src/lib/zip.js - master - andruxakonst/MCP-git-reader

src/lib/zip.js
86 строк3 KB
andruxakonst
Initial commit
26 июн 2026, 18:10
26 июн 2026, 18:10b091eb8
const zlib = require('node:zlib');

const EOCD_SIGNATURE = 0x06054b50;
const CENTRAL_DIRECTORY_SIGNATURE = 0x02014b50;
const LOCAL_FILE_HEADER_SIGNATURE = 0x04034b50;

function findEocd(buffer) {
  const minOffset = Math.max(0, buffer.length - 22 - 0xffff);
  for (let offset = buffer.length - 22; offset >= minOffset; offset -= 1) {
    if (buffer.readUInt32LE(offset) === EOCD_SIGNATURE) {
      return offset;
    }
  }
  throw new Error('Invalid ZIP archive: EOCD not found');
}

function listZipEntries(buffer) {
  const eocdOffset = findEocd(buffer);
  const centralDirectoryOffset = buffer.readUInt32LE(eocdOffset + 16);
  const entryCount = buffer.readUInt16LE(eocdOffset + 10);

  const entries = [];
  let offset = centralDirectoryOffset;

  for (let index = 0; index < entryCount; index += 1) {
    const signature = buffer.readUInt32LE(offset);
    if (signature !== CENTRAL_DIRECTORY_SIGNATURE) {
      throw new Error('Invalid ZIP archive: central directory entry missing');
    }

    const compressionMethod = buffer.readUInt16LE(offset + 10);
    const compressedSize = buffer.readUInt32LE(offset + 20);
    const uncompressedSize = buffer.readUInt32LE(offset + 24);
    const fileNameLength = buffer.readUInt16LE(offset + 28);
    const extraLength = buffer.readUInt16LE(offset + 30);
    const commentLength = buffer.readUInt16LE(offset + 32);
    const localHeaderOffset = buffer.readUInt32LE(offset + 42);
    const fileName = buffer.toString('utf8', offset + 46, offset + 46 + fileNameLength);

    entries.push({
      path: fileName,
      size: uncompressedSize,
      compressedSize,
      compressionMethod,
      localHeaderOffset,
    });

    offset += 46 + fileNameLength + extraLength + commentLength;
  }

  return entries;
}

function extractEntry(buffer, entry) {
  const localHeaderOffset = entry.localHeaderOffset;
  if (buffer.readUInt32LE(localHeaderOffset) !== LOCAL_FILE_HEADER_SIGNATURE) {
    throw new Error(`Invalid ZIP archive: missing local header for ${entry.path}`);
  }

  const fileNameLength = buffer.readUInt16LE(localHeaderOffset + 26);
  const extraLength = buffer.readUInt16LE(localHeaderOffset + 28);
  const dataOffset = localHeaderOffset + 30 + fileNameLength + extraLength;
  const compressed = buffer.subarray(dataOffset, dataOffset + entry.compressedSize);

  if (entry.compressionMethod === 0) {
    return compressed;
  }
  if (entry.compressionMethod === 8) {
    return zlib.inflateRawSync(compressed);
  }

  throw new Error(`Unsupported ZIP compression method: ${entry.compressionMethod}`);
}

function readZipEntry(buffer, path) {
  const entry = listZipEntries(buffer).find((candidate) => candidate.path === path);
  if (!entry) {
    throw new Error(`ZIP entry not found: ${path}`);
  }
  return extractEntry(buffer, entry);
}

module.exports = {
  listZipEntries,
  readZipEntry,
};