binutils-gdb/gdbserver/fork-child.cc

/* Fork a Unix child process, and set up to debug it, for GDBserver.
   Copyright (C) 1989-2020 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 "server.h"
#include "gdbsupport/job-control.h"
#include "nat/fork-inferior.h"
#ifdef HAVE_SIGNAL_H
#include <signal.h>
#endif

#ifdef SIGTTOU
/* A file descriptor for the controlling terminal.  */
static int terminal_fd;

/* TERMINAL_FD's original foreground group.  */
static pid_t old_foreground_pgrp;

/* Hand back terminal ownership to the original foreground group.  */

static void
restore_old_foreground_pgrp (void)
{
  tcsetpgrp (terminal_fd, old_foreground_pgrp);
}
#endif

/* See nat/fork-inferior.h.  */

void
prefork_hook (const char *args)
{
  client_state &cs = get_client_state ();
  if (debug_threads)
    {
      debug_printf ("args: %s\n", args);
      debug_flush ();
    }

#ifdef SIGTTOU
  signal (SIGTTOU, SIG_DFL);
  signal (SIGTTIN, SIG_DFL);
#endif

  /* Clear this so the backend doesn't get confused, thinking
     CONT_THREAD died, and it needs to resume all threads.  */
  cs.cont_thread = null_ptid;
}

/* See nat/fork-inferior.h.  */

void
postfork_hook (pid_t pid)
{
}

/* See nat/fork-inferior.h.  */

void
postfork_child_hook ()
{
  /* This is set to the result of setpgrp, which if vforked, will be
     visible to you in the parent process.  It's only used by humans
     for debugging.  */
  static int debug_setpgrp = 657473;

  debug_setpgrp = gdb_setpgid ();
  if (debug_setpgrp == -1)
    perror (_("setpgrp failed in child"));
}

/* See nat/fork-inferior.h.  */

void
gdb_flush_out_err ()
{
  fflush (stdout);
  fflush (stderr);
}

/* See server.h.  */

void
post_fork_inferior (int pid, const char *program)
{
  client_state &cs = get_client_state ();
#ifdef SIGTTOU
  signal (SIGTTOU, SIG_IGN);
  signal (SIGTTIN, SIG_IGN);
  terminal_fd = fileno (stderr);
  old_foreground_pgrp = tcgetpgrp (terminal_fd);
  tcsetpgrp (terminal_fd, pid);
  atexit (restore_old_foreground_pgrp);
#endif

  startup_inferior (the_target, pid,
		    START_INFERIOR_TRAPS_EXPECTED,
		    &cs.last_status, &cs.last_ptid);
  current_thread->last_resume_kind = resume_stop;
  current_thread->last_status = cs.last_status;
  signal_pid = pid;
  target_post_create_inferior ();
  fprintf (stderr, "Process %s created; pid = %d\n", program, pid);
  fflush (stderr);
}