1 files changed, 707 insertions, 0 deletions

diff --git a/js/xpconnect/loader/URLPreloader.cpp b/js/xpconnect/loader/URLPreloader.cpp
new file mode 100644
index 0000000000..c5bcbad5bb
--- /dev/null
+++ b/js/xpconnect/loader/URLPreloader.cpp
@@ -0,0 +1,707 @@
+/* -*- 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 "ScriptPreloader-inl.h"
+#include "mozilla/URLPreloader.h"
+#include "mozilla/loader/AutoMemMap.h"
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/FileUtils.h"
+#include "mozilla/IOBuffers.h"
+#include "mozilla/Logging.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/Services.h"
+#include "mozilla/Unused.h"
+#include "mozilla/Vector.h"
+#include "mozilla/scache/StartupCache.h"
+
+#include "crc32c.h"
+#include "MainThreadUtils.h"
+#include "nsPrintfCString.h"
+#include "nsDebug.h"
+#include "nsIFile.h"
+#include "nsIFileURL.h"
+#include "nsNetUtil.h"
+#include "nsPromiseFlatString.h"
+#include "nsProxyRelease.h"
+#include "nsThreadUtils.h"
+#include "nsXULAppAPI.h"
+#include "nsZipArchive.h"
+#include "xpcpublic.h"
+
+namespace mozilla {
+namespace {
+static LazyLogModule gURLLog("URLPreloader");
+
+#define LOG(level, ...) MOZ_LOG(gURLLog, LogLevel::level, (__VA_ARGS__))
+
+template <typename T>
+bool StartsWith(const T& haystack, const T& needle) {
+  return StringHead(haystack, needle.Length()) == needle;
+}
+}  // anonymous namespace
+
+using namespace mozilla::loader;
+using mozilla::scache::StartupCache;
+
+nsresult URLPreloader::CollectReports(nsIHandleReportCallback* aHandleReport,
+                                      nsISupports* aData, bool aAnonymize) {
+  MOZ_COLLECT_REPORT("explicit/url-preloader/other", KIND_HEAP, UNITS_BYTES,
+                     ShallowSizeOfIncludingThis(MallocSizeOf),
+                     "Memory used by the URL preloader service itself.");
+
+  for (const auto& elem : mCachedURLs.Values()) {
+    nsAutoCString pathName;
+    pathName.Append(elem->mPath);
+    // The backslashes will automatically be replaced with slashes in
+    // about:memory, without splitting each path component into a separate
+    // branch in the memory report tree.
+    pathName.ReplaceChar('/', '\\');
+
+    nsPrintfCString path("explicit/url-preloader/cached-urls/%s/[%s]",
+                         elem->TypeString(), pathName.get());
+
+    aHandleReport->Callback(
+        ""_ns, path, KIND_HEAP, UNITS_BYTES,
+        elem->SizeOfIncludingThis(MallocSizeOf),
+        nsLiteralCString("Memory used to hold cache data for files which "
+                         "have been read or pre-loaded during this session."),
+        aData);
+  }
+
+  return NS_OK;
+}
+
+// static
+already_AddRefed<URLPreloader> URLPreloader::Create(bool* aInitialized) {
+  // The static APIs like URLPreloader::Read work in the child process because
+  // they fall back to a synchronous read. The actual preloader must be
+  // explicitly initialized, and this should only be done in the parent.
+  MOZ_RELEASE_ASSERT(XRE_IsParentProcess());
+
+  RefPtr<URLPreloader> preloader = new URLPreloader();
+  if (preloader->InitInternal().isOk()) {
+    *aInitialized = true;
+    RegisterWeakMemoryReporter(preloader);
+  } else {
+    *aInitialized = false;
+  }
+
+  return preloader.forget();
+}
+
+URLPreloader& URLPreloader::GetSingleton() {
+  if (!sSingleton) {
+    sSingleton = Create(&sInitialized);
+    ClearOnShutdown(&sSingleton);
+  }
+
+  return *sSingleton;
+}
+
+bool URLPreloader::sInitialized = false;
+
+StaticRefPtr<URLPreloader> URLPreloader::sSingleton;
+
+URLPreloader::~URLPreloader() {
+  if (sInitialized) {
+    UnregisterWeakMemoryReporter(this);
+    sInitialized = false;
+  }
+}
+
+Result<Ok, nsresult> URLPreloader::InitInternal() {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  if (Omnijar::HasOmnijar(Omnijar::GRE)) {
+    MOZ_TRY(Omnijar::GetURIString(Omnijar::GRE, mGREPrefix));
+  }
+  if (Omnijar::HasOmnijar(Omnijar::APP)) {
+    MOZ_TRY(Omnijar::GetURIString(Omnijar::APP, mAppPrefix));
+  }
+
+  nsresult rv;
+  nsCOMPtr<nsIIOService> ios = do_GetIOService(&rv);
+  MOZ_TRY(rv);
+
+  nsCOMPtr<nsIProtocolHandler> ph;
+  MOZ_TRY(ios->GetProtocolHandler("resource", getter_AddRefs(ph)));
+
+  mResProto = do_QueryInterface(ph, &rv);
+  MOZ_TRY(rv);
+
+  mChromeReg = services::GetChromeRegistry();
+  if (!mChromeReg) {
+    return Err(NS_ERROR_UNEXPECTED);
+  }
+
+  MOZ_TRY(NS_GetSpecialDirectory("ProfLDS", getter_AddRefs(mProfD)));
+
+  return Ok();
+}
+
+URLPreloader& URLPreloader::ReInitialize() {
+  MOZ_ASSERT(sSingleton);
+  sSingleton = nullptr;
+  sSingleton = Create(&sInitialized);
+  return *sSingleton;
+}
+
+Result<nsCOMPtr<nsIFile>, nsresult> URLPreloader::GetCacheFile(
+    const nsAString& suffix) {
+  if (!mProfD) {
+    return Err(NS_ERROR_NOT_INITIALIZED);
+  }
+
+  nsCOMPtr<nsIFile> cacheFile;
+  MOZ_TRY(mProfD->Clone(getter_AddRefs(cacheFile)));
+
+  MOZ_TRY(cacheFile->AppendNative("startupCache"_ns));
+  Unused << cacheFile->Create(nsIFile::DIRECTORY_TYPE, 0777);
+
+  MOZ_TRY(cacheFile->Append(u"urlCache"_ns + suffix));
+
+  return std::move(cacheFile);
+}
+
+static const uint8_t URL_MAGIC[] = "mozURLcachev003";
+
+Result<nsCOMPtr<nsIFile>, nsresult> URLPreloader::FindCacheFile() {
+  if (StartupCache::GetIgnoreDiskCache()) {
+    return Err(NS_ERROR_ABORT);
+  }
+
+  nsCOMPtr<nsIFile> cacheFile;
+  MOZ_TRY_VAR(cacheFile, GetCacheFile(u".bin"_ns));
+
+  bool exists;
+  MOZ_TRY(cacheFile->Exists(&exists));
+  if (exists) {
+    MOZ_TRY(cacheFile->MoveTo(nullptr, u"urlCache-current.bin"_ns));
+  } else {
+    MOZ_TRY(cacheFile->SetLeafName(u"urlCache-current.bin"_ns));
+    MOZ_TRY(cacheFile->Exists(&exists));
+    if (!exists) {
+      return Err(NS_ERROR_FILE_NOT_FOUND);
+    }
+  }
+
+  return std::move(cacheFile);
+}
+
+Result<Ok, nsresult> URLPreloader::WriteCache() {
+  MOZ_ASSERT(!NS_IsMainThread());
+  MOZ_DIAGNOSTIC_ASSERT(mStartupFinished);
+
+  // The script preloader might call us a second time, if it has to re-write
+  // its cache after a cache flush. We don't care about cache flushes, since
+  // our cache doesn't store any file data, only paths. And we currently clear
+  // our cached file list after the first write, which means that a second
+  // write would (aside from breaking the invariant that we never touch
+  // mCachedURLs off-main-thread after the first write, and trigger a data
+  // race) mean we get no pre-loading on the next startup.
+  if (mCacheWritten) {
+    return Ok();
+  }
+  mCacheWritten = true;
+
+  LOG(Debug, "Writing cache...");
+
+  nsCOMPtr<nsIFile> cacheFile;
+  MOZ_TRY_VAR(cacheFile, GetCacheFile(u"-new.bin"_ns));
+
+  bool exists;
+  MOZ_TRY(cacheFile->Exists(&exists));
+  if (exists) {
+    MOZ_TRY(cacheFile->Remove(false));
+  }
+
+  {
+    AutoFDClose fd;
+    MOZ_TRY(cacheFile->OpenNSPRFileDesc(PR_WRONLY | PR_CREATE_FILE, 0644,
+                                        &fd.rwget()));
+
+    nsTArray<URLEntry*> entries;
+    for (const auto& entry : mCachedURLs.Values()) {
+      if (entry->mReadTime) {
+        entries.AppendElement(entry.get());
+      }
+    }
+
+    entries.Sort(URLEntry::Comparator());
+
+    OutputBuffer buf;
+    for (auto entry : entries) {
+      entry->Code(buf);
+    }
+
+    uint8_t headerSize[4];
+    LittleEndian::writeUint32(headerSize, buf.cursor());
+
+    uint8_t crc[4];
+    LittleEndian::writeUint32(crc, ComputeCrc32c(~0, buf.Get(), buf.cursor()));
+
+    MOZ_TRY(Write(fd, URL_MAGIC, sizeof(URL_MAGIC)));
+    MOZ_TRY(Write(fd, headerSize, sizeof(headerSize)));
+    MOZ_TRY(Write(fd, crc, sizeof(crc)));
+    MOZ_TRY(Write(fd, buf.Get(), buf.cursor()));
+  }
+
+  MOZ_TRY(cacheFile->MoveTo(nullptr, u"urlCache.bin"_ns));
+
+  NS_DispatchToMainThread(
+      NewRunnableMethod("URLPreloader::Cleanup", this, &URLPreloader::Cleanup));
+
+  return Ok();
+}
+
+void URLPreloader::Cleanup() { mCachedURLs.Clear(); }
+
+Result<Ok, nsresult> URLPreloader::ReadCache(
+    LinkedList<URLEntry>& pendingURLs) {
+  LOG(Debug, "Reading cache...");
+
+  nsCOMPtr<nsIFile> cacheFile;
+  MOZ_TRY_VAR(cacheFile, FindCacheFile());
+
+  AutoMemMap cache;
+  MOZ_TRY(cache.init(cacheFile));
+
+  auto size = cache.size();
+
+  uint32_t headerSize;
+  uint32_t crc;
+  if (size < sizeof(URL_MAGIC) + sizeof(headerSize) + sizeof(crc)) {
+    return Err(NS_ERROR_UNEXPECTED);
+  }
+
+  auto data = cache.get<uint8_t>();
+  auto end = data + size;
+
+  if (memcmp(URL_MAGIC, data.get(), sizeof(URL_MAGIC))) {
+    return Err(NS_ERROR_UNEXPECTED);
+  }
+  data += sizeof(URL_MAGIC);
+
+  headerSize = LittleEndian::readUint32(data.get());
+  data += sizeof(headerSize);
+
+  crc = LittleEndian::readUint32(data.get());
+  data += sizeof(crc);
+
+  if (data + headerSize > end) {
+    return Err(NS_ERROR_UNEXPECTED);
+  }
+
+  if (crc != ComputeCrc32c(~0, data.get(), headerSize)) {
+    return Err(NS_ERROR_UNEXPECTED);
+  }
+
+  {
+    mMonitor.AssertCurrentThreadOwns();
+
+    auto cleanup = MakeScopeExit([&]() {
+      while (auto* elem = pendingURLs.getFirst()) {
+        elem->remove();
+      }
+      mCachedURLs.Clear();
+    });
+
+    Range<uint8_t> header(data, data + headerSize);
+    data += headerSize;
+
+    InputBuffer buf(header);
+    while (!buf.finished()) {
+      CacheKey key(buf);
+
+      LOG(Debug, "Cached file: %s %s", key.TypeString(), key.mPath.get());
+
+      // Don't bother doing anything else if the key didn't load correctly.
+      // We're going to throw it out right away, and it is possible that this
+      // leads to pendingURLs getting into a weird state.
+      if (buf.error()) {
+        return Err(NS_ERROR_UNEXPECTED);
+      }
+
+      auto entry = mCachedURLs.GetOrInsertNew(key, key);
+      entry->mResultCode = NS_ERROR_NOT_INITIALIZED;
+
+      if (entry->isInList()) {
+#ifdef NIGHTLY_BUILD
+        MOZ_DIAGNOSTIC_ASSERT(pendingURLs.contains(entry),
+                              "Entry should be in pendingURLs");
+        MOZ_DIAGNOSTIC_ASSERT(key.mPath.Length() > 0,
+                              "Path should be non-empty");
+        MOZ_DIAGNOSTIC_ASSERT(false, "Entry should be new and not in any list");
+#endif
+        return Err(NS_ERROR_UNEXPECTED);
+      }
+
+      pendingURLs.insertBack(entry);
+    }
+
+    MOZ_RELEASE_ASSERT(!buf.error(),
+                       "We should have already bailed on an error");
+
+    cleanup.release();
+  }
+
+  return Ok();
+}
+
+void URLPreloader::BackgroundReadFiles() {
+  auto cleanup = MakeScopeExit([&]() {
+    auto lock = mReaderThread.Lock();
+    auto& readerThread = lock.ref();
+    NS_DispatchToMainThread(NewRunnableMethod(
+        "nsIThread::AsyncShutdown", readerThread, &nsIThread::AsyncShutdown));
+
+    readerThread = nullptr;
+  });
+
+  Vector<nsZipCursor> cursors;
+  LinkedList<URLEntry> pendingURLs;
+  {
+    MonitorAutoLock mal(mMonitor);
+
+    if (ReadCache(pendingURLs).isErr()) {
+      mReaderInitialized = true;
+      mal.NotifyAll();
+      return;
+    }
+
+    int numZipEntries = 0;
+    for (auto entry : pendingURLs) {
+      if (entry->mType != entry->TypeFile) {
+        numZipEntries++;
+      }
+    }
+    MOZ_RELEASE_ASSERT(cursors.reserve(numZipEntries));
+
+    // Initialize the zip cursors for all files in Omnijar while the monitor
+    // is locked. Omnijar is not threadsafe, so the caller of
+    // AutoBeginReading guard must ensure that no code accesses Omnijar
+    // until this segment is done. Once the cursors have been initialized,
+    // the actual reading and decompression can safely be done off-thread,
+    // as is the case for thread-retargeted jar: channels.
+    for (auto entry : pendingURLs) {
+      if (entry->mType == entry->TypeFile) {
+        continue;
+      }
+
+      RefPtr<nsZipArchive> zip = entry->Archive();
+      if (!zip) {
+        MOZ_CRASH_UNSAFE_PRINTF(
+            "Failed to get Omnijar %s archive for entry (path: \"%s\")",
+            entry->TypeString(), entry->mPath.get());
+      }
+
+      auto item = zip->GetItem(entry->mPath.get());
+      if (!item) {
+        entry->mResultCode = NS_ERROR_FILE_NOT_FOUND;
+        continue;
+      }
+
+      size_t size = item->RealSize();
+
+      entry->mData.SetLength(size);
+      auto data = entry->mData.BeginWriting();
+
+      cursors.infallibleEmplaceBack(item, zip, reinterpret_cast<uint8_t*>(data),
+                                    size, true);
+    }
+
+    mReaderInitialized = true;
+    mal.NotifyAll();
+  }
+
+  // Loop over the entries, read the file's contents, store them in the
+  // entry's mData pointer, and notify any waiting threads to check for
+  // completion.
+  uint32_t i = 0;
+  for (auto entry : pendingURLs) {
+    // If there is any other error code, the entry has already failed at
+    // this point, so don't bother trying to read it again.
+    if (entry->mResultCode != NS_ERROR_NOT_INITIALIZED) {
+      continue;
+    }
+
+    nsresult rv = NS_OK;
+
+    LOG(Debug, "Background reading %s file %s", entry->TypeString(),
+        entry->mPath.get());
+
+    if (entry->mType == entry->TypeFile) {
+      auto result = entry->Read();
+      if (result.isErr()) {
+        rv = result.unwrapErr();
+      }
+    } else {
+      auto& cursor = cursors[i++];
+
+      uint32_t len;
+      cursor.Copy(&len);
+      if (len != entry->mData.Length()) {
+        entry->mData.Truncate();
+        rv = NS_ERROR_FAILURE;
+      }
+    }
+
+    entry->mResultCode = rv;
+    mMonitor.NotifyAll();
+  }
+
+  // We're done reading pending entries, so clear the list.
+  pendingURLs.clear();
+}
+
+void URLPreloader::BeginBackgroundRead() {
+  auto lock = mReaderThread.Lock();
+  auto& readerThread = lock.ref();
+  if (!readerThread && !mReaderInitialized && sInitialized) {
+    nsresult rv;
+    rv = NS_NewNamedThread("BGReadURLs", getter_AddRefs(readerThread));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return;
+    }
+
+    nsCOMPtr<nsIRunnable> runnable =
+        NewRunnableMethod("URLPreloader::BackgroundReadFiles", this,
+                          &URLPreloader::BackgroundReadFiles);
+    rv = readerThread->Dispatch(runnable.forget(), NS_DISPATCH_NORMAL);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      // If we can't launch the task, just destroy the thread
+      readerThread = nullptr;
+      return;
+    }
+  }
+}
+
+Result<nsCString, nsresult> URLPreloader::ReadInternal(const CacheKey& key,
+                                                       ReadType readType) {
+  if (mStartupFinished || !mReaderInitialized) {
+    URLEntry entry(key);
+
+    return entry.Read();
+  }
+
+  auto entry = mCachedURLs.GetOrInsertNew(key, key);
+
+  entry->UpdateUsedTime();
+
+  return entry->ReadOrWait(readType);
+}
+
+Result<nsCString, nsresult> URLPreloader::ReadURIInternal(nsIURI* uri,
+                                                          ReadType readType) {
+  CacheKey key;
+  MOZ_TRY_VAR(key, ResolveURI(uri));
+
+  return ReadInternal(key, readType);
+}
+
+/* static */ Result<nsCString, nsresult> URLPreloader::Read(const CacheKey& key,
+                                                            ReadType readType) {
+  // If we're being called before the preloader has been initialized (i.e.,
+  // before the profile has been initialized), just fall back to a synchronous
+  // read. This happens when we're reading .ini and preference files that are
+  // needed to locate and initialize the profile.
+  if (!sInitialized) {
+    return URLEntry(key).Read();
+  }
+
+  return GetSingleton().ReadInternal(key, readType);
+}
+
+/* static */ Result<nsCString, nsresult> URLPreloader::ReadURI(
+    nsIURI* uri, ReadType readType) {
+  if (!sInitialized) {
+    return Err(NS_ERROR_NOT_INITIALIZED);
+  }
+
+  return GetSingleton().ReadURIInternal(uri, readType);
+}
+
+/* static */ Result<nsCString, nsresult> URLPreloader::ReadFile(
+    nsIFile* file, ReadType readType) {
+  return Read(CacheKey(file), readType);
+}
+
+/* static */ Result<nsCString, nsresult> URLPreloader::Read(
+    FileLocation& location, ReadType readType) {
+  if (location.IsZip()) {
+    if (location.GetBaseZip()) {
+      nsCString path;
+      location.GetPath(path);
+      return ReadZip(location.GetBaseZip(), path);
+    }
+    return URLEntry::ReadLocation(location);
+  }
+
+  nsCOMPtr<nsIFile> file = location.GetBaseFile();
+  return ReadFile(file, readType);
+}
+
+/* static */ Result<nsCString, nsresult> URLPreloader::ReadZip(
+    nsZipArchive* zip, const nsACString& path, ReadType readType) {
+  // If the zip archive belongs to an Omnijar location, map it to a cache
+  // entry, and cache it as normal. Otherwise, simply read the entry
+  // synchronously, since other JAR archives are currently unsupported by the
+  // cache.
+  RefPtr<nsZipArchive> reader = Omnijar::GetReader(Omnijar::GRE);
+  if (zip == reader) {
+    CacheKey key(CacheKey::TypeGREJar, path);
+    return Read(key, readType);
+  }
+
+  reader = Omnijar::GetReader(Omnijar::APP);
+  if (zip == reader) {
+    CacheKey key(CacheKey::TypeAppJar, path);
+    return Read(key, readType);
+  }
+
+  // Not an Omnijar archive, so just read it directly.
+  FileLocation location(zip, PromiseFlatCString(path).BeginReading());
+  return URLEntry::ReadLocation(location);
+}
+
+Result<URLPreloader::CacheKey, nsresult> URLPreloader::ResolveURI(nsIURI* uri) {
+  nsCString spec;
+  nsCString scheme;
+  MOZ_TRY(uri->GetSpec(spec));
+  MOZ_TRY(uri->GetScheme(scheme));
+
+  nsCOMPtr<nsIURI> resolved;
+
+  // If the URI is a resource: or chrome: URI, first resolve it to the
+  // underlying URI that it wraps.
+  if (scheme.EqualsLiteral("resource")) {
+    MOZ_TRY(mResProto->ResolveURI(uri, spec));
+    MOZ_TRY(NS_NewURI(getter_AddRefs(resolved), spec));
+  } else if (scheme.EqualsLiteral("chrome")) {
+    MOZ_TRY(mChromeReg->ConvertChromeURL(uri, getter_AddRefs(resolved)));
+    MOZ_TRY(resolved->GetSpec(spec));
+  } else {
+    resolved = uri;
+  }
+  MOZ_TRY(resolved->GetScheme(scheme));
+
+  // Try the GRE and App Omnijar prefixes.
+  if (mGREPrefix.Length() && StartsWith(spec, mGREPrefix)) {
+    return CacheKey(CacheKey::TypeGREJar, Substring(spec, mGREPrefix.Length()));
+  }
+
+  if (mAppPrefix.Length() && StartsWith(spec, mAppPrefix)) {
+    return CacheKey(CacheKey::TypeAppJar, Substring(spec, mAppPrefix.Length()));
+  }
+
+  // Try for a file URI.
+  if (scheme.EqualsLiteral("file")) {
+    nsCOMPtr<nsIFileURL> fileURL = do_QueryInterface(resolved);
+    MOZ_ASSERT(fileURL);
+
+    nsCOMPtr<nsIFile> file;
+    MOZ_TRY(fileURL->GetFile(getter_AddRefs(file)));
+
+    nsString path;
+    MOZ_TRY(file->GetPath(path));
+
+    return CacheKey(CacheKey::TypeFile, NS_ConvertUTF16toUTF8(path));
+  }
+
+  // Not a file or Omnijar URI, so currently unsupported.
+  return Err(NS_ERROR_INVALID_ARG);
+}
+
+size_t URLPreloader::ShallowSizeOfIncludingThis(
+    mozilla::MallocSizeOf mallocSizeOf) {
+  return (mallocSizeOf(this) +
+          mAppPrefix.SizeOfExcludingThisEvenIfShared(mallocSizeOf) +
+          mGREPrefix.SizeOfExcludingThisEvenIfShared(mallocSizeOf) +
+          mCachedURLs.ShallowSizeOfExcludingThis(mallocSizeOf));
+}
+
+Result<FileLocation, nsresult> URLPreloader::CacheKey::ToFileLocation() {
+  if (mType == TypeFile) {
+    nsCOMPtr<nsIFile> file;
+    MOZ_TRY(NS_NewLocalFile(NS_ConvertUTF8toUTF16(mPath), false,
+                            getter_AddRefs(file)));
+    return FileLocation(file);
+  }
+
+  RefPtr<nsZipArchive> zip = Archive();
+  return FileLocation(zip, mPath.get());
+}
+
+Result<nsCString, nsresult> URLPreloader::URLEntry::Read() {
+  FileLocation location;
+  MOZ_TRY_VAR(location, ToFileLocation());
+
+  MOZ_TRY_VAR(mData, ReadLocation(location));
+  return mData;
+}
+
+/* static */ Result<nsCString, nsresult> URLPreloader::URLEntry::ReadLocation(
+    FileLocation& location) {
+  FileLocation::Data data;
+  MOZ_TRY(location.GetData(data));
+
+  uint32_t size;
+  MOZ_TRY(data.GetSize(&size));
+
+  nsCString result;
+  result.SetLength(size);
+  MOZ_TRY(data.Copy(result.BeginWriting(), size));
+
+  return std::move(result);
+}
+
+Result<nsCString, nsresult> URLPreloader::URLEntry::ReadOrWait(
+    ReadType readType) {
+  auto now = TimeStamp::Now();
+  LOG(Info, "Reading %s\n", mPath.get());
+  auto cleanup = MakeScopeExit([&]() {
+    LOG(Info, "Read in %fms\n", (TimeStamp::Now() - now).ToMilliseconds());
+  });
+
+  if (mResultCode == NS_ERROR_NOT_INITIALIZED) {
+    MonitorAutoLock mal(GetSingleton().mMonitor);
+
+    while (mResultCode == NS_ERROR_NOT_INITIALIZED) {
+      mal.Wait();
+    }
+  }
+
+  if (mResultCode == NS_OK && mData.IsVoid()) {
+    LOG(Info, "Reading synchronously...\n");
+    return Read();
+  }
+
+  if (NS_FAILED(mResultCode)) {
+    return Err(mResultCode);
+  }
+
+  nsCString res = mData;
+
+  if (readType == Forget) {
+    mData.SetIsVoid(true);
+  }
+  return res;
+}
+
+inline URLPreloader::CacheKey::CacheKey(InputBuffer& buffer) {
+  Code(buffer);
+  MOZ_DIAGNOSTIC_ASSERT(
+      mType == TypeAppJar || mType == TypeGREJar || mType == TypeFile,
+      "mType should be valid");
+}
+
+NS_IMPL_ISUPPORTS(URLPreloader, nsIMemoryReporter)
+
+#undef LOG
+
+}  // namespace mozilla