Re: [remote/rfc] Let GDB know if a remote server originally attached to a process.

[Pedro Alves <pedro@codesourcery.com>]

On Friday 13 March 2009 16:00:20, Daniel Jacobowitz wrote:
> On Fri, Mar 06, 2009 at 09:24:01PM +0000, Pedro Alves wrote:
> > Daniel, are you OK with this and the gdbserver bit?
> 
> Yes, I am.  Thanks!

Thanks everyone!  I've checked it in.

-- 
Pedro Alves

2009-03-14  Pedro Alves  <pedro@codesourcery.com>

	gdb/
	* remote.c (PACKET_qAttached): New.
	(remote_query_attached): New.
	(remote_add_inferior): Add new `attached' argument.  Handle it.
	(remote_notice_new_inferior, remote_start_remote): Adjust to pass
	-1 to remote_add_inferior in new parameter.
	(extended_remote_attach_1): Adjust to pass 1 to
	remote_add_inferior in the new parameter.
	(extended_remote_create_inferior_1): Adjust to pass 0 to
	remote_add_inferior in the new parameter.
	(_initialize_remote): Add "set/show remote query-attached-packet"
	commands.

2009-03-14  Pedro Alves  <pedro@codesourcery.com>

	gdb/gdbserver/
	* server.c (handle_query): Handle "qAttached".

2009-03-14  Pedro Alves  <pedro@codesourcery.com>

	gdb/doc/
	* gdb.texinfo (Remote Configuration): Document query-attached.
        (General Query Packets): Document qAttached.

---
 gdb/doc/gdb.texinfo    |   28 ++++++++++++++++++++
 gdb/gdbserver/server.c |    7 +++++
 gdb/remote.c           |   66 +++++++++++++++++++++++++++++++++++++++++++------
 3 files changed, 93 insertions(+), 8 deletions(-)

Index: src/gdb/remote.c
===================================================================
--- src.orig/gdb/remote.c	2009-03-06 21:05:26.000000000 +0000
+++ src/gdb/remote.c	2009-03-06 21:08:25.000000000 +0000
@@ -992,6 +992,7 @@ enum {
   PACKET_vKill,
   PACKET_qXfer_siginfo_read,
   PACKET_qXfer_siginfo_write,
+  PACKET_qAttached,
   PACKET_MAX
 };
 
@@ -1118,18 +1119,66 @@ static ptid_t any_thread_ptid;
 static ptid_t general_thread;
 static ptid_t continue_thread;
 
+/* Find out if the stub attached to PID (and hence GDB should offer to
+   detach instead of killing it when bailing out).  */
+
+static int
+remote_query_attached (int pid)
+{
+  struct remote_state *rs = get_remote_state ();
+
+  if (remote_protocol_packets[PACKET_qAttached].support == PACKET_DISABLE)
+    return 0;
+
+  if (remote_multi_process_p (rs))
+    sprintf (rs->buf, "qAttached:%x", pid);
+  else
+    sprintf (rs->buf, "qAttached");
+
+  putpkt (rs->buf);
+  getpkt (&rs->buf, &rs->buf_size, 0);
+
+  switch (packet_ok (rs->buf,
+		     &remote_protocol_packets[PACKET_qAttached]) == PACKET_OK)
+    {
+    case PACKET_OK:
+      if (strcmp (rs->buf, "1") == 0)
+	return 1;
+      break;
+    case PACKET_ERROR:
+      warning (_("Remote failure reply: %s"), rs->buf);
+      break;
+    case PACKET_UNKNOWN:
+      break;
+    }
+
+  return 0;
+}
+
 /* Add PID to GDB's inferior table.  Since we can be connected to a
    remote system before before knowing about any inferior, mark the
-   target with execution when we find the first inferior.  */
+   target with execution when we find the first inferior.  If ATTACHED
+   is 1, then we had just attached to this inferior.  If it is 0, then
+   we just created this inferior.  If it is -1, then try querying the
+   remote stub to find out if it had attached to the inferior or
+   not.  */
 
 static struct inferior *
-remote_add_inferior (int pid)
+remote_add_inferior (int pid, int attached)
 {
   struct remote_state *rs = get_remote_state ();
   struct inferior *inf;
 
+  /* Check whether this process we're learning about is to be
+     considered attached, or if is to be considered to have been
+     spawned by the stub.  */
+  if (attached == -1)
+    attached = remote_query_attached (pid);
+
   inf = add_inferior (pid);
 
+  inf->attach_flag = attached;
+
   /* This may be the first inferior we hear about.  */
   if (!target_has_execution)
     {
@@ -1207,7 +1256,7 @@ remote_notice_new_inferior (ptid_t currt
 	 may not know about it yet.  Add it before adding its child
 	 thread, so notifications are emitted in a sensible order.  */
       if (!in_inferior_list (ptid_get_pid (currthread)))
-	inf = remote_add_inferior (ptid_get_pid (currthread));
+	inf = remote_add_inferior (ptid_get_pid (currthread), -1);
 
       /* This is really a new thread.  Add it.  */
       remote_add_thread (currthread, running);
@@ -2665,7 +2714,7 @@ remote_start_remote (struct ui_out *uiou
       /* Now, if we have thread information, update inferior_ptid.  */
       inferior_ptid = remote_current_thread (inferior_ptid);
 
-      remote_add_inferior (ptid_get_pid (inferior_ptid));
+      remote_add_inferior (ptid_get_pid (inferior_ptid), -1);
 
       /* Always add the main thread.  */
       add_thread_silent (inferior_ptid);
@@ -3390,7 +3439,6 @@ extended_remote_attach_1 (struct target_
   int pid;
   char *dummy;
   char *wait_status = NULL;
-  struct inferior *inf;
 
   if (!args)
     error_no_arg (_("process-id to attach"));
@@ -3436,8 +3484,7 @@ extended_remote_attach_1 (struct target_
   /* Now, if we have thread information, update inferior_ptid.  */
   inferior_ptid = remote_current_thread (inferior_ptid);
 
-  inf = remote_add_inferior (pid);
-  inf->attach_flag = 1;
+  remote_add_inferior (pid, 1);
 
   if (non_stop)
     /* Get list of threads.  */
@@ -6761,7 +6808,7 @@ extended_remote_create_inferior_1 (char 
   /* Now, if we have thread information, update inferior_ptid.  */
   inferior_ptid = remote_current_thread (inferior_ptid);
 
-  remote_add_inferior (ptid_get_pid (inferior_ptid));
+  remote_add_inferior (ptid_get_pid (inferior_ptid), 0);
   add_thread_silent (inferior_ptid);
 
   /* Get updated offsets, if the stub uses qOffsets.  */
@@ -9161,6 +9208,9 @@ Show the maximum size of the address (in
   add_packet_config_cmd (&remote_protocol_packets[PACKET_vKill],
 			 "vKill", "kill", 0);
 
+  add_packet_config_cmd (&remote_protocol_packets[PACKET_qAttached],
+			 "qAttached", "query-attached", 0);
+
   /* Keep the old ``set remote Z-packet ...'' working.  Each individual
      Z sub-packet has its own set and show commands, but users may
      have sets to this variable in their .gdbinit files (or in their
Index: src/gdb/gdbserver/server.c
===================================================================
--- src.orig/gdb/gdbserver/server.c	2009-03-06 21:05:26.000000000 +0000
+++ src/gdb/gdbserver/server.c	2009-03-06 21:08:25.000000000 +0000
@@ -1040,6 +1040,13 @@ handle_query (char *own_buf, int packet_
       return;
     }
 
+  if (strcmp (own_buf, "qAttached") == 0)
+    {
+      require_running (own_buf);
+      strcpy (own_buf, attached ? "1" : "0");
+      return;
+    }
+
   /* Otherwise we didn't know what packet it was.  Say we didn't
      understand it.  */
   own_buf[0] = 0;
Index: src/gdb/doc/gdb.texinfo
===================================================================
--- src.orig/gdb/doc/gdb.texinfo	2009-03-06 21:05:26.000000000 +0000
+++ src/gdb/doc/gdb.texinfo	2009-03-07 14:49:42.000000000 +0000
@@ -14425,6 +14425,10 @@ are:
 @item @code{osdata}
 @tab @code{qXfer:osdata:read}
 @tab @code{info os}
+
+@item @code{query-attached}
+@tab @code{qAttached}
+@tab Querying remote process attach state.
 @end multitable
 
 @node Remote Stub
@@ -27306,6 +27310,30 @@ not recognize the @var{object} keyword, 
 @var{object} does not recognize the @var{operation} keyword, the stub
 must respond with an empty packet.
 
+@item qAttached:@var{pid}
+@cindex query attached, remote request
+@cindex @samp{qAttached} packet
+Return an indication of whether the remote server attached to an
+existing process or created a new process.  When the multiprocess
+protocol extensions are supported (@pxref{multiprocess extensions}),
+@var{pid} is an integer in hexadecimal format identifying the target
+process.  Otherwise, @value{GDBN} will omit the @var{pid} field and
+the query packet will be simplified as @samp{qAttached}.
+
+This query is used, for example, to know whether the remote process
+should be detached or killed when a @value{GDBN} session is ended with
+the @code{quit} command.
+
+Reply:
+@table @samp
+@item 1
+The remote server attached to an existing process.
+@item 0
+The remote server created a new process.
+@item E @var{NN}
+A badly formed request or an error was encountered.
+@end table
+
 @end table
 
 @node Register Packet Format