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fune/dom/system/IOUtils.h

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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_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 "nsISerialEventTarget.h"
#include "nsPrintfCString.h"
#include "nsProxyRelease.h"
#include "nsString.h"
#include "nsStringFwd.h"
#include "nsTArray.h"
#include "prio.h"
class nsFileStream;
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> SetModificationTime(
GlobalObject& aGlobal, const nsAString& aPath,
const Optional<int64_t>& aModification, ErrorResult& aError);
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 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 modification time of the file at |aFile|.
*
* @param aFile The location of the file.
* @param aNewModTime Some value in milliseconds since Epoch. For the current
* system time, use |Nothing|.
*
* @return Timestamp of the file if the operation was successful, or an error.
*/
static Result<int64_t, IOError> SetModificationTimeSync(
nsIFile* aFile, const Maybe<int64_t>& aNewModTime);
/**
* 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;
uint64_t mLastModified = 0;
Maybe<uint64_t> mCreationTime;
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<nsFileStream>&& 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<nsFileStream> mStream;
int64_t mSize = 0;
};
} // namespace dom
} // namespace mozilla
#endif
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