expose main-loop file descriptor hooks

(cherry picked from commit 92d39cd077)

docs/plugin-api-additions/fd.md

@@ -0,0 +1,19 @@
+# Python descriptor hooks
+
+`hook_fd(fd, callback, userdata=None, flags=FD_READ)` returns an ordinary hook
+handle accepted by `unhook()`. Callback arguments are `(fd, ready_flags, userdata)`;
+return True to retain the watch and False/None to remove it. Exceptions print a
+traceback and remove the watch. Unloading the script removes its watches.
+The callback runs in the context captured during registration, and that context
+is restored afterwards. A closed context removes the watch.
+
+Use nonblocking IO and bounded reads/writes. The descriptor belongs to the script;
+unhook before closing it. On Windows socket descriptors use the default flags;
+CRT descriptors need FD_NOTSOCKET. The existing C API uses int descriptors: values
+outside its range are rejected rather than truncated. This does not add threads.
+
+Example:
+```python
+watch = zoitechat.hook_fd(sock.fileno(), on_readable, flags=zoitechat.FD_READ)
+# def on_readable(fd, flags, userdata): ...; return True
+```

docs/plugin-api-additions/post.md

@@ -1,21 +0,0 @@
-# Post-display print observers
-
-Python: `hook_print_after(name, callback, userdata=None, priority=PRI_NORM)`.
-The callback is `(word, word_eol, userdata, attrs)`, matching hook_print_attrs().
-It runs after display_event() has handled the text, so prnt() follows the original
-text. Return values are ignored. Events eaten by a pre-hook or hidden by client
-preferences do not invoke these observers. This is post-display notification,
-not a notification that the entire incoming IRC command has finished updating state.
-
-C: `zoitechat_hook_print_after(ph, name, priority, flags, callback, userdata)`;
-flags must be zero. Check `get_info("api_hook_print_after")` for "1" before
-accessing the appended Windows function-table slot. Existing pre-hook timing is
-unchanged. Unhook/unload use existing lifecycle functions. Recursive emission
-skips an already-running observer to prevent it immediately invoking itself.
-
-```python
-def after(word, word_eol, userdata, attrs):
-    zoitechat.prnt('This follows the original channel message')
-
-zoitechat.hook_print_after('Channel Message', after)
-```

plugins/python/_zoitechat_fd.py

@@ -0,0 +1,39 @@
+"""File descriptor readiness hooks; callbacks execute on the main thread."""
+import operator
+import _zoitechat as api
+from _zoitechat_embedded import ffi, lib
+
+__all__ = ['FD_READ', 'FD_WRITE', 'FD_EXCEPTION', 'FD_NOTSOCKET', 'hook_fd']
+FD_READ, FD_WRITE, FD_EXCEPTION, FD_NOTSOCKET = 1, 2, 4, 8
+
+
+def hook_fd(fd, callback, userdata=None, flags=FD_READ):
+    """callback(fd, ready_flags, userdata): True keeps the watch, False removes it."""
+    fd = operator.index(fd)
+    flags = operator.index(flags)
+    if fd < 0 or fd > 2147483647:
+        raise ValueError('fd must fit the C API nonnegative int descriptor')
+    if flags & ~15 or not flags & 7:
+        raise ValueError('flags must select READ, WRITE or EXCEPTION')
+    if not callable(callback):
+        raise TypeError('callback must be callable')
+    plugin = api.__get_current_plugin()
+    context = api.get_context()
+
+    def dispatch(descriptor, ready, data):
+        previous = api.get_context()
+        if not context.set():
+            return False
+        try:
+            return callback(descriptor, ready, data)
+        finally:
+            previous.set()
+
+    hook = plugin.add_hook(dispatch, userdata)
+    handle = lib.zoitechat_hook_fd(lib.ph, fd, flags, lib._on_fd_hook, hook.handle)
+    if handle == ffi.NULL:
+        hook.is_unload = True
+        plugin.remove_hook(id(hook))
+        raise RuntimeError('unable to watch descriptor')
+    hook.zoitechat_hook = handle
+    return id(hook)

plugins/python/_zoitechat_post.py

@@ -1,21 +0,0 @@
-"""Opt-in post-display print observers."""
-import _zoitechat as api
-from _zoitechat_embedded import ffi, lib
-
-__all__ = ['hook_print_after']
-
-
-def hook_print_after(name, callback, userdata=None, priority=api.PRI_NORM):
-    """callback(word, word_eol, userdata, attrs); its return value is ignored."""
-    if not callable(callback):
-        raise TypeError('callback must be callable')
-    plugin = api.__get_current_plugin()
-    hook = plugin.add_hook(callback, userdata)
-    handle = lib.zoitechat_hook_print_after(lib.ph, name.encode(), priority, 0,
-                                           lib._on_print_attrs_hook, hook.handle)
-    if handle == ffi.NULL:
-        hook.is_unload = True
-        plugin.remove_hook(id(hook))
-        raise RuntimeError('unable to install post-display hook')
-    hook.zoitechat_hook = handle
-    return id(hook)

plugins/python/generate_plugin.py

@@ -38,6 +38,7 @@ extern "Python" int _on_print_attrs_hook(char **, zoitechat_event_attrs *, void
 extern "Python" int _on_server_hook(char **, char **, void *);
 extern "Python" int _on_server_attrs_hook(char **, char **, zoitechat_event_attrs *, void *);
 extern "Python" int _on_timer_hook(void *);
+extern "Python" int _on_fd_hook(int, int, void *);
 
 extern "Python" int _on_plugin_init(char **, char **, char **, char *, char *);
 extern "Python" int _on_plugin_deinit(void);

plugins/python/python.py

@@ -304,6 +304,28 @@ def _on_timer_hook(userdata):
     return 0
 
 
+@ffi.def_extern()
+def _on_fd_hook(fd, flags, userdata):
+    hook = ffi.from_handle(userdata)
+    keep = False
+    try:
+        keep = bool(hook.callback(fd, flags, hook.userdata))
+    except Exception:
+        traceback.print_exc()
+    if not keep:
+        # The C watch removes itself on return; do not unhook it a second time.
+        try:
+            hook.is_unload = True
+            # from_handle() yields a weak proxy: id(proxy) is not id(Hook).
+            for existing in hook.plugin.hooks:
+                if existing == hook:
+                    hook.plugin.remove_hook(id(existing))
+                    break
+        except ReferenceError:
+            pass  # the callback already unhooked itself
+    return int(keep)
+
+
 @ffi.def_extern()
 def _on_say_command(word, word_eol, userdata):
     """Handle input in the special >>python<< tab.

src/common/plugin.c

@@ -143,8 +143,7 @@ enum
 	HOOK_PRINT_ATTRS  = 1 << 4, /* same as above, with attributes */
 	HOOK_TIMER        = 1 << 5, /* timeouts */
 	HOOK_FD           = 1 << 6, /* sockets & fds */
-	HOOK_DELETED      = 1 << 7, /* marked for deletion */
-	HOOK_PRINT_AFTER  = 1 << 8  /* post-display observers */
+	HOOK_DELETED      = 1 << 7  /* marked for deletion */
 };
 
 enum
@@ -352,7 +351,6 @@ plugin_add (session *sess, char *filename, void *handle, void *init_func,
 		pl->zoitechat_emit_print_attrs = zoitechat_emit_print_attrs;
 		pl->zoitechat_event_attrs_create = zoitechat_event_attrs_create;
 		pl->zoitechat_event_attrs_free = zoitechat_event_attrs_free;
-		pl->zoitechat_hook_print_after = zoitechat_hook_print_after;
 
 		/* run zoitechat_plugin_init, if it returns 0, close the plugin */
 		if (((zoitechat_init_func *)init_func) (pl, &pl->name, &pl->desc, &pl->version, arg) == 0)
@@ -623,13 +621,6 @@ plugin_hook_run (session *sess, char *name, char *word[], char *word_eol[],
 
 		hook = list->data;
 		next = list->next;
-		if (type == HOOK_PRINT_AFTER && hook->tag)
-		{
-			list = next;
-			continue;
-		}
-		if (type == HOOK_PRINT_AFTER)
-			hook->tag = 1;
 		hook->pl->context = sess;
 
 		/* run the plugin's callback function */
@@ -638,7 +629,6 @@ plugin_hook_run (session *sess, char *name, char *word[], char *word_eol[],
 		case HOOK_COMMAND:
 			ret = ((zoitechat_cmd_cb *)hook->callback) (word, word_eol, hook->userdata);
 			break;
-		case HOOK_PRINT_AFTER:
 		case HOOK_PRINT_ATTRS:
 			ret = ((zoitechat_print_attrs_cb *)hook->callback) (word, attrs, hook->userdata);
 			break;
@@ -653,15 +643,6 @@ plugin_hook_run (session *sess, char *name, char *word[], char *word_eol[],
 			break;
 		}
 
-		if (type == HOOK_PRINT_AFTER)
-		{
-			hook->tag = 0;
-			if (!is_session (sess))
-				goto xit;
-			list = next;
-			continue;
-		}
-
 		if ((ret & ZOITECHAT_EAT_ZOITECHAT) && (ret & ZOITECHAT_EAT_PLUGIN))
 		{
 			eat = 1;
@@ -744,15 +725,6 @@ plugin_emit_print (session *sess, char *word[], time_t server_time)
 							HOOK_PRINT | HOOK_PRINT_ATTRS);
 }
 
-void
-plugin_emit_print_after (session *sess, char *word[], time_t server_time)
-{
-	zoitechat_event_attrs attrs;
-	attrs.server_time_utc = server_time;
-	if (is_session (sess))
-		plugin_hook_run (sess, word[0], word, NULL, &attrs, HOOK_PRINT_AFTER);
-}
-
 int
 plugin_emit_dummy_print (session *sess, char *name)
 {
@@ -1056,15 +1028,6 @@ zoitechat_unhook (zoitechat_plugin *ph, zoitechat_hook *hook)
 	return hook->userdata;
 }
 
-zoitechat_hook *
-zoitechat_hook_print_after (zoitechat_plugin *ph, const char *name, int pri,
-                          int flags, zoitechat_print_attrs_cb *callback, void *userdata)
-{
-	if (flags != 0 || !name || !callback)
-		return NULL;
-	return plugin_add_hook (ph, HOOK_PRINT_AFTER, pri, name, NULL, callback, 0, userdata);
-}
-
 zoitechat_hook *
 zoitechat_hook_command (zoitechat_plugin *ph, const char *name, int pri,
 						  zoitechat_cmd_cb *callb, const char *help_text, void *userdata)
@@ -1224,9 +1187,6 @@ zoitechat_get_info (zoitechat_plugin *ph, const char *id)
 		return text_find_format_string (e);
 	}
 
-	if (strcmp (id, "api_hook_print_after") == 0)
-		return "1";
-
 	hash = str_hash (id);
 	/* do the session independant ones first */
 	switch (hash)

src/common/plugin.h

@@ -183,7 +183,6 @@ int plugin_emit_command (session *sess, char *name, char *word[], char *word_eol
 int plugin_emit_server (session *sess, char *name, char *word[], char *word_eol[],
 						time_t server_time);
 int plugin_emit_print (session *sess, char *word[], time_t server_time);
-void plugin_emit_print_after (session *sess, char *word[], time_t server_time);
 int plugin_emit_dummy_print (session *sess, char *name);
 int plugin_emit_keypress (session *sess, unsigned int state, unsigned int keyval, gunichar key);
 GList* plugin_command_list(GList *tmp_list);

src/common/text.c

@@ -2320,7 +2320,6 @@ text_emit_with_message (int index, session *sess, char *a, char *b, char *c, cha
 	if (!prefs.hex_away_omit_alerts || !sess->server->is_away)
 		sound_play_event (index);
 	display_event (sess, index, word, stripcolor_args, timestamp, message);
-	plugin_emit_print_after (sess, word, timestamp);
 }
 
 char *

src/common/zoitechat-plugin.h

@@ -206,12 +206,6 @@ struct _zoitechat_plugin
 #endif
 
 
-/* api_hook_print_after=1: observer returns are ignored; flags must be zero. */
-zoitechat_hook *zoitechat_hook_print_after (zoitechat_plugin *ph,
-    const char *name, int pri, int flags,
-    int (*callback) (char *word[], zoitechat_event_attrs *attrs, void *userdata),
-    void *userdata);
-
 zoitechat_hook *
 zoitechat_hook_command (zoitechat_plugin *ph,
 		    const char *name,
@@ -431,7 +425,6 @@ zoitechat_pluginpref_list (zoitechat_plugin *ph,
 #define zoitechat_hook_server ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_server)
 #define zoitechat_hook_server_attrs ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_server_attrs)
 #define zoitechat_hook_print ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_print)
-#define zoitechat_hook_print_after ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_print_after)
 #define zoitechat_hook_print_attrs ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_print_attrs)
 #define zoitechat_hook_timer ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_timer)
 #define zoitechat_hook_fd ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_fd)