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Mini Shell
Mini Shell
'use strict'
// parse a 512-byte header block to a data object, or vice-versa
// encode returns `true` if a pax extended header is needed, because
// the data could not be faithfully encoded in a simple header.
// (Also, check header.needPax to see if it needs a pax header.)
const types = require('./types.js')
const pathModule = require('path').posix
const large = require('./large-numbers.js')
const SLURP = Symbol('slurp')
const TYPE = Symbol('type')
class Header {
constructor (data, off, ex, gex) {
this.cksumValid = false
this.needPax = false
this.nullBlock = false
this.block = null
this.path = null
this.mode = null
this.uid = null
this.gid = null
this.size = null
this.mtime = null
this.cksum = null
this[TYPE] = '0'
this.linkpath = null
this.uname = null
this.gname = null
this.devmaj = 0
this.devmin = 0
this.atime = null
this.ctime = null
if (Buffer.isBuffer(data))
this.decode(data, off || 0, ex, gex)
else if (data)
this.set(data)
}
decode (buf, off, ex, gex) {
if (!off)
off = 0
if (!buf || !(buf.length >= off + 512))
throw new Error('need 512 bytes for header')
this.path = decString(buf, off, 100)
this.mode = decNumber(buf, off + 100, 8)
this.uid = decNumber(buf, off + 108, 8)
this.gid = decNumber(buf, off + 116, 8)
this.size = decNumber(buf, off + 124, 12)
this.mtime = decDate(buf, off + 136, 12)
this.cksum = decNumber(buf, off + 148, 12)
// if we have extended or global extended headers, apply them now
// See https://github.com/npm/node-tar/pull/187
this[SLURP](ex)
this[SLURP](gex, true)
// old tar versions marked dirs as a file with a trailing /
this[TYPE] = decString(buf, off + 156, 1)
if (this[TYPE] === '')
this[TYPE] = '0'
if (this[TYPE] === '0' && this.path.substr(-1) === '/')
this[TYPE] = '5'
// tar implementations sometimes incorrectly put the stat(dir).size
// as the size in the tarball, even though Directory entries are
// not able to have any body at all. In the very rare chance that
// it actually DOES have a body, we weren't going to do anything with
// it anyway, and it'll just be a warning about an invalid header.
if (this[TYPE] === '5')
this.size = 0
this.linkpath = decString(buf, off + 157, 100)
if (buf.slice(off + 257, off + 265).toString() === 'ustar\u000000') {
this.uname = decString(buf, off + 265, 32)
this.gname = decString(buf, off + 297, 32)
this.devmaj = decNumber(buf, off + 329, 8)
this.devmin = decNumber(buf, off + 337, 8)
if (buf[off + 475] !== 0) {
// definitely a prefix, definitely >130 chars.
const prefix = decString(buf, off + 345, 155)
this.path = prefix + '/' + this.path
} else {
const prefix = decString(buf, off + 345, 130)
if (prefix)
this.path = prefix + '/' + this.path
this.atime = decDate(buf, off + 476, 12)
this.ctime = decDate(buf, off + 488, 12)
}
}
let sum = 8 * 0x20
for (let i = off; i < off + 148; i++)
sum += buf[i]
for (let i = off + 156; i < off + 512; i++)
sum += buf[i]
this.cksumValid = sum === this.cksum
if (this.cksum === null && sum === 8 * 0x20)
this.nullBlock = true
}
[SLURP] (ex, global) {
for (const k in ex) {
// we slurp in everything except for the path attribute in
// a global extended header, because that's weird.
if (ex[k] !== null && ex[k] !== undefined &&
!(global && k === 'path'))
this[k] = ex[k]
}
}
encode (buf, off) {
if (!buf) {
buf = this.block = Buffer.alloc(512)
off = 0
}
if (!off)
off = 0
if (!(buf.length >= off + 512))
throw new Error('need 512 bytes for header')
const prefixSize = this.ctime || this.atime ? 130 : 155
const split = splitPrefix(this.path || '', prefixSize)
const path = split[0]
const prefix = split[1]
this.needPax = split[2]
this.needPax = encString(buf, off, 100, path) || this.needPax
this.needPax = encNumber(buf, off + 100, 8, this.mode) || this.needPax
this.needPax = encNumber(buf, off + 108, 8, this.uid) || this.needPax
this.needPax = encNumber(buf, off + 116, 8, this.gid) || this.needPax
this.needPax = encNumber(buf, off + 124, 12, this.size) || this.needPax
this.needPax = encDate(buf, off + 136, 12, this.mtime) || this.needPax
buf[off + 156] = this[TYPE].charCodeAt(0)
this.needPax = encString(buf, off + 157, 100, this.linkpath) || this.needPax
buf.write('ustar\u000000', off + 257, 8)
this.needPax = encString(buf, off + 265, 32, this.uname) || this.needPax
this.needPax = encString(buf, off + 297, 32, this.gname) || this.needPax
this.needPax = encNumber(buf, off + 329, 8, this.devmaj) || this.needPax
this.needPax = encNumber(buf, off + 337, 8, this.devmin) || this.needPax
this.needPax = encString(buf, off + 345, prefixSize, prefix) || this.needPax
if (buf[off + 475] !== 0)
this.needPax = encString(buf, off + 345, 155, prefix) || this.needPax
else {
this.needPax = encString(buf, off + 345, 130, prefix) || this.needPax
this.needPax = encDate(buf, off + 476, 12, this.atime) || this.needPax
this.needPax = encDate(buf, off + 488, 12, this.ctime) || this.needPax
}
let sum = 8 * 0x20
for (let i = off; i < off + 148; i++)
sum += buf[i]
for (let i = off + 156; i < off + 512; i++)
sum += buf[i]
this.cksum = sum
encNumber(buf, off + 148, 8, this.cksum)
this.cksumValid = true
return this.needPax
}
set (data) {
for (const i in data) {
if (data[i] !== null && data[i] !== undefined)
this[i] = data[i]
}
}
get type () {
return types.name.get(this[TYPE]) || this[TYPE]
}
get typeKey () {
return this[TYPE]
}
set type (type) {
if (types.code.has(type))
this[TYPE] = types.code.get(type)
else
this[TYPE] = type
}
}
const splitPrefix = (p, prefixSize) => {
const pathSize = 100
let pp = p
let prefix = ''
let ret
const root = pathModule.parse(p).root || '.'
if (Buffer.byteLength(pp) < pathSize)
ret = [pp, prefix, false]
else {
// first set prefix to the dir, and path to the base
prefix = pathModule.dirname(pp)
pp = pathModule.basename(pp)
do {
// both fit!
if (Buffer.byteLength(pp) <= pathSize &&
Buffer.byteLength(prefix) <= prefixSize)
ret = [pp, prefix, false]
// prefix fits in prefix, but path doesn't fit in path
else if (Buffer.byteLength(pp) > pathSize &&
Buffer.byteLength(prefix) <= prefixSize)
ret = [pp.substr(0, pathSize - 1), prefix, true]
else {
// make path take a bit from prefix
pp = pathModule.join(pathModule.basename(prefix), pp)
prefix = pathModule.dirname(prefix)
}
} while (prefix !== root && !ret)
// at this point, found no resolution, just truncate
if (!ret)
ret = [p.substr(0, pathSize - 1), '', true]
}
return ret
}
const decString = (buf, off, size) =>
buf.slice(off, off + size).toString('utf8').replace(/\0.*/, '')
const decDate = (buf, off, size) =>
numToDate(decNumber(buf, off, size))
const numToDate = num => num === null ? null : new Date(num * 1000)
const decNumber = (buf, off, size) =>
buf[off] & 0x80 ? large.parse(buf.slice(off, off + size))
: decSmallNumber(buf, off, size)
const nanNull = value => isNaN(value) ? null : value
const decSmallNumber = (buf, off, size) =>
nanNull(parseInt(
buf.slice(off, off + size)
.toString('utf8').replace(/\0.*$/, '').trim(), 8))
// the maximum encodable as a null-terminated octal, by field size
const MAXNUM = {
12: 0o77777777777,
8: 0o7777777,
}
const encNumber = (buf, off, size, number) =>
number === null ? false :
number > MAXNUM[size] || number < 0
? (large.encode(number, buf.slice(off, off + size)), true)
: (encSmallNumber(buf, off, size, number), false)
const encSmallNumber = (buf, off, size, number) =>
buf.write(octalString(number, size), off, size, 'ascii')
const octalString = (number, size) =>
padOctal(Math.floor(number).toString(8), size)
const padOctal = (string, size) =>
(string.length === size - 1 ? string
: new Array(size - string.length - 1).join('0') + string + ' ') + '\0'
const encDate = (buf, off, size, date) =>
date === null ? false :
encNumber(buf, off, size, date.getTime() / 1000)
// enough to fill the longest string we've got
const NULLS = new Array(156).join('\0')
// pad with nulls, return true if it's longer or non-ascii
const encString = (buf, off, size, string) =>
string === null ? false :
(buf.write(string + NULLS, off, size, 'utf8'),
string.length !== Buffer.byteLength(string) || string.length > size)
module.exports = Header
Zerion Mini Shell 1.0