1 /* Fork a Unix child process, and set up to debug it, for GDB. 2 3 Copyright (C) 1990-2023 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 "defs.h" 23 #include "inferior.h" 24 #include "gdbcmd.h" 25 #include "terminal.h" 26 #include "gdbthread.h" 27 #include "top.h" 28 #include "gdbsupport/job-control.h" 29 #include "gdbsupport/filestuff.h" 30 #include "nat/fork-inferior.h" 31 #include "gdbsupport/common-inferior.h" 32 33 /* The exec-wrapper, if any, that will be used when starting the 34 inferior. */ 35 36 static std::string exec_wrapper; 37 38 /* See gdbsupport/common-inferior.h. */ 39 40 const char * 41 get_exec_wrapper () 42 { 43 return !exec_wrapper.empty () ? exec_wrapper.c_str () : nullptr; 44 } 45 46 /* See nat/fork-inferior.h. */ 47 48 void 49 gdb_flush_out_err () 50 { 51 gdb_flush (main_ui->m_gdb_stdout); 52 gdb_flush (main_ui->m_gdb_stderr); 53 } 54 55 /* The ui structure that will be saved on 'prefork_hook' and 56 restored on 'postfork_hook'. */ 57 static struct ui *saved_ui = NULL; 58 59 /* See nat/fork-inferior.h. */ 60 61 void 62 prefork_hook (const char *args) 63 { 64 gdb_assert (saved_ui == NULL); 65 /* Retain a copy of our UI, since the child will replace this value 66 and if we're vforked, we have to restore it. */ 67 saved_ui = current_ui; 68 69 /* Tell the terminal handling subsystem what tty we plan to run on; 70 it will just record the information for later. */ 71 new_tty_prefork (current_inferior ()->tty ()); 72 } 73 74 /* See nat/fork-inferior.h. */ 75 76 void 77 postfork_hook (pid_t pid) 78 { 79 inferior *inf = current_inferior (); 80 81 inferior_appeared (inf, pid); 82 83 gdb_assert (saved_ui != NULL); 84 current_ui = saved_ui; 85 saved_ui = NULL; 86 87 new_tty_postfork (); 88 } 89 90 /* See nat/fork-inferior.h. */ 91 92 void 93 postfork_child_hook () 94 { 95 /* This is set to the result of setpgrp, which if vforked, will be 96 visible to you in the parent process. It's only used by humans 97 for debugging. */ 98 static int debug_setpgrp = 657473; 99 100 /* Make sure we switch to main_ui here in order to be able to 101 use the gdb_printf/warning/error functions. */ 102 current_ui = main_ui; 103 104 /* Create a new session for the inferior process, if necessary. 105 It will also place the inferior in a separate process group. */ 106 if (create_tty_session () <= 0) 107 { 108 /* No session was created, but we still want to run the inferior 109 in a separate process group. */ 110 debug_setpgrp = gdb_setpgid (); 111 if (debug_setpgrp == -1) 112 perror (_("setpgrp failed in child")); 113 } 114 115 /* Ask the tty subsystem to switch to the one we specified 116 earlier (or to share the current terminal, if none was 117 specified). */ 118 new_tty (); 119 } 120 121 /* See inferior.h. */ 122 123 ptid_t 124 gdb_startup_inferior (pid_t pid, int num_traps) 125 { 126 inferior *inf = current_inferior (); 127 process_stratum_target *proc_target = inf->process_target (); 128 129 scoped_restore save_starting_up 130 = make_scoped_restore (&inf->starting_up, true); 131 132 ptid_t ptid = startup_inferior (proc_target, pid, num_traps, NULL, NULL); 133 134 /* Mark all threads non-executing. */ 135 set_executing (proc_target, ptid, false); 136 137 return ptid; 138 } 139 140 /* Implement the "unset exec-wrapper" command. */ 141 142 static void 143 unset_exec_wrapper_command (const char *args, int from_tty) 144 { 145 exec_wrapper.clear (); 146 } 147 148 static void 149 show_startup_with_shell (struct ui_file *file, int from_tty, 150 struct cmd_list_element *c, const char *value) 151 { 152 gdb_printf (file, 153 _("Use of shell to start subprocesses is %s.\n"), 154 value); 155 } 156 157 void _initialize_fork_child (); 158 void 159 _initialize_fork_child () 160 { 161 add_setshow_filename_cmd ("exec-wrapper", class_run, &exec_wrapper, _("\ 162 Set a wrapper for running programs.\n\ 163 The wrapper prepares the system and environment for the new program."), 164 _("\ 165 Show the wrapper for running programs."), NULL, 166 NULL, NULL, 167 &setlist, &showlist); 168 169 add_cmd ("exec-wrapper", class_run, unset_exec_wrapper_command, 170 _("Disable use of an execution wrapper."), 171 &unsetlist); 172 173 add_setshow_boolean_cmd ("startup-with-shell", class_support, 174 &startup_with_shell, _("\ 175 Set use of shell to start subprocesses. The default is on."), _("\ 176 Show use of shell to start subprocesses."), NULL, 177 NULL, 178 show_startup_with_shell, 179 &setlist, &showlist); 180 } 181