misc/logsave.c

   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
  31 extern char *optarg;
  32 extern int optind;
  33 #endif
  34
  35 static int      outfd = -1;
  36 static int      outbufsize = 0;
  37 static void     *outbuf = 0;
  38 static int      verbose = 0;
  39 static int      do_skip = 0;
  40 static int      skip_mode = 0;
  41 static pid_t    child_pid = -1;
  42
  43 static 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 EAGAIN/EINTR error.
  56  */
  57 static 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
  76 static 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
 118 static 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
 154 static void signal_term(int sig)
 155 {
 156         if (child_pid > 0)
 157                 kill(child_pid, sig);
 158 }
 159
 160 static 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, " exited with status code %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                         return 1;
 223                 }
 224                 rc = 0;
 225         }
 226         return rc;
 227 }
 228
 229 static 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
 252 int 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 }