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/* -*- 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
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "SharedStringMap.h"
#include "MemMapSnapshot.h"
#include "ScriptPreloader-inl.h"
#include "mozilla/BinarySearch.h"
#include "mozilla/Try.h"
#include "mozilla/ipc/FileDescriptor.h"
using namespace mozilla::loader;
namespace mozilla {
using namespace ipc;
namespace dom::ipc {
static constexpr uint32_t kSharedStringMapMagic = 0x9e3779b9;
static inline size_t GetAlignmentOffset(size_t aOffset, size_t aAlign) {
auto mod = aOffset % aAlign;
return mod ? aAlign - mod : 0;
}
SharedStringMap::SharedStringMap(const FileDescriptor& aMapFile,
size_t aMapSize) {
auto result = mMap.initWithHandle(aMapFile, aMapSize);
MOZ_RELEASE_ASSERT(result.isOk());
MOZ_RELEASE_ASSERT(GetHeader().mMagic == kSharedStringMapMagic);
// We return literal nsStrings and nsCStrings pointing to the mapped data,
// which means that we may still have references to the mapped data even
// after this instance is destroyed. That means that we need to keep the
// mapping alive until process shutdown, in order to be safe.
mMap.setPersistent();
}
SharedStringMap::SharedStringMap(SharedStringMapBuilder&& aBuilder) {
auto result = aBuilder.Finalize(mMap);
MOZ_RELEASE_ASSERT(result.isOk());
MOZ_RELEASE_ASSERT(GetHeader().mMagic == kSharedStringMapMagic);
mMap.setPersistent();
}
mozilla::ipc::FileDescriptor SharedStringMap::CloneFileDescriptor() const {
return mMap.cloneHandle();
}
bool SharedStringMap::Has(const nsCString& aKey) {
size_t index;
return Find(aKey, &index);
}
bool SharedStringMap::Get(const nsCString& aKey, nsAString& aValue) {
const auto& entries = Entries();
size_t index;
if (!Find(aKey, &index)) {
return false;
}
aValue.Assign(ValueTable().Get(entries[index].mValue));
return true;
}
bool SharedStringMap::Find(const nsCString& aKey, size_t* aIndex) {
const auto& keys = KeyTable();
return BinarySearchIf(
Entries(), 0, EntryCount(),
[&](const Entry& aEntry) { return Compare(aKey, keys.Get(aEntry.mKey)); },
aIndex);
}
void SharedStringMapBuilder::Add(const nsCString& aKey,
const nsString& aValue) {
mEntries.InsertOrUpdate(aKey,
Entry{mKeyTable.Add(aKey), mValueTable.Add(aValue)});
}
Result<Ok, nsresult> SharedStringMapBuilder::Finalize(
loader::AutoMemMap& aMap) {
using Header = SharedStringMap::Header;
MOZ_ASSERT(mEntries.Count() == mKeyTable.Count());
auto keys = ToTArray<nsTArray<nsCString>>(mEntries.Keys());
keys.Sort();
Header header = {kSharedStringMapMagic, uint32_t(keys.Length())};
size_t offset = sizeof(header);
offset += GetAlignmentOffset(offset, alignof(Header));
offset += keys.Length() * sizeof(SharedStringMap::Entry);
header.mKeyStringsOffset = offset;
header.mKeyStringsSize = mKeyTable.Size();
offset += header.mKeyStringsSize;
offset +=
GetAlignmentOffset(offset, alignof(decltype(mValueTable)::ElemType));
header.mValueStringsOffset = offset;
header.mValueStringsSize = mValueTable.Size();
offset += header.mValueStringsSize;
MemMapSnapshot mem;
MOZ_TRY(mem.Init(offset));
auto headerPtr = mem.Get<Header>();
headerPtr[0] = header;
auto* entry = reinterpret_cast<Entry*>(&headerPtr[1]);
for (auto& key : keys) {
*entry++ = mEntries.Get(key);
}
auto ptr = mem.Get<uint8_t>();
mKeyTable.Write({&ptr[header.mKeyStringsOffset], header.mKeyStringsSize});
mValueTable.Write(
{&ptr[header.mValueStringsOffset], header.mValueStringsSize});
mKeyTable.Clear();
mValueTable.Clear();
mEntries.Clear();
return mem.Finalize(aMap);
}
} // namespace dom::ipc
} // namespace mozilla
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