431166d995
We don't actually need to worry about sign extension if we reject negative values ourselves. Previously it was possible to come up with negative but aligned values that we would pass to the kernel; in the case of mmap (as opposed to mmap64) we'd incorrectly turn those into large positive offsets. Change-Id: I2aa583e0f892d59bb77429aea8730b72db32dcb0
57 lines
2.2 KiB
C++
57 lines
2.2 KiB
C++
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <errno.h>
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#include <sys/mman.h>
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#include <unistd.h>
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#include "private/ErrnoRestorer.h"
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// mmap2(2) is like mmap(2), but the offset is in 4096-byte blocks, not bytes.
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extern "C" void* __mmap2(void*, size_t, int, int, int, size_t);
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#define MMAP2_SHIFT 12 // 2**12 == 4096
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void* mmap64(void* addr, size_t size, int prot, int flags, int fd, off64_t offset) {
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if (offset < 0 || (offset & ((1UL << MMAP2_SHIFT)-1)) != 0) {
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errno = EINVAL;
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return MAP_FAILED;
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}
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void* result = __mmap2(addr, size, prot, flags, fd, offset >> MMAP2_SHIFT);
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if (result != MAP_FAILED && (flags & (MAP_PRIVATE | MAP_ANONYMOUS)) != 0) {
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ErrnoRestorer errno_restorer;
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madvise(result, size, MADV_MERGEABLE);
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}
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return result;
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}
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void* mmap(void* addr, size_t size, int prot, int flags, int fd, off_t offset) {
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return mmap64(addr, size, prot, flags, fd, static_cast<off64_t>(offset));
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}
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