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bc72d9813e
This patch adds two things: 1. An optional fixed_address argument to SharedMemoryBasic::Map, which is the address to map the shared memory at. 2. A FindFreeAddressSpace function that callers can use to find a contiguous block of free address space, which can then be used to determine an address to pass in to Map that is likely to be free. Patches in bug 1474793 will use these to place the User Agent style sheets in a shared memory buffer in the parent process at an address that is also likely to be free in content processes. Differential Revision: https://phabricator.services.mozilla.com/D15057 --HG-- extra : moz-landing-system : lando
93 lines
2.5 KiB
C++
93 lines
2.5 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* 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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#ifndef mozilla_ipc_SharedMemoryBasic_chromium_h
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#define mozilla_ipc_SharedMemoryBasic_chromium_h
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#include "base/shared_memory.h"
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#include "SharedMemory.h"
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#ifdef FUZZING
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# include "SharedMemoryFuzzer.h"
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#endif
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#include "nsDebug.h"
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//
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// This is a low-level wrapper around platform shared memory. Don't
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// use it directly; use Shmem allocated through IPDL interfaces.
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//
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namespace mozilla {
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namespace ipc {
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class SharedMemoryBasic final
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: public SharedMemoryCommon<base::SharedMemoryHandle> {
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public:
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SharedMemoryBasic() {}
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virtual bool SetHandle(const Handle& aHandle, OpenRights aRights) override {
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return mSharedMemory.SetHandle(aHandle, aRights == RightsReadOnly);
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}
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virtual bool Create(size_t aNbytes) override {
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bool ok = mSharedMemory.Create(aNbytes);
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if (ok) {
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Created(aNbytes);
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}
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return ok;
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}
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virtual bool Map(size_t nBytes, void* fixed_address = nullptr) override {
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bool ok = mSharedMemory.Map(nBytes, fixed_address);
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if (ok) {
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Mapped(nBytes);
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}
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return ok;
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}
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virtual void CloseHandle() override { mSharedMemory.Close(false); }
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virtual void* memory() const override {
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#ifdef FUZZING
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return SharedMemoryFuzzer::MutateSharedMemory(mSharedMemory.memory(),
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mAllocSize);
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#else
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return mSharedMemory.memory();
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#endif
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}
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virtual SharedMemoryType Type() const override { return TYPE_BASIC; }
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static Handle NULLHandle() { return base::SharedMemory::NULLHandle(); }
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virtual bool IsHandleValid(const Handle& aHandle) const override {
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return base::SharedMemory::IsHandleValid(aHandle);
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}
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virtual bool ShareToProcess(base::ProcessId aProcessId,
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Handle* new_handle) override {
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base::SharedMemoryHandle handle;
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bool ret = mSharedMemory.ShareToProcess(aProcessId, &handle);
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if (ret) *new_handle = handle;
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return ret;
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}
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static void* FindFreeAddressSpace(size_t size) {
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return base::SharedMemory::FindFreeAddressSpace(size);
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}
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private:
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~SharedMemoryBasic() {}
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base::SharedMemory mSharedMemory;
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};
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} // namespace ipc
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} // namespace mozilla
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#endif // ifndef mozilla_ipc_SharedMemoryBasic_chromium_h
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