logsave.c revision 53462aad719011c969e21fb039acd595ba027b9e 
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 "config.h"
16#include <stdio.h>
17#include <stdlib.h>
18#include <unistd.h>
19#include <string.h>
20#include <sys/types.h>
21#include <sys/wait.h>
22#include <fcntl.h>
23#include <time.h>
24#include <errno.h>
25#ifdef HAVE_SIGNAL_H
26#include <signal.h>
27#endif
28#ifdef HAVE_GETOPT_H
29#include <getopt.h>
30#else
31extern char *optarg;
32extern int optind;
33#endif
34
35int	outfd = -1;
36int	outbufsize = 0;
37void	*outbuf = 0;
38int	verbose = 0;
39int	do_skip = 0;
40int	skip_mode = 0;
41pid_t	child_pid = -1;
42
43static void usage(char *progname)
44{
45	printf("Usage: %s [-asv] logfile program\n", progname);
46	exit(1);
47}
48
49#define SEND_LOG	0x01
50#define SEND_CONSOLE	0x02
51#define SEND_BOTH	0x03
52
53/*
54 * Helper function that does the right thing if write returns a
55 * partial write, or an EGAIN/EINTR error.
56 */
57static int write_all(int fd, const char *buf, size_t count)
58{
59	ssize_t ret;
60	int c = 0;
61
62	while (count > 0) {
63		ret = write(fd, buf, count);
64		if (ret < 0) {
65			if ((errno == EAGAIN) || (errno == EINTR))
66				continue;
67			return -1;
68		}
69		count -= ret;
70		buf += ret;
71		c += ret;
72	}
73	return c;
74}
75
76static void send_output(const char *buffer, int c, int flag)
77{
78	const char	*cp;
79	char		*n;
80	int		cnt, d, del;
81
82	if (c == 0)
83		c = strlen(buffer);
84
85	if (flag & SEND_CONSOLE) {
86		cnt = c;
87		cp = buffer;
88		while (cnt) {
89			del = 0;
90			for (d=0; d < cnt; d++) {
91				if (skip_mode &&
92				    (cp[d] == '\001' || cp[d] == '\002')) {
93					del = 1;
94					break;
95				}
96			}
97			write_all(1, cp, d);
98			if (del)
99				d++;
100			cnt -= d;
101			cp += d;
102		}
103	}
104	if (!(flag & SEND_LOG))
105		return;
106	if (outfd > 0)
107		write_all(outfd, buffer, c);
108	else {
109		n = realloc(outbuf, outbufsize + c);
110		if (n) {
111			outbuf = n;
112			memcpy(((char *)outbuf)+outbufsize, buffer, c);
113			outbufsize += c;
114		}
115	}
116}
117
118static int do_read(int fd)
119{
120	int	c;
121	char	buffer[4096], *cp, *sep;
122
123	c = read(fd, buffer, sizeof(buffer)-1);
124	if (c <= 0)
125		return c;
126	if (do_skip) {
127		send_output(buffer, c, SEND_CONSOLE);
128		buffer[c] = 0;
129		cp = buffer;
130		while (*cp) {
131			if (skip_mode) {
132				cp = strchr(cp, '\002');
133				if (!cp)
134					return 0;
135				cp++;
136				skip_mode = 0;
137				continue;
138			}
139			sep = strchr(cp, '\001');
140			if (sep)
141				*sep = 0;
142			send_output(cp, 0, SEND_LOG);
143			if (sep) {
144				cp = sep + 1;
145				skip_mode = 1;
146			} else
147				break;
148		}
149	} else
150		send_output(buffer, c, SEND_BOTH);
151	return c;
152}
153
154static void signal_term(int sig)
155{
156	if (child_pid > 0)
157		kill(child_pid, sig);
158}
159
160static int run_program(char **argv)
161{
162	int	fds[2];
163	int	status, rc, pid;
164	char	buffer[80];
165#ifdef HAVE_SIGNAL_H
166	struct sigaction	sa;
167#endif
168
169	if (pipe(fds) < 0) {
170		perror("pipe");
171		exit(1);
172	}
173
174#ifdef HAVE_SIGNAL_H
175	memset(&sa, 0, sizeof(struct sigaction));
176	sa.sa_handler = signal_term;
177	sigaction(SIGINT, &sa, 0);
178	sigaction(SIGTERM, &sa, 0);
179#ifdef SA_RESTART
180	sa.sa_flags = SA_RESTART;
181#endif
182#endif
183
184	pid = fork();
185	if (pid < 0) {
186		perror("vfork");
187		exit(1);
188	}
189	if (pid == 0) {
190		dup2(fds[1],1);		/* fds[1] replaces stdout */
191		dup2(fds[1],2);  	/* fds[1] replaces stderr */
192		close(fds[0]);	/* don't need this here */
193		close(fds[1]);
194
195		execvp(argv[0], argv);
196		perror(argv[0]);
197		exit(1);
198	}
199	child_pid = pid;
200	close(fds[1]);
201
202	while (!(waitpid(pid, &status, WNOHANG ))) {
203		do_read(fds[0]);
204	}
205	child_pid = -1;
206	do_read(fds[0]);
207	close(fds[0]);
208
209	if ( WIFEXITED(status) ) {
210		rc = WEXITSTATUS(status);
211		if (rc) {
212			send_output(argv[0], 0, SEND_BOTH);
213			sprintf(buffer, " died with exit status %d\n", rc);
214			send_output(buffer, 0, SEND_BOTH);
215		}
216	} else {
217		if (WIFSIGNALED(status)) {
218			send_output(argv[0], 0, SEND_BOTH);
219			sprintf(buffer, "died with signal %d\n",
220				WTERMSIG(status));
221			send_output(buffer, 0, SEND_BOTH);
222			rc = 1;
223		}
224		rc = 0;
225	}
226	return rc;
227}
228
229static int copy_from_stdin(void)
230{
231	int	c, bad_read = 0;
232
233	while (1) {
234		c = do_read(0);
235		if ((c == 0 ) ||
236		    ((c < 0) && ((errno == EAGAIN) || (errno == EINTR)))) {
237			if (bad_read++ > 3)
238				break;
239			continue;
240		}
241		if (c < 0) {
242			perror("read");
243			exit(1);
244		}
245		bad_read = 0;
246	}
247	return 0;
248}
249
250
251
252int main(int argc, char **argv)
253{
254	int	c, pid, rc;
255	char	*outfn, **cpp;
256	int	openflags = O_CREAT|O_WRONLY|O_TRUNC;
257	int	send_flag = SEND_LOG;
258	int	do_stdin;
259	time_t	t;
260
261	while ((c = getopt(argc, argv, "+asv")) != EOF) {
262		switch (c) {
263		case 'a':
264			openflags &= ~O_TRUNC;
265			openflags |= O_APPEND;
266			break;
267		case 's':
268			do_skip = 1;
269			break;
270		case 'v':
271			verbose++;
272			send_flag |= SEND_CONSOLE;
273			break;
274		}
275	}
276	if (optind == argc || optind+1 == argc)
277		usage(argv[0]);
278	outfn = argv[optind];
279	optind++;
280	argv += optind;
281	argc -= optind;
282
283	outfd = open(outfn, openflags, 0644);
284	do_stdin = !strcmp(argv[0], "-");
285
286	send_output("Log of ", 0, send_flag);
287	if (do_stdin)
288		send_output("stdin", 0, send_flag);
289	else {
290		for (cpp = argv; *cpp; cpp++) {
291			send_output(*cpp, 0, send_flag);
292			send_output(" ", 0, send_flag);
293		}
294	}
295	send_output("\n", 0, send_flag);
296	t = time(0);
297	send_output(ctime(&t), 0, send_flag);
298	send_output("\n", 0, send_flag);
299
300	if (do_stdin)
301		rc = copy_from_stdin();
302	else
303		rc = run_program(argv);
304
305	send_output("\n", 0, send_flag);
306	t = time(0);
307	send_output(ctime(&t), 0, send_flag);
308	send_output("----------------\n", 0, send_flag);
309
310	if (outbuf) {
311		pid = fork();
312		if (pid < 0) {
313			perror("fork");
314			exit(1);
315		}
316		if (pid) {
317			if (verbose)
318				printf("Backgrounding to save %s later\n",
319				       outfn);
320			exit(rc);
321		}
322		setsid();	/* To avoid getting killed by init */
323		while (outfd < 0) {
324			outfd = open(outfn, openflags, 0644);
325			sleep(1);
326		}
327		write_all(outfd, outbuf, outbufsize);
328		free(outbuf);
329	}
330	if (outfd >= 0)
331		close(outfd);
332
333	exit(rc);
334}
335