proc.c revision 3ed2a4227d5f2a8d44f3c6ffd704a9d2e867c591 
1#include "config.h"
2
3#if defined(HAVE_LIBUNWIND)
4#include <libunwind.h>
5#include <libunwind-ptrace.h>
6#endif /* defined(HAVE_LIBUNWIND) */
7
8#include <sys/types.h>
9#include <string.h>
10#include <stdio.h>
11#include <errno.h>
12#include <stdlib.h>
13#include <assert.h>
14#include <error.h>
15
16#include "common.h"
17#include "breakpoint.h"
18#include "proc.h"
19
20static int
21process_bare_init(struct Process *proc, const char *filename, pid_t pid)
22{
23	memset(proc, 0, sizeof(*proc));
24
25	proc->filename = strdup(filename);
26	if (proc->filename == NULL) {
27	fail:
28		free(proc->filename);
29		if (proc->breakpoints != NULL)
30			dict_clear(proc->breakpoints);
31		return -1;
32	}
33
34	/* Add process so that we know who the leader is.  */
35	proc->pid = pid;
36	add_process(proc);
37	if (proc->leader == NULL)
38		goto fail;
39
40	if (proc->leader == proc) {
41		proc->breakpoints = dict_init(target_address_hash,
42					      target_address_cmp);
43		if (proc->breakpoints == NULL)
44			goto fail;
45	} else {
46		proc->breakpoints = NULL;
47	}
48
49#if defined(HAVE_LIBUNWIND)
50	proc->unwind_priv = _UPT_create(pid);
51	proc->unwind_as = unw_create_addr_space(&_UPT_accessors, 0);
52#endif /* defined(HAVE_LIBUNWIND) */
53
54	return 0;
55}
56
57static void
58process_bare_destroy(struct Process *proc)
59{
60	free(proc->filename);
61	dict_clear(proc->breakpoints);
62	remove_process(proc);
63}
64
65int
66process_init(struct Process *proc, const char *filename, pid_t pid, int enable)
67{
68	if (process_bare_init(proc, filename, pid) < 0) {
69		error(0, errno, "init process %d", pid);
70		return -1;
71	}
72
73	if (proc->leader == proc && breakpoints_init(proc, enable) < 0) {
74		fprintf(stderr, "failed to init breakpoints %d\n",
75			proc->pid);
76		process_bare_destroy(proc);
77		return -1;
78	}
79
80	return 0;
81}
82
83struct Process *
84open_program(const char *filename, pid_t pid, int enable)
85{
86	assert(pid != 0);
87	struct Process *proc = malloc(sizeof(*proc));
88	if (proc == NULL
89	    || process_init(proc, filename, pid, enable) < 0) {
90		free(proc);
91		return NULL;
92	}
93	return proc;
94}
95
96struct clone_single_bp_data {
97	struct Process *old_proc;
98	struct Process *new_proc;
99	int error;
100};
101
102struct find_symbol_data {
103	struct library_symbol *old_libsym;
104	struct library_symbol *found_libsym;
105};
106
107static enum callback_status
108find_sym_in_lib(struct Process *proc, struct library *lib, void *u)
109{
110	struct find_symbol_data *fs = u;
111	fs->found_libsym
112		= library_each_symbol(lib, NULL, library_symbol_equal_cb,
113				      fs->old_libsym);
114	return fs->found_libsym != NULL ? CBS_STOP : CBS_CONT;
115}
116
117static void
118clone_single_bp(void *key, void *value, void *u)
119{
120	target_address_t addr = (target_address_t)key;
121	struct breakpoint *bp = value;
122	struct clone_single_bp_data *data = u;
123
124	/* Find library and symbol that this symbol was linked to.  */
125	struct library_symbol *libsym = bp->libsym;
126	struct library *lib = NULL;
127	if (libsym != NULL) {
128		struct find_symbol_data f_data = {
129			.old_libsym = libsym,
130		};
131		lib = proc_each_library(data->old_proc, NULL,
132					find_sym_in_lib, &f_data);
133		assert(lib != NULL);
134		libsym = f_data.found_libsym;
135	}
136
137	/* LIB and LIBSYM now hold the new library and symbol that
138	 * correspond to the original breakpoint.  Now we can do the
139	 * clone itself.  */
140	struct breakpoint *clone = malloc(sizeof(*clone));
141	if (clone == NULL
142	    || breakpoint_init(clone, data->new_proc, addr, libsym) < 0) {
143		data->error = -1;
144		return;
145	}
146	breakpoint_set_callbacks(clone, bp->cbs);
147}
148
149int
150process_clone(struct Process *retp, struct Process *proc, pid_t pid)
151{
152	if (process_bare_init(retp, proc->filename, pid) < 0) {
153	fail:
154		error(0, errno, "clone process %d->%d", proc->pid, pid);
155		return -1;
156	}
157
158	/* For non-leader processes, that's all we need to do.  */
159	if (proc->leader != proc)
160		return 0;
161
162	/* Clone symbols first so that we can clone and relink
163	 * breakpoints.  */
164	struct library *lib;
165	struct library **nlibp = &retp->libraries;
166	for (lib = proc->libraries; lib != NULL; lib = lib->next) {
167		*nlibp = malloc(sizeof(**nlibp));
168		if (*nlibp == NULL
169		    || library_clone(*nlibp, lib) < 0) {
170		fail2:
171			process_bare_destroy(retp);
172
173			/* Error when cloning.  Unroll what was done.  */
174			for (lib = retp->libraries; lib != NULL; ) {
175				struct library *next = lib->next;
176				library_destroy(lib);
177				free(lib);
178				lib = next;
179			}
180			goto fail;
181		}
182
183		nlibp = &(*nlibp)->next;
184	}
185
186	/* Now clone breakpoints.  Symbol relinking is done in
187	 * clone_single_bp.  */
188	struct clone_single_bp_data data = {
189		.old_proc = proc,
190		.new_proc = retp,
191		.error = 0,
192	};
193	dict_apply_to_all(proc->breakpoints, &clone_single_bp, &data);
194
195	if (data.error < 0)
196		goto fail2;
197
198	return 0;
199}
200
201static int
202open_one_pid(pid_t pid)
203{
204	Process *proc;
205	char *filename;
206	debug(DEBUG_PROCESS, "open_one_pid(pid=%d)", pid);
207
208	/* Get the filename first.  Should the trace_pid fail, we can
209	 * easily free it, untracing is more work.  */
210	if ((filename = pid2name(pid)) == NULL
211	    || trace_pid(pid) < 0) {
212		free(filename);
213		return -1;
214	}
215
216	proc = open_program(filename, pid, 0);
217	if (proc == NULL)
218		return -1;
219	trace_set_options(proc);
220
221	return 0;
222}
223
224static enum callback_status
225start_one_pid(Process * proc, void * data)
226{
227	continue_process(proc->pid);
228	return CBS_CONT;
229}
230
231void
232open_pid(pid_t pid)
233{
234	debug(DEBUG_PROCESS, "open_pid(pid=%d)", pid);
235	/* If we are already tracing this guy, we should be seeing all
236	 * his children via normal tracing route.  */
237	if (pid2proc(pid) != NULL)
238		return;
239
240	/* First, see if we can attach the requested PID itself.  */
241	if (open_one_pid(pid)) {
242		fprintf(stderr, "Cannot attach to pid %u: %s\n",
243			pid, strerror(errno));
244		trace_fail_warning(pid);
245		return;
246	}
247
248	/* Now attach to all tasks that belong to that PID.  There's a
249	 * race between process_tasks and open_one_pid.  So when we
250	 * fail in open_one_pid below, we just do another round.
251	 * Chances are that by then that PID will have gone away, and
252	 * that's why we have seen the failure.  The processes that we
253	 * manage to open_one_pid are stopped, so we should eventually
254	 * reach a point where process_tasks doesn't give any new
255	 * processes (because there's nobody left to produce
256	 * them).  */
257	size_t old_ntasks = 0;
258	int have_all;
259	while (1) {
260		pid_t *tasks;
261		size_t ntasks;
262		size_t i;
263
264		if (process_tasks(pid, &tasks, &ntasks) < 0) {
265			fprintf(stderr, "Cannot obtain tasks of pid %u: %s\n",
266				pid, strerror(errno));
267			break;
268		}
269
270		have_all = 1;
271		for (i = 0; i < ntasks; ++i)
272			if (pid2proc(tasks[i]) == NULL
273			    && open_one_pid(tasks[i]))
274				have_all = 0;
275
276		free(tasks);
277
278		if (have_all && old_ntasks == ntasks)
279			break;
280		old_ntasks = ntasks;
281	}
282
283	/* Done.  Now initialize breakpoints and then continue
284	 * everyone.  */
285	Process * leader;
286	leader = pid2proc(pid)->leader;
287	enable_all_breakpoints(leader);
288
289	each_task(pid2proc(pid)->leader, NULL, start_one_pid, NULL);
290}
291
292static enum callback_status
293find_proc(Process * proc, void * data)
294{
295	pid_t pid = (pid_t)(uintptr_t)data;
296	return proc->pid == pid ? CBS_STOP : CBS_CONT;
297}
298
299Process *
300pid2proc(pid_t pid) {
301	return each_process(NULL, &find_proc, (void *)(uintptr_t)pid);
302}
303
304static Process * list_of_processes = NULL;
305
306static void
307unlist_process(Process * proc)
308{
309	Process *tmp;
310
311	if (list_of_processes == proc) {
312		list_of_processes = list_of_processes->next;
313		return;
314	}
315
316	for (tmp = list_of_processes; ; tmp = tmp->next) {
317		/* If the following assert fails, the process wasn't
318		 * in the list.  */
319		assert(tmp->next != NULL);
320
321		if (tmp->next == proc) {
322			tmp->next = tmp->next->next;
323			return;
324		}
325	}
326}
327
328struct Process *
329each_process(struct Process *start_after,
330	     enum callback_status(*cb)(struct Process *proc, void *data),
331	     void *data)
332{
333	struct Process *it = start_after == NULL ? list_of_processes
334		: start_after->next;
335
336	while (it != NULL) {
337		/* Callback might call remove_process.  */
338		struct Process *next = it->next;
339		switch ((*cb)(it, data)) {
340		case CBS_FAIL:
341			/* XXX handle me */
342		case CBS_STOP:
343			return it;
344		case CBS_CONT:
345			break;
346		}
347		it = next;
348	}
349	return NULL;
350}
351
352Process *
353each_task(struct Process *proc, struct Process *start_after,
354	  enum callback_status(*cb)(struct Process *proc, void *data),
355	  void *data)
356{
357	assert(proc != NULL);
358	struct Process *it = start_after == NULL ? proc->leader
359		: start_after->next;
360
361	if (it != NULL) {
362		struct Process *leader = it->leader;
363		while (it != NULL && it->leader == leader) {
364			/* Callback might call remove_process.  */
365			struct Process *next = it->next;
366			switch ((*cb)(it, data)) {
367			case CBS_FAIL:
368				/* XXX handle me */
369			case CBS_STOP:
370				return it;
371			case CBS_CONT:
372				break;
373			}
374			it = next;
375		}
376	}
377	return NULL;
378}
379
380void
381add_process(Process * proc)
382{
383	Process ** leaderp = &list_of_processes;
384	if (proc->pid) {
385		pid_t tgid = process_leader(proc->pid);
386		if (tgid == 0)
387			/* Must have been terminated before we managed
388			 * to fully attach.  */
389			return;
390		if (tgid == proc->pid)
391			proc->leader = proc;
392		else {
393			Process * leader = pid2proc(tgid);
394			proc->leader = leader;
395			if (leader != NULL)
396				leaderp = &leader->next;
397		}
398	}
399	proc->next = *leaderp;
400	*leaderp = proc;
401}
402
403void
404change_process_leader(Process * proc, Process * leader)
405{
406	Process ** leaderp = &list_of_processes;
407	if (proc->leader == leader)
408		return;
409
410	assert(leader != NULL);
411	unlist_process(proc);
412	if (proc != leader)
413		leaderp = &leader->next;
414
415	proc->leader = leader;
416	proc->next = *leaderp;
417	*leaderp = proc;
418}
419
420static enum callback_status
421clear_leader(struct Process *proc, void *data)
422{
423	debug(DEBUG_FUNCTION, "detach_task %d from leader %d",
424	      proc->pid, proc->leader->pid);
425	proc->leader = NULL;
426	return CBS_CONT;
427}
428
429static enum ecb_status
430event_for_proc(Event * event, void * data)
431{
432	if (event->proc == data)
433		return ecb_deque;
434	else
435		return ecb_cont;
436}
437
438static void
439delete_events_for(Process * proc)
440{
441	Event * event;
442	while ((event = each_qd_event(&event_for_proc, proc)) != NULL)
443		free(event);
444}
445
446void
447remove_process(Process *proc)
448{
449	debug(DEBUG_FUNCTION, "remove_proc(pid=%d)", proc->pid);
450
451	if (proc->leader == proc)
452		each_task(proc, NULL, &clear_leader, NULL);
453
454	unlist_process(proc);
455	delete_events_for(proc);
456}
457
458void
459install_event_handler(Process *proc, struct event_handler *handler)
460{
461	debug(DEBUG_FUNCTION, "install_event_handler(pid=%d, %p)", proc->pid, handler);
462	assert(proc->event_handler == NULL);
463	proc->event_handler = handler;
464}
465
466void
467destroy_event_handler(Process * proc)
468{
469	struct event_handler *handler = proc->event_handler;
470	debug(DEBUG_FUNCTION, "destroy_event_handler(pid=%d, %p)", proc->pid, handler);
471	assert(handler != NULL);
472	if (handler->destroy != NULL)
473		handler->destroy(handler);
474	free(handler);
475	proc->event_handler = NULL;
476}
477
478static enum callback_status
479breakpoint_for_symbol(struct library_symbol *libsym, void *data)
480{
481	struct Process *proc = data;
482	assert(proc->leader == proc);
483
484	/* If there is an artificial breakpoint on the same address,
485	 * its libsym will be NULL, and we can smuggle our libsym
486	 * there.  That artificial breakpoint is there presumably for
487	 * the callbacks, which we don't touch.  If there is a real
488	 * breakpoint, then this is a bug.  ltrace-elf.c should filter
489	 * symbols and ignore extra symbol aliases.
490	 *
491	 * The other direction is more complicated and currently not
492	 * supported.  If a breakpoint has custom callbacks, it might
493	 * be also custom-allocated, and we would really need to swap
494	 * the two: delete the one now in the dictionary, swap values
495	 * around, and put the new breakpoint back in.  */
496	struct breakpoint *bp = dict_find_entry(proc->breakpoints,
497						libsym->enter_addr);
498	if (bp != NULL) {
499		assert(bp->libsym == NULL);
500		bp->libsym = libsym;
501		return CBS_CONT;
502	}
503
504	bp = malloc(sizeof(*bp));
505	if (bp == NULL
506	    || breakpoint_init(bp, proc, libsym->enter_addr, libsym) < 0) {
507	fail:
508		free(bp);
509		return CBS_FAIL;
510	}
511	if (proc_add_breakpoint(proc, bp) < 0) {
512		breakpoint_destroy(bp);
513		goto fail;
514	}
515
516	/* If this is dlopened library, turn on the breakpoint right
517	 * away.  */
518	if (proc->fixed_libs != NULL
519	    && breakpoint_turn_on(bp) < 0) {
520		proc_remove_breakpoint(proc, bp);
521		breakpoint_destroy(bp);
522		goto fail;
523	}
524
525	return CBS_CONT;
526}
527
528void
529proc_add_library(struct Process *proc, struct library *lib)
530{
531	assert(lib->next == NULL);
532	lib->next = proc->libraries;
533	proc->libraries = lib;
534	debug(DEBUG_PROCESS, "added library %s@%p (%s) to %d",
535	      lib->soname, lib->base, lib->pathname, proc->pid);
536
537	struct library_symbol *libsym = NULL;
538	while ((libsym = library_each_symbol(lib, libsym, breakpoint_for_symbol,
539					     proc)) != NULL)
540		error(0, errno, "insert breakpoint for %s", libsym->name);
541}
542
543int
544proc_remove_library(struct Process *proc, struct library *lib)
545{
546	struct library **libp;
547	for (libp = &proc->libraries; *libp != NULL; libp = &(*libp)->next)
548		if (*libp == lib) {
549			*libp = lib->next;
550			return 0;
551		}
552	return -1;
553}
554
555struct library *
556proc_each_library(struct Process *proc, struct library *it,
557		  enum callback_status (*cb)(struct Process *proc,
558					     struct library *lib, void *data),
559		  void *data)
560{
561	if (it == NULL)
562		it = proc->libraries;
563
564	while (it != NULL) {
565		struct library *next = it->next;
566
567		switch (cb(proc, it, data)) {
568		case CBS_FAIL:
569			/* XXX handle me */
570		case CBS_STOP:
571			return it;
572		case CBS_CONT:
573			break;
574		}
575
576		it = next;
577	}
578
579	return NULL;
580}
581
582int
583proc_add_breakpoint(struct Process *proc, struct breakpoint *bp)
584{
585	struct Process *leader = proc->leader;
586
587	/* Only the group leader should be getting the breakpoints and
588	 * thus have ->breakpoint initialized.  */
589	assert(leader != NULL);
590	assert(leader->breakpoints != NULL);
591
592	/* Make sure it wasn't inserted yet.  */
593	assert(bp->proc == NULL);
594
595	debug(DEBUG_FUNCTION, "proc_insert_breakpoint(pid=%d, %s@%p)",
596	      proc->pid, breakpoint_name(bp), bp->addr);
597
598	/* XXX We might merge bp->libsym instead of the following
599	 * assert, but that's not necessary right now.  Look into
600	 * breakpoint_for_symbol.  */
601	assert(dict_find_entry(leader->breakpoints, bp->addr) == NULL);
602
603	if (dict_enter(leader->breakpoints, bp->addr, bp) < 0) {
604		error(0, errno, "couldn't enter breakpoint %s@%p to dictionary",
605		      breakpoint_name(bp), bp->addr);
606		return -1;
607	}
608
609	bp->proc = proc;
610	return 0;
611}
612
613int
614proc_remove_breakpoint(struct Process *proc, struct breakpoint *bp)
615{
616	/* XXX We can't, really.  We are missing dict_remove.  */
617	assert(!"Not yet implemented!");
618	abort();
619}
620