1 files changed, 107 insertions, 0 deletions
diff --git a/gdb/gdbserver/target.c b/gdb/gdbserver/target.c
index 80512d86..b376ce8 100644
--- a/gdb/gdbserver/target.c
+++ b/gdb/gdbserver/target.c
@@ -37,6 +37,113 @@ set_desired_thread (int use_general)
   return (current_thread != NULL);
 }
 
+/* Structure used to look up a thread to use as current when accessing
+   memory.  */
+
+struct thread_search
+{
+  /* The PTID of the current general thread.  This is an input
+     parameter.  */
+  ptid_t current_gen_ptid;
+
+  /* The first thread found.  */
+  struct thread_info *first;
+
+  /* The first stopped thread found.  */
+  struct thread_info *stopped;
+
+  /* The current general thread, if found.  */
+  struct thread_info *current;
+};
+
+/* Callback for find_inferior.  Search for a thread to use as current
+   when accessing memory.  */
+
+static int
+thread_search_callback (struct inferior_list_entry *entry, void *args)
+{
+  struct thread_info *thread = (struct thread_info *) entry;
+  struct thread_search *s = (struct thread_search *) args;
+
+  if (ptid_get_pid (entry->id) == ptid_get_pid (s->current_gen_ptid)
+      && mythread_alive (ptid_of (thread)))
+    {
+      if (s->stopped == NULL && thread_stopped (thread))
+	s->stopped = thread;
+
+      if (s->first == NULL)
+	s->first = thread;
+
+      if (s->current == NULL && ptid_equal (s->current_gen_ptid, entry->id))
+	s->current = thread;
+    }
+
+  return 0;
+}
+
+/* The thread that was current before prepare_to_access_memory was
+   called.  done_accessing_memory uses this to restore the previous
+   selected thread.  */
+static ptid_t prev_general_thread;
+
+/* See target.h.  */
+
+int
+prepare_to_access_memory (void)
+{
+  struct thread_search search;
+  struct thread_info *thread;
+
+  memset (&search, 0, sizeof (search));
+  search.current_gen_ptid = general_thread;
+  prev_general_thread = general_thread;
+
+  if (the_target->prepare_to_access_memory != NULL)
+    {
+      int res;
+
+      res = the_target->prepare_to_access_memory ();
+      if (res != 0)
+	return res;
+    }
+
+  find_inferior (&all_threads, thread_search_callback, &search);
+
+  /* Prefer a stopped thread.  If none is found, try the current
+     thread.  Otherwise, take the first thread in the process.  If
+     none is found, undo the effects of
+     target->prepare_to_access_memory() and return error.  */
+  if (search.stopped != NULL)
+    thread = search.stopped;
+  else if (search.current != NULL)
+    thread = search.current;
+  else if (search.first != NULL)
+    thread = search.first;
+  else
+    {
+      done_accessing_memory ();
+      return 1;
+    }
+
+  current_thread = thread;
+  general_thread = ptid_of (thread);
+
+  return 0;
+}
+
+/* See target.h.  */
+
+void
+done_accessing_memory (void)
+{
+  if (the_target->done_accessing_memory != NULL)
+    the_target->done_accessing_memory ();
+
+  /* Restore the previous selected thread.  */
+  general_thread = prev_general_thread;
+  current_thread = find_thread_ptid (general_thread);
+}
+
 int
 read_inferior_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
 {