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 static 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 (uint64_t)-1;
  43     }
  44     return timestamp;
  45 }
  46
  47 static void print_to_buf(const char * string, size_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         if (write (1, buf, BUFSIZE) <= 0) {
  58             perror("write to stdout failed");
  59             exit(1);
  60         }
  61         offset = 0;
  62     }
  63     strncpy(buf + offset, string + string_offset, remaining);
  64     offset += remaining;
  65 }
  66
  67 static void print_cursor(sd_journal *j) {
  68     int r;
  69     char *cursor = NULL;
  70     r = sd_journal_get_cursor(j, &cursor);
  71     if (r < 0) {
  72         fprintf(stderr, "Failed to get cursor: %s\n", strerror(-r));
  73         exit(1);
  74     }
  75     print_to_buf(cursor, strlen(cursor));
  76     print_to_buf("\n", 1);
  77     free(cursor);
  78 }
  79
  80 static void print_first_cursor(sd_journal *j) {
  81     static bool printed_first_cursor = false;
  82     if (!printed_first_cursor) {
  83         print_cursor(j);
  84         printed_first_cursor = true;
  85     }
  86 }
  87
  88 static void print_reboot(sd_journal *j) {
  89     const char *d;
  90     size_t l;
  91     int r = sd_journal_get_data(j, "_BOOT_ID", (const void **)&d, &l);
  92     if (r < 0) {
  93         fprintf(stderr, "Failed  %s\n", strerror(-r));
  94         return;
  95     }
  96
  97     // remove '_BOOT_ID='
  98     d += 9;
  99     l -= 9;
 100
 101     static char bootid[32];
 102     if (bootid[0] != '\0') { // we have some bootid
 103         if (strncmp(bootid, d, l)) { // a new bootid found
 104             strncpy(bootid, d, l);
 105             print_to_buf("-- Reboot --\n", 13);
 106         }
 107     } else {
 108         strncpy(bootid, d, l);
 109     }
 110 }
 111
 112 static void print_timestamp(sd_journal *j) {
 113     uint64_t timestamp = get_timestamp(j);
 114     if (timestamp == (uint64_t)-1) {
 115         return;
 116     }
 117
 118     static uint64_t last_timestamp;
 119     static char timestring[16];
 120     if (timestamp >= (last_timestamp+(1000*1000))) {
 121         timestamp = timestamp / (1000*1000); // usec to sec
 122         struct tm time;
 123         localtime_r((time_t *)&timestamp, &time);
 124         strftime(timestring, 16, "%b %d %T", &time);
 125         last_timestamp = timestamp;
 126     }
 127
 128     print_to_buf(timestring, 15);
 129 }
 130
 131 static void print_pid(sd_journal *j) {
 132     const char *d;
 133     size_t l;
 134     int r = sd_journal_get_data(j, "_PID", (const void **)&d, &l);
 135     if (r < 0) {
 136         // we sometimes have no pid, e.g., kernel messages
 137         return;
 138     }
 139
 140     // remove '_PID='
 141     d += 5;
 142     l -= 5;
 143
 144     print_to_buf("[", 1);
 145     print_to_buf(d, l);
 146     print_to_buf("]", 1);
 147 }
 148
 149 static bool print_field(sd_journal *j, const char *field) {
 150     const char *d;
 151     size_t l;
 152     int r = sd_journal_get_data(j, field, (const void **)&d, &l);
 153     if (r < 0) {
 154         // some fields do not exists
 155         return false;
 156     }
 157
 158     size_t fieldlen = strlen(field)+1;
 159     d += fieldlen;
 160     l -= fieldlen;
 161     print_to_buf(d, l);
 162     return true;
 163 }
 164
 165
 166 static void print_line(sd_journal *j) {
 167     print_reboot(j);
 168     print_timestamp(j);
 169     print_to_buf(" ", 1);
 170     print_field(j, "_HOSTNAME");
 171     print_to_buf(" ", 1);
 172     if (!print_field(j, "SYSLOG_IDENTIFIER") &&
 173             !print_field(j, "_COMM")) {
 174         print_to_buf("unknown", strlen("unknown") - 1);
 175     }
 176     print_pid(j);
 177     print_to_buf(": ", 2);
 178     print_field(j, "MESSAGE");
 179     print_to_buf("\n", 1);
 180 }
 181
 182 static char *progname;
 183
 184 _Noreturn static void usage(char *error) {
 185     if (error) {
 186         fprintf(stderr, "ERROR: %s\n", error);
 187     }
 188     fprintf(stderr, "usage: %s [OPTIONS]\n", progname);
 189     fprintf(stderr,
 190         "  -b <timestamp>\tbegin at this UNIX epoch based timestamp\n"
 191         "  -e <timestamp>\tend at this UNIX epoch based timestamp\n"
 192         "  -d <directory>\tpath to a journal directory\n"
 193         "  -n <integer>\t\tprint the last number entries logged\n"
 194         "  -f <cursor>\t\tprint from this cursor\n"
 195         "  -t <cursor>\t\tprint to this cursor\n"
 196         "  -h \t\t\tthis help\n"
 197         "\n"
 198         "Passing no range option will dump all the available journal\n"
 199         "Giving a range conflicts with -n\n"
 200         "-b and -f conflict\n"
 201         "-e and -t conflict\n");
 202     exit(error ? 1 : 0);
 203 }
 204
 205 static uint64_t arg_to_uint64(const char *argument) {
 206     errno = 0;
 207     char * end;
 208     uint64_t value = strtoull(argument, &end, 10);
 209     if (errno != 0 || *end != '\0') {
 210         fprintf(stderr, "%s is not a valid integer number\n", argument);
 211         exit(1);
 212     }
 213
 214     return value;
 215 }
 216
 217
 218 int main(int argc, char *argv[]) {
 219     uint64_t number = 0;
 220     const char *directory = NULL;
 221     const char *startcursor = NULL;
 222     const char *endcursor = NULL;
 223     uint64_t begin = 0;
 224     uint64_t end = 0;
 225     char c;
 226
 227     progname = argv[0];
 228
 229     while ((c = (char)getopt (argc, argv, "b:e:d:n:f:t:h")) != -1) {
 230         switch (c) {
 231             case 'b':
 232                 begin = arg_to_uint64(optarg);
 233                 begin = begin * 1000 * 1000; // µs
 234                 break;
 235             case 'e':
 236                 end = arg_to_uint64(optarg);
 237                 end = end * 1000 * 1000; // µs
 238                 break;
 239             case 'd':
 240                 directory = optarg;
 241                 break;
 242             case 'n':
 243                 number = arg_to_uint64(optarg);
 244                 break;
 245             case 'f':
 246                 startcursor = optarg;
 247                 break;
 248             case 't':
 249                 endcursor = optarg;
 250                 break;
 251             case 'h':
 252                 usage(NULL);
 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     sd_journal_close(j);
 355
 356     // print remaining buffer
 357     if (write (1, buf, offset) <= 0) {
 358         perror("write to stdout failed");
 359         return 1;
 360     }
 361
 362     return 0;
 363 }
 364