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1 | /* GNU/Linux native-dependent code for debugging multiple forks. | |
2 | ||
3 | Copyright (C) 2005-2020 Free Software Foundation, Inc. | |
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 3 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, see <http://www.gnu.org/licenses/>. */ | |
19 | ||
20 | #include "defs.h" | |
21 | #include "arch-utils.h" | |
22 | #include "inferior.h" | |
23 | #include "infrun.h" | |
24 | #include "regcache.h" | |
25 | #include "gdbcmd.h" | |
26 | #include "infcall.h" | |
27 | #include "objfiles.h" | |
28 | #include "linux-fork.h" | |
29 | #include "linux-nat.h" | |
30 | #include "gdbthread.h" | |
31 | #include "source.h" | |
32 | ||
33 | #include "nat/gdb_ptrace.h" | |
34 | #include "gdbsupport/gdb_wait.h" | |
35 | #include <dirent.h> | |
36 | #include <ctype.h> | |
37 | ||
38 | #include <list> | |
39 | ||
40 | /* Fork list data structure: */ | |
41 | struct fork_info | |
42 | { | |
43 | explicit fork_info (pid_t pid) | |
44 | : ptid (pid, pid, 0) | |
45 | { | |
46 | } | |
47 | ||
48 | ~fork_info () | |
49 | { | |
50 | /* Notes on step-resume breakpoints: since this is a concern for | |
51 | threads, let's convince ourselves that it's not a concern for | |
52 | forks. There are two ways for a fork_info to be created. | |
53 | First, by the checkpoint command, in which case we're at a gdb | |
54 | prompt and there can't be any step-resume breakpoint. Second, | |
55 | by a fork in the user program, in which case we *may* have | |
56 | stepped into the fork call, but regardless of whether we follow | |
57 | the parent or the child, we will return to the same place and | |
58 | the step-resume breakpoint, if any, will take care of itself as | |
59 | usual. And unlike threads, we do not save a private copy of | |
60 | the step-resume breakpoint -- so we're OK. */ | |
61 | ||
62 | if (savedregs) | |
63 | delete savedregs; | |
64 | if (filepos) | |
65 | xfree (filepos); | |
66 | } | |
67 | ||
68 | ptid_t ptid = null_ptid; | |
69 | ptid_t parent_ptid = null_ptid; | |
70 | ||
71 | /* Convenient handle (GDB fork id). */ | |
72 | int num = 0; | |
73 | ||
74 | /* Convenient for info fork, saves having to actually switch | |
75 | contexts. */ | |
76 | readonly_detached_regcache *savedregs = nullptr; | |
77 | ||
78 | CORE_ADDR pc = 0; | |
79 | ||
80 | /* Set of open file descriptors' offsets. */ | |
81 | off_t *filepos = nullptr; | |
82 | ||
83 | int maxfd = 0; | |
84 | }; | |
85 | ||
86 | static std::list<fork_info> fork_list; | |
87 | static int highest_fork_num; | |
88 | ||
89 | /* Fork list methods: */ | |
90 | ||
91 | int | |
92 | forks_exist_p (void) | |
93 | { | |
94 | return !fork_list.empty (); | |
95 | } | |
96 | ||
97 | /* Return the last fork in the list. */ | |
98 | ||
99 | static struct fork_info * | |
100 | find_last_fork (void) | |
101 | { | |
102 | if (fork_list.empty ()) | |
103 | return NULL; | |
104 | ||
105 | return &fork_list.back (); | |
106 | } | |
107 | ||
108 | /* Return true iff there's one fork in the list. */ | |
109 | ||
110 | static bool | |
111 | one_fork_p () | |
112 | { | |
113 | return fork_list.size () == 1; | |
114 | } | |
115 | ||
116 | /* Add a new fork to the internal fork list. */ | |
117 | ||
118 | void | |
119 | add_fork (pid_t pid) | |
120 | { | |
121 | fork_list.emplace_back (pid); | |
122 | ||
123 | if (one_fork_p ()) | |
124 | highest_fork_num = 0; | |
125 | ||
126 | fork_info *fp = &fork_list.back (); | |
127 | fp->num = ++highest_fork_num; | |
128 | } | |
129 | ||
130 | static void | |
131 | delete_fork (ptid_t ptid) | |
132 | { | |
133 | linux_target->low_forget_process (ptid.pid ()); | |
134 | ||
135 | for (auto it = fork_list.begin (); it != fork_list.end (); ++it) | |
136 | if (it->ptid == ptid) | |
137 | { | |
138 | fork_list.erase (it); | |
139 | ||
140 | /* Special case: if there is now only one process in the list, | |
141 | and if it is (hopefully!) the current inferior_ptid, then | |
142 | remove it, leaving the list empty -- we're now down to the | |
143 | default case of debugging a single process. */ | |
144 | if (one_fork_p () && fork_list.front ().ptid == inferior_ptid) | |
145 | { | |
146 | /* Last fork -- delete from list and handle as solo | |
147 | process (should be a safe recursion). */ | |
148 | delete_fork (inferior_ptid); | |
149 | } | |
150 | return; | |
151 | } | |
152 | } | |
153 | ||
154 | /* Find a fork_info by matching PTID. */ | |
155 | static struct fork_info * | |
156 | find_fork_ptid (ptid_t ptid) | |
157 | { | |
158 | for (fork_info &fi : fork_list) | |
159 | if (fi.ptid == ptid) | |
160 | return &fi; | |
161 | ||
162 | return NULL; | |
163 | } | |
164 | ||
165 | /* Find a fork_info by matching ID. */ | |
166 | static struct fork_info * | |
167 | find_fork_id (int num) | |
168 | { | |
169 | for (fork_info &fi : fork_list) | |
170 | if (fi.num == num) | |
171 | return &fi; | |
172 | ||
173 | return NULL; | |
174 | } | |
175 | ||
176 | /* Find a fork_info by matching pid. */ | |
177 | extern struct fork_info * | |
178 | find_fork_pid (pid_t pid) | |
179 | { | |
180 | for (fork_info &fi : fork_list) | |
181 | if (pid == fi.ptid.pid ()) | |
182 | return &fi; | |
183 | ||
184 | return NULL; | |
185 | } | |
186 | ||
187 | static ptid_t | |
188 | fork_id_to_ptid (int num) | |
189 | { | |
190 | struct fork_info *fork = find_fork_id (num); | |
191 | if (fork) | |
192 | return fork->ptid; | |
193 | else | |
194 | return ptid_t (-1); | |
195 | } | |
196 | ||
197 | /* Fork list <-> gdb interface. */ | |
198 | ||
199 | /* Utility function for fork_load/fork_save. | |
200 | Calls lseek in the (current) inferior process. */ | |
201 | ||
202 | static off_t | |
203 | call_lseek (int fd, off_t offset, int whence) | |
204 | { | |
205 | char exp[80]; | |
206 | ||
207 | snprintf (&exp[0], sizeof (exp), "(long) lseek (%d, %ld, %d)", | |
208 | fd, (long) offset, whence); | |
209 | return (off_t) parse_and_eval_long (&exp[0]); | |
210 | } | |
211 | ||
212 | /* Load infrun state for the fork PTID. */ | |
213 | ||
214 | static void | |
215 | fork_load_infrun_state (struct fork_info *fp) | |
216 | { | |
217 | int i; | |
218 | ||
219 | linux_nat_switch_fork (fp->ptid); | |
220 | ||
221 | if (fp->savedregs) | |
222 | get_current_regcache ()->restore (fp->savedregs); | |
223 | ||
224 | registers_changed (); | |
225 | reinit_frame_cache (); | |
226 | ||
227 | inferior_thread ()->suspend.stop_pc | |
228 | = regcache_read_pc (get_current_regcache ()); | |
229 | nullify_last_target_wait_ptid (); | |
230 | ||
231 | /* Now restore the file positions of open file descriptors. */ | |
232 | if (fp->filepos) | |
233 | { | |
234 | for (i = 0; i <= fp->maxfd; i++) | |
235 | if (fp->filepos[i] != (off_t) -1) | |
236 | call_lseek (i, fp->filepos[i], SEEK_SET); | |
237 | /* NOTE: I can get away with using SEEK_SET and SEEK_CUR because | |
238 | this is native-only. If it ever has to be cross, we'll have | |
239 | to rethink this. */ | |
240 | } | |
241 | } | |
242 | ||
243 | /* Save infrun state for the fork FP. */ | |
244 | ||
245 | static void | |
246 | fork_save_infrun_state (struct fork_info *fp) | |
247 | { | |
248 | char path[PATH_MAX]; | |
249 | struct dirent *de; | |
250 | DIR *d; | |
251 | ||
252 | if (fp->savedregs) | |
253 | delete fp->savedregs; | |
254 | ||
255 | fp->savedregs = new readonly_detached_regcache (*get_current_regcache ()); | |
256 | fp->pc = regcache_read_pc (get_current_regcache ()); | |
257 | ||
258 | /* Now save the 'state' (file position) of all open file descriptors. | |
259 | Unfortunately fork does not take care of that for us... */ | |
260 | snprintf (path, PATH_MAX, "/proc/%ld/fd", (long) fp->ptid.pid ()); | |
261 | if ((d = opendir (path)) != NULL) | |
262 | { | |
263 | long tmp; | |
264 | ||
265 | fp->maxfd = 0; | |
266 | while ((de = readdir (d)) != NULL) | |
267 | { | |
268 | /* Count open file descriptors (actually find highest | |
269 | numbered). */ | |
270 | tmp = strtol (&de->d_name[0], NULL, 10); | |
271 | if (fp->maxfd < tmp) | |
272 | fp->maxfd = tmp; | |
273 | } | |
274 | /* Allocate array of file positions. */ | |
275 | fp->filepos = XRESIZEVEC (off_t, fp->filepos, fp->maxfd + 1); | |
276 | ||
277 | /* Initialize to -1 (invalid). */ | |
278 | for (tmp = 0; tmp <= fp->maxfd; tmp++) | |
279 | fp->filepos[tmp] = -1; | |
280 | ||
281 | /* Now find actual file positions. */ | |
282 | rewinddir (d); | |
283 | while ((de = readdir (d)) != NULL) | |
284 | if (isdigit (de->d_name[0])) | |
285 | { | |
286 | tmp = strtol (&de->d_name[0], NULL, 10); | |
287 | fp->filepos[tmp] = call_lseek (tmp, 0, SEEK_CUR); | |
288 | } | |
289 | closedir (d); | |
290 | } | |
291 | } | |
292 | ||
293 | /* Kill 'em all, let God sort 'em out... */ | |
294 | ||
295 | void | |
296 | linux_fork_killall (void) | |
297 | { | |
298 | /* Walk list and kill every pid. No need to treat the | |
299 | current inferior_ptid as special (we do not return a | |
300 | status for it) -- however any process may be a child | |
301 | or a parent, so may get a SIGCHLD from a previously | |
302 | killed child. Wait them all out. */ | |
303 | ||
304 | for (fork_info &fi : fork_list) | |
305 | { | |
306 | pid_t pid = fi.ptid.pid (); | |
307 | int status; | |
308 | pid_t ret; | |
309 | do { | |
310 | /* Use SIGKILL instead of PTRACE_KILL because the former works even | |
311 | if the thread is running, while the later doesn't. */ | |
312 | kill (pid, SIGKILL); | |
313 | ret = waitpid (pid, &status, 0); | |
314 | /* We might get a SIGCHLD instead of an exit status. This is | |
315 | aggravated by the first kill above - a child has just | |
316 | died. MVS comment cut-and-pasted from linux-nat. */ | |
317 | } while (ret == pid && WIFSTOPPED (status)); | |
318 | } | |
319 | ||
320 | /* Clear list, prepare to start fresh. */ | |
321 | fork_list.clear (); | |
322 | } | |
323 | ||
324 | /* The current inferior_ptid has exited, but there are other viable | |
325 | forks to debug. Delete the exiting one and context-switch to the | |
326 | first available. */ | |
327 | ||
328 | void | |
329 | linux_fork_mourn_inferior (void) | |
330 | { | |
331 | struct fork_info *last; | |
332 | int status; | |
333 | ||
334 | /* Wait just one more time to collect the inferior's exit status. | |
335 | Do not check whether this succeeds though, since we may be | |
336 | dealing with a process that we attached to. Such a process will | |
337 | only report its exit status to its original parent. */ | |
338 | waitpid (inferior_ptid.pid (), &status, 0); | |
339 | ||
340 | /* OK, presumably inferior_ptid is the one who has exited. | |
341 | We need to delete that one from the fork_list, and switch | |
342 | to the next available fork. */ | |
343 | delete_fork (inferior_ptid); | |
344 | ||
345 | /* There should still be a fork - if there's only one left, | |
346 | delete_fork won't remove it, because we haven't updated | |
347 | inferior_ptid yet. */ | |
348 | gdb_assert (!fork_list.empty ()); | |
349 | ||
350 | last = find_last_fork (); | |
351 | fork_load_infrun_state (last); | |
352 | printf_filtered (_("[Switching to %s]\n"), | |
353 | target_pid_to_str (inferior_ptid).c_str ()); | |
354 | ||
355 | /* If there's only one fork, switch back to non-fork mode. */ | |
356 | if (one_fork_p ()) | |
357 | delete_fork (inferior_ptid); | |
358 | } | |
359 | ||
360 | /* The current inferior_ptid is being detached, but there are other | |
361 | viable forks to debug. Detach and delete it and context-switch to | |
362 | the first available. */ | |
363 | ||
364 | void | |
365 | linux_fork_detach (int from_tty) | |
366 | { | |
367 | /* OK, inferior_ptid is the one we are detaching from. We need to | |
368 | delete it from the fork_list, and switch to the next available | |
369 | fork. */ | |
370 | ||
371 | if (ptrace (PTRACE_DETACH, inferior_ptid.pid (), 0, 0)) | |
372 | error (_("Unable to detach %s"), | |
373 | target_pid_to_str (inferior_ptid).c_str ()); | |
374 | ||
375 | delete_fork (inferior_ptid); | |
376 | ||
377 | /* There should still be a fork - if there's only one left, | |
378 | delete_fork won't remove it, because we haven't updated | |
379 | inferior_ptid yet. */ | |
380 | gdb_assert (!fork_list.empty ()); | |
381 | ||
382 | fork_load_infrun_state (&fork_list.front ()); | |
383 | ||
384 | if (from_tty) | |
385 | printf_filtered (_("[Switching to %s]\n"), | |
386 | target_pid_to_str (inferior_ptid).c_str ()); | |
387 | ||
388 | /* If there's only one fork, switch back to non-fork mode. */ | |
389 | if (one_fork_p ()) | |
390 | delete_fork (inferior_ptid); | |
391 | } | |
392 | ||
393 | /* Temporarily switch to the infrun state stored on the fork_info | |
394 | identified by a given ptid_t. When this object goes out of scope, | |
395 | restore the currently selected infrun state. */ | |
396 | ||
397 | class scoped_switch_fork_info | |
398 | { | |
399 | public: | |
400 | /* Switch to the infrun state held on the fork_info identified by | |
401 | PPTID. If PPTID is the current inferior then no switch is done. */ | |
402 | explicit scoped_switch_fork_info (ptid_t pptid) | |
403 | : m_oldfp (nullptr) | |
404 | { | |
405 | if (pptid != inferior_ptid) | |
406 | { | |
407 | struct fork_info *newfp = nullptr; | |
408 | ||
409 | /* Switch to pptid. */ | |
410 | m_oldfp = find_fork_ptid (inferior_ptid); | |
411 | gdb_assert (m_oldfp != nullptr); | |
412 | newfp = find_fork_ptid (pptid); | |
413 | gdb_assert (newfp != nullptr); | |
414 | fork_save_infrun_state (m_oldfp); | |
415 | remove_breakpoints (); | |
416 | fork_load_infrun_state (newfp); | |
417 | insert_breakpoints (); | |
418 | } | |
419 | } | |
420 | ||
421 | /* Restore the previously selected infrun state. If the constructor | |
422 | didn't need to switch states, then nothing is done here either. */ | |
423 | ~scoped_switch_fork_info () | |
424 | { | |
425 | if (m_oldfp != nullptr) | |
426 | { | |
427 | /* Switch back to inferior_ptid. */ | |
428 | try | |
429 | { | |
430 | remove_breakpoints (); | |
431 | fork_load_infrun_state (m_oldfp); | |
432 | insert_breakpoints (); | |
433 | } | |
434 | catch (const gdb_exception &ex) | |
435 | { | |
436 | warning (_("Couldn't restore checkpoint state in %s: %s"), | |
437 | target_pid_to_str (m_oldfp->ptid).c_str (), | |
438 | ex.what ()); | |
439 | } | |
440 | } | |
441 | } | |
442 | ||
443 | DISABLE_COPY_AND_ASSIGN (scoped_switch_fork_info); | |
444 | ||
445 | private: | |
446 | /* The fork_info for the previously selected infrun state, or nullptr if | |
447 | we were already in the desired state, and nothing needs to be | |
448 | restored. */ | |
449 | struct fork_info *m_oldfp; | |
450 | }; | |
451 | ||
452 | static int | |
453 | inferior_call_waitpid (ptid_t pptid, int pid) | |
454 | { | |
455 | struct objfile *waitpid_objf; | |
456 | struct value *waitpid_fn = NULL; | |
457 | int ret = -1; | |
458 | ||
459 | scoped_switch_fork_info switch_fork_info (pptid); | |
460 | ||
461 | /* Get the waitpid_fn. */ | |
462 | if (lookup_minimal_symbol ("waitpid", NULL, NULL).minsym != NULL) | |
463 | waitpid_fn = find_function_in_inferior ("waitpid", &waitpid_objf); | |
464 | if (!waitpid_fn | |
465 | && lookup_minimal_symbol ("_waitpid", NULL, NULL).minsym != NULL) | |
466 | waitpid_fn = find_function_in_inferior ("_waitpid", &waitpid_objf); | |
467 | if (waitpid_fn != nullptr) | |
468 | { | |
469 | struct gdbarch *gdbarch = get_current_arch (); | |
470 | struct value *argv[3], *retv; | |
471 | ||
472 | /* Get the argv. */ | |
473 | argv[0] = value_from_longest (builtin_type (gdbarch)->builtin_int, pid); | |
474 | argv[1] = value_from_pointer (builtin_type (gdbarch)->builtin_data_ptr, 0); | |
475 | argv[2] = value_from_longest (builtin_type (gdbarch)->builtin_int, 0); | |
476 | ||
477 | retv = call_function_by_hand (waitpid_fn, NULL, argv); | |
478 | ||
479 | if (value_as_long (retv) >= 0) | |
480 | ret = 0; | |
481 | } | |
482 | ||
483 | return ret; | |
484 | } | |
485 | ||
486 | /* Fork list <-> user interface. */ | |
487 | ||
488 | static void | |
489 | delete_checkpoint_command (const char *args, int from_tty) | |
490 | { | |
491 | ptid_t ptid, pptid; | |
492 | struct fork_info *fi; | |
493 | ||
494 | if (!args || !*args) | |
495 | error (_("Requires argument (checkpoint id to delete)")); | |
496 | ||
497 | ptid = fork_id_to_ptid (parse_and_eval_long (args)); | |
498 | if (ptid == minus_one_ptid) | |
499 | error (_("No such checkpoint id, %s"), args); | |
500 | ||
501 | if (ptid == inferior_ptid) | |
502 | error (_("\ | |
503 | Please switch to another checkpoint before deleting the current one")); | |
504 | ||
505 | if (ptrace (PTRACE_KILL, ptid.pid (), 0, 0)) | |
506 | error (_("Unable to kill pid %s"), target_pid_to_str (ptid).c_str ()); | |
507 | ||
508 | fi = find_fork_ptid (ptid); | |
509 | gdb_assert (fi); | |
510 | pptid = fi->parent_ptid; | |
511 | ||
512 | if (from_tty) | |
513 | printf_filtered (_("Killed %s\n"), target_pid_to_str (ptid).c_str ()); | |
514 | ||
515 | delete_fork (ptid); | |
516 | ||
517 | /* If fi->parent_ptid is not a part of lwp but it's a part of checkpoint | |
518 | list, waitpid the ptid. | |
519 | If fi->parent_ptid is a part of lwp and it is stopped, waitpid the | |
520 | ptid. */ | |
521 | thread_info *parent = find_thread_ptid (linux_target, pptid); | |
522 | if ((parent == NULL && find_fork_ptid (pptid)) | |
523 | || (parent != NULL && parent->state == THREAD_STOPPED)) | |
524 | { | |
525 | if (inferior_call_waitpid (pptid, ptid.pid ())) | |
526 | warning (_("Unable to wait pid %s"), | |
527 | target_pid_to_str (ptid).c_str ()); | |
528 | } | |
529 | } | |
530 | ||
531 | static void | |
532 | detach_checkpoint_command (const char *args, int from_tty) | |
533 | { | |
534 | ptid_t ptid; | |
535 | ||
536 | if (!args || !*args) | |
537 | error (_("Requires argument (checkpoint id to detach)")); | |
538 | ||
539 | ptid = fork_id_to_ptid (parse_and_eval_long (args)); | |
540 | if (ptid == minus_one_ptid) | |
541 | error (_("No such checkpoint id, %s"), args); | |
542 | ||
543 | if (ptid == inferior_ptid) | |
544 | error (_("\ | |
545 | Please switch to another checkpoint before detaching the current one")); | |
546 | ||
547 | if (ptrace (PTRACE_DETACH, ptid.pid (), 0, 0)) | |
548 | error (_("Unable to detach %s"), target_pid_to_str (ptid).c_str ()); | |
549 | ||
550 | if (from_tty) | |
551 | printf_filtered (_("Detached %s\n"), target_pid_to_str (ptid).c_str ()); | |
552 | ||
553 | delete_fork (ptid); | |
554 | } | |
555 | ||
556 | /* Print information about currently known checkpoints. */ | |
557 | ||
558 | static void | |
559 | info_checkpoints_command (const char *arg, int from_tty) | |
560 | { | |
561 | struct gdbarch *gdbarch = get_current_arch (); | |
562 | int requested = -1; | |
563 | const fork_info *printed = NULL; | |
564 | ||
565 | if (arg && *arg) | |
566 | requested = (int) parse_and_eval_long (arg); | |
567 | ||
568 | for (const fork_info &fi : fork_list) | |
569 | { | |
570 | if (requested > 0 && fi.num != requested) | |
571 | continue; | |
572 | ||
573 | printed = &fi; | |
574 | if (fi.ptid == inferior_ptid) | |
575 | printf_filtered ("* "); | |
576 | else | |
577 | printf_filtered (" "); | |
578 | ||
579 | ULONGEST pc = fi.pc; | |
580 | printf_filtered ("%d %s", fi.num, target_pid_to_str (fi.ptid).c_str ()); | |
581 | if (fi.num == 0) | |
582 | printf_filtered (_(" (main process)")); | |
583 | printf_filtered (_(" at ")); | |
584 | fputs_filtered (paddress (gdbarch, pc), gdb_stdout); | |
585 | ||
586 | symtab_and_line sal = find_pc_line (pc, 0); | |
587 | if (sal.symtab) | |
588 | printf_filtered (_(", file %s"), | |
589 | symtab_to_filename_for_display (sal.symtab)); | |
590 | if (sal.line) | |
591 | printf_filtered (_(", line %d"), sal.line); | |
592 | if (!sal.symtab && !sal.line) | |
593 | { | |
594 | struct bound_minimal_symbol msym; | |
595 | ||
596 | msym = lookup_minimal_symbol_by_pc (pc); | |
597 | if (msym.minsym) | |
598 | printf_filtered (", <%s>", msym.minsym->linkage_name ()); | |
599 | } | |
600 | ||
601 | putchar_filtered ('\n'); | |
602 | } | |
603 | if (printed == NULL) | |
604 | { | |
605 | if (requested > 0) | |
606 | printf_filtered (_("No checkpoint number %d.\n"), requested); | |
607 | else | |
608 | printf_filtered (_("No checkpoints.\n")); | |
609 | } | |
610 | } | |
611 | ||
612 | /* The PID of the process we're checkpointing. */ | |
613 | static int checkpointing_pid = 0; | |
614 | ||
615 | int | |
616 | linux_fork_checkpointing_p (int pid) | |
617 | { | |
618 | return (checkpointing_pid == pid); | |
619 | } | |
620 | ||
621 | /* Return true if the current inferior is multi-threaded. */ | |
622 | ||
623 | static bool | |
624 | inf_has_multiple_threads () | |
625 | { | |
626 | int count = 0; | |
627 | ||
628 | /* Return true as soon as we see the second thread of the current | |
629 | inferior. */ | |
630 | for (thread_info *tp ATTRIBUTE_UNUSED : current_inferior ()->threads ()) | |
631 | if (++count > 1) | |
632 | return true; | |
633 | ||
634 | return false; | |
635 | } | |
636 | ||
637 | static void | |
638 | checkpoint_command (const char *args, int from_tty) | |
639 | { | |
640 | struct objfile *fork_objf; | |
641 | struct gdbarch *gdbarch; | |
642 | struct target_waitstatus last_target_waitstatus; | |
643 | ptid_t last_target_ptid; | |
644 | struct value *fork_fn = NULL, *ret; | |
645 | struct fork_info *fp; | |
646 | pid_t retpid; | |
647 | ||
648 | if (!target_has_execution) | |
649 | error (_("The program is not being run.")); | |
650 | ||
651 | /* Ensure that the inferior is not multithreaded. */ | |
652 | update_thread_list (); | |
653 | if (inf_has_multiple_threads ()) | |
654 | error (_("checkpoint: can't checkpoint multiple threads.")); | |
655 | ||
656 | /* Make the inferior fork, record its (and gdb's) state. */ | |
657 | ||
658 | if (lookup_minimal_symbol ("fork", NULL, NULL).minsym != NULL) | |
659 | fork_fn = find_function_in_inferior ("fork", &fork_objf); | |
660 | if (!fork_fn) | |
661 | if (lookup_minimal_symbol ("_fork", NULL, NULL).minsym != NULL) | |
662 | fork_fn = find_function_in_inferior ("fork", &fork_objf); | |
663 | if (!fork_fn) | |
664 | error (_("checkpoint: can't find fork function in inferior.")); | |
665 | ||
666 | gdbarch = get_objfile_arch (fork_objf); | |
667 | ret = value_from_longest (builtin_type (gdbarch)->builtin_int, 0); | |
668 | ||
669 | /* Tell linux-nat.c that we're checkpointing this inferior. */ | |
670 | { | |
671 | scoped_restore save_pid | |
672 | = make_scoped_restore (&checkpointing_pid, inferior_ptid.pid ()); | |
673 | ||
674 | ret = call_function_by_hand (fork_fn, NULL, {}); | |
675 | } | |
676 | ||
677 | if (!ret) /* Probably can't happen. */ | |
678 | error (_("checkpoint: call_function_by_hand returned null.")); | |
679 | ||
680 | retpid = value_as_long (ret); | |
681 | get_last_target_status (nullptr, &last_target_ptid, &last_target_waitstatus); | |
682 | ||
683 | fp = find_fork_pid (retpid); | |
684 | ||
685 | if (from_tty) | |
686 | { | |
687 | int parent_pid; | |
688 | ||
689 | printf_filtered (_("checkpoint %d: fork returned pid %ld.\n"), | |
690 | fp != NULL ? fp->num : -1, (long) retpid); | |
691 | if (info_verbose) | |
692 | { | |
693 | parent_pid = last_target_ptid.lwp (); | |
694 | if (parent_pid == 0) | |
695 | parent_pid = last_target_ptid.pid (); | |
696 | printf_filtered (_(" gdb says parent = %ld.\n"), | |
697 | (long) parent_pid); | |
698 | } | |
699 | } | |
700 | ||
701 | if (!fp) | |
702 | error (_("Failed to find new fork")); | |
703 | ||
704 | if (one_fork_p ()) | |
705 | { | |
706 | /* Special case -- if this is the first fork in the list (the | |
707 | list was hitherto empty), then add inferior_ptid first, as a | |
708 | special zeroeth fork id. */ | |
709 | fork_list.emplace_front (inferior_ptid.pid ()); | |
710 | } | |
711 | ||
712 | fork_save_infrun_state (fp); | |
713 | fp->parent_ptid = last_target_ptid; | |
714 | } | |
715 | ||
716 | static void | |
717 | linux_fork_context (struct fork_info *newfp, int from_tty) | |
718 | { | |
719 | /* Now we attempt to switch processes. */ | |
720 | struct fork_info *oldfp; | |
721 | ||
722 | gdb_assert (newfp != NULL); | |
723 | ||
724 | oldfp = find_fork_ptid (inferior_ptid); | |
725 | gdb_assert (oldfp != NULL); | |
726 | ||
727 | fork_save_infrun_state (oldfp); | |
728 | remove_breakpoints (); | |
729 | fork_load_infrun_state (newfp); | |
730 | insert_breakpoints (); | |
731 | ||
732 | printf_filtered (_("Switching to %s\n"), | |
733 | target_pid_to_str (inferior_ptid).c_str ()); | |
734 | ||
735 | print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC, 1); | |
736 | } | |
737 | ||
738 | /* Switch inferior process (checkpoint) context, by checkpoint id. */ | |
739 | static void | |
740 | restart_command (const char *args, int from_tty) | |
741 | { | |
742 | struct fork_info *fp; | |
743 | ||
744 | if (!args || !*args) | |
745 | error (_("Requires argument (checkpoint id to restart)")); | |
746 | ||
747 | if ((fp = find_fork_id (parse_and_eval_long (args))) == NULL) | |
748 | error (_("Not found: checkpoint id %s"), args); | |
749 | ||
750 | linux_fork_context (fp, from_tty); | |
751 | } | |
752 | ||
753 | void _initialize_linux_fork (); | |
754 | void | |
755 | _initialize_linux_fork () | |
756 | { | |
757 | /* Checkpoint command: create a fork of the inferior process | |
758 | and set it aside for later debugging. */ | |
759 | ||
760 | add_com ("checkpoint", class_obscure, checkpoint_command, _("\ | |
761 | Fork a duplicate process (experimental).")); | |
762 | ||
763 | /* Restart command: restore the context of a specified checkpoint | |
764 | process. */ | |
765 | ||
766 | add_com ("restart", class_obscure, restart_command, _("\ | |
767 | Restore program context from a checkpoint.\n\ | |
768 | Usage: restart N\n\ | |
769 | Argument N is checkpoint ID, as displayed by 'info checkpoints'.")); | |
770 | ||
771 | /* Delete checkpoint command: kill the process and remove it from | |
772 | the fork list. */ | |
773 | ||
774 | add_cmd ("checkpoint", class_obscure, delete_checkpoint_command, _("\ | |
775 | Delete a checkpoint (experimental)."), | |
776 | &deletelist); | |
777 | ||
778 | /* Detach checkpoint command: release the process to run independently, | |
779 | and remove it from the fork list. */ | |
780 | ||
781 | add_cmd ("checkpoint", class_obscure, detach_checkpoint_command, _("\ | |
782 | Detach from a checkpoint (experimental)."), | |
783 | &detachlist); | |
784 | ||
785 | /* Info checkpoints command: list all forks/checkpoints | |
786 | currently under gdb's control. */ | |
787 | ||
788 | add_info ("checkpoints", info_checkpoints_command, | |
789 | _("IDs of currently known checkpoints.")); | |
790 | } |