Commit | Line | Data |
---|---|---|
c906108c | 1 | /* Fork a Unix child process, and set up to debug it, for GDB. |
74a4fe32 MK |
2 | |
3 | Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, | |
4 | 2000, 2001, 2004 Free Software Foundation, Inc. | |
5 | ||
c906108c SS |
6 | Contributed by Cygnus Support. |
7 | ||
c5aa993b | 8 | This file is part of GDB. |
c906108c | 9 | |
c5aa993b JM |
10 | This program is free software; you can redistribute it and/or modify |
11 | it under the terms of the GNU General Public License as published by | |
12 | the Free Software Foundation; either version 2 of the License, or | |
13 | (at your option) any later version. | |
c906108c | 14 | |
c5aa993b JM |
15 | This program is distributed in the hope that it will be useful, |
16 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | GNU General Public License for more details. | |
c906108c | 19 | |
c5aa993b JM |
20 | You should have received a copy of the GNU General Public License |
21 | along with this program; if not, write to the Free Software | |
22 | Foundation, Inc., 59 Temple Place - Suite 330, | |
23 | Boston, MA 02111-1307, USA. */ | |
c906108c SS |
24 | |
25 | #include "defs.h" | |
26 | #include "gdb_string.h" | |
27 | #include "frame.h" /* required by inferior.h */ | |
28 | #include "inferior.h" | |
29 | #include "target.h" | |
03f2053f | 30 | #include "gdb_wait.h" |
74c1b268 | 31 | #include "gdb_vfork.h" |
c906108c SS |
32 | #include "gdbcore.h" |
33 | #include "terminal.h" | |
34 | #include "gdbthread.h" | |
c2d11a7d | 35 | #include "command.h" /* for dont_repeat () */ |
c906108c SS |
36 | |
37 | #include <signal.h> | |
c906108c | 38 | |
74a4fe32 | 39 | /* This just gets used as a default if we can't find SHELL. */ |
c906108c SS |
40 | #ifndef SHELL_FILE |
41 | #define SHELL_FILE "/bin/sh" | |
42 | #endif | |
43 | ||
44 | extern char **environ; | |
45 | ||
74a4fe32 MK |
46 | /* Break up SCRATCH into an argument vector suitable for passing to |
47 | execvp and store it in ARGV. E.g., on "run a b c d" this routine | |
48 | would get as input the string "a b c d", and as output it would | |
49 | fill in ARGV with the four arguments "a", "b", "c", "d". */ | |
50 | ||
c906108c | 51 | static void |
fba45db2 | 52 | breakup_args (char *scratch, char **argv) |
c906108c SS |
53 | { |
54 | char *cp = scratch; | |
55 | ||
c906108c SS |
56 | for (;;) |
57 | { | |
c906108c SS |
58 | /* Scan past leading separators */ |
59 | while (*cp == ' ' || *cp == '\t' || *cp == '\n') | |
74a4fe32 | 60 | cp++; |
c906108c | 61 | |
74a4fe32 | 62 | /* Break if at end of string. */ |
c906108c SS |
63 | if (*cp == '\0') |
64 | break; | |
65 | ||
74a4fe32 | 66 | /* Take an arg. */ |
c906108c SS |
67 | *argv++ = cp; |
68 | ||
74a4fe32 | 69 | /* Scan for next arg separator. */ |
c906108c SS |
70 | cp = strchr (cp, ' '); |
71 | if (cp == NULL) | |
72 | cp = strchr (cp, '\t'); | |
73 | if (cp == NULL) | |
74 | cp = strchr (cp, '\n'); | |
75 | ||
74a4fe32 | 76 | /* No separators => end of string => break. */ |
c906108c SS |
77 | if (cp == NULL) |
78 | break; | |
79 | ||
74a4fe32 | 80 | /* Replace the separator with a terminator. */ |
c906108c SS |
81 | *cp++ = '\0'; |
82 | } | |
83 | ||
74a4fe32 | 84 | /* Null-terminate the vector. */ |
c906108c | 85 | *argv = NULL; |
c906108c SS |
86 | } |
87 | ||
74a4fe32 MK |
88 | /* When executing a command under the given shell, return non-zero if |
89 | the '!' character should be escaped when embedded in a quoted | |
6037b830 JB |
90 | command-line argument. */ |
91 | ||
92 | static int | |
93 | escape_bang_in_quoted_argument (const char *shell_file) | |
94 | { | |
95 | const int shell_file_len = strlen (shell_file); | |
74a4fe32 | 96 | |
6037b830 JB |
97 | /* Bang should be escaped only in C Shells. For now, simply check |
98 | that the shell name ends with 'csh', which covers at least csh | |
99 | and tcsh. This should be good enough for now. */ | |
100 | ||
101 | if (shell_file_len < 3) | |
102 | return 0; | |
103 | ||
104 | if (shell_file[shell_file_len - 3] == 'c' | |
105 | && shell_file[shell_file_len - 2] == 's' | |
106 | && shell_file[shell_file_len - 1] == 'h') | |
107 | return 1; | |
108 | ||
109 | return 0; | |
110 | } | |
c906108c | 111 | |
74a4fe32 MK |
112 | /* Start an inferior Unix child process and sets inferior_ptid to its |
113 | pid. EXEC_FILE is the file to run. ALLARGS is a string containing | |
114 | the arguments to the program. ENV is the environment vector to | |
115 | pass. SHELL_FILE is the shell file, or NULL if we should pick | |
116 | one. */ | |
c906108c | 117 | |
74a4fe32 MK |
118 | /* This function is NOT reentrant. Some of the variables have been |
119 | made static to ensure that they survive the vfork call. */ | |
c65ecaf3 | 120 | |
c906108c | 121 | void |
c65ecaf3 | 122 | fork_inferior (char *exec_file_arg, char *allargs, char **env, |
073063d7 | 123 | void (*traceme_fun) (void), void (*init_trace_fun) (int), |
c65ecaf3 | 124 | void (*pre_trace_fun) (void), char *shell_file_arg) |
c906108c SS |
125 | { |
126 | int pid; | |
127 | char *shell_command; | |
128 | static char default_shell_file[] = SHELL_FILE; | |
129 | int len; | |
130 | /* Set debug_fork then attach to the child while it sleeps, to debug. */ | |
131 | static int debug_fork = 0; | |
132 | /* This is set to the result of setpgrp, which if vforked, will be visible | |
133 | to you in the parent process. It's only used by humans for debugging. */ | |
134 | static int debug_setpgrp = 657473; | |
c65ecaf3 AC |
135 | static char *shell_file; |
136 | static char *exec_file; | |
c906108c SS |
137 | char **save_our_env; |
138 | int shell = 0; | |
c65ecaf3 | 139 | static char **argv; |
c906108c | 140 | |
74a4fe32 MK |
141 | /* If no exec file handed to us, get it from the exec-file command |
142 | -- with a good, common error message if none is specified. */ | |
c65ecaf3 | 143 | exec_file = exec_file_arg; |
c906108c SS |
144 | if (exec_file == 0) |
145 | exec_file = get_exec_file (1); | |
146 | ||
74a4fe32 MK |
147 | /* STARTUP_WITH_SHELL is defined in inferior.h. If 0,e we'll just |
148 | do a fork/exec, no shell, so don't bother figuring out what | |
149 | shell. */ | |
c65ecaf3 | 150 | shell_file = shell_file_arg; |
c906108c SS |
151 | if (STARTUP_WITH_SHELL) |
152 | { | |
74a4fe32 | 153 | /* Figure out what shell to start up the user program under. */ |
c906108c SS |
154 | if (shell_file == NULL) |
155 | shell_file = getenv ("SHELL"); | |
156 | if (shell_file == NULL) | |
157 | shell_file = default_shell_file; | |
158 | shell = 1; | |
159 | } | |
160 | ||
74a4fe32 MK |
161 | /* Multiplying the length of exec_file by 4 is to account for the |
162 | fact that it may expand when quoted; it is a worst-case number | |
163 | based on every character being '. */ | |
c5aa993b | 164 | len = 5 + 4 * strlen (exec_file) + 1 + strlen (allargs) + 1 + /*slop */ 12; |
c906108c SS |
165 | /* If desired, concat something onto the front of ALLARGS. |
166 | SHELL_COMMAND is the result. */ | |
167 | #ifdef SHELL_COMMAND_CONCAT | |
168 | shell_command = (char *) alloca (strlen (SHELL_COMMAND_CONCAT) + len); | |
169 | strcpy (shell_command, SHELL_COMMAND_CONCAT); | |
170 | #else | |
171 | shell_command = (char *) alloca (len); | |
172 | shell_command[0] = '\0'; | |
173 | #endif | |
174 | ||
175 | if (!shell) | |
176 | { | |
74a4fe32 MK |
177 | /* We're going to call execvp. Create argument vector. |
178 | Calculate an upper bound on the length of the vector by | |
179 | assuming that every other character is a separate | |
180 | argument. */ | |
181 | int argc = (strlen (allargs) + 1) / 2 + 2; | |
182 | argv = (char **) xmalloc (argc * sizeof (*argv)); | |
c906108c SS |
183 | argv[0] = exec_file; |
184 | breakup_args (allargs, &argv[1]); | |
c906108c SS |
185 | } |
186 | else | |
187 | { | |
74a4fe32 | 188 | /* We're going to call a shell. */ |
c906108c SS |
189 | |
190 | /* Now add exec_file, quoting as necessary. */ | |
191 | ||
192 | char *p; | |
193 | int need_to_quote; | |
6037b830 | 194 | const int escape_bang = escape_bang_in_quoted_argument (shell_file); |
c906108c SS |
195 | |
196 | strcat (shell_command, "exec "); | |
197 | ||
74a4fe32 MK |
198 | /* Quoting in this style is said to work with all shells. But |
199 | csh on IRIX 4.0.1 can't deal with it. So we only quote it if | |
200 | we need to. */ | |
c906108c SS |
201 | p = exec_file; |
202 | while (1) | |
203 | { | |
204 | switch (*p) | |
205 | { | |
206 | case '\'': | |
d8849953 | 207 | case '!': |
c906108c SS |
208 | case '"': |
209 | case '(': | |
210 | case ')': | |
211 | case '$': | |
212 | case '&': | |
213 | case ';': | |
214 | case '<': | |
215 | case '>': | |
216 | case ' ': | |
217 | case '\n': | |
218 | case '\t': | |
219 | need_to_quote = 1; | |
220 | goto end_scan; | |
221 | ||
222 | case '\0': | |
223 | need_to_quote = 0; | |
224 | goto end_scan; | |
225 | ||
226 | default: | |
227 | break; | |
228 | } | |
229 | ++p; | |
230 | } | |
231 | end_scan: | |
232 | if (need_to_quote) | |
233 | { | |
234 | strcat (shell_command, "'"); | |
235 | for (p = exec_file; *p != '\0'; ++p) | |
236 | { | |
237 | if (*p == '\'') | |
238 | strcat (shell_command, "'\\''"); | |
6037b830 | 239 | else if (*p == '!' && escape_bang) |
d8849953 | 240 | strcat (shell_command, "\\!"); |
c906108c SS |
241 | else |
242 | strncat (shell_command, p, 1); | |
243 | } | |
244 | strcat (shell_command, "'"); | |
245 | } | |
246 | else | |
247 | strcat (shell_command, exec_file); | |
248 | ||
249 | strcat (shell_command, " "); | |
250 | strcat (shell_command, allargs); | |
c906108c SS |
251 | } |
252 | ||
74a4fe32 | 253 | /* On some systems an exec will fail if the executable is open. */ |
c906108c SS |
254 | close_exec_file (); |
255 | ||
256 | /* Retain a copy of our environment variables, since the child will | |
74a4fe32 | 257 | replace the value of environ and if we're vforked, we have to |
c906108c SS |
258 | restore it. */ |
259 | save_our_env = environ; | |
260 | ||
261 | /* Tell the terminal handling subsystem what tty we plan to run on; | |
262 | it will just record the information for later. */ | |
c906108c SS |
263 | new_tty_prefork (inferior_io_terminal); |
264 | ||
265 | /* It is generally good practice to flush any possible pending stdio | |
74a4fe32 MK |
266 | output prior to doing a fork, to avoid the possibility of both |
267 | the parent and child flushing the same data after the fork. */ | |
c906108c SS |
268 | gdb_flush (gdb_stdout); |
269 | gdb_flush (gdb_stderr); | |
270 | ||
74a4fe32 MK |
271 | /* If there's any initialization of the target layers that must |
272 | happen to prepare to handle the child we're about fork, do it | |
273 | now... */ | |
c906108c SS |
274 | if (pre_trace_fun != NULL) |
275 | (*pre_trace_fun) (); | |
276 | ||
3919e12c MK |
277 | /* Create the child process. Since the child process is going to |
278 | exec(3) shortlty afterwards, try to reduce the overhead by | |
279 | calling vfork(2). However, if PRE_TRACE_FUN is non-null, it's | |
280 | likely that this optimization won't work since there's too much | |
281 | work to do between the vfork(2) and the exec(3). This is known | |
282 | to be the case on ttrace(2)-based HP-UX, where some handshaking | |
283 | between parent and child needs to happen between fork(2) and | |
284 | exec(2). However, since the parent is suspended in the vforked | |
285 | state, this doesn't work. Also note that the vfork(2) call might | |
286 | actually be a call to fork(2) due to the fact that autoconf will | |
287 | ``#define vfork fork'' on certain platforms. */ | |
288 | if (pre_trace_fun || debug_fork) | |
c906108c SS |
289 | pid = fork (); |
290 | else | |
291 | pid = vfork (); | |
c906108c SS |
292 | |
293 | if (pid < 0) | |
e2e0b3e5 | 294 | perror_with_name (("vfork")); |
c906108c SS |
295 | |
296 | if (pid == 0) | |
297 | { | |
298 | if (debug_fork) | |
299 | sleep (debug_fork); | |
300 | ||
301 | /* Run inferior in a separate process group. */ | |
302 | debug_setpgrp = gdb_setpgid (); | |
303 | if (debug_setpgrp == -1) | |
304 | perror ("setpgrp failed in child"); | |
305 | ||
74a4fe32 MK |
306 | /* Ask the tty subsystem to switch to the one we specified |
307 | earlier (or to share the current terminal, if none was | |
308 | specified). */ | |
c906108c SS |
309 | new_tty (); |
310 | ||
311 | /* Changing the signal handlers for the inferior after | |
c5aa993b JM |
312 | a vfork can also change them for the superior, so we don't mess |
313 | with signals here. See comments in | |
314 | initialize_signals for how we get the right signal handlers | |
315 | for the inferior. */ | |
c906108c SS |
316 | |
317 | /* "Trace me, Dr. Memory!" */ | |
318 | (*traceme_fun) (); | |
74a4fe32 | 319 | |
c906108c | 320 | /* The call above set this process (the "child") as debuggable |
74a4fe32 MK |
321 | by the original gdb process (the "parent"). Since processes |
322 | (unlike people) can have only one parent, if you are debugging | |
323 | gdb itself (and your debugger is thus _already_ the | |
324 | controller/parent for this child), code from here on out is | |
325 | undebuggable. Indeed, you probably got an error message | |
326 | saying "not parent". Sorry; you'll have to use print | |
327 | statements! */ | |
c906108c SS |
328 | |
329 | /* There is no execlpe call, so we have to set the environment | |
c5aa993b JM |
330 | for our child in the global variable. If we've vforked, this |
331 | clobbers the parent, but environ is restored a few lines down | |
332 | in the parent. By the way, yes we do need to look down the | |
333 | path to find $SHELL. Rich Pixley says so, and I agree. */ | |
c906108c SS |
334 | environ = env; |
335 | ||
74a4fe32 MK |
336 | /* If we decided above to start up with a shell, we exec the |
337 | shell, "-c" says to interpret the next arg as a shell command | |
338 | to execute, and this command is "exec <target-program> | |
339 | <args>". "-f" means "fast startup" to the c-shell, which | |
340 | means don't do .cshrc file. Doing .cshrc may cause fork/exec | |
341 | events which will confuse debugger start-up code. */ | |
c906108c SS |
342 | if (shell) |
343 | { | |
c906108c | 344 | execlp (shell_file, shell_file, "-c", shell_command, (char *) 0); |
c906108c | 345 | |
74a4fe32 | 346 | /* If we get here, it's an error. */ |
c906108c SS |
347 | fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file, |
348 | safe_strerror (errno)); | |
349 | gdb_flush (gdb_stderr); | |
350 | _exit (0177); | |
351 | } | |
352 | else | |
353 | { | |
74a4fe32 MK |
354 | /* Otherwise, we directly exec the target program with |
355 | execvp. */ | |
c906108c SS |
356 | int i; |
357 | char *errstring; | |
cce74817 | 358 | |
c906108c SS |
359 | execvp (exec_file, argv); |
360 | ||
74a4fe32 | 361 | /* If we get here, it's an error. */ |
c906108c SS |
362 | errstring = safe_strerror (errno); |
363 | fprintf_unfiltered (gdb_stderr, "Cannot exec %s ", exec_file); | |
364 | ||
365 | i = 1; | |
366 | while (argv[i] != NULL) | |
367 | { | |
368 | if (i != 1) | |
369 | fprintf_unfiltered (gdb_stderr, " "); | |
370 | fprintf_unfiltered (gdb_stderr, "%s", argv[i]); | |
371 | i++; | |
372 | } | |
373 | fprintf_unfiltered (gdb_stderr, ".\n"); | |
74a4fe32 MK |
374 | #if 0 |
375 | /* This extra info seems to be useless. */ | |
376 | fprintf_unfiltered (gdb_stderr, "Got error %s.\n", errstring); | |
377 | #endif | |
c906108c SS |
378 | gdb_flush (gdb_stderr); |
379 | _exit (0177); | |
380 | } | |
381 | } | |
382 | ||
383 | /* Restore our environment in case a vforked child clob'd it. */ | |
384 | environ = save_our_env; | |
385 | ||
386 | init_thread_list (); | |
387 | ||
74a4fe32 MK |
388 | /* Needed for wait_for_inferior stuff below. */ |
389 | inferior_ptid = pid_to_ptid (pid); | |
c906108c SS |
390 | |
391 | /* Now that we have a child process, make it our target, and | |
74a4fe32 MK |
392 | initialize anything target-vector-specific that needs |
393 | initializing. */ | |
c906108c SS |
394 | (*init_trace_fun) (pid); |
395 | ||
396 | /* We are now in the child process of interest, having exec'd the | |
397 | correct program, and are poised at the first instruction of the | |
398 | new program. */ | |
399 | ||
74a4fe32 MK |
400 | /* Allow target dependent code to play with the new process. This |
401 | might be used to have target-specific code initialize a variable | |
402 | in the new process prior to executing the first instruction. */ | |
c906108c SS |
403 | TARGET_CREATE_INFERIOR_HOOK (pid); |
404 | ||
405 | #ifdef SOLIB_CREATE_INFERIOR_HOOK | |
406 | SOLIB_CREATE_INFERIOR_HOOK (pid); | |
407 | #endif | |
408 | } | |
409 | ||
c906108c SS |
410 | /* Accept NTRAPS traps from the inferior. */ |
411 | ||
412 | void | |
fba45db2 | 413 | startup_inferior (int ntraps) |
c906108c SS |
414 | { |
415 | int pending_execs = ntraps; | |
74a4fe32 | 416 | int terminal_initted = 0; |
c906108c | 417 | |
74a4fe32 MK |
418 | /* The process was started by the fork that created it, but it will |
419 | have stopped one instruction after execing the shell. Here we | |
420 | must get it up to actual execution of the real program. */ | |
c906108c SS |
421 | |
422 | clear_proceed_status (); | |
423 | ||
424 | init_wait_for_inferior (); | |
425 | ||
c906108c SS |
426 | if (STARTUP_WITH_SHELL) |
427 | inferior_ignoring_startup_exec_events = ntraps; | |
428 | else | |
429 | inferior_ignoring_startup_exec_events = 0; | |
430 | inferior_ignoring_leading_exec_events = | |
431 | target_reported_exec_events_per_exec_call () - 1; | |
432 | ||
c906108c SS |
433 | while (1) |
434 | { | |
74a4fe32 | 435 | /* Make wait_for_inferior be quiet. */ |
c0236d92 | 436 | stop_soon = STOP_QUIETLY; |
c906108c SS |
437 | wait_for_inferior (); |
438 | if (stop_signal != TARGET_SIGNAL_TRAP) | |
439 | { | |
74a4fe32 MK |
440 | /* Let shell child handle its own signals in its own way. |
441 | FIXME: what if child has exited? Must exit loop | |
442 | somehow. */ | |
c906108c SS |
443 | resume (0, stop_signal); |
444 | } | |
445 | else | |
446 | { | |
447 | /* We handle SIGTRAP, however; it means child did an exec. */ | |
448 | if (!terminal_initted) | |
449 | { | |
74a4fe32 MK |
450 | /* Now that the child has exec'd we know it has already |
451 | set its process group. On POSIX systems, tcsetpgrp | |
452 | will fail with EPERM if we try it before the child's | |
453 | setpgid. */ | |
c906108c SS |
454 | |
455 | /* Set up the "saved terminal modes" of the inferior | |
c5aa993b | 456 | based on what modes we are starting it with. */ |
c906108c SS |
457 | target_terminal_init (); |
458 | ||
459 | /* Install inferior's terminal modes. */ | |
460 | target_terminal_inferior (); | |
461 | ||
462 | terminal_initted = 1; | |
463 | } | |
464 | ||
74a4fe32 | 465 | if (--pending_execs == 0) |
c906108c SS |
466 | break; |
467 | ||
74a4fe32 | 468 | resume (0, TARGET_SIGNAL_0); /* Just make it go on. */ |
c906108c SS |
469 | } |
470 | } | |
c0236d92 | 471 | stop_soon = NO_STOP_QUIETLY; |
c906108c | 472 | } |