Add "info connections" command, "info inferiors" connection number/string

This commit extends the CLI a bit for multi-target, in three ways.

#1 - New "info connections" command.

This is a new command that lists the open connections (process_stratum
targets).  For example, if you're debugging two remote connections, a
couple local/native processes, and a core dump, all at the same time,
you might see something like this:

 (gdb) info connections
   Num  What                     Description
   1    remote 192.168.0.1:9999  Remote serial target in gdb-specific protocol
   2    remote 192.168.0.2:9998  Remote serial target in gdb-specific protocol
 * 3    native                   Native process
   4    core                     Local core dump file

#2 - New "info inferiors" "Connection" column

You'll also see a new matching "Connection" column in "info
inferiors", showing you which connection an inferior is bound to:

 (gdb) info inferiors
   Num  Description       Connection                   Executable
   1    process 18526     1 (remote 192.168.0.1:9999)  target:/tmp/a.out
   2    process 18531     2 (remote 192.168.0.2:9998)  target:/tmp/a.out
   3    process 19115     3 (native)                   /tmp/prog1
   4    process 6286      4 (core)                     myprogram
 * 5    process 19122     3 (native)                   /bin/hello

#3 - Makes "add-inferior" show the inferior's target connection

"add-inferior" now shows you the connection you've just bound the
inferior to, which is the current process_stratum target:

 (gdb) add-inferior
 [New inferior 2]
 Added inferior 2 on connection 1 (extended-remote localhost:2346)

gdb/ChangeLog:
2020-01-10  Pedro Alves  <palves@redhat.com>

	* Makefile.in (COMMON_SFILES): Add target-connection.c.
	* inferior.c (uiout_field_connection): New function.
	(print_inferior): Add new "connection-id" column.
	(add_inferior_command): Show connection number/string of added
	inferior.
	* process-stratum-target.h
	(process_stratum_target::connection_string): New virtual method.
	(process_stratum_target::connection_number): New field.
	* remote.c (remote_target::connection_string): New override.
	* target-connection.c: New file.
	* target-connection.h: New file.
	* target.c (decref_target): Remove process_stratum targets from
	the connection list.
	(target_stack::push): Add process_stratum targets to the
	connection list.

gdb/testsuite/ChangeLog:
2020-01-10  Pedro Alves  <palves@redhat.com>

	* gdb.base/kill-detach-inferiors-cmd.exp: Adjust expected output
	of "add-inferior".
	* gdb.base/quit-live.exp: Likewise.
	* gdb.base/remote-exec-file.exp: Likewise.
	* gdb.guile/scm-progspace.exp: Likewise.
	* gdb.linespec/linespec.exp: Likewise.
	* gdb.mi/new-ui-mi-sync.exp: Likewise.
	* gdb.mi/user-selected-context-sync.exp: Likewise.
	* gdb.multi/multi-target.exp (setup): Add "info connection" and
	"info inferiors" tests.
	* gdb.multi/remove-inferiors.exp: Adjust expected output of
	"add-inferior".
	* gdb.multi/watchpoint-multi.exp: Likewise.
	* gdb.python/py-inferior.exp: Likewise.
	* gdb.server/extended-remote-restart.exp: Likewise.
	* gdb.threads/fork-plus-threads.exp: Adjust expected output of
	"info inferiors".
	* gdb.threads/forking-threads-plus-breakpoint.exp: Likewise.
	* gdb.trace/report.exp: Likewise.

1 files changed, 52 insertions, 4 deletions

diff --git a/gdb/inferior.c b/gdb/inferior.c
index d732690..3ce4386 100644
--- a/gdb/inferior.c
+++ b/gdb/inferior.c
@@ -428,6 +428,31 @@ print_selected_inferior (struct ui_out *uiout)
 		  inf->num, inferior_pid_to_str (inf->pid).c_str (), filename);
 }
 
+/* Helper for print_inferior.  Returns the 'connection-id' string for
+   PROC_TARGET.  */
+
+static std::string
+uiout_field_connection (process_stratum_target *proc_target)
+{
+  if (proc_target == NULL)
+    {
+      return {};
+    }
+  else if (proc_target->connection_string () != NULL)
+    {
+      return string_printf ("%d (%s %s)",
+			    proc_target->connection_number,
+			    proc_target->shortname (),
+			    proc_target->connection_string ());
+    }
+  else
+    {
+      return string_printf ("%d (%s)",
+			    proc_target->connection_number,
+			    proc_target->shortname ());
+    }
+}
+
 /* Prints the list of inferiors and their details on UIOUT.  This is a
    version of 'info_inferior_command' suitable for use from MI.
 
@@ -439,6 +464,7 @@ static void
 print_inferior (struct ui_out *uiout, const char *requested_inferiors)
 {
   int inf_count = 0;
+  size_t connection_id_len = 20;
 
   /* Compute number of inferiors we will print.  */
   for (inferior *inf : all_inferiors ())
@@ -446,6 +472,10 @@ print_inferior (struct ui_out *uiout, const char *requested_inferiors)
       if (!number_is_in_list (requested_inferiors, inf->num))
 	continue;
 
+      std::string conn = uiout_field_connection (inf->process_target ());
+      if (connection_id_len < conn.size ())
+	connection_id_len = conn.size ();
+
       ++inf_count;
     }
 
@@ -455,10 +485,12 @@ print_inferior (struct ui_out *uiout, const char *requested_inferiors)
       return;
     }
 
-  ui_out_emit_table table_emitter (uiout, 4, inf_count, "inferiors");
+  ui_out_emit_table table_emitter (uiout, 5, inf_count, "inferiors");
   uiout->table_header (1, ui_left, "current", "");
   uiout->table_header (4, ui_left, "number", "Num");
   uiout->table_header (17, ui_left, "target-id", "Description");
+  uiout->table_header (connection_id_len, ui_left,
+		       "connection-id", "Connection");
   uiout->table_header (17, ui_left, "exec", "Executable");
 
   uiout->table_body ();
@@ -478,6 +510,9 @@ print_inferior (struct ui_out *uiout, const char *requested_inferiors)
 
       uiout->field_string ("target-id", inferior_pid_to_str (inf->pid));
 
+      std::string conn = uiout_field_connection (inf->process_target ());
+      uiout->field_string ("connection-id", conn.c_str ());
+
       if (inf->pspace->pspace_exec_filename != NULL)
 	uiout->field_string ("exec", inf->pspace->pspace_exec_filename);
       else
@@ -712,9 +747,22 @@ switch_to_inferior_and_push_target (inferior *new_inf,
 
   /* Reuse the target for new inferior.  */
   if (!no_connection && proc_target != NULL)
-    push_target (proc_target);
-
-  printf_filtered (_("Added inferior %d\n"), new_inf->num);
+    {
+      push_target (proc_target);
+      if (proc_target->connection_string () != NULL)
+	printf_filtered (_("Added inferior %d on connection %d (%s %s)\n"),
+			 new_inf->num,
+			 proc_target->connection_number,
+			 proc_target->shortname (),
+			 proc_target->connection_string ());
+      else
+	printf_filtered (_("Added inferior %d on connection %d (%s)\n"),
+			 new_inf->num,
+			 proc_target->connection_number,
+			 proc_target->shortname ());
+    }
+  else
+    printf_filtered (_("Added inferior %d\n"), new_inf->num);
 }
 
 /* add-inferior [-copies N] [-exec FILENAME] [-no-connection] */