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