| |
| """Extract one manifest-selected clip, verifying member hashes; stdlib only.""" |
| import argparse |
| import hashlib |
| import json |
| from pathlib import Path, PurePosixPath |
| import tarfile |
|
|
|
|
| def safe_relative(name): |
| path = PurePosixPath(name) |
| if path.is_absolute() or '..' in path.parts or '\\' in name: |
| raise ValueError(f'Unsafe relative path: {name!r}') |
| return path |
|
|
|
|
| def find_sample(root, sample_id): |
| with (root / 'manifests/train.jsonl').open(encoding='utf-8') as stream: |
| for line in stream: |
| row = json.loads(line) |
| if sample_id is None or row['sample_id'] == sample_id: |
| return row |
| raise ValueError(f'Sample not found: {sample_id}') |
|
|
|
|
| def extract(root, sample_id, destination): |
| row = find_sample(root, sample_id) |
| shard = (root / safe_relative(row['shard'])).resolve() |
| shard.relative_to(root.resolve()) |
| if destination.exists(): |
| raise FileExistsError(f'Choose a new output directory: {destination}') |
| destination.mkdir(parents=True) |
| files = {} |
| try: |
| with tarfile.open(shard, 'r:') as archive: |
| for kind, name in row['members'].items(): |
| relative = safe_relative(name) |
| if len(relative.parts) != 1: |
| raise ValueError(f'Expected a flat sample member: {name}') |
| member = archive.getmember(name) |
| if not member.isfile(): |
| raise ValueError(f'Expected regular file: {name}') |
| expected = row['sha256'].get(kind) |
| if not expected: |
| raise ValueError(f'No expected hash for {kind}') |
| path = destination / relative.name |
| digest = hashlib.sha256() |
| source = archive.extractfile(member) |
| if source is None: |
| raise ValueError(f'Unreadable member: {name}') |
| with source, path.open('xb') as output: |
| while chunk := source.read(1024 * 1024): |
| digest.update(chunk) |
| output.write(chunk) |
| if digest.hexdigest() != expected: |
| path.unlink() |
| raise ValueError(f'SHA256 mismatch: {name}') |
| files[kind] = str(path) |
| return {'sample_id': row['sample_id'], 'shard': row['shard'], |
| 'num_frames': row['num_frames'], 'fps': row['fps'], |
| 'duration_seconds': row['duration_seconds'], 'files': files} |
| except Exception: |
| |
| raise |
|
|
|
|
| def main(): |
| parser = argparse.ArgumentParser(description=__doc__) |
| parser.add_argument('--release-root', type=Path, required=True) |
| parser.add_argument('--sample-id', help='Defaults to the first manifest row') |
| parser.add_argument('--output', type=Path, required=True) |
| args = parser.parse_args() |
| result = extract(args.release_root, args.sample_id, args.output) |
| print(json.dumps(result, ensure_ascii=False, indent=2)) |
|
|
|
|
| if __name__ == '__main__': |
| main() |
|
|
