1 files changed, 57 insertions, 0 deletions
diff --git a/src/ipcMain/crxToZip.ts b/src/ipcMain/crxToZip.ts
new file mode 100644
index 0000000..ca43890
--- /dev/null
+++ b/src/ipcMain/crxToZip.ts
@@ -0,0 +1,57 @@
+/* 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);
+}