2008-10-23  Michael Snyder  <msnyder@vmware.com>
	    Pedro Alves  <pedro@codesourcery.com>

	* remote.c (remote_thread_alive): Emit leading zeros in the
	single-process case to preserve remote protocol behavior.

---
 gdb/remote.c |   28 ++++++++++++++++++++++------
 1 file changed, 22 insertions(+), 6 deletions(-)

Index: src/gdb/remote.c
===================================================================
--- src.orig/gdb/remote.c	2008-10-23 15:57:07.000000000 +0100
+++ src/gdb/remote.c	2008-10-23 16:30:19.000000000 +0100
@@ -1279,8 +1279,6 @@ static int
 remote_thread_alive (ptid_t ptid)
 {
   struct remote_state *rs = get_remote_state ();
-  int tid = ptid_get_tid (ptid);
-  char *p, *endp;
 
   if (ptid_equal (ptid, magic_null_ptid))
     /* The main thread is always alive.  */
@@ -1292,11 +1290,29 @@ remote_thread_alive (ptid_t ptid)
        multi-threading.  */
     return 1;
 
-  p = rs->buf;
-  endp = rs->buf + get_remote_packet_size ();
+  /* Note: We don't use write_ptid unconditionally here, since it
+     doesn't output leading zeros (%08x below).  Although nothing in
+     the docs suggests that the leading zeros are required, there's no
+     reason to break backwards compatibility, in case stubs are
+     relying on them being present.  */
+  if (!remote_multi_process_p (rs))
+    {
+      int tid = ptid_get_tid (ptid);
+
+      if (tid < 0)
+	xsnprintf (rs->buf, get_remote_packet_size (), "T-%08x", -tid);
+      else
+	xsnprintf (rs->buf, get_remote_packet_size (), "T%08x", tid);
+    }
+  else
+    {
+      char *p, *endp;
 
-  *p++ = 'T';
-  write_ptid (p, endp, ptid);
+      p = rs->buf;
+      endp = rs->buf + get_remote_packet_size ();
+      *p++ = 'T';
+      write_ptid (p, endp, ptid);
+    }
 
   putpkt (rs->buf);
   getpkt (&rs->buf, &rs->buf_size, 0);