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
30 extern char *optarg;
31 extern int optind;
32 #endif
33
34 static int outfd = -1;
35 static int outbufsize = 0;
36 static void *outbuf = 0;
37 static int verbose = 0;
38 static int do_skip = 0;
39 static int skip_mode = 0;
40 static pid_t child_pid = -1;
41
usage(char * progname)42 static 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 */
write_all(int fd,const char * buf,size_t count)56 static 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
send_output(const char * buffer,int c,int flag)75 static 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
do_read(int fd)117 static 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
signal_term(int sig)153 static void signal_term(int sig)
154 {
155 if (child_pid > 0)
156 kill(child_pid, sig);
157 }
158
run_program(char ** argv)159 static 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
copy_from_stdin(void)228 static 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
main(int argc,char ** argv)251 int 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