logsave.c revision e0ed7404719a9ddd2ba427a80db5365c8bad18c0 
1/*
2 * logsave.c --- A program which saves the output of a program until
3 *	/var/log is mounted.
4 *
5 * Copyright (C) 2003 Theodore Ts'o.
6 *
7 * %Begin-Header%
8 * This file may be redistributed under the terms of the GNU Public
9 * License.
10 * %End-Header%
11 */
12
13#define _XOPEN_SOURCE 600 /* for inclusion of sa_handler in Solaris */
14
15#include <stdio.h>
16#include <stdlib.h>
17#include <unistd.h>
18#include <string.h>
19#include <sys/types.h>
20#include <sys/wait.h>
21#include <fcntl.h>
22#include <time.h>
23#include <errno.h>
24#ifdef HAVE_SIGNAL_H
25#include <signal.h>
26#endif
27#ifdef HAVE_GETOPT_H
28#include <getopt.h>
29#else
30extern char *optarg;
31extern int optind;
32#endif
33
34static int	outfd = -1;
35static int	outbufsize = 0;
36static void	*outbuf = 0;
37static int	verbose = 0;
38static int	do_skip = 0;
39static int	skip_mode = 0;
40static pid_t	child_pid = -1;
41
42static void usage(char *progname)
43{
44	printf("Usage: %s [-asv] logfile program\n", progname);
45	exit(1);
46}
47
48#define SEND_LOG	0x01
49#define SEND_CONSOLE	0x02
50#define SEND_BOTH	0x03
51
52/*
53 * Helper function that does the right thing if write returns a
54 * partial write, or an EGAIN/EINTR error.
55 */
56static int write_all(int fd, const char *buf, size_t count)
57{
58	ssize_t ret;
59	int c = 0;
60
61	while (count > 0) {
62		ret = write(fd, buf, count);
63		if (ret < 0) {
64			if ((errno == EAGAIN) || (errno == EINTR))
65				continue;
66			return -1;
67		}
68		count -= ret;
69		buf += ret;
70		c += ret;
71	}
72	return c;
73}
74
75static void send_output(const char *buffer, int c, int flag)
76{
77	const char	*cp;
78	char		*n;
79	int		cnt, d, del;
80
81	if (c == 0)
82		c = strlen(buffer);
83
84	if (flag & SEND_CONSOLE) {
85		cnt = c;
86		cp = buffer;
87		while (cnt) {
88			del = 0;
89			for (d=0; d < cnt; d++) {
90				if (skip_mode &&
91				    (cp[d] == '\001' || cp[d] == '\002')) {
92					del = 1;
93					break;
94				}
95			}
96			write_all(1, cp, d);
97			if (del)
98				d++;
99			cnt -= d;
100			cp += d;
101		}
102	}
103	if (!(flag & SEND_LOG))
104		return;
105	if (outfd > 0)
106		write_all(outfd, buffer, c);
107	else {
108		n = realloc(outbuf, outbufsize + c);
109		if (n) {
110			outbuf = n;
111			memcpy(((char *)outbuf)+outbufsize, buffer, c);
112			outbufsize += c;
113		}
114	}
115}
116
117static int do_read(int fd)
118{
119	int	c;
120	char	buffer[4096], *cp, *sep;
121
122	c = read(fd, buffer, sizeof(buffer)-1);
123	if (c <= 0)
124		return c;
125	if (do_skip) {
126		send_output(buffer, c, SEND_CONSOLE);
127		buffer[c] = 0;
128		cp = buffer;
129		while (*cp) {
130			if (skip_mode) {
131				cp = strchr(cp, '\002');
132				if (!cp)
133					return 0;
134				cp++;
135				skip_mode = 0;
136				continue;
137			}
138			sep = strchr(cp, '\001');
139			if (sep)
140				*sep = 0;
141			send_output(cp, 0, SEND_LOG);
142			if (sep) {
143				cp = sep + 1;
144				skip_mode = 1;
145			} else
146				break;
147		}
148	} else
149		send_output(buffer, c, SEND_BOTH);
150	return c;
151}
152
153static void signal_term(int sig)
154{
155	if (child_pid > 0)
156		kill(child_pid, sig);
157}
158
159static int run_program(char **argv)
160{
161	int	fds[2];
162	int	status, rc, pid;
163	char	buffer[80];
164#ifdef HAVE_SIGNAL_H
165	struct sigaction	sa;
166#endif
167
168	if (pipe(fds) < 0) {
169		perror("pipe");
170		exit(1);
171	}
172
173#ifdef HAVE_SIGNAL_H
174	memset(&sa, 0, sizeof(struct sigaction));
175	sa.sa_handler = signal_term;
176	sigaction(SIGINT, &sa, 0);
177	sigaction(SIGTERM, &sa, 0);
178#ifdef SA_RESTART
179	sa.sa_flags = SA_RESTART;
180#endif
181#endif
182
183	pid = fork();
184	if (pid < 0) {
185		perror("vfork");
186		exit(1);
187	}
188	if (pid == 0) {
189		dup2(fds[1],1);		/* fds[1] replaces stdout */
190		dup2(fds[1],2);  	/* fds[1] replaces stderr */
191		close(fds[0]);	/* don't need this here */
192		close(fds[1]);
193
194		execvp(argv[0], argv);
195		perror(argv[0]);
196		exit(1);
197	}
198	child_pid = pid;
199	close(fds[1]);
200
201	while (!(waitpid(pid, &status, WNOHANG ))) {
202		do_read(fds[0]);
203	}
204	child_pid = -1;
205	do_read(fds[0]);
206	close(fds[0]);
207
208	if ( WIFEXITED(status) ) {
209		rc = WEXITSTATUS(status);
210		if (rc) {
211			send_output(argv[0], 0, SEND_BOTH);
212			sprintf(buffer, " died with exit status %d\n", rc);
213			send_output(buffer, 0, SEND_BOTH);
214		}
215	} else {
216		if (WIFSIGNALED(status)) {
217			send_output(argv[0], 0, SEND_BOTH);
218			sprintf(buffer, "died with signal %d\n",
219				WTERMSIG(status));
220			send_output(buffer, 0, SEND_BOTH);
221			rc = 1;
222		}
223		rc = 0;
224	}
225	return rc;
226}
227
228static int copy_from_stdin(void)
229{
230	int	c, bad_read = 0;
231
232	while (1) {
233		c = do_read(0);
234		if ((c == 0 ) ||
235		    ((c < 0) && ((errno == EAGAIN) || (errno == EINTR)))) {
236			if (bad_read++ > 3)
237				break;
238			continue;
239		}
240		if (c < 0) {
241			perror("read");
242			exit(1);
243		}
244		bad_read = 0;
245	}
246	return 0;
247}
248
249
250
251int main(int argc, char **argv)
252{
253	int	c, pid, rc;
254	char	*outfn, **cpp;
255	int	openflags = O_CREAT|O_WRONLY|O_TRUNC;
256	int	send_flag = SEND_LOG;
257	int	do_stdin;
258	time_t	t;
259
260	while ((c = getopt(argc, argv, "+asv")) != EOF) {
261		switch (c) {
262		case 'a':
263			openflags &= ~O_TRUNC;
264			openflags |= O_APPEND;
265			break;
266		case 's':
267			do_skip = 1;
268			break;
269		case 'v':
270			verbose++;
271			send_flag |= SEND_CONSOLE;
272			break;
273		}
274	}
275	if (optind == argc || optind+1 == argc)
276		usage(argv[0]);
277	outfn = argv[optind];
278	optind++;
279	argv += optind;
280	argc -= optind;
281
282	outfd = open(outfn, openflags, 0644);
283	do_stdin = !strcmp(argv[0], "-");
284
285	send_output("Log of ", 0, send_flag);
286	if (do_stdin)
287		send_output("stdin", 0, send_flag);
288	else {
289		for (cpp = argv; *cpp; cpp++) {
290			send_output(*cpp, 0, send_flag);
291			send_output(" ", 0, send_flag);
292		}
293	}
294	send_output("\n", 0, send_flag);
295	t = time(0);
296	send_output(ctime(&t), 0, send_flag);
297	send_output("\n", 0, send_flag);
298
299	if (do_stdin)
300		rc = copy_from_stdin();
301	else
302		rc = run_program(argv);
303
304	send_output("\n", 0, send_flag);
305	t = time(0);
306	send_output(ctime(&t), 0, send_flag);
307	send_output("----------------\n", 0, send_flag);
308
309	if (outbuf) {
310		pid = fork();
311		if (pid < 0) {
312			perror("fork");
313			exit(1);
314		}
315		if (pid) {
316			if (verbose)
317				printf("Backgrounding to save %s later\n",
318				       outfn);
319			exit(rc);
320		}
321		setsid();	/* To avoid getting killed by init */
322		while (outfd < 0) {
323			outfd = open(outfn, openflags, 0644);
324			sleep(1);
325		}
326		write_all(outfd, outbuf, outbufsize);
327		free(outbuf);
328	}
329	if (outfd >= 0)
330		close(outfd);
331
332	exit(rc);
333}
334