src/mini-journalreader.c

   1 /*
   2     Copyright (C) 2019 Proxmox Server Solutions GmbH
   3
   4     Copyright: mini-journal is under GNU GPL, the GNU General Public License.
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; version 2 dated June, 1991.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program; if not, write to the Free Software
  17     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  18     02111-1307, USA.
  19
  20     Author: Dominik Csapak <d.csapak@proxmox.com>
  21 */
  22
  23 #include <errno.h>
  24 #include <stdbool.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <systemd/sd-journal.h>
  29 #include <time.h>
  30 #include <unistd.h>
  31
  32 #define BUFSIZE 4095
  33
  34 static char buf[BUFSIZE + 1];
  35 static size_t offset = 0;
  36
  37 uint64_t get_timestamp(sd_journal *j) {
  38     uint64_t timestamp;
  39     int r = sd_journal_get_realtime_usec(j, &timestamp);
  40     if (r < 0) {
  41         fprintf(stderr, "Failed  %s\n", strerror(-r));
  42         return -1;
  43     }
  44     return timestamp;
  45 }
  46
  47 void print_to_buf(const char * string, uint32_t length) {
  48     if (!length) {
  49         return;
  50     }
  51     size_t string_offset = 0;
  52     size_t remaining = length;
  53     while (offset + remaining > BUFSIZE) {
  54         strncpy(buf + offset, string + string_offset, BUFSIZE - offset);
  55         string_offset += BUFSIZE - offset;
  56         remaining = length - string_offset;
  57         write (1, buf, BUFSIZE);
  58         offset = 0;
  59     }
  60     strncpy(buf + offset, string + string_offset, remaining);
  61     offset += remaining;
  62 }
  63
  64 void print_cursor(sd_journal *j) {
  65     int r;
  66     char *cursor = NULL;
  67     r = sd_journal_get_cursor(j, &cursor);
  68     if (r < 0) {
  69         fprintf(stderr, "Failed to get cursor: %s\n", strerror(-r));
  70         exit(1);
  71     }
  72     print_to_buf(cursor, strlen(cursor));
  73     print_to_buf("\n", 1);
  74     free(cursor);
  75 }
  76
  77 void print_first_cursor(sd_journal *j) {
  78     static bool printed_first_cursor = false;
  79     if (!printed_first_cursor) {
  80         print_cursor(j);
  81         printed_first_cursor = true;
  82     }
  83 }
  84
  85 void print_reboot(sd_journal *j) {
  86     const char *d;
  87     size_t l;
  88     int r = sd_journal_get_data(j, "_BOOT_ID", (const void **)&d, &l);
  89     if (r < 0) {
  90         fprintf(stderr, "Failed  %s\n", strerror(-r));
  91         return;
  92     }
  93
  94     // remove '_BOOT_ID='
  95     d += 9;
  96     l -= 9;
  97
  98     static char bootid[32];
  99     if (bootid[0] != '\0') { // we have some bootid
 100         if (strncmp(bootid, d, l)) { // a new bootid found
 101             strncpy(bootid, d, l);
 102             print_to_buf("-- Reboot --\n", 13);
 103         }
 104     } else {
 105         strncpy(bootid, d, l);
 106     }
 107 }
 108
 109 void print_timestamp(sd_journal *j) {
 110     uint64_t timestamp;
 111     int r = sd_journal_get_realtime_usec(j, &timestamp);
 112     if (r < 0) {
 113         fprintf(stderr, "Failed  %s\n", strerror(-r));
 114         return;
 115     }
 116
 117     static uint64_t last_timestamp;
 118     static char timestring[16];
 119     if (timestamp >= (last_timestamp+(1000*1000))) {
 120         timestamp = timestamp / (1000*1000); // usec to sec
 121         struct tm time;
 122         localtime_r((time_t *)&timestamp, &time);
 123         strftime(timestring, 16, "%b %d %T", &time);
 124         last_timestamp = timestamp;
 125     }
 126
 127     print_to_buf(timestring, 15);
 128 }
 129
 130 void print_pid(sd_journal *j) {
 131     const char *d;
 132     size_t l;
 133     int r = sd_journal_get_data(j, "_PID", (const void **)&d, &l);
 134     if (r < 0) {
 135         // we sometimes have no pid, e.g., kernel messages
 136         return;
 137     }
 138
 139     // remove '_PID='
 140     d += 5;
 141     l -= 5;
 142
 143     print_to_buf("[", 1);
 144     print_to_buf(d, l);
 145     print_to_buf("]", 1);
 146 }
 147
 148 bool print_field(sd_journal *j, const char *field) {
 149     const char *d;
 150     size_t l;
 151     int r = sd_journal_get_data(j, field, (const void **)&d, &l);
 152     if (r < 0) {
 153         // some fields do not exists
 154         return false;
 155     }
 156
 157     int fieldlen = strlen(field)+1;
 158     d += fieldlen;
 159     l -= fieldlen;
 160     print_to_buf(d, l);
 161     return true;
 162 }
 163
 164
 165 void print_line(sd_journal *j) {
 166     print_reboot(j);
 167     print_timestamp(j);
 168     print_to_buf(" ", 1);
 169     print_field(j, "_HOSTNAME");
 170     print_to_buf(" ", 1);
 171     if (!print_field(j, "SYSLOG_IDENTIFIER") &&
 172             !print_field(j, "_COMM")) {
 173         print_to_buf("unknown", strlen("unknown") - 1);
 174     }
 175     print_pid(j);
 176     print_to_buf(": ", 2);
 177     print_field(j, "MESSAGE");
 178     print_to_buf("\n", 1);
 179 }
 180
 181 char *progname;
 182
 183 void usage(char *error) {
 184     if (error) {
 185         fprintf(stderr, "ERROR: %s\n", error);
 186     }
 187     fprintf(stderr, "usage: %s [OPTIONS]\n", progname);
 188     fprintf(stderr,
 189         "  -b <timestamp>\tbegin at this UNIX epoch based timestamp\n"
 190         "  -e <timestamp>\tend at this UNIX epoch based timestamp\n"
 191         "  -d <directory>\tpath to a journal directory\n"
 192         "  -n <integer>\t\tprint the last number entries logged\n"
 193         "  -f <cursor>\t\tprint from this cursor\n"
 194         "  -t <cursor>\t\tprint to this cursor\n"
 195         "  -h \t\t\tthis help\n"
 196         "\n"
 197         "Passing no range option will dump all the available journal\n"
 198         "Giving a range conflicts with -n\n"
 199         "-b and -f conflict\n"
 200         "-e and -t conflict\n");
 201     exit(error ? 1 : 0);
 202 }
 203
 204 static uint64_t arg_to_uint64(const char *argument) {
 205     errno = 0;
 206     char * end;
 207     uint64_t value = strtoull(argument, &end, 10);
 208     if (errno != 0 || *end != '\0') {
 209         fprintf(stderr, "%s is not a valid integer number\n", argument);
 210         exit(1);
 211     }
 212
 213     return value;
 214 }
 215
 216
 217 int main(int argc, char *argv[]) {
 218     uint64_t number = 0;
 219     const char *directory = NULL;
 220     const char *startcursor = NULL;
 221     const char *endcursor = NULL;
 222     uint64_t begin = 0;
 223     uint64_t end = 0;
 224     char c;
 225
 226     progname = argv[0];
 227
 228     while ((c = getopt (argc, argv, "b:e:d:n:f:t:h")) != -1) {
 229         switch (c) {
 230             case 'b':
 231                 begin = arg_to_uint64(optarg);
 232                 begin = begin * 1000 * 1000; // µs
 233                 break;
 234             case 'e':
 235                 end = arg_to_uint64(optarg);
 236                 end = end * 1000 * 1000; // µs
 237                 break;
 238             case 'd':
 239                 directory = optarg;
 240                 break;
 241             case 'n':
 242                 number = arg_to_uint64(optarg);
 243                 break;
 244             case 'f':
 245                 startcursor = optarg;
 246                 break;
 247             case 't':
 248                 endcursor = optarg;
 249                 break;
 250             case 'h':
 251                 usage(NULL);
 252                 break;
 253             case '?':
 254             default:
 255                 usage("invalid option or missing argument");
 256         }
 257     }
 258
 259     if (number && (begin || startcursor)) {
 260         usage("-n conflicts with -b and/or -f");
 261     }
 262
 263     if (begin && startcursor) {
 264         usage("-b and -f conflict");
 265     }
 266
 267     if (end && endcursor) {
 268         usage("-e and -t conflict");
 269     }
 270
 271     if (argc > optind) {
 272         usage("unkown, or to many arguments");
 273     }
 274
 275     // to prevent calling it everytime we generate a timestamp
 276     tzset();
 277
 278     int r;
 279     sd_journal *j;
 280     if (directory == NULL) {
 281         r = sd_journal_open(&j, SD_JOURNAL_LOCAL_ONLY);
 282     } else {
 283         r = sd_journal_open_directory(&j, directory, 0);
 284     }
 285
 286     if (r < 0) {
 287         fprintf(stderr, "Failed to open journal: %s\n", strerror(-r));
 288         return 1;
 289     }
 290
 291     // if we want to print the last x entries, seek to cursor or end,
 292     // then x entries back, print the cursor and finally print the
 293     // entries until end or cursor
 294     if (number) {
 295         if (end) {
 296             r = sd_journal_seek_realtime_usec(j, end);
 297         } else if (endcursor != NULL) {
 298             r = sd_journal_seek_cursor(j, endcursor);
 299             number++;
 300         } else {
 301             r = sd_journal_seek_tail(j);
 302         }
 303
 304         if (r < 0) {
 305             fprintf(stderr, "Failed to seek to end/cursor: %s\n", strerror(-r));
 306             exit(1);
 307         }
 308
 309         // seek back number entries and print cursor
 310         r = sd_journal_previous_skip(j, number + 1);
 311         if (r < 0) {
 312             fprintf(stderr, "Failed to seek back: %s\n", strerror(-r));
 313             exit(1);
 314         }
 315     } else {
 316         if (begin) {
 317             r = sd_journal_seek_realtime_usec(j, begin);
 318         } else if (startcursor) {
 319             r = sd_journal_seek_cursor(j, startcursor);
 320         } else {
 321             r = sd_journal_seek_head(j);
 322         }
 323
 324         if (r < 0) {
 325             fprintf(stderr, "Failed to seek to begin/cursor: %s\n", strerror(-r));
 326             exit(1);
 327         }
 328
 329         // if we have a start cursor, we want to skip the first entry
 330         if (startcursor) {
 331             r = sd_journal_next(j);
 332             if (r < 0) {
 333                 fprintf(stderr, "Failed to seek to begin/cursor: %s\n", strerror(-r));
 334                 exit(1);
 335             }
 336             print_first_cursor(j);
 337         }
 338     }
 339
 340
 341     while ((r = sd_journal_next(j)) > 0 && (end == 0 || get_timestamp(j) < end)) {
 342         print_first_cursor(j);
 343         if (endcursor != NULL && sd_journal_test_cursor(j, endcursor)) {
 344             break;
 345         }
 346         print_line(j);
 347     }
 348
 349     // print optional reboot
 350     print_reboot(j);
 351
 352     // print final cursor
 353     print_cursor(j);
 354
 355     // print remaining buffer
 356     write(1, buf, offset);
 357     sd_journal_close(j);
 358
 359     return 0;
 360 }
 361