Re: [RFA] Implement 'detach pid'.

[Vladimir Prus <vladimir@codesourcery.com>]

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On Thursday 13 November 2008 02:19:57 Pedro Alves wrote:

> On Wednesday 12 November 2008 20:39:02, Vladimir Prus wrote:
> > This patch makes CLI 'detach' and MI '-target-detach' accept the PID
> > of the process to detach from.
>
> I see several issues with this patch:
>
>  - The target is not the right layer to do this.  Before you reach here,
>    you've already done things to the current inferior.  E.g.,
> target.c:target_detach will call remove_breakpoints before reaching
> remote_detach_1.  This means that, if you have e.g., selected inferior 1,
> and do detach 3, you'll remove breakpoints from inferior 1, and detach
> process 3.  Breakpoints are an example.  Other example is that before you
> reach the process stratum, you can pass by the thread_stratum, which again
> would do anything to the wrong detachee, since it's usually the
> process_statum that does the final real detach.  That's bad.

How about the attached -- where mostly everything is done on MI side?

- Volodya


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commit da4c2b7d1163dfd36c492f9f793c04f9bdb36d2b
Author: vladimir <vladimir@e7755896-6108-0410-9592-8049d3e74e28>
Date:   Thu Jul 31 13:23:59 2008 +0000

    Implement '-target-detach pid'.
    
    	* gdbthread.h (thread_callback_func): Clarify comment.
    	* infcmd.c (detach_command): Make nonstatic.
    	* inferior.h (detach_command): Declare.
    	* mi/mi-cmds.c (mi_cmds): Don't route -target-detach via CLI.
    	* mi/mi-cmds.h (mi_cmd_target_detach): Declare.
    	* /mi/mi-main.c (find_thread_of_process, mi_cmd_target_detach): New.

diff --git a/gdb/gdbthread.h b/gdb/gdbthread.h
index cac20f7..1a65aa8 100644
--- a/gdb/gdbthread.h
+++ b/gdb/gdbthread.h
@@ -229,7 +229,9 @@ struct thread_info *find_thread_id (int num);
 void thread_change_ptid (ptid_t old_ptid, ptid_t new_ptid);
 
 /* Iterator function to call a user-provided callback function
-   once for each known thread.  */
+   once for each known thread.  Returns 0 to continue iteration,
+   and 1 to stop -- which causes iterate_over_threads to return
+   the current thread_info.  */
 typedef int (*thread_callback_func) (struct thread_info *, void *);
 extern struct thread_info *iterate_over_threads (thread_callback_func, void *);
 
diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index b3af31f..810b3b7 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -86,8 +86,6 @@ static void unset_command (char *, int);
 
 static void float_info (char *, int);
 
-static void detach_command (char *, int);
-
 static void disconnect_command (char *, int);
 
 static void unset_environment_command (char *, int);
@@ -2344,7 +2342,7 @@ attach_command (char *args, int from_tty)
  * started via the normal ptrace (PTRACE_TRACEME).
  */
 
-static void
+void
 detach_command (char *args, int from_tty)
 {
   dont_repeat ();		/* Not for the faint of heart.  */
diff --git a/gdb/inferior.h b/gdb/inferior.h
index 1be6cc5..f004d44 100644
--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -269,6 +269,8 @@ extern void interrupt_target_command (char *args, int from_tty);
 
 extern void interrupt_target_1 (int all_threads);
 
+extern void detach_command (char *, int);
+
 /* Address at which inferior stopped.  */
 
 extern CORE_ADDR stop_pc;
diff --git a/gdb/mi/mi-cmds.c b/gdb/mi/mi-cmds.c
index d38de35..51c720e 100644
--- a/gdb/mi/mi-cmds.c
+++ b/gdb/mi/mi-cmds.c
@@ -121,7 +121,7 @@ struct mi_cmd mi_cmds[] =
   { "symbol-type", { NULL, 0 }, NULL },
   { "target-attach", { "attach", 1 }, NULL },
   { "target-compare-sections", { NULL, 0 }, NULL },
-  { "target-detach", { "detach", 0 }, 0 },
+  { "target-detach", { NULL, 0 }, mi_cmd_target_detach },
   { "target-disconnect", { "disconnect", 0 }, 0 },
   { "target-download", { "load", 1 }, NULL},
   { "target-exec-status", { NULL, 0 }, NULL },
diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
index a9bb1e0..a399b9e 100644
--- a/gdb/mi/mi-cmds.h
+++ b/gdb/mi/mi-cmds.h
@@ -75,6 +75,7 @@ extern mi_cmd_argv_ftype mi_cmd_stack_list_frames;
 extern mi_cmd_argv_ftype mi_cmd_stack_list_locals;
 extern mi_cmd_argv_ftype mi_cmd_stack_select_frame;
 extern mi_cmd_argv_ftype mi_cmd_symbol_list_lines;
+extern mi_cmd_argv_ftype mi_cmd_target_detach;
 extern mi_cmd_argv_ftype mi_cmd_target_file_get;
 extern mi_cmd_argv_ftype mi_cmd_target_file_put;
 extern mi_cmd_argv_ftype mi_cmd_target_file_delete;
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index 43ec0b4..36c0223 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -199,6 +199,42 @@ mi_cmd_exec_interrupt (char *command, char **argv, int argc)
     error ("Usage: -exec-interrupt [--all]");
 }
 
+static int
+find_thread_of_process (struct thread_info *ti, void *p)
+{
+  int pid = *(int *)p;
+  if (PIDGET (ti->ptid) == pid && !is_exited (ti->ptid))
+    return 1;
+
+  return 0;
+}
+
+void
+mi_cmd_target_detach (char *command, char **argv, int argc)
+{
+  if (argc != 0 && argc != 1)
+    error ("Usage: -target-detach [thread-group]");
+
+  if (argc == 1)
+    {
+      struct thread_info *tp;
+      char *end = argv[0];
+      int pid = strtol (argv[0], &end, 10);
+      if (*end != '\0')
+	error (_("Cannot parse thread group id '%s'"), argv[0]);
+
+      /* Pick any thread in the desired process.  Current
+	 target_detach deteches from the parent of inferior_ptid.  */
+      tp = iterate_over_threads (find_thread_of_process, &pid);
+      if (!tp)
+	error (_("Thread group is empty"));
+
+      switch_to_thread (tp->ptid);
+    }
+
+  detach_command (NULL, 0);
+}
+
 void
 mi_cmd_thread_select (char *command, char **argv, int argc)
 {