sdjournal cursor

#include <systemd/sd-journal.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

int main(int argc, const char **argv) {
  int res;
  sd_journal *j;
  const char *journal_dir = "/var/log/journal";
  if (argc > 1) {
    journal_dir = argv[1];
  }
  printf("Using journal in %s\n", journal_dir);
  assert(sd_journal_open_directory(&j, journal_dir, SD_JOURNAL_SYSTEM) == 0);
  assert(sd_journal_seek_tail(j) == 0);
  res = sd_journal_previous_skip(j, 2);
  printf("prev skip res: %d\n", res);
  char *cursor = malloc(1024);
  cursor[0] = '\0';
  sd_journal_get_cursor(j, &cursor);
  printf("Cursor: %s\n", cursor);
  free(cursor);
}