Commit | Line | Data |
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c906108c | 1 | /* Fork a Unix child process, and set up to debug it, for GDB. |
74a4fe32 | 2 | |
6aba47ca | 3 | Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, |
9b254dd1 | 4 | 2001, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc. |
74a4fe32 | 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 | |
a9762ec7 | 12 | the Free Software Foundation; either version 3 of the License, or |
c5aa993b | 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 | 20 | You should have received a copy of the GNU General Public License |
a9762ec7 | 21 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
c906108c SS |
22 | |
23 | #include "defs.h" | |
24 | #include "gdb_string.h" | |
25 | #include "frame.h" /* required by inferior.h */ | |
26 | #include "inferior.h" | |
27 | #include "target.h" | |
03f2053f | 28 | #include "gdb_wait.h" |
74c1b268 | 29 | #include "gdb_vfork.h" |
c906108c SS |
30 | #include "gdbcore.h" |
31 | #include "terminal.h" | |
32 | #include "gdbthread.h" | |
c2d11a7d | 33 | #include "command.h" /* for dont_repeat () */ |
a77053c2 | 34 | #include "solib.h" |
c906108c SS |
35 | |
36 | #include <signal.h> | |
c906108c | 37 | |
74a4fe32 | 38 | /* This just gets used as a default if we can't find SHELL. */ |
c906108c | 39 | #define SHELL_FILE "/bin/sh" |
c906108c SS |
40 | |
41 | extern char **environ; | |
42 | ||
74a4fe32 MK |
43 | /* Break up SCRATCH into an argument vector suitable for passing to |
44 | execvp and store it in ARGV. E.g., on "run a b c d" this routine | |
45 | would get as input the string "a b c d", and as output it would | |
46 | fill in ARGV with the four arguments "a", "b", "c", "d". */ | |
47 | ||
c906108c | 48 | static void |
fba45db2 | 49 | breakup_args (char *scratch, char **argv) |
c906108c SS |
50 | { |
51 | char *cp = scratch; | |
52 | ||
c906108c SS |
53 | for (;;) |
54 | { | |
c906108c SS |
55 | /* Scan past leading separators */ |
56 | while (*cp == ' ' || *cp == '\t' || *cp == '\n') | |
74a4fe32 | 57 | cp++; |
c906108c | 58 | |
74a4fe32 | 59 | /* Break if at end of string. */ |
c906108c SS |
60 | if (*cp == '\0') |
61 | break; | |
62 | ||
74a4fe32 | 63 | /* Take an arg. */ |
c906108c SS |
64 | *argv++ = cp; |
65 | ||
74a4fe32 | 66 | /* Scan for next arg separator. */ |
c906108c SS |
67 | cp = strchr (cp, ' '); |
68 | if (cp == NULL) | |
69 | cp = strchr (cp, '\t'); | |
70 | if (cp == NULL) | |
71 | cp = strchr (cp, '\n'); | |
72 | ||
74a4fe32 | 73 | /* No separators => end of string => break. */ |
c906108c SS |
74 | if (cp == NULL) |
75 | break; | |
76 | ||
74a4fe32 | 77 | /* Replace the separator with a terminator. */ |
c906108c SS |
78 | *cp++ = '\0'; |
79 | } | |
80 | ||
74a4fe32 | 81 | /* Null-terminate the vector. */ |
c906108c | 82 | *argv = NULL; |
c906108c SS |
83 | } |
84 | ||
74a4fe32 MK |
85 | /* When executing a command under the given shell, return non-zero if |
86 | the '!' character should be escaped when embedded in a quoted | |
6037b830 JB |
87 | command-line argument. */ |
88 | ||
89 | static int | |
90 | escape_bang_in_quoted_argument (const char *shell_file) | |
91 | { | |
92 | const int shell_file_len = strlen (shell_file); | |
74a4fe32 | 93 | |
6037b830 JB |
94 | /* Bang should be escaped only in C Shells. For now, simply check |
95 | that the shell name ends with 'csh', which covers at least csh | |
96 | and tcsh. This should be good enough for now. */ | |
97 | ||
98 | if (shell_file_len < 3) | |
99 | return 0; | |
100 | ||
101 | if (shell_file[shell_file_len - 3] == 'c' | |
102 | && shell_file[shell_file_len - 2] == 's' | |
103 | && shell_file[shell_file_len - 1] == 'h') | |
104 | return 1; | |
105 | ||
106 | return 0; | |
107 | } | |
c906108c | 108 | |
74a4fe32 MK |
109 | /* Start an inferior Unix child process and sets inferior_ptid to its |
110 | pid. EXEC_FILE is the file to run. ALLARGS is a string containing | |
111 | the arguments to the program. ENV is the environment vector to | |
112 | pass. SHELL_FILE is the shell file, or NULL if we should pick | |
113 | one. */ | |
c906108c | 114 | |
74a4fe32 MK |
115 | /* This function is NOT reentrant. Some of the variables have been |
116 | made static to ensure that they survive the vfork call. */ | |
c65ecaf3 | 117 | |
c906108c | 118 | void |
c65ecaf3 | 119 | fork_inferior (char *exec_file_arg, char *allargs, char **env, |
073063d7 | 120 | void (*traceme_fun) (void), void (*init_trace_fun) (int), |
c65ecaf3 | 121 | void (*pre_trace_fun) (void), char *shell_file_arg) |
c906108c SS |
122 | { |
123 | int pid; | |
124 | char *shell_command; | |
125 | static char default_shell_file[] = SHELL_FILE; | |
126 | int len; | |
127 | /* Set debug_fork then attach to the child while it sleeps, to debug. */ | |
128 | static int debug_fork = 0; | |
129 | /* This is set to the result of setpgrp, which if vforked, will be visible | |
130 | to you in the parent process. It's only used by humans for debugging. */ | |
131 | static int debug_setpgrp = 657473; | |
c65ecaf3 AC |
132 | static char *shell_file; |
133 | static char *exec_file; | |
c906108c SS |
134 | char **save_our_env; |
135 | int shell = 0; | |
c65ecaf3 | 136 | static char **argv; |
3cb3b8df | 137 | const char *inferior_io_terminal = get_inferior_io_terminal (); |
c906108c | 138 | |
74a4fe32 MK |
139 | /* If no exec file handed to us, get it from the exec-file command |
140 | -- with a good, common error message if none is specified. */ | |
c65ecaf3 | 141 | exec_file = exec_file_arg; |
c906108c SS |
142 | if (exec_file == 0) |
143 | exec_file = get_exec_file (1); | |
144 | ||
74a4fe32 MK |
145 | /* STARTUP_WITH_SHELL is defined in inferior.h. If 0,e we'll just |
146 | do a fork/exec, no shell, so don't bother figuring out what | |
147 | shell. */ | |
c65ecaf3 | 148 | shell_file = shell_file_arg; |
c906108c SS |
149 | if (STARTUP_WITH_SHELL) |
150 | { | |
74a4fe32 | 151 | /* Figure out what shell to start up the user program under. */ |
c906108c SS |
152 | if (shell_file == NULL) |
153 | shell_file = getenv ("SHELL"); | |
154 | if (shell_file == NULL) | |
155 | shell_file = default_shell_file; | |
156 | shell = 1; | |
157 | } | |
158 | ||
74a4fe32 MK |
159 | /* Multiplying the length of exec_file by 4 is to account for the |
160 | fact that it may expand when quoted; it is a worst-case number | |
161 | based on every character being '. */ | |
c5aa993b | 162 | len = 5 + 4 * strlen (exec_file) + 1 + strlen (allargs) + 1 + /*slop */ 12; |
c906108c SS |
163 | shell_command = (char *) alloca (len); |
164 | shell_command[0] = '\0'; | |
c906108c SS |
165 | |
166 | if (!shell) | |
167 | { | |
74a4fe32 MK |
168 | /* We're going to call execvp. Create argument vector. |
169 | Calculate an upper bound on the length of the vector by | |
170 | assuming that every other character is a separate | |
171 | argument. */ | |
172 | int argc = (strlen (allargs) + 1) / 2 + 2; | |
173 | argv = (char **) xmalloc (argc * sizeof (*argv)); | |
c906108c SS |
174 | argv[0] = exec_file; |
175 | breakup_args (allargs, &argv[1]); | |
c906108c SS |
176 | } |
177 | else | |
178 | { | |
74a4fe32 | 179 | /* We're going to call a shell. */ |
c906108c SS |
180 | |
181 | /* Now add exec_file, quoting as necessary. */ | |
182 | ||
183 | char *p; | |
184 | int need_to_quote; | |
6037b830 | 185 | const int escape_bang = escape_bang_in_quoted_argument (shell_file); |
c906108c SS |
186 | |
187 | strcat (shell_command, "exec "); | |
188 | ||
74a4fe32 MK |
189 | /* Quoting in this style is said to work with all shells. But |
190 | csh on IRIX 4.0.1 can't deal with it. So we only quote it if | |
191 | we need to. */ | |
c906108c SS |
192 | p = exec_file; |
193 | while (1) | |
194 | { | |
195 | switch (*p) | |
196 | { | |
197 | case '\'': | |
d8849953 | 198 | case '!': |
c906108c SS |
199 | case '"': |
200 | case '(': | |
201 | case ')': | |
202 | case '$': | |
203 | case '&': | |
204 | case ';': | |
205 | case '<': | |
206 | case '>': | |
207 | case ' ': | |
208 | case '\n': | |
209 | case '\t': | |
210 | need_to_quote = 1; | |
211 | goto end_scan; | |
212 | ||
213 | case '\0': | |
214 | need_to_quote = 0; | |
215 | goto end_scan; | |
216 | ||
217 | default: | |
218 | break; | |
219 | } | |
220 | ++p; | |
221 | } | |
222 | end_scan: | |
223 | if (need_to_quote) | |
224 | { | |
225 | strcat (shell_command, "'"); | |
226 | for (p = exec_file; *p != '\0'; ++p) | |
227 | { | |
228 | if (*p == '\'') | |
229 | strcat (shell_command, "'\\''"); | |
6037b830 | 230 | else if (*p == '!' && escape_bang) |
d8849953 | 231 | strcat (shell_command, "\\!"); |
c906108c SS |
232 | else |
233 | strncat (shell_command, p, 1); | |
234 | } | |
235 | strcat (shell_command, "'"); | |
236 | } | |
237 | else | |
238 | strcat (shell_command, exec_file); | |
239 | ||
240 | strcat (shell_command, " "); | |
241 | strcat (shell_command, allargs); | |
c906108c SS |
242 | } |
243 | ||
74a4fe32 | 244 | /* On some systems an exec will fail if the executable is open. */ |
c906108c SS |
245 | close_exec_file (); |
246 | ||
247 | /* Retain a copy of our environment variables, since the child will | |
74a4fe32 | 248 | replace the value of environ and if we're vforked, we have to |
c906108c SS |
249 | restore it. */ |
250 | save_our_env = environ; | |
251 | ||
252 | /* Tell the terminal handling subsystem what tty we plan to run on; | |
253 | it will just record the information for later. */ | |
c906108c SS |
254 | new_tty_prefork (inferior_io_terminal); |
255 | ||
256 | /* It is generally good practice to flush any possible pending stdio | |
74a4fe32 MK |
257 | output prior to doing a fork, to avoid the possibility of both |
258 | the parent and child flushing the same data after the fork. */ | |
c906108c SS |
259 | gdb_flush (gdb_stdout); |
260 | gdb_flush (gdb_stderr); | |
261 | ||
74a4fe32 MK |
262 | /* If there's any initialization of the target layers that must |
263 | happen to prepare to handle the child we're about fork, do it | |
264 | now... */ | |
c906108c SS |
265 | if (pre_trace_fun != NULL) |
266 | (*pre_trace_fun) (); | |
267 | ||
3919e12c | 268 | /* Create the child process. Since the child process is going to |
7a0b0196 | 269 | exec(3) shortly afterwards, try to reduce the overhead by |
3919e12c MK |
270 | calling vfork(2). However, if PRE_TRACE_FUN is non-null, it's |
271 | likely that this optimization won't work since there's too much | |
272 | work to do between the vfork(2) and the exec(3). This is known | |
273 | to be the case on ttrace(2)-based HP-UX, where some handshaking | |
274 | between parent and child needs to happen between fork(2) and | |
275 | exec(2). However, since the parent is suspended in the vforked | |
276 | state, this doesn't work. Also note that the vfork(2) call might | |
277 | actually be a call to fork(2) due to the fact that autoconf will | |
278 | ``#define vfork fork'' on certain platforms. */ | |
279 | if (pre_trace_fun || debug_fork) | |
c906108c SS |
280 | pid = fork (); |
281 | else | |
282 | pid = vfork (); | |
c906108c SS |
283 | |
284 | if (pid < 0) | |
e2e0b3e5 | 285 | perror_with_name (("vfork")); |
c906108c SS |
286 | |
287 | if (pid == 0) | |
288 | { | |
289 | if (debug_fork) | |
290 | sleep (debug_fork); | |
291 | ||
292 | /* Run inferior in a separate process group. */ | |
293 | debug_setpgrp = gdb_setpgid (); | |
294 | if (debug_setpgrp == -1) | |
295 | perror ("setpgrp failed in child"); | |
296 | ||
74a4fe32 MK |
297 | /* Ask the tty subsystem to switch to the one we specified |
298 | earlier (or to share the current terminal, if none was | |
299 | specified). */ | |
c906108c SS |
300 | new_tty (); |
301 | ||
302 | /* Changing the signal handlers for the inferior after | |
c5aa993b JM |
303 | a vfork can also change them for the superior, so we don't mess |
304 | with signals here. See comments in | |
305 | initialize_signals for how we get the right signal handlers | |
306 | for the inferior. */ | |
c906108c SS |
307 | |
308 | /* "Trace me, Dr. Memory!" */ | |
309 | (*traceme_fun) (); | |
74a4fe32 | 310 | |
c906108c | 311 | /* The call above set this process (the "child") as debuggable |
74a4fe32 MK |
312 | by the original gdb process (the "parent"). Since processes |
313 | (unlike people) can have only one parent, if you are debugging | |
314 | gdb itself (and your debugger is thus _already_ the | |
315 | controller/parent for this child), code from here on out is | |
316 | undebuggable. Indeed, you probably got an error message | |
317 | saying "not parent". Sorry; you'll have to use print | |
318 | statements! */ | |
c906108c SS |
319 | |
320 | /* There is no execlpe call, so we have to set the environment | |
c5aa993b JM |
321 | for our child in the global variable. If we've vforked, this |
322 | clobbers the parent, but environ is restored a few lines down | |
323 | in the parent. By the way, yes we do need to look down the | |
324 | path to find $SHELL. Rich Pixley says so, and I agree. */ | |
c906108c SS |
325 | environ = env; |
326 | ||
74a4fe32 | 327 | /* If we decided above to start up with a shell, we exec the |
9dcbb931 DJ |
328 | shell, "-c" says to interpret the next arg as a shell command |
329 | to execute, and this command is "exec <target-program> | |
330 | <args>". */ | |
c906108c SS |
331 | if (shell) |
332 | { | |
c906108c | 333 | execlp (shell_file, shell_file, "-c", shell_command, (char *) 0); |
c906108c | 334 | |
74a4fe32 | 335 | /* If we get here, it's an error. */ |
c906108c SS |
336 | fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file, |
337 | safe_strerror (errno)); | |
338 | gdb_flush (gdb_stderr); | |
339 | _exit (0177); | |
340 | } | |
341 | else | |
342 | { | |
74a4fe32 MK |
343 | /* Otherwise, we directly exec the target program with |
344 | execvp. */ | |
c906108c SS |
345 | int i; |
346 | char *errstring; | |
cce74817 | 347 | |
c906108c SS |
348 | execvp (exec_file, argv); |
349 | ||
74a4fe32 | 350 | /* If we get here, it's an error. */ |
c906108c SS |
351 | errstring = safe_strerror (errno); |
352 | fprintf_unfiltered (gdb_stderr, "Cannot exec %s ", exec_file); | |
353 | ||
354 | i = 1; | |
355 | while (argv[i] != NULL) | |
356 | { | |
357 | if (i != 1) | |
358 | fprintf_unfiltered (gdb_stderr, " "); | |
359 | fprintf_unfiltered (gdb_stderr, "%s", argv[i]); | |
360 | i++; | |
361 | } | |
362 | fprintf_unfiltered (gdb_stderr, ".\n"); | |
74a4fe32 MK |
363 | #if 0 |
364 | /* This extra info seems to be useless. */ | |
365 | fprintf_unfiltered (gdb_stderr, "Got error %s.\n", errstring); | |
366 | #endif | |
c906108c SS |
367 | gdb_flush (gdb_stderr); |
368 | _exit (0177); | |
369 | } | |
370 | } | |
371 | ||
372 | /* Restore our environment in case a vforked child clob'd it. */ | |
373 | environ = save_our_env; | |
374 | ||
375 | init_thread_list (); | |
376 | ||
74a4fe32 MK |
377 | /* Needed for wait_for_inferior stuff below. */ |
378 | inferior_ptid = pid_to_ptid (pid); | |
c906108c SS |
379 | |
380 | /* Now that we have a child process, make it our target, and | |
74a4fe32 MK |
381 | initialize anything target-vector-specific that needs |
382 | initializing. */ | |
c906108c SS |
383 | (*init_trace_fun) (pid); |
384 | ||
385 | /* We are now in the child process of interest, having exec'd the | |
386 | correct program, and are poised at the first instruction of the | |
387 | new program. */ | |
c906108c SS |
388 | } |
389 | ||
c906108c SS |
390 | /* Accept NTRAPS traps from the inferior. */ |
391 | ||
392 | void | |
fba45db2 | 393 | startup_inferior (int ntraps) |
c906108c SS |
394 | { |
395 | int pending_execs = ntraps; | |
74a4fe32 | 396 | int terminal_initted = 0; |
c906108c | 397 | |
74a4fe32 MK |
398 | /* The process was started by the fork that created it, but it will |
399 | have stopped one instruction after execing the shell. Here we | |
400 | must get it up to actual execution of the real program. */ | |
c906108c SS |
401 | |
402 | clear_proceed_status (); | |
403 | ||
404 | init_wait_for_inferior (); | |
405 | ||
c906108c SS |
406 | inferior_ignoring_leading_exec_events = |
407 | target_reported_exec_events_per_exec_call () - 1; | |
408 | ||
c906108c SS |
409 | while (1) |
410 | { | |
74a4fe32 | 411 | /* Make wait_for_inferior be quiet. */ |
c0236d92 | 412 | stop_soon = STOP_QUIETLY; |
ae123ec6 | 413 | wait_for_inferior (1); |
c906108c SS |
414 | if (stop_signal != TARGET_SIGNAL_TRAP) |
415 | { | |
74a4fe32 MK |
416 | /* Let shell child handle its own signals in its own way. |
417 | FIXME: what if child has exited? Must exit loop | |
418 | somehow. */ | |
c906108c SS |
419 | resume (0, stop_signal); |
420 | } | |
421 | else | |
422 | { | |
423 | /* We handle SIGTRAP, however; it means child did an exec. */ | |
424 | if (!terminal_initted) | |
425 | { | |
74a4fe32 MK |
426 | /* Now that the child has exec'd we know it has already |
427 | set its process group. On POSIX systems, tcsetpgrp | |
428 | will fail with EPERM if we try it before the child's | |
429 | setpgid. */ | |
c906108c SS |
430 | |
431 | /* Set up the "saved terminal modes" of the inferior | |
c5aa993b | 432 | based on what modes we are starting it with. */ |
c906108c SS |
433 | target_terminal_init (); |
434 | ||
435 | /* Install inferior's terminal modes. */ | |
436 | target_terminal_inferior (); | |
437 | ||
438 | terminal_initted = 1; | |
439 | } | |
440 | ||
74a4fe32 | 441 | if (--pending_execs == 0) |
c906108c SS |
442 | break; |
443 | ||
74a4fe32 | 444 | resume (0, TARGET_SIGNAL_0); /* Just make it go on. */ |
c906108c SS |
445 | } |
446 | } | |
c0236d92 | 447 | stop_soon = NO_STOP_QUIETLY; |
c906108c | 448 | } |