Function process_file

src/traffic_logstats/logstats.cc:1768–1887

////////////////////////////////////////////////////////////////////////// Process a file (FD)

///////////////////////////////////////////////////////////////////////////////
// Process a file (FD)
int
process_file(int in_fd, off_t offset, unsigned max_age)
{
  char buffer[MAX_LOGBUFFER_SIZE];
  int  nread, buffer_bytes;

  Dbg(dbg_ctl_logstats, "Processing file [offset=%" PRId64 "].", (int64_t)offset);
  while (true) {
    Dbg(dbg_ctl_logstats, "Reading initial header.");
    buffer[0] = '\0';

    unsigned         first_read_size = sizeof(uint32_t) + sizeof(uint32_t);
    LogBufferHeader *header          = (LogBufferHeader *)&buffer[0];

    // Find the next log header, aligning us properly. This is not
    // particularly optimal, but we should only have to do this
    // once, and hopefully we'll be aligned immediately.
    if (offset > 0) {
      Dbg(dbg_ctl_logstats, "Re-aligning file read.");
      while (true) {
        if (lseek(in_fd, offset, SEEK_SET) < 0) {
          Dbg(dbg_ctl_logstats, "Internal seek failed (offset=%" PRId64 ").", (int64_t)offset);
          return 1;
        }

        // read the first 8 bytes of the header, which will give us the
        // cookie and the version number.
        nread = read(in_fd, buffer, first_read_size);
        if (!nread || EOF == nread) {
          return 0;
        }
        // ensure that this is a valid logbuffer header
        if (header->cookie && (LOG_SEGMENT_COOKIE == header->cookie)) {
          offset = 0;
          break;
        }
        offset++;
      }
      if (!header->cookie) {
        return 0;
      }
    } else {
      nread = read(in_fd, buffer, first_read_size);
      if (!nread || EOF == nread || !header->cookie) {
        return 0;
      }

      // ensure that this is a valid logbuffer header
      if (header->cookie != LOG_SEGMENT_COOKIE) {
        Dbg(dbg_ctl_logstats, "Invalid segment cookie (expected %d, got %d)", LOG_SEGMENT_COOKIE, header->cookie);
        return 1;
      }
    }

    Dbg(dbg_ctl_logstats, "LogBuffer version %d, current = %d", header->version, LOG_SEGMENT_VERSION);
    if (header->version != LOG_SEGMENT_VERSION) {
      return 1;
    }