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Mini Shell
Mini Shell
'use strict'
const MiniPass = require('minipass')
const EE = require('events').EventEmitter
const fs = require('fs')
let writev = fs.writev
/* istanbul ignore next */
if (!writev) {
// This entire block can be removed if support for earlier than Node.js
// 12.9.0 is not needed.
const binding = process.binding('fs')
const FSReqWrap = binding.FSReqWrap || binding.FSReqCallback
writev = (fd, iovec, pos, cb) => {
const done = (er, bw) => cb(er, bw, iovec)
const req = new FSReqWrap()
req.oncomplete = done
binding.writeBuffers(fd, iovec, pos, req)
}
}
const _autoClose = Symbol('_autoClose')
const _close = Symbol('_close')
const _ended = Symbol('_ended')
const _fd = Symbol('_fd')
const _finished = Symbol('_finished')
const _flags = Symbol('_flags')
const _flush = Symbol('_flush')
const _handleChunk = Symbol('_handleChunk')
const _makeBuf = Symbol('_makeBuf')
const _mode = Symbol('_mode')
const _needDrain = Symbol('_needDrain')
const _onerror = Symbol('_onerror')
const _onopen = Symbol('_onopen')
const _onread = Symbol('_onread')
const _onwrite = Symbol('_onwrite')
const _open = Symbol('_open')
const _path = Symbol('_path')
const _pos = Symbol('_pos')
const _queue = Symbol('_queue')
const _read = Symbol('_read')
const _readSize = Symbol('_readSize')
const _reading = Symbol('_reading')
const _remain = Symbol('_remain')
const _size = Symbol('_size')
const _write = Symbol('_write')
const _writing = Symbol('_writing')
const _defaultFlag = Symbol('_defaultFlag')
const _errored = Symbol('_errored')
class ReadStream extends MiniPass {
constructor (path, opt) {
opt = opt || {}
super(opt)
this.readable = true
this.writable = false
if (typeof path !== 'string')
throw new TypeError('path must be a string')
this[_errored] = false
this[_fd] = typeof opt.fd === 'number' ? opt.fd : null
this[_path] = path
this[_readSize] = opt.readSize || 16*1024*1024
this[_reading] = false
this[_size] = typeof opt.size === 'number' ? opt.size : Infinity
this[_remain] = this[_size]
this[_autoClose] = typeof opt.autoClose === 'boolean' ?
opt.autoClose : true
if (typeof this[_fd] === 'number')
this[_read]()
else
this[_open]()
}
get fd () { return this[_fd] }
get path () { return this[_path] }
write () {
throw new TypeError('this is a readable stream')
}
end () {
throw new TypeError('this is a readable stream')
}
[_open] () {
fs.open(this[_path], 'r', (er, fd) => this[_onopen](er, fd))
}
[_onopen] (er, fd) {
if (er)
this[_onerror](er)
else {
this[_fd] = fd
this.emit('open', fd)
this[_read]()
}
}
[_makeBuf] () {
return Buffer.allocUnsafe(Math.min(this[_readSize], this[_remain]))
}
[_read] () {
if (!this[_reading]) {
this[_reading] = true
const buf = this[_makeBuf]()
/* istanbul ignore if */
if (buf.length === 0)
return process.nextTick(() => this[_onread](null, 0, buf))
fs.read(this[_fd], buf, 0, buf.length, null, (er, br, buf) =>
this[_onread](er, br, buf))
}
}
[_onread] (er, br, buf) {
this[_reading] = false
if (er)
this[_onerror](er)
else if (this[_handleChunk](br, buf))
this[_read]()
}
[_close] () {
if (this[_autoClose] && typeof this[_fd] === 'number') {
const fd = this[_fd]
this[_fd] = null
fs.close(fd, er => er ? this.emit('error', er) : this.emit('close'))
}
}
[_onerror] (er) {
this[_reading] = true
this[_close]()
this.emit('error', er)
}
[_handleChunk] (br, buf) {
let ret = false
// no effect if infinite
this[_remain] -= br
if (br > 0)
ret = super.write(br < buf.length ? buf.slice(0, br) : buf)
if (br === 0 || this[_remain] <= 0) {
ret = false
this[_close]()
super.end()
}
return ret
}
emit (ev, data) {
switch (ev) {
case 'prefinish':
case 'finish':
break
case 'drain':
if (typeof this[_fd] === 'number')
this[_read]()
break
case 'error':
if (this[_errored])
return
this[_errored] = true
return super.emit(ev, data)
default:
return super.emit(ev, data)
}
}
}
class ReadStreamSync extends ReadStream {
[_open] () {
let threw = true
try {
this[_onopen](null, fs.openSync(this[_path], 'r'))
threw = false
} finally {
if (threw)
this[_close]()
}
}
[_read] () {
let threw = true
try {
if (!this[_reading]) {
this[_reading] = true
do {
const buf = this[_makeBuf]()
/* istanbul ignore next */
const br = buf.length === 0 ? 0
: fs.readSync(this[_fd], buf, 0, buf.length, null)
if (!this[_handleChunk](br, buf))
break
} while (true)
this[_reading] = false
}
threw = false
} finally {
if (threw)
this[_close]()
}
}
[_close] () {
if (this[_autoClose] && typeof this[_fd] === 'number') {
const fd = this[_fd]
this[_fd] = null
fs.closeSync(fd)
this.emit('close')
}
}
}
class WriteStream extends EE {
constructor (path, opt) {
opt = opt || {}
super(opt)
this.readable = false
this.writable = true
this[_errored] = false
this[_writing] = false
this[_ended] = false
this[_needDrain] = false
this[_queue] = []
this[_path] = path
this[_fd] = typeof opt.fd === 'number' ? opt.fd : null
this[_mode] = opt.mode === undefined ? 0o666 : opt.mode
this[_pos] = typeof opt.start === 'number' ? opt.start : null
this[_autoClose] = typeof opt.autoClose === 'boolean' ?
opt.autoClose : true
// truncating makes no sense when writing into the middle
const defaultFlag = this[_pos] !== null ? 'r+' : 'w'
this[_defaultFlag] = opt.flags === undefined
this[_flags] = this[_defaultFlag] ? defaultFlag : opt.flags
if (this[_fd] === null)
this[_open]()
}
emit (ev, data) {
if (ev === 'error') {
if (this[_errored])
return
this[_errored] = true
}
return super.emit(ev, data)
}
get fd () { return this[_fd] }
get path () { return this[_path] }
[_onerror] (er) {
this[_close]()
this[_writing] = true
this.emit('error', er)
}
[_open] () {
fs.open(this[_path], this[_flags], this[_mode],
(er, fd) => this[_onopen](er, fd))
}
[_onopen] (er, fd) {
if (this[_defaultFlag] &&
this[_flags] === 'r+' &&
er && er.code === 'ENOENT') {
this[_flags] = 'w'
this[_open]()
} else if (er)
this[_onerror](er)
else {
this[_fd] = fd
this.emit('open', fd)
this[_flush]()
}
}
end (buf, enc) {
if (buf)
this.write(buf, enc)
this[_ended] = true
// synthetic after-write logic, where drain/finish live
if (!this[_writing] && !this[_queue].length &&
typeof this[_fd] === 'number')
this[_onwrite](null, 0)
return this
}
write (buf, enc) {
if (typeof buf === 'string')
buf = Buffer.from(buf, enc)
if (this[_ended]) {
this.emit('error', new Error('write() after end()'))
return false
}
if (this[_fd] === null || this[_writing] || this[_queue].length) {
this[_queue].push(buf)
this[_needDrain] = true
return false
}
this[_writing] = true
this[_write](buf)
return true
}
[_write] (buf) {
fs.write(this[_fd], buf, 0, buf.length, this[_pos], (er, bw) =>
this[_onwrite](er, bw))
}
[_onwrite] (er, bw) {
if (er)
this[_onerror](er)
else {
if (this[_pos] !== null)
this[_pos] += bw
if (this[_queue].length)
this[_flush]()
else {
this[_writing] = false
if (this[_ended] && !this[_finished]) {
this[_finished] = true
this[_close]()
this.emit('finish')
} else if (this[_needDrain]) {
this[_needDrain] = false
this.emit('drain')
}
}
}
}
[_flush] () {
if (this[_queue].length === 0) {
if (this[_ended])
this[_onwrite](null, 0)
} else if (this[_queue].length === 1)
this[_write](this[_queue].pop())
else {
const iovec = this[_queue]
this[_queue] = []
writev(this[_fd], iovec, this[_pos],
(er, bw) => this[_onwrite](er, bw))
}
}
[_close] () {
if (this[_autoClose] && typeof this[_fd] === 'number') {
const fd = this[_fd]
this[_fd] = null
fs.close(fd, er => er ? this.emit('error', er) : this.emit('close'))
}
}
}
class WriteStreamSync extends WriteStream {
[_open] () {
let fd
// only wrap in a try{} block if we know we'll retry, to avoid
// the rethrow obscuring the error's source frame in most cases.
if (this[_defaultFlag] && this[_flags] === 'r+') {
try {
fd = fs.openSync(this[_path], this[_flags], this[_mode])
} catch (er) {
if (er.code === 'ENOENT') {
this[_flags] = 'w'
return this[_open]()
} else
throw er
}
} else
fd = fs.openSync(this[_path], this[_flags], this[_mode])
this[_onopen](null, fd)
}
[_close] () {
if (this[_autoClose] && typeof this[_fd] === 'number') {
const fd = this[_fd]
this[_fd] = null
fs.closeSync(fd)
this.emit('close')
}
}
[_write] (buf) {
// throw the original, but try to close if it fails
let threw = true
try {
this[_onwrite](null,
fs.writeSync(this[_fd], buf, 0, buf.length, this[_pos]))
threw = false
} finally {
if (threw)
try { this[_close]() } catch (_) {}
}
}
}
exports.ReadStream = ReadStream
exports.ReadStreamSync = ReadStreamSync
exports.WriteStream = WriteStream
exports.WriteStreamSync = WriteStreamSync
Zerion Mini Shell 1.0