mirror of
https://github.com/mozilla/gecko-dev.git
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b77d0f1d19
Since essentially everything is linked to libmozglue and libmozglue takes precedence in symbol resolution in our dynamic linker, there is no need to wrap most symbols. PR_GetEnv/PR_SetEnv still needs wrapping because there's no other way to actually wrap the calls from NSPR itself and NSS, as well as the symbols wrapped because our dynamic linker can't find them in system libraries on some devices because they're weak.
134 lines
2.5 KiB
C++
134 lines
2.5 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/NullPtr.h"
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#include "mozilla/mozalloc.h"
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#include <fcntl.h>
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#include <linux/ashmem.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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#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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: mBuf(nullptr)
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, mSize(0)
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, mLockCount(0)
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, mFd(-1)
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{
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}
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bool
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VolatileBuffer::Init(size_t aSize, size_t aAlignment)
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{
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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 = open("/" ASHMEM_NAME_DEF, O_RDWR);
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if (mFd < 0) {
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goto heap_alloc;
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}
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if (ioctl(mFd, ASHMEM_SET_SIZE, mSize) < 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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{
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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
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VolatileBuffer::Lock(void** aBuf)
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{
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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
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VolatileBuffer::Unlock()
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{
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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
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VolatileBuffer::OnHeap() const
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{
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return mFd < 0;
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}
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size_t
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VolatileBuffer::HeapSizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
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{
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return OnHeap() ? aMallocSizeOf(mBuf) : 0;
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}
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size_t
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VolatileBuffer::NonHeapSizeOfExcludingThis() const
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{
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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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