBC_2_1);
versioned_symbol (libc, _real_chown, chown, GLIBC_2_1);
#else
strong_alias (__chown_is_lchown, __chown_is_lchown21)
strong_alias (__chown_is_lchown, _chown_is_lchown21)
versioned_symbol (libc, __chown_is_lchown21, __chown, GLIBC_2_1);
versioned_symbol (libc, _chown_is_lchown21, chown, GLIBC_2_1);
#endif