gdb/gdbserver/fork-child.c

   1 /* Fork a Unix child process, and set up to debug it, for GDBserver.
   2    Copyright (C) 1989-2018 Free Software Foundation, Inc.
   3
   4    This file is part of GDB.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #include "server.h"
  20 #include "job-control.h"
  21 #include "nat/fork-inferior.h"
  22 #ifdef HAVE_SIGNAL_H
  23 #include <signal.h>
  24 #endif
  25
  26 #ifdef SIGTTOU
  27 /* A file descriptor for the controlling terminal.  */
  28 static int terminal_fd;
  29
  30 /* TERMINAL_FD's original foreground group.  */
  31 static pid_t old_foreground_pgrp;
  32
  33 /* Hand back terminal ownership to the original foreground group.  */
  34
  35 static void
  36 restore_old_foreground_pgrp (void)
  37 {
  38   tcsetpgrp (terminal_fd, old_foreground_pgrp);
  39 }
  40 #endif
  41
  42 /* See nat/fork-inferior.h.  */
  43
  44 void
  45 prefork_hook (const char *args)
  46 {
  47   if (debug_threads)
  48     {
  49       debug_printf ("args: %s\n", args);
  50       debug_flush ();
  51     }
  52
  53 #ifdef SIGTTOU
  54   signal (SIGTTOU, SIG_DFL);
  55   signal (SIGTTIN, SIG_DFL);
  56 #endif
  57
  58   /* Clear this so the backend doesn't get confused, thinking
  59      CONT_THREAD died, and it needs to resume all threads.  */
  60   cont_thread = null_ptid;
  61 }
  62
  63 /* See nat/fork-inferior.h.  */
  64
  65 void
  66 postfork_hook (pid_t pid)
  67 {
  68 }
  69
  70 /* See nat/fork-inferior.h.  */
  71
  72 void
  73 postfork_child_hook ()
  74 {
  75   /* This is set to the result of setpgrp, which if vforked, will be
  76      visible to you in the parent process.  It's only used by humans
  77      for debugging.  */
  78   static int debug_setpgrp = 657473;
  79
  80   debug_setpgrp = gdb_setpgid ();
  81   if (debug_setpgrp == -1)
  82     perror (_("setpgrp failed in child"));
  83 }
  84
  85 /* See nat/fork-inferior.h.  */
  86
  87 void
  88 gdb_flush_out_err ()
  89 {
  90   fflush (stdout);
  91   fflush (stderr);
  92 }
  93
  94 /* See server.h.  */
  95
  96 void
  97 post_fork_inferior (int pid, const char *program)
  98 {
  99 #ifdef SIGTTOU
 100   signal (SIGTTOU, SIG_IGN);
 101   signal (SIGTTIN, SIG_IGN);
 102   terminal_fd = fileno (stderr);
 103   old_foreground_pgrp = tcgetpgrp (terminal_fd);
 104   tcsetpgrp (terminal_fd, pid);
 105   atexit (restore_old_foreground_pgrp);
 106 #endif
 107
 108   startup_inferior (pid, START_INFERIOR_TRAPS_EXPECTED,
 109                     &last_status, &last_ptid);
 110   current_thread->last_resume_kind = resume_stop;
 111   current_thread->last_status = last_status;
 112   signal_pid = pid;
 113   target_post_create_inferior ();
 114   fprintf (stderr, "Process %s created; pid = %d\n", program, pid);
 115   fflush (stderr);
 116 }