taglib-wasm/dist/src/taglib/metadata-extent.js

TagLib-Wasm is the universal tagging library for TypeScript/JavaScript platforms: Browsers, Node.js, Deno, Bun, Cloudflare Workers, and Electron apps

function be32(b, offset) {
  return (b[offset] << 24 | b[offset + 1] << 16 | b[offset + 2] << 8 | b[offset + 3]) >>> 0;
}
function startsWith(bytes, magic, at = 0) {
  if (bytes.length < at + magic.length) return false;
  for (let i = 0; i < magic.length; i++) {
    if (bytes[at + i] !== magic.charCodeAt(i)) return false;
  }
  return true;
}
function id3v2End(bytes) {
  if (bytes.length < 10) return void 0;
  const size = bytes[6] << 21 | bytes[7] << 14 | bytes[8] << 7 | bytes[9];
  const hasFooter = (bytes[5] & 16) !== 0;
  return 10 + size + (hasFooter ? 10 : 0);
}
function flacEnd(bytes, limit, start) {
  let offset = start + 4;
  for (; ; ) {
    if (offset + 4 > bytes.length) return void 0;
    const isLast = (bytes[offset] & 128) !== 0;
    const length = bytes[offset + 1] << 16 | bytes[offset + 2] << 8 | bytes[offset + 3];
    offset += 4 + length;
    if (offset > limit) return offset;
    if (isLast) return offset;
  }
}
function mp4MoovEnd(bytes, limit, start) {
  let offset = start;
  const readable = Math.min(bytes.length, limit);
  while (offset + 8 <= readable) {
    const size = be32(bytes, offset);
    const type = String.fromCharCode(
      bytes[offset + 4],
      bytes[offset + 5],
      bytes[offset + 6],
      bytes[offset + 7]
    );
    if (size < 8) return void 0;
    if (type === "moov") return offset + size;
    offset += size;
  }
  return void 0;
}
function oggMetadataEnd(bytes, limit, start) {
  let offset = start;
  let packetsCompleted = 0;
  let first = true;
  for (; ; ) {
    if (offset + 27 > bytes.length || !startsWith(bytes, "OggS", offset)) {
      return void 0;
    }
    const segmentCount = bytes[offset + 26];
    const tableStart = offset + 27;
    if (tableStart + segmentCount > bytes.length) return void 0;
    let payload = 0;
    for (let i = 0; i < segmentCount; i++) {
      const segment = bytes[tableStart + i];
      payload += segment;
      if (segment < 255) packetsCompleted++;
    }
    if (first) {
      const payloadStart = tableStart + segmentCount;
      if (payloadStart + 5 > bytes.length) return void 0;
      if (bytes[payloadStart] === 127 && startsWith(bytes, "FLAC", payloadStart + 1)) {
        return void 0;
      }
      first = false;
    }
    offset = tableStart + segmentCount + payload;
    if (packetsCompleted >= 2 || offset > limit) return offset;
  }
}
function isMpegFrameSync(bytes, at = 0) {
  if (bytes.length < at + 4) return false;
  if (bytes[at] !== 255 || (bytes[at + 1] & 224) !== 224) return false;
  const version = bytes[at + 1] >> 3 & 3;
  const layer = bytes[at + 1] >> 1 & 3;
  if (version === 1 || layer === 0) return false;
  const bitrateIndex = bytes[at + 2] >> 4 & 15;
  const sampleRateIndex = bytes[at + 2] >> 2 & 3;
  return bitrateIndex !== 0 && bitrateIndex !== 15 && sampleRateIndex !== 3;
}
function containerEnd(bytes, at, limit) {
  if (at >= bytes.length) return bytes.length < limit ? null : void 0;
  if (at + 8 > bytes.length) return void 0;
  if (startsWith(bytes, "fLaC", at)) return flacEnd(bytes, limit, at);
  if (startsWith(bytes, "ftyp", at + 4)) return mp4MoovEnd(bytes, limit, at);
  if (startsWith(bytes, "OggS", at)) return oggMetadataEnd(bytes, limit, at);
  return null;
}
function metadataFitsInHeader(header, limit) {
  let end;
  if (startsWith(header, "ID3")) {
    const tagEnd = id3v2End(header);
    if (tagEnd === void 0) return false;
    end = tagEnd;
    if (tagEnd <= limit) {
      const behind = containerEnd(header, tagEnd, limit);
      if (behind === void 0) return false;
      if (behind !== null) end = behind;
    }
  } else {
    const container = containerEnd(header, 0, limit);
    if (container === null) {
      end = isMpegFrameSync(header) ? 0 : void 0;
    } else {
      end = container;
    }
  }
  if (end === void 0 || end > header.length) return false;
  return end <= limit;
}
function trailerFitsInFooter(tail, footerSize) {
  if (tail.length < Math.min(footerSize, 32)) return false;
  for (const offsetFromEnd of [32, 32 + 128]) {
    const at = tail.length - offsetFromEnd;
    if (at < 0 || !startsWith(tail, "APETAGEX", at)) continue;
    const size = (tail[at + 12] | tail[at + 13] << 8 | tail[at + 14] << 16 | tail[at + 15] << 24) >>> 0;
    const trailing = offsetFromEnd === 32 ? 0 : 128;
    if (size + 32 + trailing > footerSize) return false;
  }
  return true;
}
export {
  metadataFitsInHeader,
  trailerFitsInFooter
};