Add a new per-breakpoint callback on_install

Author: Petr Machata

breakpoint.h

@@ -1,6 +1,6 @@
 /*
  * This file is part of ltrace.
- * Copyright (C) 2012, 2013 Petr Machata, Red Hat Inc.
+ * Copyright (C) 2012,2013,2014 Petr Machata, Red Hat Inc.
  * Copyright (C) 2009 Juan Cespedes
  *
  * This program is free software; you can redistribute it and/or
@@ -46,6 +46,7 @@
 struct bp_callbacks {
 	void (*on_hit)(struct breakpoint *bp, struct process *proc);
 	void (*on_continue)(struct breakpoint *bp, struct process *proc);
+	void (*on_install)(struct breakpoint *bp, struct process *proc);
 	void (*on_retract)(struct breakpoint *bp, struct process *proc);
 
 	/* Create a new breakpoint that should handle return from the
@@ -84,6 +85,12 @@ void breakpoint_on_continue(struct breakpoint *bp, struct process *proc);
  * the instruction underneath it).  */
 void breakpoint_on_retract(struct breakpoint *bp, struct process *proc);
 
+/* Call ON_INSTALL handler of BP, if any is set.  This should be
+ * called after the breakpoint is enabled for the first time, not
+ * every time it's enabled (such as after stepping over a site of a
+ * temporarily disabled breakpoint).  */
+void breakpoint_on_install(struct breakpoint *bp, struct process *proc);
+
 /* Call GET_RETURN_BP handler of BP, if any is set.  If none is set,
  * call CREATE_DEFAULT_RETURN_BP to obtain one.  */
 int breakpoint_get_return_bp(struct breakpoint **ret,

breakpoints.c

@@ -1,6 +1,6 @@
 /*
  * This file is part of ltrace.
- * Copyright (C) 2006,2007,2011,2012,2013 Petr Machata, Red Hat Inc.
+ * Copyright (C) 2006,2007,2011,2012,2013,2014 Petr Machata, Red Hat Inc.
  * Copyright (C) 2009 Juan Cespedes
  * Copyright (C) 1998,2001,2002,2003,2007,2008,2009 Juan Cespedes
  * Copyright (C) 2006 Ian Wienand
@@ -85,6 +85,14 @@ breakpoint_on_retract(struct breakpoint *bp, struct process *proc)
 		(bp->cbs->on_retract)(bp, proc);
 }
 
+void
+breakpoint_on_install(struct breakpoint *bp, struct process *proc)
+{
+	assert(bp != NULL);
+	if (bp->cbs != NULL && bp->cbs->on_install != NULL)
+		(bp->cbs->on_install)(bp, proc);
+}
+
 int
 breakpoint_get_return_bp(struct breakpoint **ret,
 			 struct breakpoint *bp, struct process *proc)
@@ -229,6 +237,7 @@ breakpoint_turn_on(struct breakpoint *bp, struct process *proc)
 	if (bp->enabled == 1) {
 		assert(proc->pid != 0);
 		enable_breakpoint(proc, bp);
+		breakpoint_on_install(bp, proc);
 	}
 	return 0;
 }