libltrace.c revision 418584d25da07c5a9f7a61b74cfe713c1f8d7085 
1/*
2 * This file is part of ltrace.
3 * Copyright (C) 2011,2012 Petr Machata, Red Hat Inc.
4 * Copyright (C) 2009 Juan Cespedes
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation; either version 2 of the
9 * License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
19 * 02110-1301 USA
20 */
21
22#include "config.h"
23
24#include <limits.h>
25#include <sys/param.h>
26#include <sys/wait.h>
27#include <errno.h>
28#include <signal.h>
29#include <stdio.h>
30#include <stdlib.h>
31#include <string.h>
32#include <unistd.h>
33
34#include "common.h"
35#include "proc.h"
36#include "read_config_file.h"
37#include "backend.h"
38#include "prototype.h"
39
40char *command = NULL;
41
42int exiting = 0;		/* =1 if a SIGINT or SIGTERM has been received */
43
44static enum callback_status
45stop_non_p_processes(struct process *proc, void *data)
46{
47	int stop = 1;
48
49	struct opt_p_t *it;
50	for (it = opt_p; it != NULL; it = it->next) {
51		struct process *p_proc = pid2proc(it->pid);
52		if (p_proc == NULL) {
53			printf("stop_non_p_processes: %d terminated?\n", it->pid);
54			continue;
55		}
56		if (p_proc == proc || p_proc->leader == proc->leader) {
57			stop = 0;
58			break;
59		}
60	}
61
62	if (stop) {
63		debug(2, "Sending SIGSTOP to process %u", proc->pid);
64		kill(proc->pid, SIGSTOP);
65	}
66
67	return CBS_CONT;
68}
69
70static void
71signal_alarm(int sig) {
72	signal(SIGALRM, SIG_DFL);
73	each_process(NULL, &stop_non_p_processes, NULL);
74}
75
76static void
77signal_exit(int sig)
78{
79	if (exiting != 0)
80		return;
81
82	exiting = 1 + !!os_ltrace_exiting_sighandler();
83
84	signal(SIGINT, SIG_IGN);
85	signal(SIGTERM, SIG_IGN);
86	signal(SIGALRM, signal_alarm);
87	//alarm(1);
88}
89
90static void
91normal_exit(void)
92{
93	if (options.summary) {
94		show_summary();
95		destroy_global_config();
96	}
97	if (options.output) {
98		fclose(options.output);
99		options.output = NULL;
100	}
101}
102
103void
104ltrace_init(int argc, char **argv) {
105	struct opt_p_t *opt_p_tmp;
106
107	atexit(normal_exit);
108	signal(SIGINT, signal_exit);	/* Detach processes when interrupted */
109	signal(SIGTERM, signal_exit);	/*  ... or killed */
110
111	argv = process_options(argc, argv);
112	init_global_config();
113
114	if (command) {
115		/* Check that the binary ABI is supported before
116		 * calling execute_program.  */
117		struct ltelf lte = {};
118		open_elf(&lte, command);
119		do_close_elf(&lte);
120
121		pid_t pid = execute_program(command, argv);
122		struct process *proc = open_program(command, pid);
123		if (proc == NULL) {
124			fprintf(stderr, "couldn't open program '%s': %s\n",
125				command, strerror(errno));
126			exit(EXIT_FAILURE);
127		}
128
129		trace_set_options(proc);
130		continue_process(pid);
131	}
132	opt_p_tmp = opt_p;
133	while (opt_p_tmp) {
134		open_pid(opt_p_tmp->pid);
135		opt_p_tmp = opt_p_tmp->next;
136	}
137}
138
139static int num_ltrace_callbacks[EVENT_MAX];
140static callback_func * ltrace_callbacks[EVENT_MAX];
141
142void
143ltrace_add_callback(callback_func func, Event_type type) {
144	ltrace_callbacks[type] = realloc(ltrace_callbacks[type], (num_ltrace_callbacks[type]+1)*sizeof(callback_func));
145	ltrace_callbacks[type][num_ltrace_callbacks[type]++] = func;
146}
147
148static void
149dispatch_callbacks(Event * ev) {
150	int i;
151	/* Ignoring case 1: signal into a dying tracer */
152	if (ev->type==EVENT_SIGNAL &&
153			exiting && ev->e_un.signum == SIGSTOP) {
154		return;
155	}
156	/* Ignoring case 2: process being born before a clone event */
157	if (ev->proc && ev->proc->state == STATE_IGNORED) {
158		return;
159	}
160	for (i=0; i<num_ltrace_callbacks[ev->type]; i++) {
161		ltrace_callbacks[ev->type][i](ev);
162	}
163}
164
165void
166ltrace_main(void) {
167	Event * ev;
168	while (1) {
169		ev = next_event();
170		dispatch_callbacks(ev);
171		handle_event(ev);
172	}
173}
174