binutils-gdb/gdb/terminal.h
Pedro Alves d9de1fe3d5 Fix PR20494 - User input stops being echoed in CLI
This patch fixes a problem that problem triggers if you start an
inferior, e.g., with the "start" command, in a UI created with the
new-ui command, and then run a foreground execution command in the
main UI.  Once the program stops for the latter command, typing in the
main UI no longer echoes back to the user.

The problem revolves around this:

- gdb_has_a_terminal computes its result lazily, on first call.

  that is what saves gdb's initial main UI terminal state (the UI
  associated with stdin):

          our_terminal_info.ttystate = serial_get_tty_state (stdin_serial);

  This is the state that target_terminal_ours() restores.

- In this scenario, the gdb_has_a_terminal function happens to be
  first ever called from within the target_terminal_init call in
  startup_inferior:

      (top-gdb) bt
      #0  gdb_has_a_terminal () at src/gdb/inflow.c:157
      #1  0x000000000079db22 in child_terminal_init_with_pgrp () at src/gdb/inflow.c:217
       [...]
      #4  0x000000000065bacb in target_terminal_init () at src/gdb/target.c:456
      #5  0x00000000004676d2 in startup_inferior () at src/gdb/fork-child.c:531
       [...]
      #7  0x000000000046b168 in linux_nat_create_inferior () at src/gdb/linux-nat.c:1112
       [...]
      #9  0x00000000005f20c9 in start_command (args=0x0, from_tty=1) at src/gdb/infcmd.c:657

If the command to start the inferior is issued on the main UI, then
readline will have deprepped the terminal when we reach the above, and
the problem doesn't appear.

If however the command is issued on a non-main UI, then when we reach
that gdb_has_a_terminal call, the main UI's terminal state is still
set to whatever readline has sets it to in rl_prep_terminal, which
happens to have echo disabled.  Later, when the following synchronous
execution command finishes, we'll call target_terminal_ours to restore
gdb's the main UI's terminal settings, and that restores the terminal
state with echo disabled...

Conceptually, the fix is to move the gdb_has_a_terminal call earlier,
to someplace during GDB initialization, before readline/ncurses have
had a chance to change terminal settings.  Turns out that
"set_initial_gdb_ttystate" is exactly such a place.

I say conceptually, because the fix actually inlines the
gdb_has_a_terminal part that saves the terminal state in
set_initial_gdb_ttystate and then simplifies gdb_has_a_terminal, since
there's no point in making gdb_has_a_terminal do lazy computation.

gdb/ChangeLog:
2016-08-23  Pedro Alves  <palves@redhat.com>

	PR gdb/20494
	* inflow.c (our_terminal_info, initial_gdb_ttystate): Update
	comments.
	(enum gdb_has_a_terminal_flag_enum, gdb_has_a_terminal_flag):
	Delete.
	(set_initial_gdb_ttystate): Record our_terminal_info here too,
	instead of ...
	(gdb_has_a_terminal): ... here.  Reimplement in terms of
	initial_gdb_ttystate.  Make static.
	* terminal.h (gdb_has_a_terminal): Delete declaration.
	(set_initial_gdb_ttystate): Add comment.
	* top.c (show_interactive_mode): Use input_interactive_p instead
	of gdb_has_a_terminal.

gdb/testsuite/ChangeLog:
2016-08-23  Pedro Alves  <palves@redhat.com>

	PR gdb/20494
	* gdb.base/new-ui-echo.c: New file.
	* gdb.base/new-ui-echo.exp: New file.
2016-08-23 16:03:28 +01:00

113 lines
3.4 KiB
C

/* Terminal interface definitions for GDB, the GNU Debugger.
Copyright (C) 1986-2016 Free Software Foundation, Inc.
This file is part of GDB.
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/>. */
#if !defined (TERMINAL_H)
#define TERMINAL_H 1
/* If we're using autoconf, it will define HAVE_TERMIOS_H,
HAVE_TERMIO_H and HAVE_SGTTY_H for us. One day we can rewrite
ser-unix.c and inflow.c to inspect those names instead of
HAVE_TERMIOS, HAVE_TERMIO and the implicit HAVE_SGTTY (when neither
HAVE_TERMIOS or HAVE_TERMIO is set). Until then, make sure that
nothing has already defined the one of the names, and do the right
thing. */
#if !defined (HAVE_TERMIOS) && !defined(HAVE_TERMIO) && !defined(HAVE_SGTTY)
#if defined(HAVE_TERMIOS_H)
#define HAVE_TERMIOS
#else /* ! defined (HAVE_TERMIOS_H) */
#if defined(HAVE_TERMIO_H)
#define HAVE_TERMIO
#else /* ! defined (HAVE_TERMIO_H) */
#if defined(HAVE_SGTTY_H)
#define HAVE_SGTTY
#endif /* ! defined (HAVE_SGTTY_H) */
#endif /* ! defined (HAVE_TERMIO_H) */
#endif /* ! defined (HAVE_TERMIOS_H) */
#endif /* !defined (HAVE_TERMIOS) && !defined (HAVE_TERMIO) &&
!defined (HAVE_SGTTY) */
#if defined(HAVE_TERMIOS)
#include <termios.h>
#endif
#if !defined(_WIN32) && !defined (HAVE_TERMIOS)
/* Define a common set of macros -- BSD based -- and redefine whatever
the system offers to make it look like that. FIXME: serial.h and
ser-*.c deal with this in a much cleaner fashion; as soon as stuff
is converted to use them, can get rid of this crap. */
#ifdef HAVE_TERMIO
#include <termio.h>
#undef TIOCGETP
#define TIOCGETP TCGETA
#undef TIOCSETN
#define TIOCSETN TCSETA
#undef TIOCSETP
#define TIOCSETP TCSETAF
#define TERMINAL struct termio
#else /* sgtty */
#include <fcntl.h>
#include <sgtty.h>
#include <sys/ioctl.h>
#define TERMINAL struct sgttyb
#endif /* sgtty */
#endif
struct inferior;
extern void new_tty_prefork (const char *);
extern void new_tty (void);
extern void new_tty_postfork (void);
extern void copy_terminal_info (struct inferior *to, struct inferior *from);
/* Do we have job control? Can be assumed to always be the same within
a given run of GDB. In inflow.c. */
extern int job_control;
extern pid_t create_tty_session (void);
/* Set the process group of the caller to its own pid, or do nothing if
we lack job control. */
extern int gdb_setpgid (void);
/* Set up a serial structure describing standard input. In inflow.c. */
extern void initialize_stdin_serial (void);
extern void gdb_save_tty_state (void);
/* Take a snapshot of our initial tty state before readline/ncurses
have had a chance to alter it. */
extern void set_initial_gdb_ttystate (void);
/* Set the process group of the caller to its own pid, or do nothing
if we lack job control. */
extern int gdb_setpgid (void);
#endif /* !defined (TERMINAL_H) */