diff -urp ltrace-0.5/ltrace.h ltrace-0.5-pm/ltrace.h
--- ltrace-0.5/ltrace.h	2011-07-28 22:53:33.002612928 +0200
+++ ltrace-0.5-pm/ltrace.h	2011-07-28 22:59:22.503604556 +0200
@@ -106,6 +106,17 @@ enum Process_State {
 	STATE_IGNORED  /* ignore this process (it's a fork and no -f was used) */
 };
 
+typedef struct Event_Handler Event_Handler;
+struct Event_Handler {
+	/* Event handler that overrides the default one.  Should
+	 * return NULL if the event was handled, otherwise the
+	 * returned event is passed to the default handler.  */
+	struct event * (* on_event)(Event_Handler * self, struct event * event);
+
+	/* Called when the event handler removal is requested.  */
+	void (* destroy)(Event_Handler * self);
+};
+
 /* XXX We would rather have this all organized a little differently,
  * have Process for the whole group and Task for what's there for
  * per-thread stuff.  But for now this is the less invasive way of
@@ -143,6 +154,10 @@ struct process {
 	short e_machine;
 	short need_to_reinitialize_breakpoints;
 
+	/* Set in leader.  */
+	Event_Handler * event_handler;
+
+
 	/**
 	 * Process chaining.
 	 **/
@@ -209,6 +224,9 @@ extern struct event * each_qd_event(enum
 extern void enque_event(struct event * event);
 extern struct event *wait_for_something(void);
 
+extern void install_event_handler(struct process * proc, Event_Handler * handler);
+extern void destroy_event_handler(struct process * proc);
+
 extern void process_event(struct event *event);
 extern pid_t execute_program(const char * command, char ** argv);
 extern int display_arg(enum tof type, struct process *proc, int arg_num,
Только в ltrace-0.5-pm: ltrace.h~
diff -urp ltrace-0.5/proc.c ltrace-0.5-pm/proc.c
--- ltrace-0.5/proc.c	2011-07-28 22:53:33.002612928 +0200
+++ ltrace-0.5-pm/proc.c	2011-07-28 23:01:13.833422637 +0200
@@ -205,3 +205,20 @@ remove_process(struct process *proc)
 		tmp = tmp->next;
 	}
 }
+
+void
+install_event_handler(struct process * proc, Event_Handler * handler)
+{
+	assert(proc->event_handler == NULL);
+	proc->event_handler = handler;
+}
+
+void
+destroy_event_handler(struct process * proc)
+{
+	Event_Handler * handler = proc->event_handler;
+	assert(handler != NULL);
+	handler->destroy(handler);
+	free(handler);
+	proc->event_handler = NULL;
+}
Только в ltrace-0.5-pm: proc.c~
diff -urp ltrace-0.5/process_event.c ltrace-0.5-pm/process_event.c
--- ltrace-0.5/process_event.c	2011-07-28 22:53:32.992612588 +0200
+++ ltrace-0.5-pm/process_event.c	2011-07-28 23:00:54.753767957 +0200
@@ -118,6 +118,8 @@ static void process_clone(struct event *
 			enable_breakpoint(p, p->breakpoint_being_enabled);
 			p->breakpoint_being_enabled = NULL;
 		}
+		if (p->event_handler != NULL)
+			destroy_event_handler(p);
 		if (event->proc->state == STATE_ATTACHED && opt_f) {
 			p->state = STATE_ATTACHED;
 		} else {
@@ -142,6 +144,8 @@ static void process_new(struct event * e
 			enable_breakpoint(proc, proc->breakpoint_being_enabled);
 			proc->breakpoint_being_enabled = NULL;
 		}
+		if (proc->event_handler != NULL)
+			destroy_event_handler(proc);
 		if (opt_f) {
 			proc->state = STATE_ATTACHED;
 		} else {
@@ -201,6 +205,19 @@ static char *sysname(struct process *pro
 
 void process_event(struct event *event)
 {
+	/* If the thread group defines an overriding event handler,
+	   give it a chance to kick in.  */
+	if (event->proc != NULL
+	    && event->proc->leader != NULL) {
+		Event_Handler * handler = event->proc->leader->event_handler;
+		if (handler != NULL) {
+			event = (*handler->on_event) (handler, event);
+			if (event == NULL)
+				/* It was handled.  */
+				return;
+		}
+	}
+
 	switch (event->thing) {
 	case LT_EV_NONE:
 		debug(1, "event: none");
Только в ltrace-0.5-pm: process_event.c~
diff -urp ltrace-0.5/wait_for_something.c ltrace-0.5-pm/wait_for_something.c
--- ltrace-0.5/wait_for_something.c	2011-07-28 22:53:33.004612996 +0200
+++ ltrace-0.5-pm/wait_for_something.c	2011-07-28 23:01:49.346640045 +0200
@@ -146,7 +146,12 @@ each_qd_event(enum ecb_status (*pred)(st
 static enum ecb_status
 event_process_not_reenabling(struct event * event, void * data)
 {
-	return ecb_deque;
+	if (event->proc == NULL
+	    || event->proc->leader == NULL
+	    || event->proc->leader->event_handler == NULL)
+		return ecb_deque;
+	else
+		return ecb_cont;
 }
 
 static struct event *
Только в ltrace-0.5-pm: wait_for_something.c~