gdbserver/fork-child.cc

   1 /* Fork a Unix child process, and set up to debug it, for GDBserver.
   2    Copyright (C) 1989-2021 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 "gdbsupport/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   client_state &cs = get_client_state ();
  48   if (debug_threads)
  49     {
  50       debug_printf ("args: %s\n", args);
  51       debug_flush ();
  52     }
  53
  54 #ifdef SIGTTOU
  55   signal (SIGTTOU, SIG_DFL);
  56   signal (SIGTTIN, SIG_DFL);
  57 #endif
  58
  59   /* Clear this so the backend doesn't get confused, thinking
  60      CONT_THREAD died, and it needs to resume all threads.  */
  61   cs.cont_thread = null_ptid;
  62 }
  63
  64 /* See nat/fork-inferior.h.  */
  65
  66 void
  67 postfork_hook (pid_t pid)
  68 {
  69 }
  70
  71 /* See nat/fork-inferior.h.  */
  72
  73 void
  74 postfork_child_hook ()
  75 {
  76   /* This is set to the result of setpgrp, which if vforked, will be
  77      visible to you in the parent process.  It's only used by humans
  78      for debugging.  */
  79   static int debug_setpgrp = 657473;
  80
  81   debug_setpgrp = gdb_setpgid ();
  82   if (debug_setpgrp == -1)
  83     perror (_("setpgrp failed in child"));
  84 }
  85
  86 /* See nat/fork-inferior.h.  */
  87
  88 void
  89 gdb_flush_out_err ()
  90 {
  91   fflush (stdout);
  92   fflush (stderr);
  93 }
  94
  95 /* See server.h.  */
  96
  97 void
  98 post_fork_inferior (int pid, const char *program)
  99 {
 100   client_state &cs = get_client_state ();
 101 #ifdef SIGTTOU
 102   signal (SIGTTOU, SIG_IGN);
 103   signal (SIGTTIN, SIG_IGN);
 104   terminal_fd = fileno (stderr);
 105   old_foreground_pgrp = tcgetpgrp (terminal_fd);
 106   tcsetpgrp (terminal_fd, pid);
 107   atexit (restore_old_foreground_pgrp);
 108 #endif
 109
 110   startup_inferior (the_target, pid,
 111                     START_INFERIOR_TRAPS_EXPECTED,
 112                     &cs.last_status, &cs.last_ptid);
 113   current_thread->last_resume_kind = resume_stop;
 114   current_thread->last_status = cs.last_status;
 115   signal_pid = pid;
 116   target_post_create_inferior ();
 117   fprintf (stderr, "Process %s created; pid = %d\n", program, pid);
 118   fflush (stderr);
 119 }