proc.c revision 61196a4a81e77322bf1f3dc609007f5d35a5103a 
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
19Process *
20open_program(char *filename, pid_t pid, int enable) {
21	Process *proc;
22	assert(pid != 0);
23	proc = calloc(sizeof(Process), 1);
24	if (!proc) {
25		perror("malloc");
26		exit(1);
27	}
28
29	proc->filename = strdup(filename);
30	proc->pid = pid;
31#if defined(HAVE_LIBUNWIND)
32	proc->unwind_priv = _UPT_create(pid);
33	proc->unwind_as = unw_create_addr_space(&_UPT_accessors, 0);
34#endif /* defined(HAVE_LIBUNWIND) */
35
36	add_process(proc);
37	if (proc->leader == NULL) {
38		free(proc);
39		return NULL;
40	}
41
42	if (proc->leader == proc) {
43		trace_set_options(proc, proc->pid);
44		if (breakpoints_init(proc, enable)) {
45			fprintf(stderr, "failed to init breakpoints %d\n",
46				proc->pid);
47			remove_process(proc);
48			return NULL;
49		}
50	}
51
52	return proc;
53}
54
55static int
56open_one_pid(pid_t pid)
57{
58	Process *proc;
59	char *filename;
60	debug(DEBUG_PROCESS, "open_one_pid(pid=%d)", pid);
61
62	/* Get the filename first.  Should the trace_pid fail, we can
63	 * easily free it, untracing is more work.  */
64	if ((filename = pid2name(pid)) == NULL
65	    || trace_pid(pid) < 0) {
66		free(filename);
67		return -1;
68	}
69
70	proc = open_program(filename, pid, 0);
71	if (proc == NULL)
72		return -1;
73	trace_set_options(proc, pid);
74
75	return 0;
76}
77
78static enum pcb_status
79start_one_pid(Process * proc, void * data)
80{
81	continue_process(proc->pid);
82	return pcb_cont;
83}
84
85void
86open_pid(pid_t pid)
87{
88	debug(DEBUG_PROCESS, "open_pid(pid=%d)", pid);
89	/* If we are already tracing this guy, we should be seeing all
90	 * his children via normal tracing route.  */
91	if (pid2proc(pid) != NULL)
92		return;
93
94	/* First, see if we can attach the requested PID itself.  */
95	if (open_one_pid(pid)) {
96		fprintf(stderr, "Cannot attach to pid %u: %s\n",
97			pid, strerror(errno));
98		trace_fail_warning(pid);
99		return;
100	}
101
102	/* Now attach to all tasks that belong to that PID.  There's a
103	 * race between process_tasks and open_one_pid.  So when we
104	 * fail in open_one_pid below, we just do another round.
105	 * Chances are that by then that PID will have gone away, and
106	 * that's why we have seen the failure.  The processes that we
107	 * manage to open_one_pid are stopped, so we should eventually
108	 * reach a point where process_tasks doesn't give any new
109	 * processes (because there's nobody left to produce
110	 * them).  */
111	size_t old_ntasks = 0;
112	int have_all;
113	while (1) {
114		pid_t *tasks;
115		size_t ntasks;
116		size_t i;
117
118		if (process_tasks(pid, &tasks, &ntasks) < 0) {
119			fprintf(stderr, "Cannot obtain tasks of pid %u: %s\n",
120				pid, strerror(errno));
121			break;
122		}
123
124		have_all = 1;
125		for (i = 0; i < ntasks; ++i)
126			if (pid2proc(tasks[i]) == NULL
127			    && open_one_pid(tasks[i]))
128				have_all = 0;
129
130		free(tasks);
131
132		if (have_all && old_ntasks == ntasks)
133			break;
134		old_ntasks = ntasks;
135	}
136
137	/* Done.  Now initialize breakpoints and then continue
138	 * everyone.  */
139	Process * leader;
140	leader = pid2proc(pid)->leader;
141	enable_all_breakpoints(leader);
142
143	each_task(pid2proc(pid)->leader, start_one_pid, NULL);
144}
145
146static enum pcb_status
147find_proc(Process * proc, void * data)
148{
149	pid_t pid = (pid_t)(uintptr_t)data;
150	return proc->pid == pid ? pcb_stop : pcb_cont;
151}
152
153Process *
154pid2proc(pid_t pid) {
155	return each_process(NULL, &find_proc, (void *)(uintptr_t)pid);
156}
157
158static Process * list_of_processes = NULL;
159
160static void
161unlist_process(Process * proc)
162{
163	Process *tmp;
164
165	if (list_of_processes == proc) {
166		list_of_processes = list_of_processes->next;
167		return;
168	}
169
170	for (tmp = list_of_processes; ; tmp = tmp->next) {
171		/* If the following assert fails, the process wasn't
172		 * in the list.  */
173		assert(tmp->next != NULL);
174
175		if (tmp->next == proc) {
176			tmp->next = tmp->next->next;
177			return;
178		}
179	}
180}
181
182Process *
183each_process(Process * proc,
184	     enum pcb_status (* cb)(Process * proc, void * data),
185	     void * data)
186{
187	Process * it = proc ?: list_of_processes;
188	for (; it != NULL; ) {
189		/* Callback might call remove_process.  */
190		Process * next = it->next;
191		if ((*cb) (it, data) == pcb_stop)
192			return it;
193		it = next;
194	}
195	return NULL;
196}
197
198Process *
199each_task(Process * it, enum pcb_status (* cb)(Process * proc, void * data),
200	  void * data)
201{
202	if (it != NULL) {
203		Process * leader = it->leader;
204		for (; it != NULL && it->leader == leader; ) {
205			/* Callback might call remove_process.  */
206			Process * next = it->next;
207			if ((*cb) (it, data) == pcb_stop)
208				return it;
209			it = next;
210		}
211	}
212	return NULL;
213}
214
215void
216add_process(Process * proc)
217{
218	Process ** leaderp = &list_of_processes;
219	if (proc->pid) {
220		pid_t tgid = process_leader(proc->pid);
221		if (tgid == 0)
222			/* Must have been terminated before we managed
223			 * to fully attach.  */
224			return;
225		if (tgid == proc->pid)
226			proc->leader = proc;
227		else {
228			Process * leader = pid2proc(tgid);
229			proc->leader = leader;
230			if (leader != NULL)
231				leaderp = &leader->next;
232		}
233	}
234	proc->next = *leaderp;
235	*leaderp = proc;
236}
237
238void
239change_process_leader(Process * proc, Process * leader)
240{
241	Process ** leaderp = &list_of_processes;
242	if (proc->leader == leader)
243		return;
244
245	assert(leader != NULL);
246	unlist_process(proc);
247	if (proc != leader)
248		leaderp = &leader->next;
249
250	proc->leader = leader;
251	proc->next = *leaderp;
252	*leaderp = proc;
253}
254
255static enum pcb_status
256clear_leader(Process * proc, void * data)
257{
258	debug(DEBUG_FUNCTION, "detach_task %d from leader %d",
259	      proc->pid, proc->leader->pid);
260	proc->leader = NULL;
261	return pcb_cont;
262}
263
264static enum ecb_status
265event_for_proc(Event * event, void * data)
266{
267	if (event->proc == data)
268		return ecb_deque;
269	else
270		return ecb_cont;
271}
272
273static void
274delete_events_for(Process * proc)
275{
276	Event * event;
277	while ((event = each_qd_event(&event_for_proc, proc)) != NULL)
278		free(event);
279}
280
281void
282remove_process(Process *proc)
283{
284	debug(DEBUG_FUNCTION, "remove_proc(pid=%d)", proc->pid);
285
286	if (proc->leader == proc)
287		each_task(proc, &clear_leader, NULL);
288
289	unlist_process(proc);
290	delete_events_for(proc);
291	free(proc);
292}
293
294void
295install_event_handler(Process * proc, Event_Handler * handler)
296{
297	debug(DEBUG_FUNCTION, "install_event_handler(pid=%d, %p)", proc->pid, handler);
298	assert(proc->event_handler == NULL);
299	proc->event_handler = handler;
300}
301
302void
303destroy_event_handler(Process * proc)
304{
305	Event_Handler * handler = proc->event_handler;
306	debug(DEBUG_FUNCTION, "destroy_event_handler(pid=%d, %p)", proc->pid, handler);
307	assert(handler != NULL);
308	if (handler->destroy != NULL)
309		handler->destroy(handler);
310	free(handler);
311	proc->event_handler = NULL;
312}
313