hooks: add wget-i.py (import-safe) (#904)

bin/hooks/README.md

@@ -35,6 +35,7 @@ these are `--xiu` hooks; unlike `xbu` and `xau` (which get executed on every sin
 
 # on message
 * [wget.py](wget.py) lets you download files by POSTing URLs to copyparty
+  * [wget-i.py](wget-i.py) is an import-safe modification of this hook (starts 140x faster, but higher chance of bugs)
 * [qbittorrent-magnet.py](qbittorrent-magnet.py) starts downloading a torrent if you post a magnet url
 * [usb-eject.py](usb-eject.py) adds web-UI buttons to safe-remove usb flashdrives shared through copyparty
 * [msg-log.py](msg-log.py) is a guestbook; logs messages to a doc in the same folder
@@ -42,3 +43,4 @@ these are `--xiu` hooks; unlike `xbu` and `xau` (which get executed on every sin
 
 # general concept demos
 * [import-me.py](import-me.py) shows how the `I` flag makes the hook 140x faster (but you need to be Very Careful when writing the plugin)
+  * [wget-i.py](wget-i.py) is an import-safe modification of [wget.py](wget.py)

bin/hooks/wget-i.py

@@ -0,0 +1,97 @@
+#!/usr/bin/env python3
+
+import os
+import threading
+import subprocess as sp
+
+
+_ = r"""
+use copyparty as a file downloader by POSTing URLs as
+application/x-www-form-urlencoded (for example using the
+📟 message-to-server-log in the web-ui)
+
+this hook is a modified copy of wget.py, modified to
+make it import-safe so it can be run with the 'I' flag,
+which speeds up the startup time of the hook by 140x
+
+example usage as global config:
+    --xm aw,I,bin/hooks/wget-i.py
+
+parameters explained,
+    xm = execute on message-to-server-log
+    aw = only users with write-access can use this
+    I = import; do not fork / subprocess
+
+example usage as a volflag (per-volume config):
+    -v srv/inc:inc:r:rw,ed:c,xm=aw,I,bin/hooks/wget.py
+                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+    (share filesystem-path srv/inc as volume /inc,
+     readable by everyone, read-write for user 'ed',
+     running this plugin on all messages with the params explained above)
+
+example usage as a volflag in a copyparty config file:
+    [/inc]
+      srv/inc
+      accs:
+        r: *
+        rw: ed
+      flags:
+        xm: aw,I,bin/hooks/wget.py
+
+the volflag examples only kicks in if you send the message
+while you're in the /inc folder (or any folder below there)
+
+IMPORTANT NOTE:
+    because this hook uses the 'I' flag to run inside copyparty,
+    many other flags will not work (f,j,c3,t3600 as seen in the
+    original wget.py), and furthermore + more importantly we
+    need to be EXCEPTIONALLY CAREFUL to avoid side-effects, so
+    the os.chdir has been replaced with cwd=dirpath for example
+"""
+
+
+def do_stuff(inf):
+    """
+    worker function which is executed in another thread to
+    avoid blocking copyparty while the download is running,
+    since we cannot use the 'f,t3600' hook-flags with 'I'
+    """
+
+    # first things first; grab the logger-function which copyparty is letting us borrow
+    log = inf["log"]
+
+    url = inf["txt"]
+    if "://" not in url:
+        url = "https://" + url
+
+    proto = url.split("://")[0].lower()
+    if proto not in ("http", "https", "ftp", "ftps"):
+        raise Exception("bad proto {}".format(proto))
+
+    dirpath = inf["ap"]
+
+    name = url.split("?")[0].split("/")[-1]
+    msg = "-- DOWNLOADING " + name
+    log(msg)
+    tfn = os.path.join(dirpath, msg)
+    open(tfn, "wb").close()
+
+    cmd = ["wget", "--trust-server-names", "-nv", "--", url]
+
+    try:
+        # two things to note here:
+        # - cannot use the `c3` hook-flag with `I` so mute output with stdout=sp.DEVNULL instead;
+        # - MUST NOT use os.chdir with 'I' so use cwd=dirpath instead 
+        sp.check_call(cmd, cwd=dirpath, stdout=sp.DEVNULL)
+    except:
+        t = "-- FAILED TO DOWNLOAD " + name
+        log(t, 3)  # 3=yellow=warning
+        open(os.path.join(dirpath, t), "wb").close()
+        raise  # have copyparty scream about the details in the log
+
+    os.unlink(tfn)
+
+
+def main(inf):
+    threading.Thread(target=do_stuff, args=(inf,), daemon=True).start()