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/* eslint-disable header/header */
/*!
* crxToZip
* Copyright (c) 2013 Rob Wu <rob@robwu.nl>
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
export function crxToZip(buf: Buffer) {
function calcLength(a: number, b: number, c: number, d: number) {
let length = 0;
length += a << 0;
length += b << 8;
length += c << 16;
length += d << 24 >>> 0;
return length;
}
// 50 4b 03 04
// This is actually a zip file
if (buf[0] === 80 && buf[1] === 75 && buf[2] === 3 && buf[3] === 4) {
return buf;
}
// 43 72 32 34 (Cr24)
if (buf[0] !== 67 || buf[1] !== 114 || buf[2] !== 50 || buf[3] !== 52) {
throw new Error("Invalid header: Does not start with Cr24");
}
// 02 00 00 00
// or
// 03 00 00 00
const isV3 = buf[4] === 3;
const isV2 = buf[4] === 2;
if ((!isV2 && !isV3) || buf[5] || buf[6] || buf[7]) {
throw new Error("Unexpected crx format version number.");
}
if (isV2) {
const publicKeyLength = calcLength(buf[8], buf[9], buf[10], buf[11]);
const signatureLength = calcLength(buf[12], buf[13], buf[14], buf[15]);
// 16 = Magic number (4), CRX format version (4), lengths (2x4)
const zipStartOffset = 16 + publicKeyLength + signatureLength;
return buf.subarray(zipStartOffset, buf.length);
}
// v3 format has header size and then header
const headerSize = calcLength(buf[8], buf[9], buf[10], buf[11]);
const zipStartOffset = 12 + headerSize;
return buf.subarray(zipStartOffset, buf.length);
}
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