mmap64.c

Glibc 2.3.2源代码(解压后有100多M)

/* Copyright (C) 1999,2000,01,02 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Jakub Jelinek <[e-mail]>, 1999.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; 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 <sys/mman.h>

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

#include "kernel-features.h"

#ifdef __NR_mmap2
/* We have the system call that takes page number instead of byte address.  */
extern void *__unbounded __syscall_mmap2 (void *__unbounded, size_t,
					  int, int, int, off_t);

/* This is always 12, even on architectures where PAGE_SHIFT != 12.  */
# ifndef MMAP2_PAGE_SHIFT
#  define MMAP2_PAGE_SHIFT 12
# endif

# ifndef __ASSUME_MMAP2_SYSCALL
static int have_no_mmap2;
# endif
#endif


void *
__mmap64 (void *addr, size_t len, int prot, int flags, int fd, off64_t offset)
{
#ifdef __NR_mmap2
  if (offset & ((1 << MMAP2_PAGE_SHIFT) - 1))
    {
      __set_errno (EINVAL);
      return MAP_FAILED;
    }
# ifndef __ASSUME_MMAP2_SYSCALL
  if (! have_no_mmap2)
# endif
    {
# ifndef __ASSUME_MMAP2_SYSCALL
      int saved_errno = errno;
# endif
      void *result;
      __ptrvalue (result) = (void *__unbounded)
	INLINE_SYSCALL (mmap2, 6, __ptrvalue (addr),
			len, prot, flags, fd,
			(off_t) (offset >> MMAP2_PAGE_SHIFT));
# if __BOUNDED_POINTERS__
      __ptrlow (result) = __ptrvalue (result);
      __ptrhigh (result) = __ptrvalue (result) + len;
# endif
# ifndef __ASSUME_MMAP2_SYSCALL
      if (result != MAP_FAILED || errno != ENOSYS)
# endif
	return result;

# ifndef __ASSUME_MMAP2_SYSCALL
      __set_errno (saved_errno);
      have_no_mmap2 = 1;
# endif
    }
#endif
#ifndef __ASSUME_MMAP2_SYSCALL
  if (offset != (off_t) offset || (offset + len) != (off_t) (offset + len))
    {
      __set_errno (EINVAL);
      return MAP_FAILED;
    }

  return __mmap (addr, len, prot, flags, fd, (off_t) offset);
#endif
}
weak_alias (__mmap64, mmap64)