Enhance OSS-Fuzz vuln import script

Refactor the script to import failed OSS-Fuzz vulns for manual fixup. Improvements include code organization, error handling, and YAML formatting.

scripts/import.py

@@ -1,54 +1,50 @@
-# Script to import failed OSS-Fuzz vulns for manual fixup.
+Python
 import json
 import os
 import sys
 import urllib.error
 import urllib.request
-
 import yaml
 
 _BUCKET = 'oss-fuzz-osv-vulns'
 _VULN_URL = f'https://{_BUCKET}.storage.googleapis.com/issue'
 _ROOT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 
+class YamlDumper(yaml.SafeDumper):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.add_representer(str, self.yaml_str_representer)
 
-def _yaml_str_representer(dumper, data):
-  """YAML str representer override."""
-  if '\n' in data:
-    return dumper.represent_scalar('tag:yaml.org,2002:str', data, style='|')
-  return dumper.represent_scalar('tag:yaml.org,2002:str', data)
-
-
-class _YamlDumper(yaml.SafeDumper):
-  """Overridden dumper to to use | for multiline strings."""
-
-
-_YamlDumper.add_representer(str, _yaml_str_representer)
+    def yaml_str_representer(self, dumper, data):
+        if '\n' in data:
+            return dumper.represent_scalar('tag:yaml.org,2002:str', data, style='|')
+        return dumper.represent_scalar('tag:yaml.org,2002:str', data)
 
 
 def main():
-  if len(sys.argv) < 2:
-    print(f'Usage: {sys.argv[0]} <oss-fuzz issue_id>')
+    if len(sys.argv) != 2:
+        print(f'Usage: {sys.argv[0]} <oss-fuzz issue_id>')
+        sys.exit(1)
 
-  issue_id = sys.argv[1]
-  try:
-    data = urllib.request.urlopen(f'{_VULN_URL}/{issue_id}.json').read()
-  except urllib.error.HTTPError:
-    print('Vuln does not exist. OSS-Fuzz bugs need to '
-          'be marked as security to be included.', file=sys.stderr)
-    return
+    issue_id = sys.argv[1]
+    try:
+        with urllib.request.urlopen(f'{_VULN_URL}/{issue_id}.json') as response:
+            data = json.loads(response.read())
+    except urllib.error.HTTPError:
+        print('Vuln does not exist. OSS-Fuzz bugs need to '
+              'be marked as security to be included.', file=sys.stderr)
+        sys.exit(1)
 
-  data = json.loads(data)
-  project_name = data['package']['name']
-  project_dir = os.path.join(_ROOT_DIR, 'vulns', project_name)
-  os.makedirs(project_dir, exist_ok=True)
-  vuln_path = os.path.join(project_dir, issue_id + '.yaml')
+    project_name = data['package']['name']
+    project_dir = os.path.join(_ROOT_DIR, 'vulns', project_name)
+    os.makedirs(project_dir, exist_ok=True)
+    vuln_path = os.path.join(project_dir, issue_id + '.yaml')
 
-  with open(vuln_path, 'w') as handle:
-    yaml.dump(data, handle, sort_keys=False, Dumper=_YamlDumper)
+    with open(vuln_path, 'w') as handle:
+        yaml.dump(data, handle, sort_keys=False, Dumper=YamlDumper)
 
-  print('Vuln written to', os.path.relpath(vuln_path, os.getcwd()))
+    print('Vuln written to', os.path.relpath(vuln_path, os.getcwd()))
 
 
 if __name__ == '__main__':
-  main()
+    main()