polld.c

   1 /*
   2  * Polling daemon
   3  *
   4  * Copyright (c) 2004-2006 by Michal Čihař <michal@cihar.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18  */
  19
  20 #define _GNU_SOURCE
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <errno.h>
  24 #include <stdlib.h>
  25 #include <sys/types.h>
  26 #include <unistd.h>
  27 #include <getopt.h>
  28 #include <signal.h>
  29 #include <sys/types.h>
  30 #include <sys/stat.h>
  31 #include <fcntl.h>
  32 #if LINUX
  33 #include <sys/ioctl.h>
  34 #include <linux/fs.h>
  35 #endif
  36
  37 /* These are usually defined by make: */
  38 #ifndef CONFIGFILE
  39 #   define CONFIGFILE "/etc/polld"
  40 #endif
  41 #ifndef PIDFILE
  42 #   define PIDFILE "/var/run/polld.pid"
  43 #endif
  44 #ifndef SLEEPTIME
  45 #   define SLEEPTIME 10
  46 #endif
  47 #ifndef VERSION
  48 #   define VERSION "unknown"
  49 #endif
  50
  51 /* From linux/fs.h */
  52 #define BLKRRPART  _IO(0x12,95)    /* re-read partition table */
  53
  54 /* Commandline params */
  55 char        *config = NULL;
  56 char        *pid = NULL;
  57 int         sleeptime = SLEEPTIME;
  58
  59 /* Parameters */
  60 char        **filelist = NULL;
  61 int         listlen = 0;
  62 int         alloclen = 0;
  63
  64 /* Global flags */
  65 volatile int    shutdown = 0;
  66 volatile int    reload = 0;
  67
  68 #define ERRORPREFIX "polld: "
  69
  70 void show_version(void) {
  71     printf("polld version " VERSION "\n"
  72             "Copyright (C) 2004-2006 Michal Cihar <michal@cihar.com>\n"
  73             "This is free software.  You may redistribute copies of it under the terms of\n"
  74             "the GNU General Public License <http://www.gnu.org/licenses/gpl.html>.\n"
  75             "There is NO WARRANTY, to the extent permitted by law.\n");
  76     exit(0);
  77 }
  78
  79 void show_help(void) {
  80     printf( "Usage: polld [params]\n"
  81             "Parameters\n"
  82             " -h --help             show this help\n"
  83             " -v --version          show version information\n"
  84             " -c --config file      configuration file to use\n"
  85             " -p --pid file         lock file for storing pid, empty for no locking\n"
  86             " -s --sleep seconds    number of seconds to sleep in sleep cycle\n"
  87             "\n");
  88     exit(0);
  89 }
  90
  91 void parse_params(int argc, char **argv) {
  92     struct option long_options[] = {
  93        {"help"      , 0, 0, 'h'},
  94        {"version"   , 0, 0, 'v'},
  95        {"config"    , 1, 0, 'c'},
  96        {"sleep"     , 1, 0, 's'},
  97        {"pid"       , 1, 0, 'p'},
  98        {0           , 0, 0, 0}
  99     };
 100     int c;
 101     int option_index;
 102
 103     /* No error messages from getopt */
 104     opterr = 0;
 105
 106     while ((c = getopt_long (argc, argv, "hvc:s:p:", long_options, &option_index)) != -1) {
 107         switch (c) {
 108             case 'h':
 109                 show_help();
 110                 break;
 111             case 'v':
 112                 show_version();
 113                 break;
 114             case 'c':
 115                 if (config != NULL) free(config);
 116                 config = strdup(optarg);
 117                 break;
 118             case 'p':
 119                 if (pid != NULL) free(pid);
 120                 pid = strdup(optarg);
 121                 break;
 122             case 's':
 123                 sleeptime = atoi(optarg);
 124                 if (sleeptime <= 0) {
 125                     fprintf(stderr, ERRORPREFIX "Invalid sleep time!\n");
 126                     exit(1);
 127                 }
 128                 break;
 129             default:
 130                 fprintf(stderr, ERRORPREFIX "Invalid parameters, use --help for help.\n");
 131                 exit(1);
 132                 break;
 133         }
 134     }
 135
 136     if (optind < argc) {
 137         fprintf(stderr, ERRORPREFIX "Invalid parameters, use --help for help.\n");
 138         exit(1);
 139     }
 140     if (config == NULL) {
 141         config = strdup(CONFIGFILE);
 142     }
 143     if (pid == NULL) {
 144         pid = strdup(PIDFILE);
 145     }
 146 }
 147
 148 void load_config() {
 149     FILE        *file;
 150     char        *line = NULL;
 151     size_t      len = 0;
 152
 153     /* Open configuration */
 154     file = fopen(config, "r");
 155     if (file == NULL) {
 156         fprintf(stderr, ERRORPREFIX "Failed to open configuration %s (%s)\n", config, strerror(errno));
 157         exit(1);
 158     }
 159
 160     /* Read config file lines */
 161     while (getline(&line, &len, file) != -1) {
 162         /* Ignore comments */
 163         if (line[0] == '#') continue;
 164
 165         len = strlen(line);
 166
 167         /* Remove trailing \n */
 168         if (len > 0 && line[len - 1] == '\n') {
 169             len[line - 1] = 0;
 170             len--;
 171         }
 172
 173         /* Ignore empty lines */
 174         if (len == 0) {
 175             free(line);
 176             line = NULL;
 177             continue;
 178         }
 179
 180         /* Okay, we seem to have valid line */
 181         listlen++;
 182
 183         /* Do we need to reallocate list? */
 184         if (listlen > alloclen) {
 185             filelist = (char **)realloc(filelist, (listlen + 4 ) * sizeof(char *));
 186             if (filelist == NULL) {
 187                 fprintf(stderr, "polld: not enough memory\n");
 188                 exit(2);
 189             }
 190             alloclen = listlen + 4;
 191         }
 192
 193         /* Add to list */
 194         filelist[listlen - 1] = line;
 195
 196         /* Zero to force getline to malloc this for us */
 197         line = NULL;
 198         len = 0;
 199     }
 200
 201     /* Close config file */
 202     fclose(file);
 203 }
 204
 205 void check_lock(void) {
 206     FILE        *file;
 207     int         other;
 208
 209     if (strlen(pid) == 0) return;
 210
 211     /* Read existing pid */
 212     file = fopen(pid, "r");
 213     if (file != NULL) {
 214         if (fscanf(file, "%d", &other) == 1) {
 215             if (kill(other, 0) == 0) {
 216                 fprintf(stderr, ERRORPREFIX "Another instance is running, please stop it first!\n");
 217                 exit(1);
 218             }
 219         } else {
 220             fprintf(stderr, ERRORPREFIX "Can not parse pidfile, ignoring!\n");
 221         }
 222         fclose(file);
 223     }
 224 }
 225
 226
 227 void do_lock(void) {
 228     FILE        *file;
 229
 230     if (strlen(pid) == 0) return;
 231
 232     /* Write pid file */
 233     file = fopen(pid, "w");
 234     if (file != NULL) {
 235         fprintf(file, "%d\n", getpid());
 236         fclose(file);
 237     } else {
 238         fprintf(stderr, ERRORPREFIX "Can not create pidfile!\n");
 239         exit(1);
 240     }
 241 }
 242
 243 void bye(void) {
 244     /* Remove lock file */
 245     if (strlen(pid) != 0) {
 246         unlink(pid);
 247     }
 248
 249     exit(0);
 250 }
 251
 252 /* Signal handlers */
 253 void interrupt(int sign)
 254 {
 255     signal(sign, SIG_IGN);
 256     shutdown = 1;
 257     bye();
 258 }
 259
 260 void hup(int sign)
 261 {
 262     reload = 1;
 263 }
 264
 265
 266 int main(int argc, char **argv) {
 267     int i;
 268         int file;
 269
 270     /* Parse parameters is optionally config file name */
 271     parse_params(argc, argv);
 272
 273     /* Load configuration */
 274     load_config();
 275
 276     /* Check for locking while we have terminal */
 277     check_lock();
 278
 279     /* Fake lock while we have terminal */
 280     do_lock();
 281
 282     /* Disconnect terminal.. */
 283     daemon(0, 0);
 284
 285     /* Real lock */
 286     do_lock();
 287
 288     /* Trap signals */
 289     signal(SIGINT, interrupt);
 290     signal(SIGQUIT, interrupt);
 291     signal(SIGTERM, interrupt);
 292     signal(SIGHUP, hup);
 293
 294     /* Main loop */
 295     while (!shutdown) {
 296         sleep(sleeptime);
 297
 298         /* Should we reload? */
 299         if (reload) {
 300             for (i = 0; i < listlen; i++) {
 301                 free(filelist[i]);
 302             }
 303
 304             free(filelist);
 305             filelist = NULL;
 306             listlen = 0;
 307             alloclen = 0;
 308
 309             load_config();
 310         }
 311
 312         /* Do the main work */
 313         for (i = 0; i < listlen; i++) {
 314             file = open(filelist[i], O_RDONLY);
 315             if (file != -1) {
 316 #if LINUX
 317                                 ioctl(file, BLKRRPART);
 318 #endif
 319                                 close(file);
 320                         }
 321         }
 322     }
 323
 324     /* Cleanup */
 325     bye();
 326
 327     /* Just to make gcc happy */
 328     return 0;
 329 }