runtimes/python: Added support for providing stdin

Issue: fossunited/monschool-website#54

runtimes/python/Dockerfile

@@ -5,4 +5,5 @@ WORKDIR /app
 COPY run.sh /opt/
 COPY runtests.py /opt/
 COPY modes /opt/modes/
+COPY sitecustomize.py /usr/local/lib/python3.9/
 ENTRYPOINT ["/opt/run.sh"]

runtimes/python/sitecustomize.py

@@ -0,0 +1,27 @@
+def _customize():
+    import os
+    import sys
+    import io
+    import json
+    import builtins
+
+    FALCON_STDIN = os.getenv("FALCON_STDIN")
+    if not FALCON_STDIN:
+        return
+    try:
+        stdin_json = '"' + FALCON_STDIN + '"'
+    except ValueError:
+        stdin_json = '""'
+    stdin_text = json.loads(stdin_json)
+    sys.stdin = io.StringIO(stdin_text)
+
+    def _input(prompt=None):
+        if prompt:
+            print(prompt, end="")
+        line = sys.stdin.readline().strip("\n")
+        print(line)
+        return line
+    builtins.input = _input
+
+_customize()
+del _customize