binutils-gdb/gdb/posix-hdep.c
Tom Tromey c88afe9cf5 Fix control-c handling on Windows
As Hannes pointed out, the Windows target-async patches broke C-c
handling there.  Looking into this, I found a few oddities, fixed
here.

First, windows_nat_target::interrupt calls GenerateConsoleCtrlEvent.
I think this event can be ignored by the inferior, so it's not a great
way to interrupt.  Instead, using DebugBreakProcess (or a more
complicated thing for Wow64) seems better.

Second, windows_nat_target did not implement the pass_ctrlc method.
Implementing this lets us remove the special code to call
SetConsoleCtrlHandler and instead integrate into gdb's approach to C-c
handling.  I believe that this should also fix the race that's
described in the comment that's being removed.

Initially, I thought a simpler version of this patch would work.
However, I think what happens is that some other library (I'm not sure
what) calls SetConsoleCtrlHandler while gdb is running, and this
intercepts and handles C-c -- so that the gdb SIGINT handler is not
called.  C-break continues to work, presumably because whatever
handler is installed ignores it.

This patch works around this issue by ensuring that the gdb handler
always comes first.
2022-12-13 12:51:53 -07:00

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C

/* Host support routines for MinGW, for GDB, the GNU debugger.
Copyright (C) 2006-2022 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/>. */
#include "defs.h"
#include "gdbsupport/event-loop.h"
#include "gdbsupport/gdb_select.h"
#include "inferior.h"
#include <signal.h>
/* Wrapper for select. Nothing special needed on POSIX platforms. */
int
gdb_select (int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
struct timeval *timeout)
{
return select (n, readfds, writefds, exceptfds, timeout);
}
/* Host-dependent console fputs method. POSIX platforms always return
zero, to use the default C 'fputs'. */
int
gdb_console_fputs (const char *buf, FILE *f)
{
return 0;
}
/* See inferior.h. */
tribool
sharing_input_terminal (int pid)
{
/* Using host-dependent code here is fine, because the
child_terminal_foo functions are meant to be used by child/native
targets. */
#if defined (__linux__) || defined (__sun__)
char buf[100];
xsnprintf (buf, sizeof (buf), "/proc/%d/fd/0", pid);
return is_gdb_terminal (buf);
#else
return TRIBOOL_UNKNOWN;
#endif
}
/* Current C-c handler. */
static c_c_handler_ftype *current_handler;
/* A wrapper that reinstalls the current signal handler. */
static void
handler_wrapper (int num)
{
signal (num, handler_wrapper);
if (current_handler != SIG_IGN)
current_handler (num);
}
/* See inferior.h. */
c_c_handler_ftype *
install_sigint_handler (c_c_handler_ftype *fn)
{
signal (SIGINT, handler_wrapper);
c_c_handler_ftype *result = current_handler;
current_handler = fn;
return result;
}