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Diffstat (limited to 'dom/system/IOUtils.h')
| -rw-r--r-- | dom/system/IOUtils.h | 921 |
1 files changed, 921 insertions, 0 deletions
diff --git a/dom/system/IOUtils.h b/dom/system/IOUtils.h new file mode 100644 index 0000000000..a5fea23c60 --- /dev/null +++ b/dom/system/IOUtils.h @@ -0,0 +1,921 @@ +/* -*- 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_dom_IOUtils__ +#define mozilla_dom_IOUtils__ + +#include "js/Utility.h" +#include "mozilla/AlreadyAddRefed.h" +#include "mozilla/Attributes.h" +#include "mozilla/Buffer.h" +#include "mozilla/DataMutex.h" +#include "mozilla/MozPromise.h" +#include "mozilla/Result.h" +#include "mozilla/StaticPtr.h" +#include "mozilla/dom/BindingDeclarations.h" +#include "mozilla/dom/IOUtilsBinding.h" +#include "mozilla/dom/TypedArray.h" +#include "nsIAsyncShutdown.h" +#include "nsIFile.h" +#include "nsISerialEventTarget.h" +#include "nsPrintfCString.h" +#include "nsProxyRelease.h" +#include "nsString.h" +#include "nsStringFwd.h" +#include "nsTArray.h" +#include "prio.h" + +class nsFileRandomAccessStream; + +namespace mozilla { + +/** + * Utility class to be used with |UniquePtr| to automatically close NSPR file + * descriptors when they go out of scope. + * + * Example: + * + * UniquePtr<PRFileDesc, PR_CloseDelete> fd = PR_Open(path, flags, mode); + */ +class PR_CloseDelete { + public: + constexpr PR_CloseDelete() = default; + PR_CloseDelete(const PR_CloseDelete& aOther) = default; + PR_CloseDelete(PR_CloseDelete&& aOther) = default; + PR_CloseDelete& operator=(const PR_CloseDelete& aOther) = default; + PR_CloseDelete& operator=(PR_CloseDelete&& aOther) = default; + + void operator()(PRFileDesc* aPtr) const { PR_Close(aPtr); } +}; + +namespace dom { + +/** + * Implementation for the Web IDL interface at dom/chrome-webidl/IOUtils.webidl. + * Methods of this class must only be called from the parent process. + */ +class IOUtils final { + public: + class IOError; + + enum class ShutdownPhase : uint8_t { + ProfileBeforeChange, + SendTelemetry, + XpcomWillShutdown, + Count, + }; + + template <typename T> + using PhaseArray = + EnumeratedArray<IOUtils::ShutdownPhase, IOUtils::ShutdownPhase::Count, T>; + + static already_AddRefed<Promise> Read(GlobalObject& aGlobal, + const nsAString& aPath, + const ReadOptions& aOptions, + ErrorResult& aError); + + static already_AddRefed<Promise> ReadUTF8(GlobalObject& aGlobal, + const nsAString& aPath, + const ReadUTF8Options& aOptions, + ErrorResult& aError); + + static already_AddRefed<Promise> ReadJSON(GlobalObject& aGlobal, + const nsAString& aPath, + const ReadUTF8Options& aOptions, + ErrorResult& aError); + + static already_AddRefed<Promise> Write(GlobalObject& aGlobal, + const nsAString& aPath, + const Uint8Array& aData, + const WriteOptions& aOptions, + ErrorResult& aError); + + static already_AddRefed<Promise> WriteUTF8(GlobalObject& aGlobal, + const nsAString& aPath, + const nsACString& aString, + const WriteOptions& aOptions, + ErrorResult& aError); + + static already_AddRefed<Promise> WriteJSON(GlobalObject& aGlobal, + const nsAString& aPath, + JS::Handle<JS::Value> aValue, + const WriteOptions& aOptions, + ErrorResult& aError); + + static already_AddRefed<Promise> Move(GlobalObject& aGlobal, + const nsAString& aSourcePath, + const nsAString& aDestPath, + const MoveOptions& aOptions, + ErrorResult& aError); + + static already_AddRefed<Promise> Remove(GlobalObject& aGlobal, + const nsAString& aPath, + const RemoveOptions& aOptions, + ErrorResult& aError); + + static already_AddRefed<Promise> MakeDirectory( + GlobalObject& aGlobal, const nsAString& aPath, + const MakeDirectoryOptions& aOptions, ErrorResult& aError); + + static already_AddRefed<Promise> Stat(GlobalObject& aGlobal, + const nsAString& aPath, + ErrorResult& aError); + + static already_AddRefed<Promise> Copy(GlobalObject& aGlobal, + const nsAString& aSourcePath, + const nsAString& aDestPath, + const CopyOptions& aOptions, + ErrorResult& aError); + + static already_AddRefed<Promise> SetAccessTime( + GlobalObject& aGlobal, const nsAString& aPath, + const Optional<int64_t>& aAccess, ErrorResult& aError); + + static already_AddRefed<Promise> SetModificationTime( + GlobalObject& aGlobal, const nsAString& aPath, + const Optional<int64_t>& aModification, ErrorResult& aError); + + private: + using SetTimeFn = decltype(&nsIFile::SetLastAccessedTime); + + static_assert( + std::is_same_v<SetTimeFn, decltype(&nsIFile::SetLastModifiedTime)>); + + static already_AddRefed<Promise> SetTime(GlobalObject& aGlobal, + const nsAString& aPath, + const Optional<int64_t>& aNewTime, + SetTimeFn aSetTimeFn, + ErrorResult& aError); + + public: + static already_AddRefed<Promise> GetChildren( + GlobalObject& aGlobal, const nsAString& aPath, + const GetChildrenOptions& aOptions, ErrorResult& aError); + + static already_AddRefed<Promise> SetPermissions(GlobalObject& aGlobal, + const nsAString& aPath, + uint32_t aPermissions, + const bool aHonorUmask, + ErrorResult& aError); + + static already_AddRefed<Promise> Exists(GlobalObject& aGlobal, + const nsAString& aPath, + ErrorResult& aError); + + static already_AddRefed<Promise> CreateUniqueFile(GlobalObject& aGlobal, + const nsAString& aParent, + const nsAString& aPrefix, + const uint32_t aPermissions, + ErrorResult& aError); + static already_AddRefed<Promise> CreateUniqueDirectory( + GlobalObject& aGlobal, const nsAString& aParent, const nsAString& aPrefix, + const uint32_t aPermissions, ErrorResult& aError); + + private: + /** + * A helper method for CreateUniqueFile and CreateUniqueDirectory. + */ + static already_AddRefed<Promise> CreateUnique(GlobalObject& aGlobal, + const nsAString& aParent, + const nsAString& aPrefix, + const uint32_t aFileType, + const uint32_t aPermissions, + ErrorResult& aError); + + public: + static already_AddRefed<Promise> ComputeHexDigest( + GlobalObject& aGlobal, const nsAString& aPath, + const HashAlgorithm aAlgorithm, ErrorResult& aError); + +#if defined(XP_WIN) + static already_AddRefed<Promise> GetWindowsAttributes(GlobalObject& aGlobal, + const nsAString& aPath, + ErrorResult& aError); + + static already_AddRefed<Promise> SetWindowsAttributes( + GlobalObject& aGlobal, const nsAString& aPath, + const mozilla::dom::WindowsFileAttributes& aAttrs, ErrorResult& aError); +#elif defined(XP_MACOSX) + static already_AddRefed<Promise> HasMacXAttr(GlobalObject& aGlobal, + const nsAString& aPath, + const nsACString& aAttr, + ErrorResult& aError); + static already_AddRefed<Promise> GetMacXAttr(GlobalObject& aGlobal, + const nsAString& aPath, + const nsACString& aAttr, + ErrorResult& aError); + static already_AddRefed<Promise> SetMacXAttr(GlobalObject& aGlobal, + const nsAString& aPath, + const nsACString& aAttr, + const Uint8Array& aValue, + ErrorResult& aError); + static already_AddRefed<Promise> DelMacXAttr(GlobalObject& aGlobal, + const nsAString& aPath, + const nsACString& aAttr, + ErrorResult& aError); +#endif + +#ifdef XP_UNIX + using UnixString = OwningUTF8StringOrUint8Array; + static uint32_t LaunchProcess(GlobalObject& aGlobal, + const Sequence<UnixString>& aArgv, + const LaunchOptions& aOptions, + ErrorResult& aRv); +#endif + + static already_AddRefed<Promise> GetFile( + GlobalObject& aGlobal, const Sequence<nsString>& aComponents, + ErrorResult& aError); + + static already_AddRefed<Promise> GetDirectory( + GlobalObject& aGlobal, const Sequence<nsString>& aComponents, + ErrorResult& aError); + + static void GetProfileBeforeChange(GlobalObject& aGlobal, + JS::MutableHandle<JS::Value>, + ErrorResult& aRv); + + static void GetSendTelemetry(GlobalObject& aGlobal, + JS::MutableHandle<JS::Value>, ErrorResult& aRv); + + static RefPtr<SyncReadFile> OpenFileForSyncReading(GlobalObject& aGlobal, + const nsAString& aPath, + ErrorResult& aRv); + + class JsBuffer; + + /** + * The kind of buffer to allocate. + * + * This controls what kind of JS object (a JSString or a Uint8Array) is + * returned by |ToJSValue()|. + */ + enum class BufferKind { + String, + Uint8Array, + }; + + private: + ~IOUtils() = default; + + template <typename T> + using IOPromise = MozPromise<T, IOError, true>; + + friend class IOUtilsShutdownBlocker; + struct InternalFileInfo; + struct InternalWriteOpts; + class MozLZ4; + class EventQueue; + class State; + + template <typename Fn> + static already_AddRefed<Promise> WithPromiseAndState(GlobalObject& aGlobal, + ErrorResult& aError, + Fn aFn); + + /** + * Dispatch a task on the event queue and resolve or reject the associated + * promise based on the result. + * + * NB: If the calling thread is a worker, this function takes care of keepting + * it alive until the |IOPromise| can complete. + * + * @param aPromise The promise corresponding to the task running on the event + * queue. + * @param aFunc The task to run. + */ + template <typename OkT, typename Fn> + static void DispatchAndResolve(EventQueue* aQueue, Promise* aPromise, + Fn aFunc); + + /** + * Creates a new JS Promise. + * + * @return The new promise, or |nullptr| on failure. + */ + static already_AddRefed<Promise> CreateJSPromise(GlobalObject& aGlobal, + ErrorResult& aError); + + // Allow conversion of |InternalFileInfo| with |ToJSValue|. + friend bool ToJSValue(JSContext* aCx, + const InternalFileInfo& aInternalFileInfo, + JS::MutableHandle<JS::Value> aValue); + + /** + * Attempts to read the entire file at |aPath| into a buffer. + * + * @param aFile The location of the file. + * @param aOffset The offset to start reading from. + * @param aMaxBytes If |Some|, then only read up this this number of bytes, + * otherwise attempt to read the whole file. + * @param aDecompress If true, decompress the bytes read from disk before + * returning the result to the caller. + * @param aBufferKind The kind of buffer to allocate. + * + * @return A buffer containing the entire (decompressed) file contents, or an + * error. + */ + static Result<JsBuffer, IOError> ReadSync(nsIFile* aFile, + const uint64_t aOffset, + const Maybe<uint32_t> aMaxBytes, + const bool aDecompress, + BufferKind aBufferKind); + + /* + * Attempts to read the entire file at |aPath| as a UTF-8 string. + * + * @param aFile The location of the file. + * @param aDecompress If true, decompress the bytes read from disk before + * returning the result to the caller. + * + * @return The (decompressed) contents of the file re-encoded as a UTF-16 + * string. + */ + static Result<JsBuffer, IOError> ReadUTF8Sync(nsIFile* aFile, + const bool aDecompress); + + /** + * Attempt to write the entirety of |aByteArray| to the file at |aPath|. + * This may occur by writing to an intermediate destination and performing a + * move, depending on |aOptions|. + * + * @param aFile The location of the file. + * @param aByteArray The data to write to the file. + * @param aOptions Options to modify the way the write is completed. + * + * @return The number of bytes written to the file, or an error if the write + * failed or was incomplete. + */ + static Result<uint32_t, IOError> WriteSync( + nsIFile* aFile, const Span<const uint8_t>& aByteArray, + const InternalWriteOpts& aOptions); + + /** + * Attempts to move the file located at |aSourceFile| to |aDestFile|. + * + * @param aSourceFile The location of the file to move. + * @param aDestFile The destination for the file. + * @param aNoOverWrite If true, abort with an error if a file already exists + * at |aDestFile|. Otherwise, the file will be overwritten by the move. + * + * @return Ok if the file was moved successfully, or an error. + */ + static Result<Ok, IOError> MoveSync(nsIFile* aSourceFile, nsIFile* aDestFile, + bool aNoOverwrite); + + /** + * Attempts to copy the file at |aSourceFile| to |aDestFile|. + * + * @param aSourceFile The location of the file to copy. + * @param aDestFile The destination that the file will be copied to. + * + * @return Ok if the operation was successful, or an error. + */ + static Result<Ok, IOError> CopySync(nsIFile* aSourceFile, nsIFile* aDestFile, + bool aNoOverWrite, bool aRecursive); + + /** + * Provides the implementation for |CopySync| and |MoveSync|. + * + * @param aMethod A pointer to one of |nsIFile::MoveTo| or |CopyTo| + * instance methods. + * @param aMethodName The name of the method to the performed. Either "move" + * or "copy". + * @param aSource The source file to be copied or moved. + * @param aDest The destination file. + * @param aNoOverwrite If true, allow overwriting |aDest| during the copy or + * move. Otherwise, abort with an error if the file would + * be overwritten. + * + * @return Ok if the operation was successful, or an error. + */ + template <typename CopyOrMoveFn> + static Result<Ok, IOError> CopyOrMoveSync(CopyOrMoveFn aMethod, + const char* aMethodName, + nsIFile* aSource, nsIFile* aDest, + bool aNoOverwrite); + + /** + * Attempts to remove the file located at |aFile|. + * + * @param aFile The location of the file. + * @param aIgnoreAbsent If true, suppress errors due to an absent target file. + * @param aRecursive If true, attempt to recursively remove descendant + * files. This option is safe to use even if the target + * is not a directory. + * + * @return Ok if the file was removed successfully, or an error. + */ + static Result<Ok, IOError> RemoveSync(nsIFile* aFile, bool aIgnoreAbsent, + bool aRecursive); + + /** + * Attempts to create a new directory at |aFile|. + * + * @param aFile The location of the directory to create. + * @param aCreateAncestors If true, create missing ancestor directories as + * needed. Otherwise, report an error if the target + * has non-existing ancestor directories. + * @param aIgnoreExisting If true, suppress errors that occur if the target + * directory already exists. Otherwise, propagate the + * error if it occurs. + * @param aMode Optional file mode. Defaults to 0777 to allow the + * system umask to compute the best mode for the new + * directory. + * + * @return Ok if the directory was created successfully, or an error. + */ + static Result<Ok, IOError> MakeDirectorySync(nsIFile* aFile, + bool aCreateAncestors, + bool aIgnoreExisting, + int32_t aMode = 0777); + + /** + * Attempts to stat a file at |aFile|. + * + * @param aFile The location of the file. + * + * @return An |InternalFileInfo| struct if successful, or an error. + */ + static Result<IOUtils::InternalFileInfo, IOError> StatSync(nsIFile* aFile); + + /** + * Attempts to update the last access or modification time of the file at + * |aFile|. + * + * @param aFile The location of the file. + * @param SetTimeFn A member function pointer to either + * nsIFile::SetLastAccessedTime or + * nsIFile::SetLastModifiedTime. + * @param aNewTime Some value in milliseconds since Epoch. + * + * @return Timestamp of the file if the operation was successful, or an error. + */ + static Result<int64_t, IOError> SetTimeSync(nsIFile* aFile, + SetTimeFn aSetTimeFn, + int64_t aNewTime); + + /** + * Returns the immediate children of the directory at |aFile|, if any. + * + * @param aFile The location of the directory. + * + * @return An array of absolute paths identifying the children of |aFile|. + * If there are no children, an empty array. Otherwise, an error. + */ + static Result<nsTArray<nsString>, IOError> GetChildrenSync( + nsIFile* aFile, bool aIgnoreAbsent); + + /** + * Set the permissions of the given file. + * + * Windows does not make a distinction between user, group, and other + * permissions like UNICES do. If a permission flag is set for any of user, + * group, or other has a permission, then all users will have that + * permission. + * + * @param aFile The location of the file. + * @param aPermissions The permissions to set, as a UNIX file mode. + * + * @return |Ok| if the permissions were successfully set, or an error. + */ + static Result<Ok, IOError> SetPermissionsSync(nsIFile* aFile, + const uint32_t aPermissions); + + /** + * Return whether or not the file exists. + * + * @param aFile The location of the file. + * + * @return Whether or not the file exists. + */ + static Result<bool, IOError> ExistsSync(nsIFile* aFile); + + /** + * Create a file or directory with a unique path. + * + * @param aFile The location of the file or directory (including prefix) + * @param aFileType One of |nsIFile::NORMAL_FILE_TYPE| or + * |nsIFile::DIRECTORY_TYPE|. + * @param aperms The permissions to create the file or directory with. + * + * @return A unique path. + */ + static Result<nsString, IOError> CreateUniqueSync( + nsIFile* aFile, const uint32_t aFileType, const uint32_t aPermissions); + + /** + * Compute the hash of a file. + * + * @param aFile The file to hash. + * @param aAlgorithm The hashing algorithm to use. + * + * @return The hash of the file, as a hex digest. + */ + static Result<nsCString, IOError> ComputeHexDigestSync( + nsIFile* aFile, const HashAlgorithm aAlgorithm); + +#if defined(XP_WIN) + /** + * Return the Windows-specific attributes of the file. + * + * @param aFile The location of the file. + * + * @return The Windows-specific attributes of the file. + */ + static Result<uint32_t, IOError> GetWindowsAttributesSync(nsIFile* aFile); + + /** + * Set the Windows-specific attributes of the file. + * + * @param aFile The location of the file. + * @param aAttrs The attributes to set on the file. + * + * @return |Ok| if the attributes were successfully set, or an error. + */ + static Result<Ok, IOError> SetWindowsAttributesSync( + nsIFile* aFile, const uint32_t aSetAttrs, const uint32_t aClearAttrs); +#elif defined(XP_MACOSX) + static Result<bool, IOError> HasMacXAttrSync(nsIFile* aFile, + const nsCString& aAttr); + static Result<nsTArray<uint8_t>, IOError> GetMacXAttrSync( + nsIFile* aFile, const nsCString& aAttr); + static Result<Ok, IOError> SetMacXAttrSync(nsIFile* aFile, + const nsCString& aAttr, + const nsTArray<uint8_t>& aValue); + static Result<Ok, IOError> DelMacXAttrSync(nsIFile* aFile, + const nsCString& aAttr); +#endif + + static void GetShutdownClient(GlobalObject& aGlobal, + JS::MutableHandle<JS::Value> aClient, + ErrorResult& aRv, const ShutdownPhase aPhase); + + enum class EventQueueStatus { + Uninitialized, + Initialized, + Shutdown, + }; + + enum class ShutdownBlockerStatus { + Uninitialized, + Initialized, + Failed, + }; + + /** + * Internal IOUtils state. + */ + class State { + public: + StaticAutoPtr<EventQueue> mEventQueue; + EventQueueStatus mQueueStatus = EventQueueStatus::Uninitialized; + ShutdownBlockerStatus mBlockerStatus = ShutdownBlockerStatus::Uninitialized; + + /** + * Set up shutdown hooks to free our internals at shutdown. + * + * NB: Must be called on main thread. + */ + void SetShutdownHooks(); + }; + + using StateMutex = StaticDataMutex<State>; + + /** + * Lock the state mutex and return a handle. If shutdown has not yet + * finished, the internals will be constructed if necessary. + * + * @returns A handle to the internal state, which can be used to retrieve the + * event queue. + * If |Some| is returned, |mEventQueue| is guaranteed to be + * initialized. If shutdown has finished, |Nothing| is returned. + */ + static Maybe<StateMutex::AutoLock> GetState(); + + static StateMutex sState; +}; + +/** + * The IOUtils event queue. + */ +class IOUtils::EventQueue final { + friend void IOUtils::State::SetShutdownHooks(); + + public: + EventQueue(); + + EventQueue(const EventQueue&) = delete; + EventQueue(EventQueue&&) = delete; + EventQueue& operator=(const EventQueue&) = delete; + EventQueue& operator=(EventQueue&&) = delete; + + /** + * Dispatch a task on the event queue. + * + * NB: If using this directly from |IOUtils| instead of + * |IOUtils::DispatchAndResolve| *and* the calling thread is a worker, you + * *must* take care to keep the worker thread alive until the |IOPromise| + * resolves or rejects. See the implementation of + * |IOUtils::DispatchAndResolve| or |IOUtils::GetWindowsAttributes| for an + * example. + * + * @param aFunc The task to dispatch on the event queue. + * + * @return A promise that resolves to the task's return value or rejects with + * an error. + */ + template <typename OkT, typename Fn> + RefPtr<IOPromise<OkT>> Dispatch(Fn aFunc); + + Result<already_AddRefed<nsIAsyncShutdownBarrier>, nsresult> + GetShutdownBarrier(const ShutdownPhase aPhase); + Result<already_AddRefed<nsIAsyncShutdownClient>, nsresult> GetShutdownClient( + const ShutdownPhase aPhase); + + private: + nsresult SetShutdownHooks(); + + nsCOMPtr<nsISerialEventTarget> mBackgroundEventTarget; + IOUtils::PhaseArray<nsCOMPtr<nsIAsyncShutdownBarrier>> mBarriers; +}; + +/** + * An error class used with the |Result| type returned by most private |IOUtils| + * methods. + */ +class IOUtils::IOError { + public: + MOZ_IMPLICIT IOError(nsresult aCode) : mCode(aCode), mMessage(Nothing()) {} + + /** + * Replaces the message associated with this error. + */ + template <typename... Args> + IOError WithMessage(const char* const aMessage, Args... aArgs) { + mMessage.emplace(nsPrintfCString(aMessage, aArgs...)); + return *this; + } + IOError WithMessage(const char* const aMessage) { + mMessage.emplace(nsCString(aMessage)); + return *this; + } + IOError WithMessage(const nsCString& aMessage) { + mMessage.emplace(aMessage); + return *this; + } + + /** + * Returns the |nsresult| associated with this error. + */ + nsresult Code() const { return mCode; } + + /** + * Maybe returns a message associated with this error. + */ + const Maybe<nsCString>& Message() const { return mMessage; } + + private: + nsresult mCode; + Maybe<nsCString> mMessage; +}; + +/** + * This is an easier to work with representation of a |mozilla::dom::FileInfo| + * for private use in the IOUtils implementation. + * + * Because web IDL dictionaries are not easily copy/moveable, this class is + * used instead, until converted to the proper |mozilla::dom::FileInfo| before + * returning any results to JavaScript. + */ +struct IOUtils::InternalFileInfo { + nsString mPath; + FileType mType = FileType::Other; + uint64_t mSize = 0; + Maybe<PRTime> mCreationTime; // In ms since epoch. + PRTime mLastAccessed = 0; // In ms since epoch. + PRTime mLastModified = 0; // In ms since epoch. + uint32_t mPermissions = 0; +}; + +/** + * This is an easier to work with representation of a + * |mozilla::dom::WriteOptions| for private use in the |IOUtils| + * implementation. + * + * Because web IDL dictionaries are not easily copy/moveable, this class is + * used instead. + */ +struct IOUtils::InternalWriteOpts { + RefPtr<nsIFile> mBackupFile; + RefPtr<nsIFile> mTmpFile; + WriteMode mMode; + bool mFlush = false; + bool mCompress = false; + + static Result<InternalWriteOpts, IOUtils::IOError> FromBinding( + const WriteOptions& aOptions); +}; + +/** + * Re-implements the file compression and decompression utilities found + * in toolkit/components/lz4/lz4.js + * + * This implementation uses the non-standard data layout: + * + * - MAGIC_NUMBER (8 bytes) + * - content size (uint32_t, little endian) + * - content, as obtained from mozilla::Compression::LZ4::compress + * + * See bug 1209390 for more info. + */ +class IOUtils::MozLZ4 { + public: + static constexpr std::array<uint8_t, 8> MAGIC_NUMBER{ + {'m', 'o', 'z', 'L', 'z', '4', '0', '\0'}}; + + static const uint32_t HEADER_SIZE = 8 + sizeof(uint32_t); + + /** + * Compresses |aUncompressed| byte array, and returns a byte array with the + * correct format whose contents may be written to disk. + */ + static Result<nsTArray<uint8_t>, IOError> Compress( + Span<const uint8_t> aUncompressed); + + /** + * Checks |aFileContents| for the correct file header, and returns the + * decompressed content. + */ + static Result<IOUtils::JsBuffer, IOError> Decompress( + Span<const uint8_t> aFileContents, IOUtils::BufferKind); +}; + +class IOUtilsShutdownBlocker : public nsIAsyncShutdownBlocker, + public nsIAsyncShutdownCompletionCallback { + public: + NS_DECL_THREADSAFE_ISUPPORTS + NS_DECL_NSIASYNCSHUTDOWNBLOCKER + NS_DECL_NSIASYNCSHUTDOWNCOMPLETIONCALLBACK + + explicit IOUtilsShutdownBlocker(const IOUtils::ShutdownPhase aPhase) + : mPhase(aPhase) {} + + private: + virtual ~IOUtilsShutdownBlocker() = default; + + /** + * Called on the main thread after the event queue has been flushed. + */ + void OnFlush(); + + static constexpr IOUtils::PhaseArray<const char16_t*> PHASE_NAMES{ + u"profile-before-change", + u"profile-before-change-telemetry", + u"xpcom-will-shutdown", + }; + + // The last shutdown phase before we should shut down the event loop. + static constexpr auto LAST_IO_PHASE = IOUtils::ShutdownPhase::SendTelemetry; + + IOUtils::ShutdownPhase mPhase; + nsCOMPtr<nsIAsyncShutdownClient> mParentClient; +}; + +/** + * A buffer that is allocated inside one of JS heaps so that it can be converted + * to a JSString or Uint8Array object with at most one copy in the worst case. + */ +class IOUtils::JsBuffer final { + public: + /** + * Create a new buffer of the given kind with the requested capacity. + * + * @param aBufferKind The kind of buffer to create (either a string or an + * array). + * @param aCapacity The capacity of the buffer. + * + * @return Either a successfully created buffer or an error if it could not be + * allocated. + */ + static Result<JsBuffer, IOUtils::IOError> Create( + IOUtils::BufferKind aBufferKind, size_t aCapacity); + + /** + * Create a new, empty buffer. + * + * This operation cannot fail. + * + * @param aBufferKind The kind of buffer to create (either a string or an + * array). + * + * @return An empty JsBuffer. + */ + static JsBuffer CreateEmpty(IOUtils::BufferKind aBufferKind); + + JsBuffer(const JsBuffer&) = delete; + JsBuffer(JsBuffer&& aOther) noexcept; + JsBuffer& operator=(const JsBuffer&) = delete; + JsBuffer& operator=(JsBuffer&& aOther) noexcept; + + size_t Length() { return mLength; } + char* Elements() { return mBuffer.get(); } + void SetLength(size_t aNewLength) { + MOZ_RELEASE_ASSERT(aNewLength <= mCapacity); + mLength = aNewLength; + } + + /** + * Return a span for writing to the buffer. + * + * |SetLength| should be called after the buffer has been written to. + * + * @returns A span for writing to. The size of the span is the entire + * allocated capacity. + */ + Span<char> BeginWriting() { + MOZ_RELEASE_ASSERT(mBuffer.get()); + return Span(mBuffer.get(), mCapacity); + } + + /** + * Return a span for reading from. + * + * @returns A span for reading form. The size of the span is the set length + * of the buffer. + */ + Span<const char> BeginReading() const { + MOZ_RELEASE_ASSERT(mBuffer.get() || mLength == 0); + return Span(mBuffer.get(), mLength); + } + + /** + * Consume the JsBuffer and convert it into a JSString. + * + * NOTE: This method asserts the buffer was allocated as a string buffer. + * + * @param aBuffer The buffer to convert to a string. After this call, the + * buffer will be invaldated and |IntoString| cannot be called + * again. + * + * @returns A JSString with the contents of |aBuffer|. + */ + static JSString* IntoString(JSContext* aCx, JsBuffer aBuffer); + + /** + * Consume the JsBuffer and convert it into a Uint8Array. + * + * NOTE: This method asserts the buffer was allocated as an array buffer. + * + * @param aBuffer The buffer to convert to an array. After this call, the + * buffer will be invalidated and |IntoUint8Array| cannot be + * called again. + * + * @returns A JSBuffer + */ + static JSObject* IntoUint8Array(JSContext* aCx, JsBuffer aBuffer); + + friend bool ToJSValue(JSContext* aCx, JsBuffer&& aBuffer, + JS::MutableHandle<JS::Value> aValue); + + private: + IOUtils::BufferKind mBufferKind; + size_t mCapacity; + size_t mLength; + JS::UniqueChars mBuffer; + + JsBuffer(BufferKind aBufferKind, size_t aCapacity); +}; + +class SyncReadFile : public nsISupports, public nsWrapperCache { + public: + SyncReadFile(nsISupports* aParent, RefPtr<nsFileRandomAccessStream>&& aStream, + int64_t aSize); + + NS_DECL_CYCLE_COLLECTING_ISUPPORTS + NS_DECL_CYCLE_COLLECTION_WRAPPERCACHE_CLASS(SyncReadFile) + + nsISupports* GetParentObject() const { return mParent; } + + virtual JSObject* WrapObject(JSContext* aCx, + JS::Handle<JSObject*> aGivenProto) override; + + int64_t Size() const { return mSize; } + void ReadBytesInto(const Uint8Array&, const int64_t, ErrorResult& aRv); + void Close(); + + private: + virtual ~SyncReadFile(); + + nsCOMPtr<nsISupports> mParent; + RefPtr<nsFileRandomAccessStream> mStream; + int64_t mSize = 0; +}; + +} // namespace dom +} // namespace mozilla + +#endif |