1 /* Fork a Unix child process, and set up to debug it, for GDB. 2 Copyright 1990, 1991, 1992, 1993, 1994, 1996 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ 20 21 #include "defs.h" 22 #include "gdb_string.h" 23 #include "frame.h" /* required by inferior.h */ 24 #include "inferior.h" 25 #include "target.h" 26 #include "wait.h" 27 #include "gdbcore.h" 28 #include "terminal.h" 29 #include "gdbthread.h" 30 31 #include <signal.h> 32 #ifdef HAVE_UNISTD_H 33 #include <unistd.h> 34 #endif 35 36 extern char **environ; 37 38 #ifndef SHELL_FILE 39 #define SHELL_FILE "/bin/sh" 40 #endif 41 42 /* Start an inferior Unix child process and sets inferior_pid to its pid. 43 EXEC_FILE is the file to run. 44 ALLARGS is a string containing the arguments to the program. 45 ENV is the environment vector to pass. SHELL_FILE is the shell file, 46 or NULL if we should pick one. Errors reported with error(). */ 47 48 void 49 fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, 50 shell_file) 51 char *exec_file; 52 char *allargs; 53 char **env; 54 void (*traceme_fun) PARAMS ((void)); 55 int (*init_trace_fun) PARAMS ((int)); 56 char *shell_file; 57 { 58 int pid; 59 char *shell_command; 60 static char default_shell_file[] = SHELL_FILE; 61 int len; 62 /* Set debug_fork then attach to the child while it sleeps, to debug. */ 63 static int debug_fork = 0; 64 /* This is set to the result of setpgrp, which if vforked, will be visible 65 to you in the parent process. It's only used by humans for debugging. */ 66 static int debug_setpgrp = 657473; 67 char **save_our_env; 68 69 /* If no exec file handed to us, get it from the exec-file command -- with 70 a good, common error message if none is specified. */ 71 if (exec_file == 0) 72 exec_file = get_exec_file(1); 73 74 /* The user might want tilde-expansion, and in general probably wants 75 the program to behave the same way as if run from 76 his/her favorite shell. So we let the shell run it for us. 77 FIXME-maybe, we might want a "set shell" command so the user can change 78 the shell from within GDB (if so, change callers which pass in a non-NULL 79 shell_file too). */ 80 if (shell_file == NULL) 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. */ 101 { 102 char *p; 103 int need_to_quote; 104 105 /* Quoting in this style is said to work with all shells. But csh 106 on IRIX 4.0.1 can't deal with it. So we only quote it if we need 107 to. */ 108 p = exec_file; 109 while (1) 110 { 111 switch (*p) 112 { 113 case '\'': 114 case '"': 115 case '(': 116 case ')': 117 case '$': 118 case '&': 119 case ';': 120 case '<': 121 case '>': 122 case ' ': 123 case '\n': 124 case '\t': 125 need_to_quote = 1; 126 goto end_scan; 127 128 case '\0': 129 need_to_quote = 0; 130 goto end_scan; 131 132 default: 133 break; 134 } 135 ++p; 136 } 137 end_scan: 138 if (need_to_quote) 139 { 140 strcat (shell_command, "'"); 141 for (p = exec_file; *p != '\0'; ++p) 142 { 143 if (*p == '\'') 144 strcat (shell_command, "'\\''"); 145 else 146 strncat (shell_command, p, 1); 147 } 148 strcat (shell_command, "'"); 149 } 150 else 151 strcat (shell_command, exec_file); 152 } 153 154 strcat (shell_command, " "); 155 strcat (shell_command, allargs); 156 157 /* exec is said to fail if the executable is open. */ 158 close_exec_file (); 159 160 /* Retain a copy of our environment variables, since the child will 161 replace the value of environ and if we're vforked, we have to 162 restore it. */ 163 save_our_env = environ; 164 165 /* Tell the terminal handling subsystem what tty we plan to run on; 166 it will just record the information for later. */ 167 168 new_tty_prefork (inferior_io_terminal); 169 170 /* It is generally good practice to flush any possible pending stdio 171 output prior to doing a fork, to avoid the possibility of both the 172 parent and child flushing the same data after the fork. */ 173 174 gdb_flush (gdb_stdout); 175 gdb_flush (gdb_stderr); 176 177 #if defined(USG) && !defined(HAVE_VFORK) 178 pid = fork (); 179 #else 180 if (debug_fork) 181 pid = fork (); 182 else 183 pid = vfork (); 184 #endif 185 186 if (pid < 0) 187 perror_with_name ("vfork"); 188 189 if (pid == 0) 190 { 191 if (debug_fork) 192 sleep (debug_fork); 193 194 /* Run inferior in a separate process group. */ 195 debug_setpgrp = gdb_setpgid (); 196 if (debug_setpgrp == -1) 197 perror("setpgrp failed in child"); 198 199 /* Ask the tty subsystem to switch to the one we specified earlier 200 (or to share the current terminal, if none was specified). */ 201 202 new_tty (); 203 204 /* Changing the signal handlers for the inferior after 205 a vfork can also change them for the superior, so we don't mess 206 with signals here. See comments in 207 initialize_signals for how we get the right signal handlers 208 for the inferior. */ 209 210 /* "Trace me, Dr. Memory!" */ 211 (*traceme_fun) (); 212 213 /* There is no execlpe call, so we have to set the environment 214 for our child in the global variable. If we've vforked, this 215 clobbers the parent, but environ is restored a few lines down 216 in the parent. By the way, yes we do need to look down the 217 path to find $SHELL. Rich Pixley says so, and I agree. */ 218 environ = env; 219 execlp (shell_file, shell_file, "-c", shell_command, (char *)0); 220 221 fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file, 222 safe_strerror (errno)); 223 gdb_flush (gdb_stderr); 224 _exit (0177); 225 } 226 227 /* Restore our environment in case a vforked child clob'd it. */ 228 environ = save_our_env; 229 230 init_thread_list(); 231 232 inferior_pid = pid; /* Needed for wait_for_inferior stuff below */ 233 234 /* Now that we have a child process, make it our target, and 235 initialize anything target-vector-specific that needs initializing. */ 236 237 /* Note that pid may be modified by this function. */ 238 inferior_pid = pid = (*init_trace_fun)(pid); 239 240 /* We are now in the child process of interest, having exec'd the 241 correct program, and are poised at the first instruction of the 242 new program. */ 243 244 /* Allow target dependant code to play with the new process. This might be 245 used to have target-specific code initialize a variable in the new process 246 prior to executing the first instruction. */ 247 TARGET_CREATE_INFERIOR_HOOK (pid); 248 249 #ifdef SOLIB_CREATE_INFERIOR_HOOK 250 SOLIB_CREATE_INFERIOR_HOOK (pid); 251 #endif 252 } 253 254 /* Accept NTRAPS traps from the inferior. */ 255 256 void 257 startup_inferior (ntraps) 258 int ntraps; 259 { 260 int pending_execs = ntraps; 261 int terminal_initted; 262 263 /* The process was started by the fork that created it, 264 but it will have stopped one instruction after execing the shell. 265 Here we must get it up to actual execution of the real program. */ 266 267 clear_proceed_status (); 268 269 init_wait_for_inferior (); 270 271 terminal_initted = 0; 272 273 #ifdef STARTUP_INFERIOR 274 STARTUP_INFERIOR (pending_execs); 275 #else 276 while (1) 277 { 278 stop_soon_quietly = 1; /* Make wait_for_inferior be quiet */ 279 wait_for_inferior (); 280 if (stop_signal != TARGET_SIGNAL_TRAP) 281 { 282 /* Let shell child handle its own signals in its own way */ 283 /* FIXME, what if child has exit()ed? Must exit loop somehow */ 284 resume (0, stop_signal); 285 } 286 else 287 { 288 /* We handle SIGTRAP, however; it means child did an exec. */ 289 if (!terminal_initted) 290 { 291 /* Now that the child has exec'd we know it has already set its 292 process group. On POSIX systems, tcsetpgrp will fail with 293 EPERM if we try it before the child's setpgid. */ 294 295 /* Set up the "saved terminal modes" of the inferior 296 based on what modes we are starting it with. */ 297 target_terminal_init (); 298 299 /* Install inferior's terminal modes. */ 300 target_terminal_inferior (); 301 302 terminal_initted = 1; 303 } 304 if (0 == --pending_execs) 305 break; 306 resume (0, TARGET_SIGNAL_0); /* Just make it go on */ 307 } 308 } 309 #endif /* STARTUP_INFERIOR */ 310 stop_soon_quietly = 0; 311 } 312