Source code
Revision control
Copy as Markdown
Other Tools
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#include "mozilla/ipc/SharedMemory.h"
#include "mozilla/Atomics.h"
#include "nsIMemoryReporter.h"
#ifdef FUZZING
# include "mozilla/ipc/SharedMemoryFuzzer.h"
#endif
namespace mozilla::ipc {
static Atomic<size_t> gShmemAllocated;
static Atomic<size_t> gShmemMapped;
class ShmemReporter final : public nsIMemoryReporter {
~ShmemReporter() = default;
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_IMETHOD
CollectReports(nsIHandleReportCallback* aHandleReport, nsISupports* aData,
bool aAnonymize) override {
MOZ_COLLECT_REPORT(
"shmem-allocated", KIND_OTHER, UNITS_BYTES, gShmemAllocated,
"Memory shared with other processes that is accessible (but not "
"necessarily mapped).");
MOZ_COLLECT_REPORT(
"shmem-mapped", KIND_OTHER, UNITS_BYTES, gShmemMapped,
"Memory shared with other processes that is mapped into the address "
"space.");
return NS_OK;
}
};
NS_IMPL_ISUPPORTS(ShmemReporter, nsIMemoryReporter)
SharedMemory::SharedMemory() : mAllocSize(0), mMappedSize(0) {
static Atomic<bool> registered;
if (registered.compareExchange(false, true)) {
RegisterStrongMemoryReporter(new ShmemReporter());
}
}
SharedMemory::~SharedMemory() {
Unmap();
CloseHandle();
MOZ_ASSERT(gShmemAllocated >= mAllocSize,
"Can't destroy more than allocated");
gShmemAllocated -= mAllocSize;
mAllocSize = 0;
}
bool SharedMemory::WriteHandle(IPC::MessageWriter* aWriter) {
Handle handle = CloneHandle();
if (!handle) {
return false;
}
IPC::WriteParam(aWriter, std::move(handle));
return true;
}
bool SharedMemory::ReadHandle(IPC::MessageReader* aReader) {
Handle handle;
return IPC::ReadParam(aReader, &handle) && IsHandleValid(handle) &&
SetHandle(std::move(handle), RightsReadWrite);
}
void SharedMemory::Protect(char* aAddr, size_t aSize, int aRights) {
char* memStart = reinterpret_cast<char*>(Memory());
if (!memStart) MOZ_CRASH("SharedMemory region points at NULL!");
char* memEnd = memStart + Size();
char* protStart = aAddr;
if (!protStart) MOZ_CRASH("trying to Protect() a NULL region!");
char* protEnd = protStart + aSize;
if (!(memStart <= protStart && protEnd <= memEnd)) {
MOZ_CRASH("attempt to Protect() a region outside this SharedMemory");
}
// checks alignment etc.
SystemProtect(aAddr, aSize, aRights);
}
size_t SharedMemory::PageAlignedSize(size_t aSize) {
size_t pageSize = SystemPageSize();
size_t nPagesNeeded = size_t(ceil(double(aSize) / double(pageSize)));
return pageSize * nPagesNeeded;
}
bool SharedMemory::Create(size_t aNBytes) {
bool ok = CreateImpl(aNBytes);
if (ok) {
mAllocSize = aNBytes;
gShmemAllocated += mAllocSize;
}
return ok;
}
bool SharedMemory::Map(size_t aNBytes, void* fixedAddress) {
bool ok = MapImpl(aNBytes, fixedAddress);
if (ok) {
mMappedSize = aNBytes;
gShmemMapped += mMappedSize;
}
return ok;
}
void SharedMemory::Unmap() {
MOZ_ASSERT(gShmemMapped >= mMappedSize, "Can't unmap more than mapped");
UnmapImpl(mMappedSize);
gShmemMapped -= mMappedSize;
mMappedSize = 0;
}
void* SharedMemory::Memory() const {
#ifdef FUZZING
return SharedMemoryFuzzer::MutateSharedMemory(MemoryImpl(), mAllocSize);
#else
return MemoryImpl();
#endif
}
} // namespace mozilla::ipc