File resume.diff of Package gdb

2008-11-20  Pedro Alves  <pedro@codesourcery.com>

	* infrun.c (resume): If following a fork, reread the current
	thread.  Avoid dereferencing a possibly dangling pointer.

--- gdb/infrun.c
+++ gdb/infrun.c
@@ -965,10 +965,13 @@ resume (int step, enum target_signal sig
 {
   int should_resume = 1;
   struct cleanup *old_cleanups = make_cleanup (resume_cleanups, 0);
+
+  /* Note that these must be reset if we follow a fork below.  */
   struct regcache *regcache = get_current_regcache ();
   struct gdbarch *gdbarch = get_regcache_arch (regcache);
   struct thread_info *tp = inferior_thread ();
   CORE_ADDR pc = regcache_read_pc (regcache);
+
   QUIT;
 
   if (debug_infrun)
@@ -1053,6 +1056,13 @@ a command like `return' or `jump' to con
       pending_follow.kind = TARGET_WAITKIND_SPURIOUS;
       if (follow_fork ())
 	should_resume = 0;
+
+      /* Following a child fork will change our notion of current
+	 thread.  */
+      tp = inferior_thread ();
+      regcache = get_current_regcache ();
+      gdbarch = get_regcache_arch (regcache);
+      pc = regcache_read_pc (regcache);
       break;
 
     case TARGET_WAITKIND_EXECD:
@@ -1148,11 +1158,11 @@ a command like `return' or `jump' to con
           displaced_step_dump_bytes (gdb_stdlog, buf, sizeof (buf));
         }
 
-      target_resume (resume_ptid, step, sig);
-
       /* Avoid confusing the next resume, if the next stop/resume
 	 happens to apply to another thread.  */
       tp->stop_signal = TARGET_SIGNAL_0;
+
+      target_resume (resume_ptid, step, sig);
     }
 
   discard_cleanups (old_cleanups);