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/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <errno.h>
#include <stdint.h>
#include <sys/mman.h>
#include <unistd.h>
#include "private/bionic_macros.h"
#include "private/ErrnoRestorer.h"
// mmap2(2) is like mmap(2), but the offset is in 4096-byte blocks, not bytes.
extern "C" void* __mmap2(void*, size_t, int, int, int, size_t);
#define MMAP2_SHIFT 12 // 2**12 == 4096
static bool kernel_has_MADV_MERGEABLE = true;
void* mmap64(void* addr, size_t size, int prot, int flags, int fd, off64_t offset) {
if (offset < 0 || (offset & ((1UL << MMAP2_SHIFT)-1)) != 0) {
errno = EINVAL;
return MAP_FAILED;
}
// prevent allocations large enough for `end - start` to overflow
size_t rounded = __BIONIC_ALIGN(size, PAGE_SIZE);
if (rounded < size || rounded > PTRDIFF_MAX) {
errno = ENOMEM;
return MAP_FAILED;
}
bool is_private_anonymous =
(flags & (MAP_PRIVATE | MAP_ANONYMOUS)) == (MAP_PRIVATE | MAP_ANONYMOUS);
bool is_stack_or_grows_down = (flags & (MAP_STACK | MAP_GROWSDOWN)) != 0;
void* result = __mmap2(addr, size, prot, flags, fd, offset >> MMAP2_SHIFT);
if (result != MAP_FAILED && kernel_has_MADV_MERGEABLE &&
is_private_anonymous && !is_stack_or_grows_down) {
ErrnoRestorer errno_restorer;
int rc = madvise(result, size, MADV_MERGEABLE);
if (rc == -1 && errno == EINVAL) {
kernel_has_MADV_MERGEABLE = false;
}
}
return result;
}
void* mmap(void* addr, size_t size, int prot, int flags, int fd, off_t offset) {
return mmap64(addr, size, prot, flags, fd, static_cast<off64_t>(offset));
}
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