Allow attaching to multiple processes

[Pedro Alves <pedro@codesourcery.com>]

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Now that the remote target supports debugging multiple inferiors
simultaneously, we need to allow/expose that to the command level.  This
patch allows "attach"ing to multiple processes.  ("run"ning will come later).

Not much rocket science here --- the comments/code should be
self-explanatory.

Checked in.

-- 
Pedro Alves

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2008-10-27  Pedro Alves  <pedro@codesourcery.com>

	* target.h (struct target_ops) <to_supports_multi_process>: New
	field.
	(target_supports_multi_process): New define.
	* target.c (update_current_target): Inherit and de_fault
	to_supports_multi_process.

	* infcmd.c (attach_command): Allow attaching to multiple processes
	if the target supports it.
	(detach_command): If the target claims there is still execution,
	don't clear the thread list.

	* remote.c (remote_supports_multi_process): New.
	(init_remote_ops): Register remote_supports_multi_process.

---
 gdb/infcmd.c |   12 ++++++++++--
 gdb/remote.c |    8 ++++++++
 gdb/target.c |    4 ++++
 gdb/target.h |   10 ++++++++++
 4 files changed, 32 insertions(+), 2 deletions(-)

Index: src/gdb/target.h
===================================================================
--- src.orig/gdb/target.h	2008-10-27 12:27:28.000000000 +0000
+++ src/gdb/target.h	2008-10-27 12:27:30.000000000 +0000
@@ -536,6 +536,10 @@ struct target_ops
     /* Can target execute in reverse?  */
     int (*to_can_execute_reverse) ();
 
+    /* Does this target support debugging multiple processes
+       simultaneously?  */
+    int (*to_supports_multi_process) (void);
+
     int to_magic;
     /* Need sub-structure for target machine related rather than comm related?
      */
@@ -647,6 +651,12 @@ extern void target_resume (ptid_t ptid, 
 #define	target_prepare_to_store(regcache)	\
      (*current_target.to_prepare_to_store) (regcache)
 
+/* Returns true if this target can debug multiple processes
+   simultaneously.  */
+
+#define	target_supports_multi_process()	\
+     (*current_target.to_supports_multi_process) ()
+
 extern DCACHE *target_dcache;
 
 extern int target_read_string (CORE_ADDR, char **, int, int *);
Index: src/gdb/target.c
===================================================================
--- src.orig/gdb/target.c	2008-10-27 12:27:28.000000000 +0000
+++ src/gdb/target.c	2008-10-27 12:27:30.000000000 +0000
@@ -471,6 +471,7 @@ update_current_target (void)
       /* Do not inherit to_read_description.  */
       INHERIT (to_get_ada_task_ptid, t);
       /* Do not inherit to_search_memory.  */
+      INHERIT (to_supports_multi_process, t);
       INHERIT (to_magic, t);
       /* Do not inherit to_memory_map.  */
       /* Do not inherit to_flash_erase.  */
@@ -638,6 +639,9 @@ update_current_target (void)
   de_fault (to_get_ada_task_ptid,
             (ptid_t (*) (long, long))
             default_get_ada_task_ptid);
+  de_fault (to_supports_multi_process,
+	    (int (*) (void))
+	    return_zero);
 #undef de_fault
 
   /* Finally, position the target-stack beneath the squashed
Index: src/gdb/infcmd.c
===================================================================
--- src.orig/gdb/infcmd.c	2008-10-27 12:27:28.000000000 +0000
+++ src/gdb/infcmd.c	2008-10-27 12:32:26.000000000 +0000
@@ -2201,7 +2201,10 @@ attach_command (char *args, int from_tty
 
   dont_repeat ();		/* Not for the faint of heart */
 
-  if (target_has_execution)
+  if (target_supports_multi_process ())
+    /* Don't complain if we can be attached to multiple processes.  */
+    ;
+  else if (target_has_execution)
     {
       if (query ("A program is being debugged already.  Kill it? "))
 	target_kill ();
@@ -2311,7 +2314,12 @@ detach_command (char *args, int from_tty
   dont_repeat ();		/* Not for the faint of heart.  */
   target_detach (args, from_tty);
   no_shared_libraries (NULL, from_tty);
-  init_thread_list ();
+
+  /* If the current target interface claims there's still execution,
+     then don't mess with threads of other processes.  */
+  if (!target_has_execution)
+    init_thread_list ();
+
   if (deprecated_detach_hook)
     deprecated_detach_hook ();
 }
Index: src/gdb/remote.c
===================================================================
--- src.orig/gdb/remote.c	2008-10-27 12:27:28.000000000 +0000
+++ src/gdb/remote.c	2008-10-27 12:27:30.000000000 +0000
@@ -8554,6 +8554,13 @@ remote_supports_non_stop (void)
   return 1;
 }
 
+static int
+remote_supports_multi_process (void)
+{
+  struct remote_state *rs = get_remote_state ();
+  return remote_multi_process_p (rs);
+}
+
 static void
 init_remote_ops (void)
 {
@@ -8616,6 +8623,7 @@ Specify the serial device it is connecte
   remote_ops.to_terminal_inferior = remote_terminal_inferior;
   remote_ops.to_terminal_ours = remote_terminal_ours;
   remote_ops.to_supports_non_stop = remote_supports_non_stop;
+  remote_ops.to_supports_multi_process = remote_supports_multi_process;
 }
 
 /* Set up the extended remote vector by making a copy of the standard