Commit | Line | Data |
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c906108c | 1 | /* Fork a Unix child process, and set up to debug it, for GDB. |
cce74817 | 2 | Copyright 1990, 91, 92, 93, 94, 1996, 1999 Free Software Foundation, Inc. |
c906108c SS |
3 | Contributed by Cygnus Support. |
4 | ||
c5aa993b | 5 | This file is part of GDB. |
c906108c | 6 | |
c5aa993b JM |
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. | |
c906108c | 11 | |
c5aa993b JM |
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. | |
c906108c | 16 | |
c5aa993b JM |
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, | |
20 | Boston, MA 02111-1307, USA. */ | |
c906108c SS |
21 | |
22 | #include "defs.h" | |
23 | #include "gdb_string.h" | |
24 | #include "frame.h" /* required by inferior.h */ | |
25 | #include "inferior.h" | |
26 | #include "target.h" | |
03f2053f | 27 | #include "gdb_wait.h" |
c906108c SS |
28 | #include "gdbcore.h" |
29 | #include "terminal.h" | |
30 | #include "gdbthread.h" | |
c2d11a7d | 31 | #include "command.h" /* for dont_repeat () */ |
c906108c SS |
32 | |
33 | #include <signal.h> | |
c906108c | 34 | |
c906108c SS |
35 | /* This just gets used as a default if we can't find SHELL */ |
36 | #ifndef SHELL_FILE | |
37 | #define SHELL_FILE "/bin/sh" | |
38 | #endif | |
39 | ||
40 | extern char **environ; | |
41 | ||
42 | /* This function breaks up an argument string into an argument | |
43 | * vector suitable for passing to execvp(). | |
44 | * E.g., on "run a b c d" this routine would get as input | |
45 | * the string "a b c d", and as output it would fill in argv with | |
46 | * the four arguments "a", "b", "c", "d". | |
47 | */ | |
48 | static void | |
fba45db2 | 49 | breakup_args (char *scratch, char **argv) |
c906108c SS |
50 | { |
51 | char *cp = scratch; | |
52 | ||
c906108c SS |
53 | for (;;) |
54 | { | |
55 | ||
56 | /* Scan past leading separators */ | |
57 | while (*cp == ' ' || *cp == '\t' || *cp == '\n') | |
58 | { | |
59 | cp++; | |
60 | } | |
61 | ||
62 | /* Break if at end of string */ | |
63 | if (*cp == '\0') | |
64 | break; | |
65 | ||
66 | /* Take an arg */ | |
67 | *argv++ = cp; | |
68 | ||
69 | /* Scan for next arg separator */ | |
70 | cp = strchr (cp, ' '); | |
71 | if (cp == NULL) | |
72 | cp = strchr (cp, '\t'); | |
73 | if (cp == NULL) | |
74 | cp = strchr (cp, '\n'); | |
75 | ||
76 | /* No separators => end of string => break */ | |
77 | if (cp == NULL) | |
78 | break; | |
79 | ||
80 | /* Replace the separator with a terminator */ | |
81 | *cp++ = '\0'; | |
82 | } | |
83 | ||
84 | /* execv requires a null-terminated arg vector */ | |
85 | *argv = NULL; | |
86 | ||
87 | } | |
88 | ||
89 | ||
90 | /* Start an inferior Unix child process and sets inferior_pid to its pid. | |
91 | EXEC_FILE is the file to run. | |
92 | ALLARGS is a string containing the arguments to the program. | |
93 | ENV is the environment vector to pass. SHELL_FILE is the shell file, | |
94 | or NULL if we should pick one. Errors reported with error(). */ | |
95 | ||
96 | void | |
97 | fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, | |
98 | pre_trace_fun, shell_file) | |
99 | char *exec_file; | |
100 | char *allargs; | |
101 | char **env; | |
507f3c78 KB |
102 | void (*traceme_fun) (void); |
103 | void (*init_trace_fun) (int); | |
104 | void (*pre_trace_fun) (void); | |
c906108c SS |
105 | char *shell_file; |
106 | { | |
107 | int pid; | |
108 | char *shell_command; | |
109 | static char default_shell_file[] = SHELL_FILE; | |
110 | int len; | |
111 | /* Set debug_fork then attach to the child while it sleeps, to debug. */ | |
112 | static int debug_fork = 0; | |
113 | /* This is set to the result of setpgrp, which if vforked, will be visible | |
114 | to you in the parent process. It's only used by humans for debugging. */ | |
115 | static int debug_setpgrp = 657473; | |
116 | char **save_our_env; | |
117 | int shell = 0; | |
118 | char **argv; | |
c906108c SS |
119 | |
120 | /* If no exec file handed to us, get it from the exec-file command -- with | |
121 | a good, common error message if none is specified. */ | |
122 | if (exec_file == 0) | |
123 | exec_file = get_exec_file (1); | |
124 | ||
125 | /* STARTUP_WITH_SHELL is defined in inferior.h. | |
126 | * If 0, we'll just do a fork/exec, no shell, so don't | |
127 | * bother figuring out what shell. | |
128 | */ | |
129 | if (STARTUP_WITH_SHELL) | |
130 | { | |
131 | /* Figure out what shell to start up the user program under. */ | |
132 | if (shell_file == NULL) | |
133 | shell_file = getenv ("SHELL"); | |
134 | if (shell_file == NULL) | |
135 | shell_file = default_shell_file; | |
136 | shell = 1; | |
137 | } | |
138 | ||
c906108c SS |
139 | /* Multiplying the length of exec_file by 4 is to account for the fact |
140 | that it may expand when quoted; it is a worst-case number based on | |
141 | every character being '. */ | |
c5aa993b | 142 | len = 5 + 4 * strlen (exec_file) + 1 + strlen (allargs) + 1 + /*slop */ 12; |
c906108c SS |
143 | /* If desired, concat something onto the front of ALLARGS. |
144 | SHELL_COMMAND is the result. */ | |
145 | #ifdef SHELL_COMMAND_CONCAT | |
146 | shell_command = (char *) alloca (strlen (SHELL_COMMAND_CONCAT) + len); | |
147 | strcpy (shell_command, SHELL_COMMAND_CONCAT); | |
148 | #else | |
149 | shell_command = (char *) alloca (len); | |
150 | shell_command[0] = '\0'; | |
151 | #endif | |
152 | ||
153 | if (!shell) | |
154 | { | |
155 | /* We're going to call execvp. Create argv */ | |
156 | /* Largest case: every other character is a separate arg */ | |
c906108c SS |
157 | argv = (char **) xmalloc (((strlen (allargs) + 1) / (unsigned) 2 + 2) * sizeof (*argv)); |
158 | argv[0] = exec_file; | |
159 | breakup_args (allargs, &argv[1]); | |
160 | ||
161 | } | |
162 | else | |
163 | { | |
164 | ||
165 | /* We're going to call a shell */ | |
166 | ||
167 | /* Now add exec_file, quoting as necessary. */ | |
168 | ||
169 | char *p; | |
170 | int need_to_quote; | |
171 | ||
172 | strcat (shell_command, "exec "); | |
173 | ||
174 | /* Quoting in this style is said to work with all shells. But csh | |
c5aa993b JM |
175 | on IRIX 4.0.1 can't deal with it. So we only quote it if we need |
176 | to. */ | |
c906108c SS |
177 | p = exec_file; |
178 | while (1) | |
179 | { | |
180 | switch (*p) | |
181 | { | |
182 | case '\'': | |
183 | case '"': | |
184 | case '(': | |
185 | case ')': | |
186 | case '$': | |
187 | case '&': | |
188 | case ';': | |
189 | case '<': | |
190 | case '>': | |
191 | case ' ': | |
192 | case '\n': | |
193 | case '\t': | |
194 | need_to_quote = 1; | |
195 | goto end_scan; | |
196 | ||
197 | case '\0': | |
198 | need_to_quote = 0; | |
199 | goto end_scan; | |
200 | ||
201 | default: | |
202 | break; | |
203 | } | |
204 | ++p; | |
205 | } | |
206 | end_scan: | |
207 | if (need_to_quote) | |
208 | { | |
209 | strcat (shell_command, "'"); | |
210 | for (p = exec_file; *p != '\0'; ++p) | |
211 | { | |
212 | if (*p == '\'') | |
213 | strcat (shell_command, "'\\''"); | |
214 | else | |
215 | strncat (shell_command, p, 1); | |
216 | } | |
217 | strcat (shell_command, "'"); | |
218 | } | |
219 | else | |
220 | strcat (shell_command, exec_file); | |
221 | ||
222 | strcat (shell_command, " "); | |
223 | strcat (shell_command, allargs); | |
224 | ||
225 | } | |
226 | ||
227 | /* exec is said to fail if the executable is open. */ | |
228 | close_exec_file (); | |
229 | ||
230 | /* Retain a copy of our environment variables, since the child will | |
231 | replace the value of environ and if we're vforked, we have to | |
232 | restore it. */ | |
233 | save_our_env = environ; | |
234 | ||
235 | /* Tell the terminal handling subsystem what tty we plan to run on; | |
236 | it will just record the information for later. */ | |
237 | ||
238 | new_tty_prefork (inferior_io_terminal); | |
239 | ||
240 | /* It is generally good practice to flush any possible pending stdio | |
241 | output prior to doing a fork, to avoid the possibility of both the | |
242 | parent and child flushing the same data after the fork. */ | |
243 | ||
244 | gdb_flush (gdb_stdout); | |
245 | gdb_flush (gdb_stderr); | |
246 | ||
247 | /* If there's any initialization of the target layers that must happen | |
c5aa993b | 248 | to prepare to handle the child we're about fork, do it now... |
c906108c SS |
249 | */ |
250 | if (pre_trace_fun != NULL) | |
251 | (*pre_trace_fun) (); | |
252 | ||
253 | #if defined(USG) && !defined(HAVE_VFORK) | |
254 | pid = fork (); | |
255 | #else | |
256 | if (debug_fork) | |
257 | pid = fork (); | |
258 | else | |
259 | pid = vfork (); | |
260 | #endif | |
261 | ||
262 | if (pid < 0) | |
263 | perror_with_name ("vfork"); | |
264 | ||
265 | if (pid == 0) | |
266 | { | |
267 | if (debug_fork) | |
268 | sleep (debug_fork); | |
269 | ||
270 | /* Run inferior in a separate process group. */ | |
271 | debug_setpgrp = gdb_setpgid (); | |
272 | if (debug_setpgrp == -1) | |
273 | perror ("setpgrp failed in child"); | |
274 | ||
275 | /* Ask the tty subsystem to switch to the one we specified earlier | |
c5aa993b | 276 | (or to share the current terminal, if none was specified). */ |
c906108c SS |
277 | |
278 | new_tty (); | |
279 | ||
280 | /* Changing the signal handlers for the inferior after | |
c5aa993b JM |
281 | a vfork can also change them for the superior, so we don't mess |
282 | with signals here. See comments in | |
283 | initialize_signals for how we get the right signal handlers | |
284 | for the inferior. */ | |
c906108c SS |
285 | |
286 | /* "Trace me, Dr. Memory!" */ | |
287 | (*traceme_fun) (); | |
288 | /* The call above set this process (the "child") as debuggable | |
289 | * by the original gdb process (the "parent"). Since processes | |
290 | * (unlike people) can have only one parent, if you are | |
291 | * debugging gdb itself (and your debugger is thus _already_ the | |
292 | * controller/parent for this child), code from here on out | |
293 | * is undebuggable. Indeed, you probably got an error message | |
294 | * saying "not parent". Sorry--you'll have to use print statements! | |
295 | */ | |
296 | ||
297 | /* There is no execlpe call, so we have to set the environment | |
c5aa993b JM |
298 | for our child in the global variable. If we've vforked, this |
299 | clobbers the parent, but environ is restored a few lines down | |
300 | in the parent. By the way, yes we do need to look down the | |
301 | path to find $SHELL. Rich Pixley says so, and I agree. */ | |
c906108c SS |
302 | environ = env; |
303 | ||
304 | /* If we decided above to start up with a shell, | |
305 | * we exec the shell, | |
306 | * "-c" says to interpret the next arg as a shell command | |
307 | * to execute, and this command is "exec <target-program> <args>". | |
308 | * "-f" means "fast startup" to the c-shell, which means | |
309 | * don't do .cshrc file. Doing .cshrc may cause fork/exec | |
310 | * events which will confuse debugger start-up code. | |
311 | */ | |
312 | if (shell) | |
313 | { | |
c906108c | 314 | execlp (shell_file, shell_file, "-c", shell_command, (char *) 0); |
c906108c SS |
315 | |
316 | /* If we get here, it's an error */ | |
317 | fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file, | |
318 | safe_strerror (errno)); | |
319 | gdb_flush (gdb_stderr); | |
320 | _exit (0177); | |
321 | } | |
322 | else | |
323 | { | |
324 | /* Otherwise, we directly exec the target program with execvp. */ | |
325 | int i; | |
326 | char *errstring; | |
cce74817 | 327 | |
c906108c SS |
328 | execvp (exec_file, argv); |
329 | ||
330 | /* If we get here, it's an error */ | |
331 | errstring = safe_strerror (errno); | |
332 | fprintf_unfiltered (gdb_stderr, "Cannot exec %s ", exec_file); | |
333 | ||
334 | i = 1; | |
335 | while (argv[i] != NULL) | |
336 | { | |
337 | if (i != 1) | |
338 | fprintf_unfiltered (gdb_stderr, " "); | |
339 | fprintf_unfiltered (gdb_stderr, "%s", argv[i]); | |
340 | i++; | |
341 | } | |
342 | fprintf_unfiltered (gdb_stderr, ".\n"); | |
343 | /* This extra info seems to be useless | |
c5aa993b JM |
344 | fprintf_unfiltered (gdb_stderr, "Got error %s.\n", errstring); |
345 | */ | |
c906108c SS |
346 | gdb_flush (gdb_stderr); |
347 | _exit (0177); | |
348 | } | |
349 | } | |
350 | ||
351 | /* Restore our environment in case a vforked child clob'd it. */ | |
352 | environ = save_our_env; | |
353 | ||
354 | init_thread_list (); | |
355 | ||
356 | inferior_pid = pid; /* Needed for wait_for_inferior stuff below */ | |
357 | ||
358 | /* Now that we have a child process, make it our target, and | |
359 | initialize anything target-vector-specific that needs initializing. */ | |
360 | ||
361 | (*init_trace_fun) (pid); | |
362 | ||
363 | /* We are now in the child process of interest, having exec'd the | |
364 | correct program, and are poised at the first instruction of the | |
365 | new program. */ | |
366 | ||
367 | /* Allow target dependant code to play with the new process. This might be | |
368 | used to have target-specific code initialize a variable in the new process | |
369 | prior to executing the first instruction. */ | |
370 | TARGET_CREATE_INFERIOR_HOOK (pid); | |
371 | ||
372 | #ifdef SOLIB_CREATE_INFERIOR_HOOK | |
373 | SOLIB_CREATE_INFERIOR_HOOK (pid); | |
374 | #endif | |
375 | } | |
376 | ||
377 | /* An inferior Unix process CHILD_PID has been created by a call to | |
378 | fork() (or variants like vfork). It is presently stopped, and waiting | |
379 | to be resumed. clone_and_follow_inferior will fork the debugger, | |
380 | and that clone will "follow" (attach to) CHILD_PID. The original copy | |
381 | of the debugger will not touch CHILD_PID again. | |
382 | ||
383 | Also, the original debugger will set FOLLOWED_CHILD FALSE, while the | |
384 | clone will set it TRUE. | |
c5aa993b | 385 | */ |
c906108c | 386 | void |
fba45db2 | 387 | clone_and_follow_inferior (int child_pid, int *followed_child) |
c906108c SS |
388 | { |
389 | extern int auto_solib_add; | |
390 | ||
391 | int debugger_pid; | |
392 | int status; | |
393 | char pid_spelling[100]; /* Arbitrary but sufficient length. */ | |
394 | ||
395 | /* This semaphore is used to coordinate the two debuggers' handoff | |
396 | of CHILD_PID. The original debugger will detach from CHILD_PID, | |
397 | and then the clone debugger will attach to it. (It must be done | |
398 | this way because on some targets, only one process at a time can | |
399 | trace another. Thus, the original debugger must relinquish its | |
400 | tracing rights before the clone can pick them up.) | |
c5aa993b | 401 | */ |
c906108c SS |
402 | #define SEM_TALK (1) |
403 | #define SEM_LISTEN (0) | |
404 | int handoff_semaphore[2]; /* Original "talks" to [1], clone "listens" to [0] */ | |
405 | int talk_value = 99; | |
406 | int listen_value; | |
407 | ||
408 | /* Set debug_fork then attach to the child while it sleeps, to debug. */ | |
409 | static int debug_fork = 0; | |
410 | ||
411 | /* It is generally good practice to flush any possible pending stdio | |
412 | output prior to doing a fork, to avoid the possibility of both the | |
413 | parent and child flushing the same data after the fork. */ | |
414 | ||
415 | gdb_flush (gdb_stdout); | |
416 | gdb_flush (gdb_stderr); | |
417 | ||
418 | /* Open the semaphore pipes. | |
c5aa993b | 419 | */ |
c906108c SS |
420 | status = pipe (handoff_semaphore); |
421 | if (status < 0) | |
422 | error ("error getting pipe for handoff semaphore"); | |
423 | ||
424 | /* Clone the debugger. */ | |
425 | #if defined(USG) && !defined(HAVE_VFORK) | |
426 | debugger_pid = fork (); | |
427 | #else | |
428 | if (debug_fork) | |
429 | debugger_pid = fork (); | |
430 | else | |
431 | debugger_pid = vfork (); | |
432 | #endif | |
433 | ||
434 | if (debugger_pid < 0) | |
435 | perror_with_name ("fork"); | |
436 | ||
437 | /* Are we the original debugger? If so, we must relinquish all claims | |
c5aa993b | 438 | to CHILD_PID. */ |
c906108c SS |
439 | if (debugger_pid != 0) |
440 | { | |
c5aa993b | 441 | char signal_spelling[100]; /* Arbitrary but sufficient length */ |
c906108c SS |
442 | |
443 | /* Detach from CHILD_PID. Deliver a "stop" signal when we do, though, | |
c5aa993b JM |
444 | so that it remains stopped until the clone debugger can attach |
445 | to it. | |
c906108c SS |
446 | */ |
447 | detach_breakpoints (child_pid); | |
448 | ||
449 | sprintf (signal_spelling, "%d", target_signal_to_host (TARGET_SIGNAL_STOP)); | |
450 | target_require_detach (child_pid, signal_spelling, 1); | |
451 | ||
452 | /* Notify the clone debugger that it should attach to CHILD_PID. */ | |
453 | write (handoff_semaphore[SEM_TALK], &talk_value, sizeof (talk_value)); | |
454 | ||
455 | *followed_child = 0; | |
456 | } | |
457 | ||
458 | /* We're the child. */ | |
459 | else | |
460 | { | |
461 | if (debug_fork) | |
462 | sleep (debug_fork); | |
463 | ||
464 | /* The child (i.e., the cloned debugger) must now attach to | |
465 | CHILD_PID. inferior_pid is presently set to the parent process | |
466 | of the fork, while CHILD_PID should be the child process of the | |
467 | fork. | |
468 | ||
469 | Wait until the original debugger relinquishes control of CHILD_PID, | |
470 | though. | |
c5aa993b | 471 | */ |
c906108c SS |
472 | read (handoff_semaphore[SEM_LISTEN], &listen_value, sizeof (listen_value)); |
473 | ||
474 | /* Note that we DON'T want to actually detach from inferior_pid, | |
475 | because that would allow it to run free. The original | |
476 | debugger wants to retain control of the process. So, we | |
477 | just reset inferior_pid to CHILD_PID, and then ensure that all | |
478 | breakpoints are really set in CHILD_PID. | |
c5aa993b | 479 | */ |
c906108c SS |
480 | target_mourn_inferior (); |
481 | ||
482 | /* Ask the tty subsystem to switch to the one we specified earlier | |
483 | (or to share the current terminal, if none was specified). */ | |
484 | ||
485 | new_tty (); | |
486 | ||
487 | dont_repeat (); | |
488 | sprintf (pid_spelling, "%d", child_pid); | |
489 | target_require_attach (pid_spelling, 1); | |
490 | ||
491 | /* Perform any necessary cleanup, after attachment. (This form | |
492 | of attaching can behave differently on some targets than the | |
493 | standard method, where a process formerly not under debugger | |
494 | control was suddenly attached to..) | |
c5aa993b | 495 | */ |
c906108c SS |
496 | target_post_follow_inferior_by_clone (); |
497 | ||
498 | *followed_child = 1; | |
499 | } | |
500 | ||
501 | /* Discard the handoff sempahore. */ | |
502 | (void) close (handoff_semaphore[SEM_LISTEN]); | |
503 | (void) close (handoff_semaphore[SEM_TALK]); | |
504 | } | |
505 | ||
506 | /* Accept NTRAPS traps from the inferior. */ | |
507 | ||
508 | void | |
fba45db2 | 509 | startup_inferior (int ntraps) |
c906108c SS |
510 | { |
511 | int pending_execs = ntraps; | |
512 | int terminal_initted; | |
513 | ||
514 | /* The process was started by the fork that created it, | |
515 | but it will have stopped one instruction after execing the shell. | |
516 | Here we must get it up to actual execution of the real program. */ | |
517 | ||
518 | clear_proceed_status (); | |
519 | ||
520 | init_wait_for_inferior (); | |
521 | ||
522 | terminal_initted = 0; | |
523 | ||
524 | if (STARTUP_WITH_SHELL) | |
525 | inferior_ignoring_startup_exec_events = ntraps; | |
526 | else | |
527 | inferior_ignoring_startup_exec_events = 0; | |
528 | inferior_ignoring_leading_exec_events = | |
529 | target_reported_exec_events_per_exec_call () - 1; | |
530 | ||
531 | #ifdef STARTUP_INFERIOR | |
532 | STARTUP_INFERIOR (pending_execs); | |
533 | #else | |
534 | while (1) | |
535 | { | |
536 | stop_soon_quietly = 1; /* Make wait_for_inferior be quiet */ | |
537 | wait_for_inferior (); | |
538 | if (stop_signal != TARGET_SIGNAL_TRAP) | |
539 | { | |
540 | /* Let shell child handle its own signals in its own way */ | |
541 | /* FIXME, what if child has exit()ed? Must exit loop somehow */ | |
542 | resume (0, stop_signal); | |
543 | } | |
544 | else | |
545 | { | |
546 | /* We handle SIGTRAP, however; it means child did an exec. */ | |
547 | if (!terminal_initted) | |
548 | { | |
549 | /* Now that the child has exec'd we know it has already set its | |
c5aa993b JM |
550 | process group. On POSIX systems, tcsetpgrp will fail with |
551 | EPERM if we try it before the child's setpgid. */ | |
c906108c SS |
552 | |
553 | /* Set up the "saved terminal modes" of the inferior | |
c5aa993b | 554 | based on what modes we are starting it with. */ |
c906108c SS |
555 | target_terminal_init (); |
556 | ||
557 | /* Install inferior's terminal modes. */ | |
558 | target_terminal_inferior (); | |
559 | ||
560 | terminal_initted = 1; | |
561 | } | |
562 | ||
563 | pending_execs = pending_execs - 1; | |
564 | if (0 == pending_execs) | |
565 | break; | |
566 | ||
567 | resume (0, TARGET_SIGNAL_0); /* Just make it go on */ | |
568 | } | |
569 | } | |
570 | #endif /* STARTUP_INFERIOR */ | |
571 | stop_soon_quietly = 0; | |
572 | } |