import runpy

import sys

import json

RESULT_PREFIX = "___RESULT_JSON___:"

def main():

"""

Wrapper executed inside nsjail.

- Loads the user script from the given path.

- Retrieves and calls main().

- Ensures the return value is JSON-serializable.

- Prints a single RESULT_PREFIX + JSON line to stdout.

"""

if len(sys.argv) != 2:

print("Usage: executor.py <path_to_script>", file=sys.stderr)

sys.exit(1)

script_path = sys.argv[1]

# Execute the user's script in its own global namespace

try:

script_globals = runpy.run_path(script_path)

except Exception as e:

print(f"Error while executing user script: {e}", file=sys.stderr)

sys.exit(1)

# Get the main() function

user_main = script_globals.get("main")

if not callable(user_main):

print("Error: Script must define a callable main()", file=sys.stderr)

sys.exit(1)

# Call main()

try:

result = user_main()

except Exception as e:

print(f"Error while running main(): {e}", file=sys.stderr)

sys.exit(1)

# Ensure it's JSON-serializable

try:

json_str = json.dumps(result)

except TypeError as e:

print(f"Error: main() must return JSON-serializable object: {e}", file=sys.stderr)

sys.exit(1)

# Print the result with the defined prefix to parse it in the endpoint

print(f"{RESULT_PREFIX}{json_str}")

if __name__ == "__main__":

main()