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0ef38c0b9c
Apps targeting SDK 29 are not allowed to open /dev/ashmem directly, and instead must use NDK functions. Those functions are only available in SDK 26 and higher, so we need this shim to use the functions if they are available, else fallback to opening /dev/ashmem directly. Differential Revision: https://phabricator.services.mozilla.com/D61012 --HG-- extra : moz-landing-system : lando
121 lines
2.6 KiB
C++
121 lines
2.6 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "VolatileBuffer.h"
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#include "mozilla/Assertions.h"
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#include "mozilla/mozalloc.h"
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#include <fcntl.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include "mozilla/Ashmem.h"
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#ifdef MOZ_MEMORY
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extern "C" int posix_memalign(void** memptr, size_t alignment, size_t size);
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#endif
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#define MIN_VOLATILE_ALLOC_SIZE 8192
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namespace mozilla {
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VolatileBuffer::VolatileBuffer()
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: mMutex("VolatileBuffer"),
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mBuf(nullptr),
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mSize(0),
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mLockCount(0),
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mFd(-1) {}
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bool VolatileBuffer::Init(size_t aSize, size_t aAlignment) {
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MOZ_ASSERT(!mSize && !mBuf, "Init called twice");
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MOZ_ASSERT(!(aAlignment % sizeof(void*)),
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"Alignment must be multiple of pointer size");
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mSize = aSize;
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if (aSize < MIN_VOLATILE_ALLOC_SIZE) {
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goto heap_alloc;
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}
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mFd = mozilla::android::ashmem_create(nullptr, mSize);
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if (mFd < 0) {
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goto heap_alloc;
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}
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mBuf = mmap(nullptr, mSize, PROT_READ | PROT_WRITE, MAP_SHARED, mFd, 0);
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if (mBuf != MAP_FAILED) {
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return true;
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}
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heap_alloc:
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mBuf = nullptr;
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if (mFd >= 0) {
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close(mFd);
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mFd = -1;
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}
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#ifdef MOZ_MEMORY
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posix_memalign(&mBuf, aAlignment, aSize);
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#else
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mBuf = memalign(aAlignment, aSize);
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#endif
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return !!mBuf;
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}
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VolatileBuffer::~VolatileBuffer() {
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MOZ_ASSERT(mLockCount == 0, "Being destroyed with non-zero lock count?");
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if (OnHeap()) {
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free(mBuf);
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} else {
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munmap(mBuf, mSize);
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close(mFd);
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}
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}
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bool VolatileBuffer::Lock(void** aBuf) {
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MutexAutoLock lock(mMutex);
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MOZ_ASSERT(mBuf, "Attempting to lock an uninitialized VolatileBuffer");
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*aBuf = mBuf;
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if (++mLockCount > 1 || OnHeap()) {
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return true;
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}
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// Zero offset and zero length means we want to pin/unpin the entire thing.
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struct ashmem_pin pin = {0, 0};
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return ioctl(mFd, ASHMEM_PIN, &pin) == ASHMEM_NOT_PURGED;
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}
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void VolatileBuffer::Unlock() {
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MutexAutoLock lock(mMutex);
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MOZ_ASSERT(mLockCount > 0, "VolatileBuffer unlocked too many times!");
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if (--mLockCount || OnHeap()) {
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return;
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}
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struct ashmem_pin pin = {0, 0};
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ioctl(mFd, ASHMEM_UNPIN, &pin);
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}
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bool VolatileBuffer::OnHeap() const { return mFd < 0; }
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size_t VolatileBuffer::HeapSizeOfExcludingThis(
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MallocSizeOf aMallocSizeOf) const {
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return OnHeap() ? aMallocSizeOf(mBuf) : 0;
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}
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size_t VolatileBuffer::NonHeapSizeOfExcludingThis() const {
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if (OnHeap()) {
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return 0;
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}
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return (mSize + (PAGE_SIZE - 1)) & PAGE_MASK;
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}
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} // namespace mozilla
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