uclibc-ng/libc/sysdeps/linux/common/mmap64.c

/*
 * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
 *
 * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
 */
/* Massivly hacked up for uClibc by Erik Andersen */

#include <_lfs_64.h>
#include <stdint.h>
#include <sys/syscall.h>
#include <errno.h>
#include <sys/mman.h>

#ifndef __NR_mmap2

/*
 * This version is a stub that just chops off everything at the mmap 32 bit
 * mmap() address space...  You will probably need to add in an arch specific
 * implementation to override this as there is not a generic way for me to
 * implement this particular syscall if your arch lacks _syscall6...
 *
 */

void *mmap64(void *addr, size_t len, int prot, int flags, int fd, __off64_t offset)
{
	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);
}

#else
# include <bits/uClibc_page.h>

/* Some architectures always use 12 as page shift for mmap2() even though the
 * real PAGE_SHIFT != 12.  Other architectures use the same value as
 * PAGE_SHIFT...
 */
# ifndef MMAP2_PAGE_SHIFT
#  define MMAP2_PAGE_SHIFT 12
# endif

void *mmap64(void *addr, size_t len, int prot, int flags, int fd, __off64_t offset)
{
	/*
	 * Some arches check the size in INLINE_SYSCALL() and barf if it's
	 * too big (i.e. a 64bit value getting truncated to 32bit).
	 */
# if __WORDSIZE == 32
	uint32_t sysoff;
# else
	uint64_t sysoff;
# endif

	if (offset & ((1 << MMAP2_PAGE_SHIFT) - 1)) {
		__set_errno(EINVAL);
		return MAP_FAILED;
	}

	/*
	 * We know __off64_t is always a signed 64-bit type, but need things
	 * to be unsigned before doing the shift.  If it isn't, we might
	 * sign extend things and pass in the wrong value.  So cast it to
	 * an unsigned 64-bit value before doing the shift.
	 */
	sysoff = (uint64_t)offset >> MMAP2_PAGE_SHIFT;

	return (void*) INLINE_SYSCALL(mmap2, 6, addr, len, prot, flags, fd, sysoff);
}

#endif