| 1 | /* Fork a Unix child process, and set up to debug it, for GDB. |
| 2 | Copyright 1990, 1991, 1992 Free Software Foundation, Inc. |
| 3 | Contributed by Cygnus Support. |
| 4 | |
| 5 | This file is part of GDB. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 2 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program; if not, write to the Free Software |
| 19 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ |
| 20 | |
| 21 | #include "defs.h" |
| 22 | #include "frame.h" /* required by inferior.h */ |
| 23 | #include "inferior.h" |
| 24 | #include "target.h" |
| 25 | #include "wait.h" |
| 26 | #include "gdbcore.h" |
| 27 | #include "serial.h" /* For job_control. */ |
| 28 | #include "terminal.h" /* For new_tty */ |
| 29 | |
| 30 | #include <signal.h> |
| 31 | |
| 32 | #ifdef SET_STACK_LIMIT_HUGE |
| 33 | #include <sys/time.h> |
| 34 | #include <sys/resource.h> |
| 35 | |
| 36 | extern int original_stack_limit; |
| 37 | #endif /* SET_STACK_LIMIT_HUGE */ |
| 38 | |
| 39 | extern char **environ; |
| 40 | |
| 41 | /* Start an inferior Unix child process and sets inferior_pid to its pid. |
| 42 | EXEC_FILE is the file to run. |
| 43 | ALLARGS is a string containing the arguments to the program. |
| 44 | ENV is the environment vector to pass. Errors reported with error(). */ |
| 45 | |
| 46 | #ifndef SHELL_FILE |
| 47 | #define SHELL_FILE "/bin/sh" |
| 48 | #endif |
| 49 | |
| 50 | void |
| 51 | fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun) |
| 52 | char *exec_file; |
| 53 | char *allargs; |
| 54 | char **env; |
| 55 | void (*traceme_fun) PARAMS ((void)); |
| 56 | void (*init_trace_fun) PARAMS ((int)); |
| 57 | { |
| 58 | int pid; |
| 59 | char *shell_command; |
| 60 | char *shell_file; |
| 61 | static char default_shell_file[] = SHELL_FILE; |
| 62 | int len; |
| 63 | int pending_execs; |
| 64 | /* Set debug_fork then attach to the child while it sleeps, to debug. */ |
| 65 | static int debug_fork = 0; |
| 66 | /* This is set to the result of setpgrp, which if vforked, will be visible |
| 67 | to you in the parent process. It's only used by humans for debugging. */ |
| 68 | static int debug_setpgrp = 657473; |
| 69 | char **save_our_env; |
| 70 | |
| 71 | /* If no exec file handed to us, get it from the exec-file command -- with |
| 72 | a good, common error message if none is specified. */ |
| 73 | if (exec_file == 0) |
| 74 | exec_file = get_exec_file(1); |
| 75 | |
| 76 | /* The user might want tilde-expansion, and in general probably wants |
| 77 | the program to behave the same way as if run from |
| 78 | his/her favorite shell. So we let the shell run it for us. |
| 79 | FIXME, this should probably search the local environment (as |
| 80 | modified by the setenv command), not the env gdb inherited. */ |
| 81 | shell_file = getenv ("SHELL"); |
| 82 | if (shell_file == NULL) |
| 83 | shell_file = default_shell_file; |
| 84 | |
| 85 | /* Multiplying the length of exec_file by 4 is to account for the fact |
| 86 | that it may expand when quoted; it is a worst-case number based on |
| 87 | every character being '. */ |
| 88 | len = 5 + 4 * strlen (exec_file) + 1 + strlen (allargs) + 1 + /*slop*/ 12; |
| 89 | /* If desired, concat something onto the front of ALLARGS. |
| 90 | SHELL_COMMAND is the result. */ |
| 91 | #ifdef SHELL_COMMAND_CONCAT |
| 92 | shell_command = (char *) alloca (strlen (SHELL_COMMAND_CONCAT) + len); |
| 93 | strcpy (shell_command, SHELL_COMMAND_CONCAT); |
| 94 | #else |
| 95 | shell_command = (char *) alloca (len); |
| 96 | shell_command[0] = '\0'; |
| 97 | #endif |
| 98 | strcat (shell_command, "exec "); |
| 99 | |
| 100 | /* Now add exec_file, quoting as necessary. Quoting in this style is |
| 101 | said to work with all shells. */ |
| 102 | { |
| 103 | char *p; |
| 104 | |
| 105 | strcat (shell_command, "'"); |
| 106 | for (p = exec_file; *p != '\0'; ++p) |
| 107 | { |
| 108 | if (*p == '\'') |
| 109 | strcat (shell_command, "'\\''"); |
| 110 | else |
| 111 | strncat (shell_command, p, 1); |
| 112 | } |
| 113 | strcat (shell_command, "'"); |
| 114 | } |
| 115 | |
| 116 | strcat (shell_command, " "); |
| 117 | strcat (shell_command, allargs); |
| 118 | |
| 119 | /* exec is said to fail if the executable is open. */ |
| 120 | close_exec_file (); |
| 121 | |
| 122 | /* Retain a copy of our environment variables, since the child will |
| 123 | replace the value of environ and if we're vforked, we have to |
| 124 | restore it. */ |
| 125 | save_our_env = environ; |
| 126 | |
| 127 | /* Tell the terminal handling subsystem what tty we plan to run on; |
| 128 | it will just record the information for later. */ |
| 129 | |
| 130 | new_tty_prefork (inferior_io_terminal); |
| 131 | |
| 132 | /* It is generally good practice to flush any possible pending stdio |
| 133 | output prior to doing a fork, to avoid the possibility of both the |
| 134 | parent and child flushing the same data after the fork. */ |
| 135 | |
| 136 | fflush (stdout); |
| 137 | fflush (stderr); |
| 138 | |
| 139 | #if defined(USG) && !defined(HAVE_VFORK) |
| 140 | pid = fork (); |
| 141 | #else |
| 142 | if (debug_fork) |
| 143 | pid = fork (); |
| 144 | else |
| 145 | pid = vfork (); |
| 146 | #endif |
| 147 | |
| 148 | if (pid < 0) |
| 149 | perror_with_name ("vfork"); |
| 150 | |
| 151 | if (pid == 0) |
| 152 | { |
| 153 | if (debug_fork) |
| 154 | sleep (debug_fork); |
| 155 | |
| 156 | /* Run inferior in a separate process group. */ |
| 157 | debug_setpgrp = gdb_setpgid (); |
| 158 | if (debug_setpgrp == -1) |
| 159 | perror("setpgrp failed in child"); |
| 160 | |
| 161 | #ifdef SET_STACK_LIMIT_HUGE |
| 162 | /* Reset the stack limit back to what it was. */ |
| 163 | { |
| 164 | struct rlimit rlim; |
| 165 | |
| 166 | getrlimit (RLIMIT_STACK, &rlim); |
| 167 | rlim.rlim_cur = original_stack_limit; |
| 168 | setrlimit (RLIMIT_STACK, &rlim); |
| 169 | } |
| 170 | #endif /* SET_STACK_LIMIT_HUGE */ |
| 171 | |
| 172 | /* Ask the tty subsystem to switch to the one we specified earlier |
| 173 | (or to share the current terminal, if none was specified). */ |
| 174 | |
| 175 | new_tty (); |
| 176 | |
| 177 | /* Changing the signal handlers for the inferior after |
| 178 | a vfork can also change them for the superior, so we don't mess |
| 179 | with signals here. See comments in |
| 180 | initialize_signals for how we get the right signal handlers |
| 181 | for the inferior. */ |
| 182 | |
| 183 | /* "Trace me, Dr. Memory!" */ |
| 184 | (*traceme_fun) (); |
| 185 | |
| 186 | /* There is no execlpe call, so we have to set the environment |
| 187 | for our child in the global variable. If we've vforked, this |
| 188 | clobbers the parent, but environ is restored a few lines down |
| 189 | in the parent. By the way, yes we do need to look down the |
| 190 | path to find $SHELL. Rich Pixley says so, and I agree. */ |
| 191 | environ = env; |
| 192 | execlp (shell_file, shell_file, "-c", shell_command, (char *)0); |
| 193 | |
| 194 | fprintf (stderr, "Cannot exec %s: %s.\n", shell_file, |
| 195 | safe_strerror (errno)); |
| 196 | fflush (stderr); |
| 197 | _exit (0177); |
| 198 | } |
| 199 | |
| 200 | /* Restore our environment in case a vforked child clob'd it. */ |
| 201 | environ = save_our_env; |
| 202 | |
| 203 | /* Now that we have a child process, make it our target, and |
| 204 | initialize anything target-vector-specific that needs initializing. */ |
| 205 | (*init_trace_fun)(pid); |
| 206 | |
| 207 | #ifdef CREATE_INFERIOR_HOOK |
| 208 | CREATE_INFERIOR_HOOK (pid); |
| 209 | #endif |
| 210 | |
| 211 | /* The process was started by the fork that created it, |
| 212 | but it will have stopped one instruction after execing the shell. |
| 213 | Here we must get it up to actual execution of the real program. */ |
| 214 | |
| 215 | inferior_pid = pid; /* Needed for wait_for_inferior stuff below */ |
| 216 | |
| 217 | clear_proceed_status (); |
| 218 | |
| 219 | /* We will get a trace trap after one instruction. |
| 220 | Continue it automatically. Eventually (after shell does an exec) |
| 221 | it will get another trace trap. Then insert breakpoints and continue. */ |
| 222 | |
| 223 | #ifdef START_INFERIOR_TRAPS_EXPECTED |
| 224 | pending_execs = START_INFERIOR_TRAPS_EXPECTED; |
| 225 | #else |
| 226 | pending_execs = 2; |
| 227 | #endif |
| 228 | |
| 229 | init_wait_for_inferior (); |
| 230 | |
| 231 | /* Set up the "saved terminal modes" of the inferior |
| 232 | based on what modes we are starting it with. */ |
| 233 | target_terminal_init (); |
| 234 | |
| 235 | /* Install inferior's terminal modes. */ |
| 236 | target_terminal_inferior (); |
| 237 | |
| 238 | while (1) |
| 239 | { |
| 240 | stop_soon_quietly = 1; /* Make wait_for_inferior be quiet */ |
| 241 | wait_for_inferior (); |
| 242 | if (stop_signal != SIGTRAP) |
| 243 | { |
| 244 | /* Let shell child handle its own signals in its own way */ |
| 245 | /* FIXME, what if child has exit()ed? Must exit loop somehow */ |
| 246 | resume (0, stop_signal); |
| 247 | } |
| 248 | else |
| 249 | { |
| 250 | /* We handle SIGTRAP, however; it means child did an exec. */ |
| 251 | if (0 == --pending_execs) |
| 252 | break; |
| 253 | resume (0, 0); /* Just make it go on */ |
| 254 | } |
| 255 | } |
| 256 | stop_soon_quietly = 0; |
| 257 | |
| 258 | /* We are now in the child process of interest, having exec'd the |
| 259 | correct program, and are poised at the first instruction of the |
| 260 | new program. */ |
| 261 | #ifdef SOLIB_CREATE_INFERIOR_HOOK |
| 262 | SOLIB_CREATE_INFERIOR_HOOK (pid); |
| 263 | #endif |
| 264 | } |