Function isPNG

src/node/validate.ts:18–31

* Check if a buffer contains a valid PNG file signature

(buffer: Buffer)

 * Check if a buffer contains a valid PNG file signature
 */
function isPNG(buffer: Buffer): boolean {
  // PNG signature: 89 50 4E 47 0D 0A 1A 0A
  return (
    buffer.length >= 8 &&
    buffer[0] === 0x89 &&
    buffer[1] === 0x50 &&
    buffer[2] === 0x4e &&
    buffer[3] === 0x47 &&
    buffer[4] === 0x0d &&
    buffer[5] === 0x0a &&
    buffer[6] === 0x1a &&
    buffer[7] === 0x0a
  );
}

/**
 * Validate icon field in manifest