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calibre-web/cps/static/js/compress/libuntar.js

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// Copyright (c) 2017 Matthew Brennan Jones <matthew.brennan.jones@gmail.com>
// This software is licensed under a MIT License
// https://github.com/workhorsy/uncompress.js
"use strict";
// Based on the information from:
// https://en.wikipedia.org/wiki/Tar_(computing)
(function() {
const TAR_TYPE_FILE = 0;
const TAR_TYPE_DIR = 5;
const TAR_HEADER_SIZE = 512;
const TAR_TYPE_OFFSET = 156;
const TAR_TYPE_SIZE = 1;
const TAR_SIZE_OFFSET = 124;
const TAR_SIZE_SIZE = 12;
const TAR_NAME_OFFSET = 0;
const TAR_NAME_SIZE = 100;
function _tarRead(view, offset, size) {
return view.slice(offset, offset + size);
}
function tarGetEntries(filename, array_buffer) {
let view = new Uint8Array(array_buffer);
let offset = 0;
let entries = [];
while (offset + TAR_HEADER_SIZE < view.byteLength) {
// Get entry name
let entry_name = saneMap(_tarRead(view, offset + TAR_NAME_OFFSET, TAR_NAME_SIZE), String.fromCharCode);
entry_name = entry_name.join('').replace(/\0/g, '');
// No entry name, so probably the last block
if (entry_name.length === 0) {
break;
}
// Get entry size
let entry_size = parseInt(saneJoin(saneMap(_tarRead(view, offset + TAR_SIZE_OFFSET, TAR_SIZE_SIZE), String.fromCharCode), ''), 8);
let entry_type = saneMap(_tarRead(view, offset + TAR_TYPE_OFFSET, TAR_TYPE_SIZE), String.fromCharCode) | 0;
// Save this as en entry if it is a file or directory
if (entry_type === TAR_TYPE_FILE || entry_type === TAR_TYPE_DIR) {
let entry = {
name: entry_name,
size: entry_size,
is_file: entry_type == TAR_TYPE_FILE,
offset: offset
};
entries.push(entry);
}
// Round the offset up to be divisible by TAR_HEADER_SIZE
offset += (entry_size + TAR_HEADER_SIZE);
if (offset % TAR_HEADER_SIZE > 0) {
let even = (offset / TAR_HEADER_SIZE) | 0; // number of times it goes evenly into TAR_HEADER_SIZE
offset = (even + 1) * TAR_HEADER_SIZE;
}
}
return entries;
}
function tarGetEntryData(entry, array_buffer) {
let view = new Uint8Array(array_buffer);
let offset = entry.offset;
let size = entry.size;
// Get entry data
let entry_data = _tarRead(view, offset + TAR_HEADER_SIZE, size);
return entry_data;
}
// Figure out if we are running in a Window or Web Worker
let scope = null;
if (typeof window === 'object') {
scope = window;
} else if (typeof importScripts === 'function') {
scope = self;
}
// Set exports
scope.tarGetEntries = tarGetEntries;
scope.tarGetEntryData = tarGetEntryData;
})();