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.
5 This file is part of GDB.
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.
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.
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. */
22 #include "frame.h" /* required by inferior.h */
27 #include "serial.h" /* For job_control. */
28 #include "terminal.h" /* For new_tty */
32 #ifdef SET_STACK_LIMIT_HUGE
34 #include <sys/resource.h>
36 extern int original_stack_limit
;
37 #endif /* SET_STACK_LIMIT_HUGE */
39 extern char **environ
;
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(). */
47 #define SHELL_FILE "/bin/sh"
51 fork_inferior (exec_file
, allargs
, env
, traceme_fun
, init_trace_fun
)
55 void (*traceme_fun
) PARAMS ((void));
56 void (*init_trace_fun
) PARAMS ((int));
61 static char default_shell_file
[] = SHELL_FILE
;
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;
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. */
74 exec_file
= get_exec_file(1);
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
;
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
);
95 shell_command
= (char *) alloca (len
);
96 shell_command
[0] = '\0';
98 strcat (shell_command
, "exec ");
100 /* Now add exec_file, quoting as necessary. Quoting in this style is
101 said to work with all shells. */
105 strcat (shell_command
, "'");
106 for (p
= exec_file
; *p
!= '\0'; ++p
)
109 strcat (shell_command
, "'\\''");
111 strncat (shell_command
, p
, 1);
113 strcat (shell_command
, "'");
116 strcat (shell_command
, " ");
117 strcat (shell_command
, allargs
);
119 /* exec is said to fail if the executable is open. */
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
125 save_our_env
= environ
;
127 /* Tell the terminal handling subsystem what tty we plan to run on;
128 it will just record the information for later. */
130 new_tty_prefork (inferior_io_terminal
);
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. */
139 #if defined(USG) && !defined(HAVE_VFORK)
149 perror_with_name ("vfork");
156 /* Run inferior in a separate process group. */
157 debug_setpgrp
= gdb_setpgid ();
158 if (debug_setpgrp
== -1)
159 perror("setpgrp failed in child");
161 #ifdef SET_STACK_LIMIT_HUGE
162 /* Reset the stack limit back to what it was. */
166 getrlimit (RLIMIT_STACK
, &rlim
);
167 rlim
.rlim_cur
= original_stack_limit
;
168 setrlimit (RLIMIT_STACK
, &rlim
);
170 #endif /* SET_STACK_LIMIT_HUGE */
172 /* Ask the tty subsystem to switch to the one we specified earlier
173 (or to share the current terminal, if none was specified). */
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
183 /* "Trace me, Dr. Memory!" */
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. */
192 execlp (shell_file
, shell_file
, "-c", shell_command
, (char *)0);
194 fprintf (stderr
, "Cannot exec %s: %s.\n", shell_file
,
195 safe_strerror (errno
));
200 /* Restore our environment in case a vforked child clob'd it. */
201 environ
= save_our_env
;
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
);
207 #ifdef CREATE_INFERIOR_HOOK
208 CREATE_INFERIOR_HOOK (pid
);
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. */
215 inferior_pid
= pid
; /* Needed for wait_for_inferior stuff below */
217 clear_proceed_status ();
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. */
223 #ifdef START_INFERIOR_TRAPS_EXPECTED
224 pending_execs
= START_INFERIOR_TRAPS_EXPECTED
;
229 init_wait_for_inferior ();
231 /* Set up the "saved terminal modes" of the inferior
232 based on what modes we are starting it with. */
233 target_terminal_init ();
235 /* Install inferior's terminal modes. */
236 target_terminal_inferior ();
240 stop_soon_quietly
= 1; /* Make wait_for_inferior be quiet */
241 wait_for_inferior ();
242 if (stop_signal
!= SIGTRAP
)
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
);
250 /* We handle SIGTRAP, however; it means child did an exec. */
251 if (0 == --pending_execs
)
253 resume (0, 0); /* Just make it go on */
256 stop_soon_quietly
= 0;
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
261 #ifdef SOLIB_CREATE_INFERIOR_HOOK
262 SOLIB_CREATE_INFERIOR_HOOK (pid
);