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, 45 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.base/attach.exp b/gdb/testsuite/gdb.base/attach.exp
index a20c51a..6340496 100644
--- a/gdb/testsuite/gdb.base/attach.exp
+++ b/gdb/testsuite/gdb.base/attach.exp
@@ -396,6 +396,49 @@ proc do_command_attach_tests {} {
     remote_exec build "kill -9 ${testpid}"
 }
 
+# Test ' gdb --pid PID -ex "run" '.  GDB used to have a bug where
+# "run" would run before the attach finished - PR17347.
+
+proc test_command_line_attach_run {} {
+    global gdb_prompt
+    global binfile
+
+    if ![isnative] then {
+	unsupported "commandline attach run test"
+	return 0
+    }
+
+    with_test_prefix "cmdline attach run" {
+	set testpid [spawn_wait_for_attach $binfile]
+
+	set test "run to prompt"
+	gdb_exit
+
+	set res [gdb_spawn_with_cmdline_opts \
+		     "-iex \"set height 0\" -iex \"set width 0\" --pid=$testpid -ex \"start\""]
+	if { $res != 0} {
+	    fail $test
+	    return $res
+	}
+	gdb_test_multiple "" $test {
+	    -re {Attaching to.*Start it from the beginning\? \(y or n\) } {
+		pass $test
+	    }
+	}
+
+	send_gdb "y\n"
+
+	set test "run to main"
+	gdb_test_multiple "" $test {
+	    -re "Temporary breakpoint .* main .*$gdb_prompt $" {
+		pass $test
+	    }
+	}
+
+	# Get rid of the process
+	remote_exec build "kill -9 ${testpid}"
+    }
+}
 
 # Start with a fresh gdb
 
@@ -420,4 +463,6 @@ do_call_attach_tests
 
 do_command_attach_tests
 
+test_command_line_attach_run
+
 return 0