old-cross-binutils/gdb/testsuite/gdb.base/attach-wait-input.c
Pedro Alves 7180e04a36 Fix "attach" command vs user input race
On async targets, a synchronous attach is done like this:

   #1 - target_attach is called (PTRACE_ATTACH is issued)
   #2 - a continuation is installed
   #3 - we go back to the event loop
   #4 - target reports stop (SIGSTOP), event loop wakes up, and
        attach continuation is called
   #5 - among other things, the continuation calls
        target_terminal_inferior, which removes stdin from the event
        loop

Note that in #3, GDB is still processing user input.  If the user is
fast enough, e.g., with something like:

  echo -e "attach PID\nset xxx=1" | gdb

... then the "set" command is processed before the attach completes.

We get worse behavior even, if input is a tty and therefore
readline/editing is enabled, with e.g.,:

 (gdb) attach PID\nset xxx=1

we then crash readline/gdb, with:

 Attaching to program: attach-wait-input, process 14537
 readline: readline_callback_read_char() called with no handler!
 Aborted
 $

Fix this by calling target_terminal_inferior before #3 above.

The test covers both scenarios by running with editing/readline forced
to both on and off.

gdb/
2014-07-09  Pedro Alves  <palves@redhat.com>

	* infcmd.c (attach_command_post_wait): Don't call
	target_terminal_inferior here.
	(attach_command): Call it here instead.

gdb/testsuite/
2014-07-09  Pedro Alves  <palves@redhat.com>

	* gdb.base/attach-wait-input.exp: New file.
	* gdb.base/attach-wait-input.c: New file.
2014-07-09 15:59:02 +01:00

40 lines
1 KiB
C

/* This testcase is part of GDB, the GNU debugger.
Copyright 2014 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <sys/types.h>
#include <unistd.h>
volatile int should_exit = 0;
int mypid;
static void
setup_done (void)
{
}
int
main (void)
{
unsigned int counter = 1;
mypid = getpid ();
setup_done ();
for (counter = 0; !should_exit && counter < 100; counter++)
sleep (1);
return 0;
}