[RFA] thread.c: plug leaks, zero thread count

[Nick Duffek <nsd at redhat dot com>]

Plug leaks
----------

delete_thread() does this to each thread it deletes:

  if (tp->step_resume_breakpoint)
    delete_breakpoint (tp->step_resume_breakpoint);
  if (tp->private)
    free (tp->private);
  free (tp);

But init_thread_list() only does this to each thread it deletes:

  free (tp);

So, it leaks memory and breakpoints.  The attached patch fixes that by
moving delete_thread's cleanup code into a new function, free_thread(),
and then calling that in delete_thread() and init_thread_list().

Zero thread count
-----------------

If GDB notices all thread exit events, then when an inferior exits,
thread_list will be empty but highest_thread_num may be > 0, causing the
next run to start numbering threads at > 1.

The attached patch sets highest_thread_num to 0 before rather than after
checking for a NULL thread_list.

Okay to apply?

Nick Duffek
nsd@redhat.com

2000-07-19  Nicholas Duffek  <nsd@redhat.com>

	* thread.c (free_thread): New function.
	(init_thread_list): Always zero highest_thread_num.  Call
	free_thread() instead of free().
	(delete_thread): Move thread cleanup code to free_thread().

Index: gdb/thread.c
===================================================================
diff -up gdb/thread.c gdb/thread.c
--- gdb/thread.c	Wed Jul 19 15:22:40 2000
+++ gdb/thread.c	Wed Jul 19 15:22:08 2000
@@ -63,22 +63,38 @@ static void restore_current_thread (int)
 static void switch_to_thread (int pid);
 static void prune_threads (void);
 
+static void
+free_thread (struct thread_info *tp)
+{
+  /* NOTE: this will take care of any left-over step_resume breakpoints,
+     but not any user-specified thread-specific breakpoints. */
+  if (tp->step_resume_breakpoint)
+    delete_breakpoint (tp->step_resume_breakpoint);
+
+  /* FIXME: do I ever need to call the back-end to give it a
+     chance at this private data before deleting the thread?  */
+  if (tp->private)
+    free (tp->private);
+
+  free (tp);
+}
+
 void
 init_thread_list ()
 {
   struct thread_info *tp, *tpnext;
 
+  highest_thread_num = 0;
   if (!thread_list)
     return;
 
   for (tp = thread_list; tp; tp = tpnext)
     {
       tpnext = tp->next;
-      free (tp);
+      free_thread (tp);
     }
 
   thread_list = NULL;
-  highest_thread_num = 0;
 }
 
 /* add_thread now returns a pointer to the new thread_info, 
@@ -134,19 +150,7 @@ delete_thread (pid)
   else
     thread_list = tp->next;
 
-  /* NOTE: this will take care of any left-over step_resume breakpoints,
-     but not any user-specified thread-specific breakpoints. */
-  if (tp->step_resume_breakpoint)
-    delete_breakpoint (tp->step_resume_breakpoint);
-
-  /* FIXME: do I ever need to call the back-end to give it a
-     chance at this private data before deleting the thread?  */
-  if (tp->private)
-    free (tp->private);
-
-  free (tp);
-
-  return;
+  free_thread (tp);
 }
 
 static struct thread_info *