Verify downloaded file integrity #1
Description
After downloading a photo or video, verify the file arrived correctly.
Options to consider:
- File size check against Content-Length header
- Image validation (e.g. JPEG ends with FFD9 bytes)
- Checksum comparison (Flickr doesn't provide checksums, so only useful for detecting corruption on subsequent runs)
Down already raises on truncated downloads by default, so the worst cases may already be handled.