132 lines
4.5 KiB
TypeScript
132 lines
4.5 KiB
TypeScript
const textEncoder = new TextEncoder();
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const crcTable = new Uint32Array(256);
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for (let i = 0; i < 256; i++) {
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let crc = i;
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for (let bit = 0; bit < 8; bit++) {
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crc = (crc & 1) === 1 ? (crc >>> 1) ^ 0xedb88320 : crc >>> 1;
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}
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crcTable[i] = crc >>> 0;
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}
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function normalizeArchivePath(pathValue: string) {
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return pathValue
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.replace(/\\/g, "/")
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.split("/")
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.filter(Boolean)
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.join("/");
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}
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function crc32(bytes: Uint8Array) {
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let crc = 0xffffffff;
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for (const byte of bytes) {
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crc = (crc >>> 8) ^ crcTable[(crc ^ byte) & 0xff]!;
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}
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return (crc ^ 0xffffffff) >>> 0;
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}
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function writeUint16(target: Uint8Array, offset: number, value: number) {
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target[offset] = value & 0xff;
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target[offset + 1] = (value >>> 8) & 0xff;
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}
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function writeUint32(target: Uint8Array, offset: number, value: number) {
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target[offset] = value & 0xff;
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target[offset + 1] = (value >>> 8) & 0xff;
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target[offset + 2] = (value >>> 16) & 0xff;
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target[offset + 3] = (value >>> 24) & 0xff;
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}
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function getDosDateTime(date: Date) {
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const year = Math.min(Math.max(date.getFullYear(), 1980), 2107);
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const month = date.getMonth() + 1;
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const day = date.getDate();
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const hours = date.getHours();
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const minutes = date.getMinutes();
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const seconds = Math.floor(date.getSeconds() / 2);
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return {
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time: (hours << 11) | (minutes << 5) | seconds,
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date: ((year - 1980) << 9) | (month << 5) | day,
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};
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}
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function concatChunks(chunks: Uint8Array[]) {
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const totalLength = chunks.reduce((sum, chunk) => sum + chunk.length, 0);
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const archive = new Uint8Array(totalLength);
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let offset = 0;
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for (const chunk of chunks) {
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archive.set(chunk, offset);
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offset += chunk.length;
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}
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return archive;
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}
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export function createZipArchive(files: Record<string, string>, rootPath: string): Uint8Array {
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const normalizedRoot = normalizeArchivePath(rootPath);
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const localChunks: Uint8Array[] = [];
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const centralChunks: Uint8Array[] = [];
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const archiveDate = getDosDateTime(new Date());
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let localOffset = 0;
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let entryCount = 0;
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for (const [relativePath, contents] of Object.entries(files).sort(([left], [right]) => left.localeCompare(right))) {
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const archivePath = normalizeArchivePath(`${normalizedRoot}/${relativePath}`);
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const fileName = textEncoder.encode(archivePath);
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const body = textEncoder.encode(contents);
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const checksum = crc32(body);
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const localHeader = new Uint8Array(30 + fileName.length);
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writeUint32(localHeader, 0, 0x04034b50);
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writeUint16(localHeader, 4, 20);
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writeUint16(localHeader, 6, 0x0800);
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writeUint16(localHeader, 8, 0);
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writeUint16(localHeader, 10, archiveDate.time);
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writeUint16(localHeader, 12, archiveDate.date);
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writeUint32(localHeader, 14, checksum);
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writeUint32(localHeader, 18, body.length);
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writeUint32(localHeader, 22, body.length);
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writeUint16(localHeader, 26, fileName.length);
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writeUint16(localHeader, 28, 0);
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localHeader.set(fileName, 30);
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const centralHeader = new Uint8Array(46 + fileName.length);
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writeUint32(centralHeader, 0, 0x02014b50);
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writeUint16(centralHeader, 4, 20);
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writeUint16(centralHeader, 6, 20);
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writeUint16(centralHeader, 8, 0x0800);
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writeUint16(centralHeader, 10, 0);
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writeUint16(centralHeader, 12, archiveDate.time);
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writeUint16(centralHeader, 14, archiveDate.date);
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writeUint32(centralHeader, 16, checksum);
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writeUint32(centralHeader, 20, body.length);
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writeUint32(centralHeader, 24, body.length);
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writeUint16(centralHeader, 28, fileName.length);
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writeUint16(centralHeader, 30, 0);
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writeUint16(centralHeader, 32, 0);
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writeUint16(centralHeader, 34, 0);
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writeUint16(centralHeader, 36, 0);
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writeUint32(centralHeader, 38, 0);
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writeUint32(centralHeader, 42, localOffset);
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centralHeader.set(fileName, 46);
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localChunks.push(localHeader, body);
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centralChunks.push(centralHeader);
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localOffset += localHeader.length + body.length;
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entryCount += 1;
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}
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const centralDirectory = concatChunks(centralChunks);
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const endOfCentralDirectory = new Uint8Array(22);
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writeUint32(endOfCentralDirectory, 0, 0x06054b50);
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writeUint16(endOfCentralDirectory, 4, 0);
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writeUint16(endOfCentralDirectory, 6, 0);
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writeUint16(endOfCentralDirectory, 8, entryCount);
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writeUint16(endOfCentralDirectory, 10, entryCount);
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writeUint32(endOfCentralDirectory, 12, centralDirectory.length);
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writeUint32(endOfCentralDirectory, 16, localOffset);
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writeUint16(endOfCentralDirectory, 20, 0);
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return concatChunks([...localChunks, centralDirectory, endOfCentralDirectory]);
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}
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