1 /* Fork a Unix child process, and set up to debug it, for GDB. 2 3 Copyright (C) 1990-2019 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 "common/job-control.h" 29 #include "common/filestuff.h" 30 #include "nat/fork-inferior.h" 31 #include "common/common-inferior.h" 32 33 /* The exec-wrapper, if any, that will be used when starting the 34 inferior. */ 35 36 static char *exec_wrapper = NULL; 37 38 /* See common/common-inferior.h. */ 39 40 const char * 41 get_exec_wrapper () 42 { 43 return exec_wrapper; 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 const char *inferior_io_terminal = get_inferior_io_terminal (); 65 66 gdb_assert (saved_ui == NULL); 67 /* Retain a copy of our UI, since the child will replace this value 68 and if we're vforked, we have to restore it. */ 69 saved_ui = current_ui; 70 71 /* Tell the terminal handling subsystem what tty we plan to run on; 72 it will just record the information for later. */ 73 new_tty_prefork (inferior_io_terminal); 74 } 75 76 /* See nat/fork-inferior.h. */ 77 78 void 79 postfork_hook (pid_t pid) 80 { 81 inferior *inf = current_inferior (); 82 83 inferior_appeared (inf, pid); 84 85 /* Needed for wait_for_inferior stuff. */ 86 inferior_ptid = ptid_t (pid); 87 88 gdb_assert (saved_ui != NULL); 89 current_ui = saved_ui; 90 saved_ui = NULL; 91 92 new_tty_postfork (); 93 } 94 95 /* See nat/fork-inferior.h. */ 96 97 void 98 postfork_child_hook () 99 { 100 /* This is set to the result of setpgrp, which if vforked, will be 101 visible to you in the parent process. It's only used by humans 102 for debugging. */ 103 static int debug_setpgrp = 657473; 104 105 /* Make sure we switch to main_ui here in order to be able to 106 use the fprintf_unfiltered/warning/error functions. */ 107 current_ui = main_ui; 108 109 /* Create a new session for the inferior process, if necessary. 110 It will also place the inferior in a separate process group. */ 111 if (create_tty_session () <= 0) 112 { 113 /* No session was created, but we still want to run the inferior 114 in a separate process group. */ 115 debug_setpgrp = gdb_setpgid (); 116 if (debug_setpgrp == -1) 117 perror (_("setpgrp failed in child")); 118 } 119 120 /* Ask the tty subsystem to switch to the one we specified 121 earlier (or to share the current terminal, if none was 122 specified). */ 123 new_tty (); 124 } 125 126 /* See inferior.h. */ 127 128 ptid_t 129 gdb_startup_inferior (pid_t pid, int num_traps) 130 { 131 ptid_t ptid = startup_inferior (pid, num_traps, NULL, NULL); 132 133 /* Mark all threads non-executing. */ 134 set_executing (ptid, 0); 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 xfree (exec_wrapper); 145 exec_wrapper = NULL; 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 fprintf_filtered (file, 153 _("Use of shell to start subprocesses is %s.\n"), 154 value); 155 } 156 157 void 158 _initialize_fork_child (void) 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