1 /* Fork a Unix child process, and set up to debug it, for GDBserver. 2 Copyright (C) 1989-2024 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 "gdbsupport/job-control.h" 20 #include "gdbsupport/scoped_restore.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 threads_debug_printf ("args: %s", args); 49 50 #ifdef SIGTTOU 51 signal (SIGTTOU, SIG_DFL); 52 signal (SIGTTIN, SIG_DFL); 53 #endif 54 55 /* Clear this so the backend doesn't get confused, thinking 56 CONT_THREAD died, and it needs to resume all threads. */ 57 cs.cont_thread = null_ptid; 58 } 59 60 /* See nat/fork-inferior.h. */ 61 62 void 63 postfork_hook (pid_t pid) 64 { 65 } 66 67 /* See nat/fork-inferior.h. */ 68 69 void 70 postfork_child_hook () 71 { 72 /* This is set to the result of setpgrp, which if vforked, will be 73 visible to you in the parent process. It's only used by humans 74 for debugging. */ 75 static int debug_setpgrp = 657473; 76 77 debug_setpgrp = gdb_setpgid (); 78 if (debug_setpgrp == -1) 79 perror (_("setpgrp failed in child")); 80 } 81 82 /* See nat/fork-inferior.h. */ 83 84 void 85 gdb_flush_out_err () 86 { 87 fflush (stdout); 88 fflush (stderr); 89 } 90 91 /* See server.h. */ 92 93 void 94 post_fork_inferior (int pid, const char *program) 95 { 96 client_state &cs = get_client_state (); 97 #ifdef SIGTTOU 98 signal (SIGTTOU, SIG_IGN); 99 signal (SIGTTIN, SIG_IGN); 100 terminal_fd = fileno (stderr); 101 old_foreground_pgrp = tcgetpgrp (terminal_fd); 102 tcsetpgrp (terminal_fd, pid); 103 atexit (restore_old_foreground_pgrp); 104 #endif 105 106 process_info *proc = find_process_pid (pid); 107 108 /* If the inferior fails to start, startup_inferior mourns the 109 process (which deletes it), and then throws an error. This means 110 that on exception return, we don't need or want to clear this 111 flag back, as PROC won't exist anymore. Thus, we don't use a 112 scoped_restore. */ 113 proc->starting_up = true; 114 115 startup_inferior (the_target, pid, 116 START_INFERIOR_TRAPS_EXPECTED, 117 &cs.last_status, &cs.last_ptid); 118 119 /* If we get here, the process was successfully started. */ 120 proc->starting_up = false; 121 122 current_thread->last_resume_kind = resume_stop; 123 current_thread->last_status = cs.last_status; 124 signal_pid = pid; 125 target_post_create_inferior (); 126 fprintf (stderr, "Process %s created; pid = %d\n", program, pid); 127 fflush (stderr); 128 } 129