handling errors

extract.py

@@ -17,6 +17,10 @@ def parse_arguments():
     return parser.parse_args()
 
 
+def container_exists(container):
+    return subprocess.run('docker history {}'.format(container), shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE).returncode == 0
+
+
 def call_docker(input_file, container, target):
     tmpdir = TemporaryDirectory()
     tmp = tmpdir.name
@@ -28,12 +32,12 @@ def call_docker(input_file, container, target):
 
     subprocess.run('docker run --rm -v {}:/tmp/extractor -v /dev:/dev --privileged {}'.format(tmp, container), shell=True)
 
-    print('Moving files to {}'.format(target))
     shutil.copytree(str(Path(tmp, 'files')), target)
 
     try:
         tmpdir.cleanup()
     except PermissionError:
+        print('Cleanup requires root. If you would be so kind..')
         subprocess.run('sudo rm -rf {}'.format(tmpdir.name), shell=True)
         tmpdir.cleanup()
 
@@ -42,9 +46,21 @@ def main():
     arguments = parse_arguments()
 
     output_directory = arguments.output_directory if arguments.output_directory else str(Path(__file__).parent / 'extracted_files')
+    if Path(output_directory).exists():
+        print('Target directory exists ({}). Please choose a non-existing directory with -o option.'.format(output_directory))
+        return 1
+
+    if not container_exists(arguments.container):
+        print('Container {} doesn\'t exist. Please specify an existing container with the -c option.'.format(arguments.container))
+        return 1
+
+    if not Path(arguments.ARCHIVE[0]).is_file():
+        print('Given input file {} doesn\'t exist. Please give an existing path.'.format(arguments.ARCHIVE[0]))
 
     call_docker(arguments.ARCHIVE[0], arguments.container, output_directory)
 
+    return 0
+
 
 if __name__ == '__main__':
     sys.exit(main())