proc.c revision 366c2f46d844f040458df9b7e35fc3b8527ed2d3 
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
20Process *
21open_program(char *filename, pid_t pid, int enable) {
22	Process *proc;
23	assert(pid != 0);
24	proc = calloc(sizeof(Process), 1);
25	if (!proc) {
26		perror("malloc");
27		exit(1);
28	}
29
30	proc->filename = strdup(filename);
31	proc->pid = pid;
32#if defined(HAVE_LIBUNWIND)
33	proc->unwind_priv = _UPT_create(pid);
34	proc->unwind_as = unw_create_addr_space(&_UPT_accessors, 0);
35#endif /* defined(HAVE_LIBUNWIND) */
36
37	add_process(proc);
38	if (proc->leader == NULL) {
39		free(proc);
40		return NULL;
41	}
42
43	if (proc->leader == proc) {
44		trace_set_options(proc, proc->pid);
45		if (breakpoints_init(proc, enable)) {
46			fprintf(stderr, "failed to init breakpoints %d\n",
47				proc->pid);
48			remove_process(proc);
49			return NULL;
50		}
51	}
52
53	return proc;
54}
55
56static int
57open_one_pid(pid_t pid)
58{
59	Process *proc;
60	char *filename;
61	debug(DEBUG_PROCESS, "open_one_pid(pid=%d)", pid);
62
63	/* Get the filename first.  Should the trace_pid fail, we can
64	 * easily free it, untracing is more work.  */
65	if ((filename = pid2name(pid)) == NULL
66	    || trace_pid(pid) < 0) {
67		free(filename);
68		return -1;
69	}
70
71	proc = open_program(filename, pid, 0);
72	if (proc == NULL)
73		return -1;
74	trace_set_options(proc, pid);
75
76	return 0;
77}
78
79static enum pcb_status
80start_one_pid(Process * proc, void * data)
81{
82	continue_process(proc->pid);
83	return pcb_cont;
84}
85
86void
87open_pid(pid_t pid)
88{
89	debug(DEBUG_PROCESS, "open_pid(pid=%d)", pid);
90	/* If we are already tracing this guy, we should be seeing all
91	 * his children via normal tracing route.  */
92	if (pid2proc(pid) != NULL)
93		return;
94
95	/* First, see if we can attach the requested PID itself.  */
96	if (open_one_pid(pid)) {
97		fprintf(stderr, "Cannot attach to pid %u: %s\n",
98			pid, strerror(errno));
99		trace_fail_warning(pid);
100		return;
101	}
102
103	/* Now attach to all tasks that belong to that PID.  There's a
104	 * race between process_tasks and open_one_pid.  So when we
105	 * fail in open_one_pid below, we just do another round.
106	 * Chances are that by then that PID will have gone away, and
107	 * that's why we have seen the failure.  The processes that we
108	 * manage to open_one_pid are stopped, so we should eventually
109	 * reach a point where process_tasks doesn't give any new
110	 * processes (because there's nobody left to produce
111	 * them).  */
112	size_t old_ntasks = 0;
113	int have_all;
114	while (1) {
115		pid_t *tasks;
116		size_t ntasks;
117		size_t i;
118
119		if (process_tasks(pid, &tasks, &ntasks) < 0) {
120			fprintf(stderr, "Cannot obtain tasks of pid %u: %s\n",
121				pid, strerror(errno));
122			break;
123		}
124
125		have_all = 1;
126		for (i = 0; i < ntasks; ++i)
127			if (pid2proc(tasks[i]) == NULL
128			    && open_one_pid(tasks[i]))
129				have_all = 0;
130
131		free(tasks);
132
133		if (have_all && old_ntasks == ntasks)
134			break;
135		old_ntasks = ntasks;
136	}
137
138	/* Done.  Now initialize breakpoints and then continue
139	 * everyone.  */
140	Process * leader;
141	leader = pid2proc(pid)->leader;
142	enable_all_breakpoints(leader);
143
144	each_task(pid2proc(pid)->leader, start_one_pid, NULL);
145}
146
147static enum pcb_status
148find_proc(Process * proc, void * data)
149{
150	pid_t pid = (pid_t)(uintptr_t)data;
151	return proc->pid == pid ? pcb_stop : pcb_cont;
152}
153
154Process *
155pid2proc(pid_t pid) {
156	return each_process(NULL, &find_proc, (void *)(uintptr_t)pid);
157}
158
159static Process * list_of_processes = NULL;
160
161static void
162unlist_process(Process * proc)
163{
164	Process *tmp;
165
166	if (list_of_processes == proc) {
167		list_of_processes = list_of_processes->next;
168		return;
169	}
170
171	for (tmp = list_of_processes; ; tmp = tmp->next) {
172		/* If the following assert fails, the process wasn't
173		 * in the list.  */
174		assert(tmp->next != NULL);
175
176		if (tmp->next == proc) {
177			tmp->next = tmp->next->next;
178			return;
179		}
180	}
181}
182
183Process *
184each_process(Process * proc,
185	     enum pcb_status (* cb)(Process * proc, void * data),
186	     void * data)
187{
188	Process * it = proc ?: list_of_processes;
189	for (; it != NULL; ) {
190		/* Callback might call remove_process.  */
191		Process * next = it->next;
192		if ((*cb) (it, data) == pcb_stop)
193			return it;
194		it = next;
195	}
196	return NULL;
197}
198
199Process *
200each_task(Process * it, enum pcb_status (* cb)(Process * proc, void * data),
201	  void * data)
202{
203	if (it != NULL) {
204		Process * leader = it->leader;
205		for (; it != NULL && it->leader == leader; ) {
206			/* Callback might call remove_process.  */
207			Process * next = it->next;
208			if ((*cb) (it, data) == pcb_stop)
209				return it;
210			it = next;
211		}
212	}
213	return NULL;
214}
215
216void
217add_process(Process * proc)
218{
219	Process ** leaderp = &list_of_processes;
220	if (proc->pid) {
221		pid_t tgid = process_leader(proc->pid);
222		if (tgid == 0)
223			/* Must have been terminated before we managed
224			 * to fully attach.  */
225			return;
226		if (tgid == proc->pid)
227			proc->leader = proc;
228		else {
229			Process * leader = pid2proc(tgid);
230			proc->leader = leader;
231			if (leader != NULL)
232				leaderp = &leader->next;
233		}
234	}
235	proc->next = *leaderp;
236	*leaderp = proc;
237}
238
239void
240change_process_leader(Process * proc, Process * leader)
241{
242	Process ** leaderp = &list_of_processes;
243	if (proc->leader == leader)
244		return;
245
246	assert(leader != NULL);
247	unlist_process(proc);
248	if (proc != leader)
249		leaderp = &leader->next;
250
251	proc->leader = leader;
252	proc->next = *leaderp;
253	*leaderp = proc;
254}
255
256static enum pcb_status
257clear_leader(Process * proc, void * data)
258{
259	debug(DEBUG_FUNCTION, "detach_task %d from leader %d",
260	      proc->pid, proc->leader->pid);
261	proc->leader = NULL;
262	return pcb_cont;
263}
264
265static enum ecb_status
266event_for_proc(Event * event, void * data)
267{
268	if (event->proc == data)
269		return ecb_deque;
270	else
271		return ecb_cont;
272}
273
274static void
275delete_events_for(Process * proc)
276{
277	Event * event;
278	while ((event = each_qd_event(&event_for_proc, proc)) != NULL)
279		free(event);
280}
281
282void
283remove_process(Process *proc)
284{
285	debug(DEBUG_FUNCTION, "remove_proc(pid=%d)", proc->pid);
286
287	if (proc->leader == proc)
288		each_task(proc, &clear_leader, NULL);
289
290	unlist_process(proc);
291	delete_events_for(proc);
292	free(proc);
293}
294
295void
296install_event_handler(Process *proc, struct event_handler *handler)
297{
298	debug(DEBUG_FUNCTION, "install_event_handler(pid=%d, %p)", proc->pid, handler);
299	assert(proc->event_handler == NULL);
300	proc->event_handler = handler;
301}
302
303void
304destroy_event_handler(Process * proc)
305{
306	struct event_handler *handler = proc->event_handler;
307	debug(DEBUG_FUNCTION, "destroy_event_handler(pid=%d, %p)", proc->pid, handler);
308	assert(handler != NULL);
309	if (handler->destroy != NULL)
310		handler->destroy(handler);
311	free(handler);
312	proc->event_handler = NULL;
313}
314