xbu/xau with custom message

bin/hooks/reject-and-explain.py

@@ -0,0 +1,61 @@
+#!/usr/bin/env python3
+
+import json
+import os
+import re
+import sys
+
+
+_ = r"""
+reject file upload (with a nice explanation why)
+
+example usage as global config:
+    --xbu j,c1,bin/hooks/reject-and-explain.py
+
+example usage as a volflag (per-volume config):
+    -v srv/inc:inc:r:rw,ed:c,xbu=j,c1,bin/hooks/reject-and-explain.py
+                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+    (share filesystem-path srv/inc as volume /inc,
+     readable by everyone, read-write for user 'ed',
+     running this plugin on all uploads with the params listed below)
+
+example usage as a volflag in a copyparty config file:
+    [/inc]
+      srv/inc
+      accs:
+        r: *
+        rw: ed
+      flags:
+        xbu: j,c1,bin/hooks/reject-and-explain.py
+
+parameters explained,
+    xbu = execute-before-upload  (can also be xau, execute-after-upload)
+    j   = this hook needs upload information as json (not just the filename)
+    c1  = this hook returns json on stdout, so tell copyparty to read that
+"""
+
+
+def main():
+    inf = json.loads(sys.argv[1])
+    vdir, fn = os.path.split(inf["vp"])
+    print("inf[vp] = %r" % (inf["vp"],), file=sys.stderr)
+
+    # reject upload if the following regex-pattern does not match:
+    ok = re.search(r"(^|/)day[0-9]+$", vdir, re.IGNORECASE)
+
+    if ok:
+        # allow the upload
+        print("{}")
+        return
+
+    # the upload was rejected; display the following errortext
+    # (NOTE: you can optionally mention {0!r} anywhere in the message (zero or more times), and it will be replaced with the file's URL)
+
+    errmsg = "Files can only be uploaded into a folder named 'DayN' where N is a number, for example 'Day573'. This file was REJECTED: "
+    errmsg += inf["vp"]  # mention the file's url at the end of the message
+    print(json.dumps({"rejectmsg": errmsg}))
+
+
+if __name__ == "__main__":
+    main()