// Copyright Joyent, Inc. and other Node contributors.

//

// Permission is hereby granted, free of charge, to any person obtaining a

// copy of this software and associated documentation files (the

// "Software"), to deal in the Software without restriction, including

// without limitation the rights to use, copy, modify, merge, publish,

// distribute, sublicense, and/or sell copies of the Software, and to permit

// persons to whom the Software is furnished to do so, subject to the

// following conditions:

//

// The above copyright notice and this permission notice shall be included

// in all copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN

// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,

// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR

// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE

// USE OR OTHER DEALINGS IN THE SOFTWARE.

// A bit simpler than readable streams.

// Implement an async ._write(chunk, encoding, cb), and it'll handle all

// the drain event emission and buffering.

'use strict';

const { Object } = primordials;

module.exports = Writable;

Writable.WritableState = WritableState;

const internalUtil = require('internal/util');

const Stream = require('stream');

const { Buffer } = require('buffer');

const destroyImpl = require('internal/streams/destroy');

const { getHighWaterMark } = require('internal/streams/state');

const {

ERR_INVALID_ARG_TYPE,

ERR_METHOD_NOT_IMPLEMENTED,

ERR_MULTIPLE_CALLBACK,

ERR_STREAM_CANNOT_PIPE,

ERR_STREAM_DESTROYED,

ERR_STREAM_NULL_VALUES,

ERR_STREAM_WRITE_AFTER_END,

ERR_UNKNOWN_ENCODING

} = require('internal/errors').codes;

const { errorOrDestroy } = destroyImpl;

Object.setPrototypeOf(Writable.prototype, Stream.prototype);

Object.setPrototypeOf(Writable, Stream);

function nop() {}

function WritableState(options, stream, isDuplex) {

options = options || {};

// Duplex streams are both readable and writable, but share

// the same options object.

// However, some cases require setting options to different

// values for the readable and the writable sides of the duplex stream,

// e.g. options.readableObjectMode vs. options.writableObjectMode, etc.

if (typeof isDuplex !== 'boolean')

isDuplex = stream instanceof Stream.Duplex;

// Object stream flag to indicate whether or not this stream

// contains buffers or objects.

this.objectMode = !!options.objectMode;

if (isDuplex)

this.objectMode = this.objectMode || !!options.writableObjectMode;

// The point at which write() starts returning false

// Note: 0 is a valid value, means that we always return false if

// the entire buffer is not flushed immediately on write()

this.highWaterMark = getHighWaterMark(this, options, 'writableHighWaterMark',

isDuplex);

// if _final has been called

this.finalCalled = false;

// drain event flag.

this.needDrain = false;

// At the start of calling end()

this.ending = false;

// When end() has been called, and returned

this.ended = false;

// When 'finish' is emitted

this.finished = false;

// Has it been destroyed

this.destroyed = false;

// Should we decode strings into buffers before passing to _write?

// this is here so that some node-core streams can optimize string

// handling at a lower level.

const noDecode = options.decodeStrings === false;

this.decodeStrings = !noDecode;

// Crypto is kind of old and crusty. Historically, its default string

// encoding is 'binary' so we have to make this configurable.

// Everything else in the universe uses 'utf8', though.

this.defaultEncoding = options.defaultEncoding || 'utf8';

// Not an actual buffer we keep track of, but a measurement

// of how much we're waiting to get pushed to some underlying

// socket or file.

this.length = 0;

// A flag to see when we're in the middle of a write.

this.writing = false;

// When true all writes will be buffered until .uncork() call

this.corked = 0;

// A flag to be able to tell if the onwrite cb is called immediately,

// or on a later tick. We set this to true at first, because any

// actions that shouldn't happen until "later" should generally also

// not happen before the first write call.

this.sync = true;

// A flag to know if we're processing previously buffered items, which

// may call the _write() callback in the same tick, so that we don't

// end up in an overlapped onwrite situation.

this.bufferProcessing = false;

// The callback that's passed to _write(chunk,cb)

this.onwrite = onwrite.bind(undefined, stream);

// The callback that the user supplies to write(chunk,encoding,cb)

this.writecb = null;

// The amount that is being written when _write is called.

this.writelen = 0;

this.bufferedRequest = null;

this.lastBufferedRequest = null;

// Number of pending user-supplied write callbacks

// this must be 0 before 'finish' can be emitted

this.pendingcb = 0;

// Emit prefinish if the only thing we're waiting for is _write cbs

// This is relevant for synchronous Transform streams

this.prefinished = false;

// True if the error was already emitted and should not be thrown again

this.errorEmitted = false;

// Should close be emitted on destroy. Defaults to true.

this.emitClose = options.emitClose !== false;

// Should .destroy() be called after 'finish' (and potentially 'end')

this.autoDestroy = !!options.autoDestroy;

// Count buffered requests

this.bufferedRequestCount = 0;

// Allocate the first CorkedRequest, there is always

// one allocated and free to use, and we maintain at most two

const corkReq = { next: null, entry: null, finish: undefined };

corkReq.finish = onCorkedFinish.bind(undefined, corkReq, this);

this.corkedRequestsFree = corkReq;

}

WritableState.prototype.getBuffer = function getBuffer() {

var current = this.bufferedRequest;

const out = [];

while (current) {

out.push(current);

current = current.next;

}

return out;

};

Object.defineProperty(WritableState.prototype, 'buffer', {

get: internalUtil.deprecate(function writableStateBufferGetter() {

return this.getBuffer();

}, '_writableState.buffer is deprecated. Use _writableState.getBuffer ' +

'instead.', 'DEP0003')

});

// Test _writableState for inheritance to account for Duplex streams,

// whose prototype chain only points to Readable.

var realHasInstance;

if (typeof Symbol === 'function' && Symbol.hasInstance) {

realHasInstance = Function.prototype[Symbol.hasInstance];

Object.defineProperty(Writable, Symbol.hasInstance, {

value: function(object) {

if (realHasInstance.call(this, object))

return true;

if (this !== Writable)

return false;

return object && object._writableState instanceof WritableState;

}

});

} else {

realHasInstance = function(object) {

return object instanceof this;

};

}

function Writable(options) {

// Writable ctor is applied to Duplexes, too.

// `realHasInstance` is necessary because using plain `instanceof`

// would return false, as no `_writableState` property is attached.

// Trying to use the custom `instanceof` for Writable here will also break the

// Node.js LazyTransform implementation, which has a non-trivial getter for

// `_writableState` that would lead to infinite recursion.

// Checking for a Stream.Duplex instance is faster here instead of inside

// the WritableState constructor, at least with V8 6.5

const isDuplex = (this instanceof Stream.Duplex);

if (!isDuplex && !realHasInstance.call(Writable, this))

return new Writable(options);

this._writableState = new WritableState(options, this, isDuplex);

// legacy.

this.writable = true;

if (options) {

if (typeof options.write === 'function')

this._write = options.write;

if (typeof options.writev === 'function')

this._writev = options.writev;

if (typeof options.destroy === 'function')

this._destroy = options.destroy;

if (typeof options.final === 'function')

this._final = options.final;

}

Stream.call(this);

}

// Otherwise people can pipe Writable streams, which is just wrong.

Writable.prototype.pipe = function() {

errorOrDestroy(this, new ERR_STREAM_CANNOT_PIPE());

};

function writeAfterEnd(stream, cb) {

const er = new ERR_STREAM_WRITE_AFTER_END();

// TODO: defer error events consistently everywhere, not just the cb

errorOrDestroy(stream, er);

process.nextTick(cb, er);

}

// Checks that a user-supplied chunk is valid, especially for the particular

// mode the stream is in. Currently this means that `null` is never accepted

// and undefined/non-string values are only allowed in object mode.

function validChunk(stream, state, chunk, cb) {

var er;

if (chunk === null) {

er = new ERR_STREAM_NULL_VALUES();

} else if (typeof chunk !== 'string' && !state.objectMode) {

er = new ERR_INVALID_ARG_TYPE('chunk', ['string', 'Buffer'], chunk);

}

if (er) {

errorOrDestroy(stream, er);

process.nextTick(cb, er);

return false;

}

return true;

}

Writable.prototype.write = function(chunk, encoding, cb) {

const state = this._writableState;

var ret = false;

const isBuf = !state.objectMode && Stream._isUint8Array(chunk);

if (isBuf && Object.getPrototypeOf(chunk) !== Buffer.prototype) {

chunk = Stream._uint8ArrayToBuffer(chunk);

}

if (typeof encoding === 'function') {

cb = encoding;

encoding = null;

}

if (isBuf)

encoding = 'buffer';

else if (!encoding)

encoding = state.defaultEncoding;

if (typeof cb !== 'function')

cb = nop;

if (state.ending)

writeAfterEnd(this, cb);

else if (isBuf || validChunk(this, state, chunk, cb)) {

state.pendingcb++;

ret = writeOrBuffer(this, state, isBuf, chunk, encoding, cb);

}

return ret;

};

Writable.prototype.cork = function() {

this._writableState.corked++;

};

Writable.prototype.uncork = function() {

const state = this._writableState;

if (state.corked) {

state.corked--;

if (!state.writing &&

!state.corked &&

!state.bufferProcessing &&

state.bufferedRequest)

clearBuffer(this, state);

}

};

Writable.prototype.setDefaultEncoding = function setDefaultEncoding(encoding) {

// node::ParseEncoding() requires lower case.

if (typeof encoding === 'string')

encoding = encoding.toLowerCase();

if (!Buffer.isEncoding(encoding))

throw new ERR_UNKNOWN_ENCODING(encoding);

this._writableState.defaultEncoding = encoding;

return this;

};

Object.defineProperty(Writable.prototype, 'writableBuffer', {

// Making it explicit this property is not enumerable

// because otherwise some prototype manipulation in

// userland will fail

enumerable: false,

get: function() {

return this._writableState && this._writableState.getBuffer();

}

});

function decodeChunk(state, chunk, encoding) {

if (!state.objectMode &&

state.decodeStrings !== false &&

typeof chunk === 'string') {

chunk = Buffer.from(chunk, encoding);

}

return chunk;

}

Object.defineProperty(Writable.prototype, 'writableHighWaterMark', {

// Making it explicit this property is not enumerable

// because otherwise some prototype manipulation in

// userland will fail

enumerable: false,

get: function() {

return this._writableState.highWaterMark;

}

});

// If we're already writing something, then just put this

// in the queue, and wait our turn. Otherwise, call _write

// If we return false, then we need a drain event, so set that flag.

function writeOrBuffer(stream, state, isBuf, chunk, encoding, cb) {

if (!isBuf) {

var newChunk = decodeChunk(state, chunk, encoding);

if (chunk !== newChunk) {

isBuf = true;

encoding = 'buffer';

chunk = newChunk;

}

}

const len = state.objectMode ? 1 : chunk.length;

state.length += len;

const ret = state.length < state.highWaterMark;

// We must ensure that previous needDrain will not be reset to false.

if (!ret)

state.needDrain = true;

if (state.writing || state.corked) {

var last = state.lastBufferedRequest;

state.lastBufferedRequest = {

chunk,

encoding,

isBuf,

callback: cb,

next: null

};

if (last) {

last.next = state.lastBufferedRequest;

} else {

state.bufferedRequest = state.lastBufferedRequest;

}

state.bufferedRequestCount += 1;

} else {

doWrite(stream, state, false, len, chunk, encoding, cb);

}

return ret;

}

function doWrite(stream, state, writev, len, chunk, encoding, cb) {

state.writelen = len;

state.writecb = cb;

state.writing = true;

state.sync = true;

if (state.destroyed)

state.onwrite(new ERR_STREAM_DESTROYED('write'));

else if (writev)

stream._writev(chunk, state.onwrite);

else

stream._write(chunk, encoding, state.onwrite);

state.sync = false;

}

function onwriteError(stream, state, sync, er, cb) {

--state.pendingcb;

if (sync) {

// Defer the callback if we are being called synchronously

// to avoid piling up things on the stack

process.nextTick(cb, er);

// This can emit finish, and it will always happen

// after error

process.nextTick(finishMaybe, stream, state);

stream._writableState.errorEmitted = true;

errorOrDestroy(stream, er);

} else {

// The caller expect this to happen before if

// it is async

cb(er);

stream._writableState.errorEmitted = true;

errorOrDestroy(stream, er);

// This can emit finish, but finish must

// always follow error

finishMaybe(stream, state);

}

}

function onwrite(stream, er) {

const state = stream._writableState;

const sync = state.sync;

const cb = state.writecb;

if (typeof cb !== 'function')

throw new ERR_MULTIPLE_CALLBACK();

state.writing = false;

state.writecb = null;

state.length -= state.writelen;

state.writelen = 0;

if (er)

onwriteError(stream, state, sync, er, cb);

else {

// Check if we're actually ready to finish, but don't emit yet

var finished = needFinish(state) || stream.destroyed;

if (!finished &&

!state.corked &&

!state.bufferProcessing &&

state.bufferedRequest) {

clearBuffer(stream, state);

}

if (sync) {

process.nextTick(afterWrite, stream, state, finished, cb);

} else {

afterWrite(stream, state, finished, cb);

}

}

}

function afterWrite(stream, state, finished, cb) {

if (!finished)

onwriteDrain(stream, state);

state.pendingcb--;

cb();

finishMaybe(stream, state);

}

// Must force callback to be called on nextTick, so that we don't

// emit 'drain' before the write() consumer gets the 'false' return

// value, and has a chance to attach a 'drain' listener.

function onwriteDrain(stream, state) {

if (state.length === 0 && state.needDrain) {

state.needDrain = false;

stream.emit('drain');

}

}

// If there's something in the buffer waiting, then process it

function clearBuffer(stream, state) {

state.bufferProcessing = true;

var entry = state.bufferedRequest;

if (stream._writev && entry && entry.next) {

// Fast case, write everything using _writev()

var l = state.bufferedRequestCount;

var buffer = new Array(l);

var holder = state.corkedRequestsFree;

holder.entry = entry;

var count = 0;

var allBuffers = true;

while (entry) {

buffer[count] = entry;

if (!entry.isBuf)

allBuffers = false;

entry = entry.next;

count += 1;

}

buffer.allBuffers = allBuffers;

doWrite(stream, state, true, state.length, buffer, '', holder.finish);

// doWrite is almost always async, defer these to save a bit of time

// as the hot path ends with doWrite

state.pendingcb++;

state.lastBufferedRequest = null;

if (holder.next) {

state.corkedRequestsFree = holder.next;

holder.next = null;

} else {

var corkReq = { next: null, entry: null, finish: undefined };

corkReq.finish = onCorkedFinish.bind(undefined, corkReq, state);

state.corkedRequestsFree = corkReq;

}

state.bufferedRequestCount = 0;

} else {

// Slow case, write chunks one-by-one

while (entry) {

var chunk = entry.chunk;

var encoding = entry.encoding;

var cb = entry.callback;

var len = state.objectMode ? 1 : chunk.length;

doWrite(stream, state, false, len, chunk, encoding, cb);

entry = entry.next;

state.bufferedRequestCount--;

// If we didn't call the onwrite immediately, then

// it means that we need to wait until it does.

// also, that means that the chunk and cb are currently

// being processed, so move the buffer counter past them.

if (state.writing) {

break;

}

}

if (entry === null)

state.lastBufferedRequest = null;

}

state.bufferedRequest = entry;

state.bufferProcessing = false;

}

Writable.prototype._write = function(chunk, encoding, cb) {

cb(new ERR_METHOD_NOT_IMPLEMENTED('_write()'));

};

Writable.prototype._writev = null;

Writable.prototype.end = function(chunk, encoding, cb) {

const state = this._writableState;

if (typeof chunk === 'function') {

cb = chunk;

chunk = null;

encoding = null;

} else if (typeof encoding === 'function') {

cb = encoding;

encoding = null;

}

if (chunk !== null && chunk !== undefined)

this.write(chunk, encoding);

// .end() fully uncorks

if (state.corked) {

state.corked = 1;

this.uncork();

}

// Ignore unnecessary end() calls.

if (!state.ending)

endWritable(this, state, cb);

return this;

};

Object.defineProperty(Writable.prototype, 'writableLength', {

// Making it explicit this property is not enumerable

// because otherwise some prototype manipulation in

// userland will fail

enumerable: false,

get() {

return this._writableState.length;

}

});

function needFinish(state) {

return (state.ending &&

state.length === 0 &&

state.bufferedRequest === null &&

!state.finished &&

!state.writing);

}

function callFinal(stream, state) {

stream._final((err) => {

state.pendingcb--;

if (err) {

errorOrDestroy(stream, err);

}

state.prefinished = true;

stream.emit('prefinish');

finishMaybe(stream, state);

});

}

function prefinish(stream, state) {

if (!state.prefinished && !state.finalCalled) {

if (typeof stream._final === 'function' && !state.destroyed) {

state.pendingcb++;

state.finalCalled = true;

process.nextTick(callFinal, stream, state);

} else {

state.prefinished = true;

stream.emit('prefinish');

}

}

}

function finishMaybe(stream, state) {

const need = needFinish(state);

if (need) {

prefinish(stream, state);

if (state.pendingcb === 0) {

state.finished = true;

stream.emit('finish');

if (state.autoDestroy) {

// In case of duplex streams we need a way to detect

// if the readable side is ready for autoDestroy as well

const rState = stream._readableState;

if (!rState || (rState.autoDestroy && rState.endEmitted)) {

stream.destroy();

}

}

}

}

return need;

}

function endWritable(stream, state, cb) {

state.ending = true;

finishMaybe(stream, state);

if (cb) {

if (state.finished)

process.nextTick(cb);

else

stream.once('finish', cb);

}

state.ended = true;

stream.writable = false;

}

function onCorkedFinish(corkReq, state, err) {

var entry = corkReq.entry;

corkReq.entry = null;

while (entry) {

var cb = entry.callback;

state.pendingcb--;

cb(err);

entry = entry.next;

}

// Reuse the free corkReq.

state.corkedRequestsFree.next = corkReq;

}

Object.defineProperty(Writable.prototype, 'destroyed', {

// Making it explicit this property is not enumerable

// because otherwise some prototype manipulation in

// userland will fail

enumerable: false,

get() {

if (this._writableState === undefined) {

return false;

}

return this._writableState.destroyed;

},

set(value) {

// We ignore the value if the stream

// has not been initialized yet

if (!this._writableState) {

return;

}

// Backward compatibility, the user is explicitly

// managing destroyed

this._writableState.destroyed = value;

}

});

Object.defineProperty(Writable.prototype, 'writableObjectMode', {

enumerable: false,

get() {

return this._writableState ? this._writableState.objectMode : false;

}

});

Writable.prototype.destroy = destroyImpl.destroy;

Writable.prototype._undestroy = destroyImpl.undestroy;

Writable.prototype._destroy = function(err, cb) {

cb(err);

};