bug 775370 - (part 1/2) introduce DataStorage r=froydnj r=mmc

This commit is contained in:
David Keeler 2013-09-09 13:37:21 -07:00
parent 746732f06e
commit 20f55eaa2e
5 changed files with 1208 additions and 0 deletions

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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 "DataStorage.h"
#include "mozilla/Preferences.h"
#include "mozilla/Services.h"
#include "mozilla/unused.h"
#include "nsAppDirectoryServiceDefs.h"
#include "nsDirectoryServiceUtils.h"
#include "nsIObserverService.h"
#include "nsITimer.h"
#include "nsNetUtil.h"
#include "nsStreamUtils.h"
#include "nsThreadUtils.h"
#include "prprf.h"
// NB: Read DataStorage.h first.
// The default time between data changing and a write, in milliseconds.
static const uint32_t sDataStorageDefaultTimerDelay = 5u * 60u * 1000u;
// The maximum score an entry can have (prevents overflow)
static const uint32_t sMaxScore = UINT32_MAX;
// The maximum number of entries per type of data (limits resource use)
static const uint32_t sMaxDataEntries = 1024;
static const int64_t sOneDayInMicroseconds = int64_t(24 * 60 * 60) *
PR_USEC_PER_SEC;
namespace mozilla {
NS_IMPL_ISUPPORTS(DataStorage,
nsIObserver)
DataStorage::DataStorage(const nsString& aFilename)
: mMutex("DataStorage::mMutex")
, mPendingWrite(false)
, mShuttingDown(false)
, mReadyMonitor("DataStorage::mReadyMonitor")
, mReady(false)
, mFilename(aFilename)
{
}
DataStorage::~DataStorage()
{
}
nsresult
DataStorage::Init(bool& aDataWillPersist)
{
// Don't access the observer service or preferences off the main thread.
if (!NS_IsMainThread()) {
NS_NOTREACHED("DataStorage::Init called off main thread");
return NS_ERROR_NOT_SAME_THREAD;
}
MutexAutoLock lock(mMutex);
nsresult rv;
rv = NS_NewThread(getter_AddRefs(mWorkerThread));
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
rv = AsyncReadData(aDataWillPersist, lock);
if (NS_FAILED(rv)) {
return rv;
}
nsCOMPtr<nsIObserverService> os = services::GetObserverService();
if (NS_WARN_IF(!os)) {
return NS_ERROR_FAILURE;
}
// Clear private data as appropriate.
os->AddObserver(this, "last-pb-context-exited", false);
// Observe shutdown; save data and prevent any further writes.
os->AddObserver(this, "profile-before-change", false);
// For test purposes, we can set the write timer to be very fast.
mTimerDelay = Preferences::GetInt("test.datastorage.write_timer_ms",
sDataStorageDefaultTimerDelay);
rv = Preferences::AddStrongObserver(this, "test.datastorage.write_timer_ms");
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
return NS_OK;
}
class DataStorage::Reader : public nsRunnable
{
public:
explicit Reader(DataStorage* aDataStorage)
: mDataStorage(aDataStorage)
{
}
~Reader();
private:
NS_DECL_NSIRUNNABLE
static nsresult ParseLine(nsDependentCSubstring& aLine, nsCString& aKeyOut,
Entry& aEntryOut);
nsRefPtr<DataStorage> mDataStorage;
};
DataStorage::Reader::~Reader()
{
// Notify that calls to Get can proceed.
{
MonitorAutoLock readyLock(mDataStorage->mReadyMonitor);
mDataStorage->mReady = true;
nsresult rv = mDataStorage->mReadyMonitor.NotifyAll();
unused << NS_WARN_IF(NS_FAILED(rv));
}
// This is for tests.
nsCOMPtr<nsIRunnable> job =
NS_NewRunnableMethodWithArg<const char*>(mDataStorage,
&DataStorage::NotifyObservers,
"data-storage-ready");
nsresult rv = NS_DispatchToMainThread(job, NS_DISPATCH_NORMAL);
unused << NS_WARN_IF(NS_FAILED(rv));
}
NS_IMETHODIMP
DataStorage::Reader::Run()
{
nsresult rv;
// Concurrent operations on nsIFile objects are not guaranteed to be safe,
// so we clone the file while holding the lock and then release the lock.
// At that point, we can safely operate on the clone.
nsCOMPtr<nsIFile> file;
{
MutexAutoLock lock(mDataStorage->mMutex);
// If we don't have a profile, bail.
if (!mDataStorage->mBackingFile) {
return NS_OK;
}
rv = mDataStorage->mBackingFile->Clone(getter_AddRefs(file));
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
}
nsCOMPtr<nsIInputStream> fileInputStream;
rv = NS_NewLocalFileInputStream(getter_AddRefs(fileInputStream), file);
// If we failed for some reason other than the file doesn't exist, bail.
if (NS_WARN_IF(NS_FAILED(rv) &&
rv != NS_ERROR_FILE_TARGET_DOES_NOT_EXIST && // on Unix
rv != NS_ERROR_FILE_NOT_FOUND)) { // on Windows
return rv;
}
// If there is a file with data in it, read it. If there isn't,
// we'll essentially fall through to notifying that we're good to go.
nsCString data;
if (fileInputStream) {
// Limit to 2MB of data, but only store sMaxDataEntries entries.
rv = NS_ConsumeStream(fileInputStream, 1u << 21, data);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
}
// Atomically parse the data and insert the entries read.
// Don't clear existing entries - they may have been inserted between when
// this read was kicked-off and when it was run.
{
MutexAutoLock lock(mDataStorage->mMutex);
// The backing file consists of a list of
// <key>\t<score>\t<last accessed time>\t<value>\n
// The final \n is not optional; if it is not present the line is assumed
// to be corrupt.
int32_t currentIndex = 0;
int32_t newlineIndex = 0;
do {
newlineIndex = data.FindChar('\n', currentIndex);
// If there are no more newlines or the data table has too many
// entries, we are done.
if (newlineIndex < 0 ||
mDataStorage->mPersistentDataTable.Count() >= sMaxDataEntries) {
break;
}
nsDependentCSubstring line(data, currentIndex,
newlineIndex - currentIndex);
currentIndex = newlineIndex + 1;
nsCString key;
Entry entry;
nsresult parseRV = ParseLine(line, key, entry);
if (NS_SUCCEEDED(parseRV)) {
// It could be the case that a newer entry was added before
// we got around to reading the file. Don't overwrite new entries.
Entry newerEntry;
bool present = mDataStorage->mPersistentDataTable.Get(key, &newerEntry);
if (!present) {
mDataStorage->mPersistentDataTable.Put(key, entry);
}
}
} while (true);
}
return NS_OK;
}
// The key must be a non-empty string containing no instances of '\t' or '\n',
// and must have a length no more than 256.
// The value must not contain '\n' and must have a length no more than 1024.
// The length limits are to prevent unbounded memory and disk usage.
/* static */
nsresult
DataStorage::ValidateKeyAndValue(const nsCString& aKey, const nsCString& aValue)
{
if (aKey.IsEmpty()) {
return NS_ERROR_INVALID_ARG;
}
if (aKey.Length() > 256) {
return NS_ERROR_INVALID_ARG;
}
int32_t delimiterIndex = aKey.FindChar('\t', 0);
if (delimiterIndex >= 0) {
return NS_ERROR_INVALID_ARG;
}
delimiterIndex = aKey.FindChar('\n', 0);
if (delimiterIndex >= 0) {
return NS_ERROR_INVALID_ARG;
}
delimiterIndex = aValue.FindChar('\n', 0);
if (delimiterIndex >= 0) {
return NS_ERROR_INVALID_ARG;
}
if (aValue.Length() > 1024) {
return NS_ERROR_INVALID_ARG;
}
return NS_OK;
}
// Each line is: <key>\t<score>\t<last accessed time>\t<value>
// Where <score> is a uint32_t as a string, <last accessed time> is a
// int32_t as a string, and the rest are strings.
// <value> can contain anything but a newline.
// Returns a successful status if the line can be decoded into a key and entry.
// Otherwise, an error status is returned and the values assigned to the
// output parameters are in an undefined state.
/* static */
nsresult
DataStorage::Reader::ParseLine(nsDependentCSubstring& aLine, nsCString& aKeyOut,
Entry& aEntryOut)
{
// First find the indices to each part of the line.
int32_t scoreIndex;
scoreIndex = aLine.FindChar('\t', 0) + 1;
if (scoreIndex <= 0) {
return NS_ERROR_UNEXPECTED;
}
int32_t accessedIndex = aLine.FindChar('\t', scoreIndex) + 1;
if (accessedIndex <= 0) {
return NS_ERROR_UNEXPECTED;
}
int32_t valueIndex = aLine.FindChar('\t', accessedIndex) + 1;
if (valueIndex <= 0) {
return NS_ERROR_UNEXPECTED;
}
// Now make substrings based on where each part is.
nsDependentCSubstring keyPart(aLine, 0, scoreIndex - 1);
nsDependentCSubstring scorePart(aLine, scoreIndex,
accessedIndex - scoreIndex - 1);
nsDependentCSubstring accessedPart(aLine, accessedIndex,
valueIndex - accessedIndex - 1);
nsDependentCSubstring valuePart(aLine, valueIndex);
nsresult rv;
rv = DataStorage::ValidateKeyAndValue(nsCString(keyPart),
nsCString(valuePart));
if (NS_FAILED(rv)) {
return NS_ERROR_UNEXPECTED;
}
// Now attempt to decode the score part as a uint32_t.
// XXX nsDependentCSubstring doesn't support ToInteger
int32_t integer = nsCString(scorePart).ToInteger(&rv);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
if (integer < 0) {
return NS_ERROR_UNEXPECTED;
}
aEntryOut.mScore = (uint32_t)integer;
integer = nsCString(accessedPart).ToInteger(&rv);
if (NS_FAILED(rv)) {
return rv;
}
if (integer < 0) {
return NS_ERROR_UNEXPECTED;
}
aEntryOut.mLastAccessed = integer;
// Now set the key and value.
aKeyOut.Assign(keyPart);
aEntryOut.mValue.Assign(valuePart);
return NS_OK;
}
nsresult
DataStorage::AsyncReadData(bool& aHaveProfileDir,
const MutexAutoLock& /*aProofOfLock*/)
{
aHaveProfileDir = false;
// Allocate a Reader so that even if it isn't dispatched,
// the data-storage-ready notification will be fired and Get
// will be able to proceed (this happens in its destructor).
nsRefPtr<Reader> job(new Reader(this));
nsresult rv;
// If we don't have a profile directory, this will fail.
// That's okay - it just means there is no persistent state.
rv = NS_GetSpecialDirectory(NS_APP_USER_PROFILE_50_DIR,
getter_AddRefs(mBackingFile));
if (NS_FAILED(rv)) {
mBackingFile = nullptr;
return NS_OK;
}
rv = mBackingFile->Append(mFilename);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
rv = mWorkerThread->Dispatch(job, NS_DISPATCH_NORMAL);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
aHaveProfileDir = true;
return NS_OK;
}
void
DataStorage::WaitForReady()
{
MonitorAutoLock readyLock(mReadyMonitor);
while (!mReady) {
nsresult rv = readyLock.Wait();
if (NS_WARN_IF(NS_FAILED(rv))) {
break;
}
}
MOZ_ASSERT(mReady);
}
nsCString
DataStorage::Get(const nsCString& aKey, DataStorageType aType)
{
WaitForReady();
MutexAutoLock lock(mMutex);
Entry entry;
bool foundValue = GetInternal(aKey, &entry, aType, lock);
if (!foundValue) {
return EmptyCString();
}
// If we're here, we found a value. Maybe update its score.
if (entry.UpdateScore()) {
PutInternal(aKey, entry, aType, lock);
}
return entry.mValue;
}
bool
DataStorage::GetInternal(const nsCString& aKey, Entry* aEntry,
DataStorageType aType,
const MutexAutoLock& aProofOfLock)
{
DataStorageTable& table = GetTableForType(aType, aProofOfLock);
bool foundValue = table.Get(aKey, aEntry);
return foundValue;
}
DataStorage::DataStorageTable&
DataStorage::GetTableForType(DataStorageType aType,
const MutexAutoLock& /*aProofOfLock*/)
{
switch (aType) {
case DataStorage_Persistent:
return mPersistentDataTable;
case DataStorage_Temporary:
return mTemporaryDataTable;
case DataStorage_Private:
return mPrivateDataTable;
}
MOZ_CRASH("given bad DataStorage storage type");
}
// NB: The lock must be held when calling this function.
/* static */
PLDHashOperator
DataStorage::EvictCallback(const nsACString& aKey, Entry aEntry, void* aArg)
{
KeyAndEntry* toEvict = (KeyAndEntry*)aArg;
if (aEntry.mScore < toEvict->mEntry.mScore) {
toEvict->mKey = aKey;
toEvict->mEntry = aEntry;
}
return PLDHashOperator::PL_DHASH_NEXT;
}
// Limit the number of entries per table. This is to prevent unbounded
// resource use. The eviction strategy is as follows:
// - An entry's score is incremented once for every day it is accessed.
// - Evict an entry with score no more than any other entry in the table
// (this is the same as saying evict the entry with the lowest score,
// except for when there are multiple entries with the lowest score,
// in which case one of them is evicted - which one is not specified).
void
DataStorage::MaybeEvictOneEntry(DataStorageType aType,
const MutexAutoLock& aProofOfLock)
{
DataStorageTable& table = GetTableForType(aType, aProofOfLock);
if (table.Count() >= sMaxDataEntries) {
KeyAndEntry toEvict;
// If all entries have score sMaxScore, this won't actually remove
// anything. This will never happen, however, because having that high
// a score either means someone tampered with the backing file or every
// entry has been accessed once a day for ~4 billion days.
// The worst that will happen is there will be 1025 entries in the
// persistent data table, with the 1025th entry being replaced every time
// data with a new key is inserted into the table. This is bad but
// ultimately not that concerning, considering that if an attacker can
// modify data in the profile, they can cause much worse harm.
toEvict.mEntry.mScore = sMaxScore;
table.EnumerateRead(EvictCallback, (void*)&toEvict);
table.Remove(toEvict.mKey);
}
}
nsresult
DataStorage::Put(const nsCString& aKey, const nsCString& aValue,
DataStorageType aType)
{
WaitForReady();
MutexAutoLock lock(mMutex);
nsresult rv;
rv = ValidateKeyAndValue(aKey, aValue);
if (NS_FAILED(rv)) {
return rv;
}
Entry entry;
bool exists = GetInternal(aKey, &entry, aType, lock);
if (exists) {
entry.UpdateScore();
} else {
MaybeEvictOneEntry(aType, lock);
}
entry.mValue = aValue;
rv = PutInternal(aKey, entry, aType, lock);
if (NS_FAILED(rv)) {
return rv;
}
return NS_OK;
}
nsresult
DataStorage::PutInternal(const nsCString& aKey, Entry& aEntry,
DataStorageType aType,
const MutexAutoLock& aProofOfLock)
{
DataStorageTable& table = GetTableForType(aType, aProofOfLock);
table.Put(aKey, aEntry);
if (aType == DataStorage_Persistent && !mPendingWrite) {
return AsyncSetTimer(aProofOfLock);
}
return NS_OK;
}
void
DataStorage::Remove(const nsCString& aKey, DataStorageType aType)
{
WaitForReady();
MutexAutoLock lock(mMutex);
DataStorageTable& table = GetTableForType(aType, lock);
table.Remove(aKey);
if (aType == DataStorage_Persistent && !mPendingWrite) {
unused << AsyncSetTimer(lock);
}
}
class DataStorage::Writer : public nsRunnable
{
public:
Writer(nsCString& aData, DataStorage* aDataStorage)
: mData(aData)
, mDataStorage(aDataStorage)
{
}
private:
NS_DECL_NSIRUNNABLE
nsCString mData;
nsRefPtr<DataStorage> mDataStorage;
};
NS_IMETHODIMP
DataStorage::Writer::Run()
{
nsresult rv;
// Concurrent operations on nsIFile objects are not guaranteed to be safe,
// so we clone the file while holding the lock and then release the lock.
// At that point, we can safely operate on the clone.
nsCOMPtr<nsIFile> file;
{
MutexAutoLock lock(mDataStorage->mMutex);
// If we don't have a profile, bail.
if (!mDataStorage->mBackingFile) {
return NS_OK;
}
rv = mDataStorage->mBackingFile->Clone(getter_AddRefs(file));
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
}
nsCOMPtr<nsIOutputStream> outputStream;
rv = NS_NewLocalFileOutputStream(getter_AddRefs(outputStream), file,
PR_CREATE_FILE | PR_TRUNCATE | PR_WRONLY);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
const char* ptr = mData.get();
int32_t remaining = mData.Length();
uint32_t written = 0;
while (remaining > 0) {
rv = outputStream->Write(ptr, remaining, &written);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
remaining -= written;
ptr += written;
}
// Observed by tests.
nsCOMPtr<nsIRunnable> job =
NS_NewRunnableMethodWithArg<const char*>(mDataStorage,
&DataStorage::NotifyObservers,
"data-storage-written");
rv = NS_DispatchToMainThread(job, NS_DISPATCH_NORMAL);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
return NS_OK;
}
// NB: The lock must be held when calling this function.
/* static */
PLDHashOperator
DataStorage::WriteDataCallback(const nsACString& aKey, Entry aEntry, void* aArg)
{
nsCString* output = (nsCString*)aArg;
output->Append(aKey);
output->Append('\t');
output->AppendInt(aEntry.mScore);
output->Append('\t');
output->AppendInt(aEntry.mLastAccessed);
output->Append('\t');
output->Append(aEntry.mValue);
output->Append('\n');
return PLDHashOperator::PL_DHASH_NEXT;
}
nsresult
DataStorage::AsyncWriteData(const MutexAutoLock& /*aProofOfLock*/)
{
if (mShuttingDown || !mBackingFile) {
return NS_OK;
}
nsCString output;
mPersistentDataTable.EnumerateRead(WriteDataCallback, (void*)&output);
nsRefPtr<Writer> job(new Writer(output, this));
nsresult rv = mWorkerThread->Dispatch(job, NS_DISPATCH_NORMAL);
mPendingWrite = false;
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
return NS_OK;
}
nsresult
DataStorage::Clear()
{
WaitForReady();
MutexAutoLock lock(mMutex);
mPersistentDataTable.Clear();
mTemporaryDataTable.Clear();
mPrivateDataTable.Clear();
// Asynchronously clear the file. This is similar to the permission manager
// in that it doesn't wait to synchronously remove the data from its backing
// storage either.
nsresult rv = AsyncWriteData(lock);
if (NS_FAILED(rv)) {
return rv;
}
return NS_OK;
}
/* static */
void
DataStorage::TimerCallback(nsITimer* aTimer, void* aClosure)
{
nsRefPtr<DataStorage> aDataStorage = (DataStorage*)aClosure;
MutexAutoLock lock(aDataStorage->mMutex);
unused << aDataStorage->AsyncWriteData(lock);
}
// We only initialize the timer on the worker thread because it's not safe
// to mix what threads are operating on the timer.
nsresult
DataStorage::AsyncSetTimer(const MutexAutoLock& /*aProofOfLock*/)
{
if (mShuttingDown) {
return NS_OK;
}
mPendingWrite = true;
nsCOMPtr<nsIRunnable> job =
NS_NewRunnableMethod(this, &DataStorage::SetTimer);
nsresult rv = mWorkerThread->Dispatch(job, NS_DISPATCH_NORMAL);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
return NS_OK;
}
void
DataStorage::SetTimer()
{
MOZ_ASSERT(!NS_IsMainThread());
MutexAutoLock lock(mMutex);
nsresult rv;
if (!mTimer) {
mTimer = do_CreateInstance("@mozilla.org/timer;1", &rv);
if (NS_WARN_IF(NS_FAILED(rv))) {
return;
}
}
rv = mTimer->InitWithFuncCallback(TimerCallback, this,
mTimerDelay, nsITimer::TYPE_ONE_SHOT);
unused << NS_WARN_IF(NS_FAILED(rv));
}
void
DataStorage::NotifyObservers(const char* aTopic)
{
// Don't access the observer service off the main thread.
if (!NS_IsMainThread()) {
NS_NOTREACHED("DataStorage::NotifyObservers called off main thread");
return;
}
nsCOMPtr<nsIObserverService> os = services::GetObserverService();
if (os) {
os->NotifyObservers(nullptr, aTopic, mFilename.get());
}
}
nsresult
DataStorage::DispatchShutdownTimer(const MutexAutoLock& /*aProofOfLock*/)
{
nsCOMPtr<nsIRunnable> job =
NS_NewRunnableMethod(this, &DataStorage::ShutdownTimer);
nsresult rv = mWorkerThread->Dispatch(job, NS_DISPATCH_NORMAL);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
return NS_OK;
}
void
DataStorage::ShutdownTimer()
{
MOZ_ASSERT(!NS_IsMainThread());
MutexAutoLock lock(mMutex);
nsresult rv = mTimer->Cancel();
unused << NS_WARN_IF(NS_FAILED(rv));
mTimer = nullptr;
}
//------------------------------------------------------------
// DataStorage::nsIObserver
//------------------------------------------------------------
NS_IMETHODIMP
DataStorage::Observe(nsISupports* aSubject, const char* aTopic,
const char16_t* aData)
{
// Don't access preferences off the main thread.
if (!NS_IsMainThread()) {
NS_NOTREACHED("DataStorage::Observe called off main thread");
return NS_ERROR_NOT_SAME_THREAD;
}
nsresult rv;
if (strcmp(aTopic, "last-pb-context-exited") == 0) {
MutexAutoLock lock(mMutex);
mPrivateDataTable.Clear();
} else if (strcmp(aTopic, "profile-before-change") == 0) {
{
MutexAutoLock lock(mMutex);
rv = AsyncWriteData(lock);
mShuttingDown = true;
unused << NS_WARN_IF(NS_FAILED(rv));
if (mTimer) {
rv = DispatchShutdownTimer(lock);
unused << NS_WARN_IF(NS_FAILED(rv));
}
}
// Run the thread to completion and prevent any further events
// being scheduled to it. The thread may need the lock, so we can't
// hold it here.
rv = mWorkerThread->Shutdown();
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
} else if (strcmp(aTopic, NS_PREFBRANCH_PREFCHANGE_TOPIC_ID) == 0) {
MutexAutoLock lock(mMutex);
mTimerDelay = Preferences::GetInt("test.datastorage.write_timer_ms",
sDataStorageDefaultTimerDelay);
}
return NS_OK;
}
DataStorage::Entry::Entry()
: mScore(0)
, mLastAccessed((int32_t)(PR_Now() / sOneDayInMicroseconds))
{
}
// Updates this entry's score. Returns true if the score has actually changed.
// If it's been less than a day since this entry has been accessed, the score
// does not change. Otherwise, the score increases by 1.
// The default score is 0. The maximum score is the maximum value that can
// be represented by an unsigned 32 bit integer.
// This is to handle evictions from our tables, which in turn is to prevent
// unbounded resource use.
bool
DataStorage::Entry::UpdateScore()
{
int32_t nowInDays = (int32_t)(PR_Now() / sOneDayInMicroseconds);
int32_t daysSinceAccessed = (nowInDays - mLastAccessed);
// Update the last accessed time.
mLastAccessed = nowInDays;
// If it's been less than a day since we've been accessed,
// the score isn't updated.
if (daysSinceAccessed < 1) {
return false;
}
// Otherwise, increment the score (but don't overflow).
if (mScore < sMaxScore) {
mScore++;
}
return true;
}
} // namespace mozilla

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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/. */
#ifndef mozilla_DataStorage_h
#define mozilla_DataStorage_h
#include "mozilla/Monitor.h"
#include "mozilla/Mutex.h"
#include "nsCOMPtr.h"
#include "nsDataHashtable.h"
#include "nsIObserver.h"
#include "nsIThread.h"
#include "nsITimer.h"
#include "nsString.h"
namespace mozilla {
/**
* DataStorage is a threadsafe, generic, narrow string-based hash map that
* persists data on disk and additionally handles temporary and private data.
* However, if used in a context where there is no profile directory, data
* will not be persisted.
*
* Its lifecycle is as follows:
* - Allocate with a filename (this is or will eventually be a file in the
* profile directory, if the profile exists).
* - Call Init() from the main thread. This spins off an asynchronous read
* of the backing file.
* - Eventually observers of the topic "data-storage-ready" will be notified
* with the backing filename as the data in the notification when this
* has completed.
* - Should the profile directory not be available, (e.g. in xpcshell),
* DataStorage will not initially read any persistent data. The
* "data-storage-ready" event will still be emitted. This follows semantics
* similar to the permission manager and allows tests that test
* unrelated components to proceed without a profile.
* - When any persistent data changes, a timer is initialized that will
* eventually asynchronously write all persistent data to the backing file.
* When this happens, observers will be notified with the topic
* "data-storage-written" and the backing filename as the data.
* It is possible to receive a "data-storage-written" event while there exist
* pending persistent data changes. However, those changes will cause the
* timer to be reinitialized and another "data-storage-written" event will
* be sent.
* - When DataStorage observes the topic "profile-before-change" in
* anticipation of shutdown, all persistent data is synchronously written to
* the backing file. The worker thread responsible for these writes is then
* disabled to prevent further writes to that file (the delayed-write timer
* is cancelled when this happens).
* - For testing purposes, the preference "test.datastorage.write_timer_ms" can
* be set to cause the asynchronous writing of data to happen more quickly.
* - To prevent unbounded memory and disk use, the number of entries in each
* table is limited to 1024. Evictions are handled in by a modified LRU scheme
* (see implementation comments).
* - NB: Instances of DataStorage have long lifetimes because they are strong
* observers of events and won't go away until the observer service does.
*
* For each key/value:
* - The key must be a non-empty string containing no instances of '\t' or '\n'
* (this is a limitation of how the data is stored and will be addressed in
* the future).
* - The key must have a length no more than 256.
* - The value must not contain '\n' and must have a length no more than 1024.
* (the length limits are to prevent unbounded disk and memory usage)
*/
/**
* Data that is DataStorage_Persistent is saved on disk. DataStorage_Temporary
* and DataStorage_Private are not saved. DataStorage_Private is meant to
* only be set and accessed from private contexts. It will be cleared upon
* observing the event "last-pb-context-exited".
*/
enum DataStorageType {
DataStorage_Persistent,
DataStorage_Temporary,
DataStorage_Private
};
class DataStorage : public nsIObserver
{
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIOBSERVER
// If there is a profile directory, there is or will eventually be a file
// by the name specified by aFilename there.
explicit DataStorage(const nsString& aFilename);
// Initializes the DataStorage. Must be called before using.
// aDataWillPersist returns whether or not data can be persistently saved.
nsresult Init(/*out*/bool& aDataWillPersist);
// Given a key and a type of data, returns a value. Returns an empty string if
// the key is not present for that type of data. If Get is called before the
// "data-storage-ready" event is observed, it will block. NB: It is not
// currently possible to differentiate between missing data and data that is
// the empty string.
nsCString Get(const nsCString& aKey, DataStorageType aType);
// Give a key, value, and type of data, adds an entry as appropriate.
// Updates existing entries.
nsresult Put(const nsCString& aKey, const nsCString& aValue,
DataStorageType aType);
// Given a key and type of data, removes an entry if present.
void Remove(const nsCString& aKey, DataStorageType aType);
// Removes all entries of all types of data.
nsresult Clear();
private:
virtual ~DataStorage();
class Writer;
class Reader;
class Entry
{
public:
Entry();
bool UpdateScore();
uint32_t mScore;
int32_t mLastAccessed; // the last accessed time in days since the epoch
nsCString mValue;
};
// Utility class for scanning tables for an entry to evict.
class KeyAndEntry
{
public:
nsCString mKey;
Entry mEntry;
};
typedef nsDataHashtable<nsCStringHashKey, Entry> DataStorageTable;
void WaitForReady();
nsresult AsyncWriteData(const MutexAutoLock& aProofOfLock);
nsresult AsyncReadData(bool& aHaveProfileDir,
const MutexAutoLock& aProofOfLock);
nsresult AsyncSetTimer(const MutexAutoLock& aProofOfLock);
nsresult DispatchShutdownTimer(const MutexAutoLock& aProofOfLock);
static nsresult ValidateKeyAndValue(const nsCString& aKey,
const nsCString& aValue);
static void TimerCallback(nsITimer* aTimer, void* aClosure);
static PLDHashOperator WriteDataCallback(const nsACString& aKey, Entry aEntry,
void* aArg);
static PLDHashOperator EvictCallback(const nsACString& aKey, Entry aEntry,
void* aArg);
void SetTimer();
void ShutdownTimer();
void NotifyObservers(const char* aTopic);
bool GetInternal(const nsCString& aKey, Entry* aEntry, DataStorageType aType,
const MutexAutoLock& aProofOfLock);
nsresult PutInternal(const nsCString& aKey, Entry& aEntry,
DataStorageType aType,
const MutexAutoLock& aProofOfLock);
void MaybeEvictOneEntry(DataStorageType aType,
const MutexAutoLock& aProofOfLock);
DataStorageTable& GetTableForType(DataStorageType aType,
const MutexAutoLock& aProofOfLock);
Mutex mMutex; // This mutex protects access to the following members:
DataStorageTable mPersistentDataTable;
DataStorageTable mTemporaryDataTable;
DataStorageTable mPrivateDataTable;
nsCOMPtr<nsIThread> mWorkerThread;
nsCOMPtr<nsIFile> mBackingFile;
nsCOMPtr<nsITimer> mTimer; // All uses after init must be on the worker thread
uint32_t mTimerDelay; // in milliseconds
bool mPendingWrite; // true if a write is needed but hasn't been dispatched
bool mShuttingDown;
// (End list of members protected by mMutex)
Monitor mReadyMonitor; // Do not acquire this at the same time as mMutex.
bool mReady; // Indicates that saved data has been read and Get can proceed.
const nsString mFilename;
};
}; // namespace mozilla
#endif // mozilla_DataStorage_h

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@ -4,7 +4,12 @@
# 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/.
EXPORTS.mozilla += [
'DataStorage.h',
]
UNIFIED_SOURCES += [
'DataStorage.cpp',
'nsBOOTModule.cpp',
'nsEntropyCollector.cpp',
'nsSecurityHeaderParser.cpp',

View File

@ -0,0 +1,224 @@
/* -*- 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 "gtest/gtest.h"
#include "mozilla/DataStorage.h"
#include "nsAppDirectoryServiceDefs.h"
#include "nsDirectoryServiceUtils.h"
#include "nsNetUtil.h"
#include "nsPrintfCString.h"
#include "nsStreamUtils.h"
using namespace mozilla;
class DataStorageTest : public ::testing::Test
{
protected:
virtual void SetUp()
{
const ::testing::TestInfo* const testInfo =
::testing::UnitTest::GetInstance()->current_test_info();
NS_ConvertUTF8toUTF16 testName(testInfo->name());
storage = new DataStorage(testName);
storage->Init(dataWillPersist);
}
nsRefPtr<DataStorage> storage;
bool dataWillPersist;
};
NS_NAMED_LITERAL_CSTRING(testKey, "test");
NS_NAMED_LITERAL_CSTRING(testValue, "value");
NS_NAMED_LITERAL_CSTRING(privateTestValue, "private");
TEST_F(DataStorageTest, GetPutRemove)
{
EXPECT_TRUE(dataWillPersist);
// Test Put/Get on Persistent data
EXPECT_EQ(NS_OK, storage->Put(testKey, testValue, DataStorage_Persistent));
// Don't re-use testKey / testValue here, to make sure that this works as
// expected with objects that have the same semantic value but are not
// literally the same object.
nsCString result = storage->Get(NS_LITERAL_CSTRING("test"),
DataStorage_Persistent);
EXPECT_STREQ("value", result.get());
// Get on Temporary/Private data with the same key should give nothing
result = storage->Get(testKey, DataStorage_Temporary);
EXPECT_TRUE(result.IsEmpty());
result = storage->Get(testKey, DataStorage_Private);
EXPECT_TRUE(result.IsEmpty());
// Put with Temporary/Private data shouldn't affect Persistent data
NS_NAMED_LITERAL_CSTRING(temporaryTestValue, "temporary");
EXPECT_EQ(NS_OK, storage->Put(testKey, temporaryTestValue,
DataStorage_Temporary));
EXPECT_EQ(NS_OK, storage->Put(testKey, privateTestValue,
DataStorage_Private));
result = storage->Get(testKey, DataStorage_Temporary);
EXPECT_STREQ("temporary", result.get());
result = storage->Get(testKey, DataStorage_Private);
EXPECT_STREQ("private", result.get());
result = storage->Get(testKey, DataStorage_Persistent);
EXPECT_STREQ("value", result.get());
// Put of a previously-present key overwrites it (if of the same type)
NS_NAMED_LITERAL_CSTRING(newValue, "new");
EXPECT_EQ(NS_OK, storage->Put(testKey, newValue, DataStorage_Persistent));
result = storage->Get(testKey, DataStorage_Persistent);
EXPECT_STREQ("new", result.get());
// Removal should work
storage->Remove(testKey, DataStorage_Temporary);
result = storage->Get(testKey, DataStorage_Temporary);
EXPECT_TRUE(result.IsEmpty());
// But removing one type shouldn't affect the others
result = storage->Get(testKey, DataStorage_Private);
EXPECT_STREQ("private", result.get());
result = storage->Get(testKey, DataStorage_Persistent);
EXPECT_STREQ("new", result.get());
// Test removing the other types as well
storage->Remove(testKey, DataStorage_Private);
result = storage->Get(testKey, DataStorage_Private);
EXPECT_TRUE(result.IsEmpty());
storage->Remove(testKey, DataStorage_Persistent);
result = storage->Get(testKey, DataStorage_Persistent);
EXPECT_TRUE(result.IsEmpty());
}
TEST_F(DataStorageTest, InputValidation)
{
EXPECT_TRUE(dataWillPersist);
// Keys may not have tabs or newlines
EXPECT_EQ(NS_ERROR_INVALID_ARG,
storage->Put(NS_LITERAL_CSTRING("key\thas tab"), testValue,
DataStorage_Persistent));
nsCString result = storage->Get(NS_LITERAL_CSTRING("key\thas tab"),
DataStorage_Persistent);
EXPECT_TRUE(result.IsEmpty());
EXPECT_EQ(NS_ERROR_INVALID_ARG,
storage->Put(NS_LITERAL_CSTRING("key has\nnewline"), testValue,
DataStorage_Persistent));
result = storage->Get(NS_LITERAL_CSTRING("keyhas\nnewline"),
DataStorage_Persistent);
EXPECT_TRUE(result.IsEmpty());
// Values may not have newlines
EXPECT_EQ(NS_ERROR_INVALID_ARG,
storage->Put(testKey, NS_LITERAL_CSTRING("value\nhas newline"),
DataStorage_Persistent));
result = storage->Get(testKey, DataStorage_Persistent);
// Values may have tabs
EXPECT_TRUE(result.IsEmpty());
EXPECT_EQ(NS_OK, storage->Put(testKey,
NS_LITERAL_CSTRING("val\thas tab; this is ok"),
DataStorage_Persistent));
result = storage->Get(testKey, DataStorage_Persistent);
EXPECT_STREQ("val\thas tab; this is ok", result.get());
nsCString longKey("a");
for (int i = 0; i < 8; i++) {
longKey.Append(longKey);
}
// A key of length 256 will work
EXPECT_EQ(NS_OK, storage->Put(longKey, testValue, DataStorage_Persistent));
result = storage->Get(longKey, DataStorage_Persistent);
EXPECT_STREQ("value", result.get());
longKey.Append("a");
// A key longer than that will not work
EXPECT_EQ(NS_ERROR_INVALID_ARG,
storage->Put(longKey, testValue, DataStorage_Persistent));
result = storage->Get(longKey, DataStorage_Persistent);
EXPECT_TRUE(result.IsEmpty());
nsCString longValue("a");
for (int i = 0; i < 10; i++) {
longValue.Append(longValue);
}
// A value of length 1024 will work
EXPECT_EQ(NS_OK, storage->Put(testKey, longValue, DataStorage_Persistent));
result = storage->Get(testKey, DataStorage_Persistent);
EXPECT_STREQ(longValue.get(), result.get());
longValue.Append("a");
// A value longer than that will not work
storage->Remove(testKey, DataStorage_Persistent);
EXPECT_EQ(NS_ERROR_INVALID_ARG,
storage->Put(testKey, longValue, DataStorage_Persistent));
result = storage->Get(testKey, DataStorage_Persistent);
EXPECT_TRUE(result.IsEmpty());
}
TEST_F(DataStorageTest, Eviction)
{
EXPECT_TRUE(dataWillPersist);
// Eviction is on a per-table basis. Tables shouldn't affect each other.
EXPECT_EQ(NS_OK, storage->Put(testKey, testValue, DataStorage_Persistent));
for (int i = 0; i < 1025; i++) {
EXPECT_EQ(NS_OK, storage->Put(nsPrintfCString("%d", i),
nsPrintfCString("%d", i),
DataStorage_Temporary));
nsCString result = storage->Get(nsPrintfCString("%d", i),
DataStorage_Temporary);
EXPECT_STREQ(nsPrintfCString("%d", i).get(), result.get());
}
// We don't know which entry got evicted, but we can count them.
int entries = 0;
for (int i = 0; i < 1025; i++) {
nsCString result = storage->Get(nsPrintfCString("%d", i),
DataStorage_Temporary);
if (!result.IsEmpty()) {
entries++;
}
}
EXPECT_EQ(entries, 1024);
nsCString result = storage->Get(testKey, DataStorage_Persistent);
EXPECT_STREQ("value", result.get());
}
TEST_F(DataStorageTest, ClearPrivateData)
{
EXPECT_TRUE(dataWillPersist);
EXPECT_EQ(NS_OK, storage->Put(testKey, privateTestValue,
DataStorage_Private));
nsCString result = storage->Get(testKey, DataStorage_Private);
EXPECT_STREQ("private", result.get());
storage->Observe(nullptr, "last-pb-context-exited", nullptr);
result = storage->Get(testKey, DataStorage_Private);
EXPECT_TRUE(result.IsEmpty());
}
TEST_F(DataStorageTest, Shutdown)
{
EXPECT_TRUE(dataWillPersist);
EXPECT_EQ(NS_OK, storage->Put(testKey, testValue, DataStorage_Persistent));
nsCString result = storage->Get(testKey, DataStorage_Persistent);
EXPECT_STREQ("value", result.get());
// Get "now" (in days) close to when the data was last touched, so we won't
// get intermittent failures with the day not matching.
int64_t microsecondsPerDay = 24 * 60 * 60 * int64_t(PR_USEC_PER_SEC);
int32_t nowInDays = int32_t(PR_Now() / microsecondsPerDay);
storage->Observe(nullptr, "profile-before-change", nullptr);
nsCOMPtr<nsIFile> backingFile;
EXPECT_EQ(NS_OK, NS_GetSpecialDirectory(NS_APP_USER_PROFILE_50_DIR,
getter_AddRefs(backingFile)));
const ::testing::TestInfo* const testInfo =
::testing::UnitTest::GetInstance()->current_test_info();
NS_ConvertUTF8toUTF16 testName(testInfo->name());
EXPECT_EQ(NS_OK, backingFile->Append(testName));
nsCOMPtr<nsIInputStream> fileInputStream;
EXPECT_EQ(NS_OK, NS_NewLocalFileInputStream(getter_AddRefs(fileInputStream),
backingFile));
nsCString data;
EXPECT_EQ(NS_OK, NS_ConsumeStream(fileInputStream, UINT32_MAX, data));
// The data will be of the form 'test\t0\t<days since the epoch>\tvalue'
EXPECT_STREQ(nsPrintfCString("test\t0\t%d\tvalue\n", nowInDays).get(),
data.get());
}

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@ -5,6 +5,7 @@
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
SOURCES += [
'DataStorageTest.cpp',
'OCSPCacheTest.cpp',
'TLSIntoleranceTest.cpp',
]