Re: [RFC] Infinite backtraces...

[Randolph Chung <randolph@tausq.org>]

How about something like this to prevent infinite unwindings from pc==0
frames?

(note for reviewers: the stub frame unwinder is selected for frames
where pc == 0)

randolph

2004-12-05  Randolph Chung  <tausq@debian.org>

	* hppa-tdep.c (hppa_stub_Frame_unwind_cache): Stop unwinding if 
	unwinding from a frame with pc == 0.
	(hppa_stub_frame_this_id): Likewise.
	(hppa_stub_frame_prev_register): Only provide real values if the frame
	cache is not NULL.

Index: hppa-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/hppa-tdep.c,v
retrieving revision 1.185
diff -u -p -r1.185 hppa-tdep.c
--- hppa-tdep.c	6 Dec 2004 03:32:26 -0000	1.185
+++ hppa-tdep.c	6 Dec 2004 07:11:29 -0000
@@ -2111,10 +2115,13 @@ hppa_stub_frame_unwind_cache (struct fra
   struct gdbarch *gdbarch = get_frame_arch (next_frame);
   struct hppa_stub_unwind_cache *info;
   struct unwind_table_entry *u;
 
   if (*this_cache)
     return *this_cache;
 
+  if (frame_pc_unwind (next_frame) == 0)
+    return NULL;
+
   info = FRAME_OBSTACK_ZALLOC (struct hppa_stub_unwind_cache);
   *this_cache = info;
   info->saved_regs = trad_frame_alloc_saved_regs (next_frame);
@@ -2149,7 +2164,11 @@ hppa_stub_frame_this_id (struct frame_in
 {
   struct hppa_stub_unwind_cache *info
     = hppa_stub_frame_unwind_cache (next_frame, this_prologue_cache);
-  *this_id = frame_id_build (info->base, frame_pc_unwind (next_frame));
+
+  if (info)
+    *this_id = frame_id_build (info->base, frame_pc_unwind (next_frame));
+  else
+    *this_id = null_frame_id;
 }
 
 static void
@@ -2161,8 +2180,11 @@ hppa_stub_frame_prev_register (struct fr
 {
   struct hppa_stub_unwind_cache *info
     = hppa_stub_frame_unwind_cache (next_frame, this_prologue_cache);
-  hppa_frame_prev_register_helper (next_frame, info->saved_regs, regnum,
-		                   optimizedp, lvalp, addrp, realnump, valuep);
+
+  if (info)
+    hppa_frame_prev_register_helper (next_frame, info->saved_regs, regnum,
+				     optimizedp, lvalp, addrp, realnump, 
+				     valuep);
 }
 
 static const struct frame_unwind hppa_stub_frame_unwind = {