1 /* Fork a Unix child process, and set up to debug it, for GDB. 2 3 Copyright (C) 1990-2024 Free Software Foundation, Inc. 4 5 Contributed by Cygnus Support. 6 7 This file is part of GDB. 8 9 This program is free software; you can redistribute it and/or modify 10 it under the terms of the GNU General Public License as published by 11 the Free Software Foundation; either version 3 of the License, or 12 (at your option) any later version. 13 14 This program is distributed in the hope that it will be useful, 15 but WITHOUT ANY WARRANTY; without even the implied warranty of 16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 GNU General Public License for more details. 18 19 You should have received a copy of the GNU General Public License 20 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 21 22 #include "inferior.h" 23 #include "cli/cli-cmds.h" 24 #include "terminal.h" 25 #include "gdbthread.h" 26 #include "ui.h" 27 #include "gdbsupport/job-control.h" 28 #include "gdbsupport/filestuff.h" 29 #include "nat/fork-inferior.h" 30 #include "gdbsupport/common-inferior.h" 31 32 /* The exec-wrapper, if any, that will be used when starting the 33 inferior. */ 34 35 static std::string exec_wrapper; 36 37 /* See gdbsupport/common-inferior.h. */ 38 39 const char * 40 get_exec_wrapper () 41 { 42 return !exec_wrapper.empty () ? exec_wrapper.c_str () : nullptr; 43 } 44 45 /* See nat/fork-inferior.h. */ 46 47 void 48 gdb_flush_out_err () 49 { 50 gdb_flush (main_ui->m_gdb_stdout); 51 gdb_flush (main_ui->m_gdb_stderr); 52 } 53 54 /* The ui structure that will be saved on 'prefork_hook' and 55 restored on 'postfork_hook'. */ 56 static struct ui *saved_ui = NULL; 57 58 /* See nat/fork-inferior.h. */ 59 60 void 61 prefork_hook (const char *args) 62 { 63 gdb_assert (saved_ui == NULL); 64 /* Retain a copy of our UI, since the child will replace this value 65 and if we're vforked, we have to restore it. */ 66 saved_ui = current_ui; 67 68 /* Tell the terminal handling subsystem what tty we plan to run on; 69 it will just record the information for later. */ 70 new_tty_prefork (current_inferior ()->tty ()); 71 } 72 73 /* See nat/fork-inferior.h. */ 74 75 void 76 postfork_hook (pid_t pid) 77 { 78 inferior *inf = current_inferior (); 79 80 inferior_appeared (inf, pid); 81 82 gdb_assert (saved_ui != NULL); 83 current_ui = saved_ui; 84 saved_ui = NULL; 85 86 new_tty_postfork (); 87 } 88 89 /* See nat/fork-inferior.h. */ 90 91 void 92 postfork_child_hook () 93 { 94 /* This is set to the result of setpgrp, which if vforked, will be 95 visible to you in the parent process. It's only used by humans 96 for debugging. */ 97 static int debug_setpgrp = 657473; 98 99 /* Make sure we switch to main_ui here in order to be able to 100 use the gdb_printf/warning/error functions. */ 101 current_ui = main_ui; 102 103 /* Create a new session for the inferior process, if necessary. 104 It will also place the inferior in a separate process group. */ 105 if (create_tty_session () <= 0) 106 { 107 /* No session was created, but we still want to run the inferior 108 in a separate process group. */ 109 debug_setpgrp = gdb_setpgid (); 110 if (debug_setpgrp == -1) 111 perror (_("setpgrp failed in child")); 112 } 113 114 /* Ask the tty subsystem to switch to the one we specified 115 earlier (or to share the current terminal, if none was 116 specified). */ 117 new_tty (); 118 } 119 120 /* See inferior.h. */ 121 122 ptid_t 123 gdb_startup_inferior (pid_t pid, int num_traps) 124 { 125 inferior *inf = current_inferior (); 126 process_stratum_target *proc_target = inf->process_target (); 127 128 scoped_restore save_starting_up 129 = make_scoped_restore (&inf->starting_up, true); 130 131 ptid_t ptid = startup_inferior (proc_target, pid, num_traps, NULL, NULL); 132 133 /* Mark all threads non-executing. */ 134 set_executing (proc_target, ptid, false); 135 136 return ptid; 137 } 138 139 /* Implement the "unset exec-wrapper" command. */ 140 141 static void 142 unset_exec_wrapper_command (const char *args, int from_tty) 143 { 144 exec_wrapper.clear (); 145 } 146 147 static void 148 show_startup_with_shell (struct ui_file *file, int from_tty, 149 struct cmd_list_element *c, const char *value) 150 { 151 gdb_printf (file, 152 _("Use of shell to start subprocesses is %s.\n"), 153 value); 154 } 155 156 void _initialize_fork_child (); 157 void 158 _initialize_fork_child () 159 { 160 add_setshow_filename_cmd ("exec-wrapper", class_run, &exec_wrapper, _("\ 161 Set a wrapper for running programs.\n\ 162 The wrapper prepares the system and environment for the new program."), 163 _("\ 164 Show the wrapper for running programs."), NULL, 165 NULL, NULL, 166 &setlist, &showlist); 167 168 add_cmd ("exec-wrapper", class_run, unset_exec_wrapper_command, 169 _("Disable use of an execution wrapper."), 170 &unsetlist); 171 172 add_setshow_boolean_cmd ("startup-with-shell", class_support, 173 &startup_with_shell, _("\ 174 Set use of shell to start subprocesses. The default is on."), _("\ 175 Show use of shell to start subprocesses."), NULL, 176 NULL, 177 show_startup_with_shell, 178 &setlist, &showlist); 179 } 180