gdb/17347 - Regression: GDB stopped on run with attached process

Doing:

  gdb --pid=PID -ex run

Results in GDB getting a SIGTTIN, and thus ending stopped.  That's
usually indicative of a missing target_terminal_ours call.

E.g., from the PR:

 $ sleep 1h & p=$!; sleep 0.1; gdb -batch sleep $p -ex run
 [1] 28263
 [1]   Killed                  sleep 1h

 [2]+  Stopped                 gdb -batch sleep $p -ex run

The workaround is doing:

 gdb -ex "attach $PID" -ex "run"

instead of

 gdb [-p] $PID -ex "run"

With the former, gdb waits for the attach command to complete before
moving on to the "run" command, because the interpreter is in sync
mode at this point, within execute_command.  But for the latter,
attach_command is called directly from captured_main, and thus misses
that waiting.  IOW, "run" is running before the attach continuation
has run, before the program stops and attach completes.  The broken
terminal settings are just one symptom of that.  Any command that
queries or requires input results in the same.

The fix is to wait in catch_command_errors (which is specific to
main.c nowadays), just like we wait in execute_command.

gdb/ChangeLog:
2014-09-11  Pedro Alves  <palves@redhat.com>

	PR gdb/17347
	* main.c: Include "infrun.h".
	(catch_command_errors, catch_command_errors_const): Wait for the
	foreground command to complete.
	* top.c (maybe_wait_sync_command_done): New function, factored out
	from ...
	(maybe_wait_sync_command_done): ... here.
	* top.h (maybe_wait_sync_command_done): New declaration.

gdb/testsuite/ChangeLog:
2014-09-11  Pedro Alves  <palves@redhat.com>

	PR gdb/17347
	* lib/gdb.exp (gdb_spawn_with_cmdline_opts): New procedure.
	* gdb.base/attach.exp (test_command_line_attach_run): New
	procedure.
	(top level): Call it.

1 files changed, 18 insertions, 10 deletions

diff --git a/gdb/top.c b/gdb/top.c
index fc2b84d..d6696cd 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -373,6 +373,23 @@ check_frame_language_change (void)
     }
 }
 
+/* See top.h.  */
+
+void
+maybe_wait_sync_command_done (int was_sync)
+{
+  /* If the interpreter is in sync mode (we're running a user
+     command's list, running command hooks or similars), and we
+     just ran a synchronous command that started the target, wait
+     for that command to end.  */
+  if (!interpreter_async && !was_sync && sync_execution)
+    {
+      while (gdb_do_one_event () >= 0)
+	if (!sync_execution)
+	  break;
+    }
+}
+
 /* Execute the line P as a command, in the current user context.
    Pass FROM_TTY as second argument to the defining function.  */
 
@@ -459,16 +476,7 @@ execute_command (char *p, int from_tty)
       else
 	cmd_func (c, arg, from_tty);
 
-      /* If the interpreter is in sync mode (we're running a user
-	 command's list, running command hooks or similars), and we
-	 just ran a synchronous command that started the target, wait
-	 for that command to end.  */
-      if (!interpreter_async && !was_sync && sync_execution)
-	{
-	  while (gdb_do_one_event () >= 0)
-	    if (!sync_execution)
-	      break;
-	}
+      maybe_wait_sync_command_done (was_sync);
 
       /* If this command has been post-hooked, run the hook last.  */
       execute_cmd_post_hook (c);