hpcups does not provide PAGE: messages for CUPS page logging

What I found out so far is this:

- We've to look at whole process chains built out-of multiple filters and one backend process.
- hplip uses hp as backend
- hplip writes PAGE: 1 1 if and only if file descriptor fd is not zero (hp.c):

      if (fd != 0)
      {
         fputs("PAGE: 1 1\n", stderr);
         lseek(fd, 0, SEEK_SET);
      }

- hplip sets fd to zero if argc equals 6 (hp.c)
   if (argc == 6)
   {
      fd = 0; /* use stdin. */
      copies = 1;
   }
That means backend hp does not write PAGE: messages to cupsd if operating in normal cups environment.

- cups' job.c sets argv[6] to NULL after first filter process is started. That makes sense because argv[6] is a pointer to print job source file and only first filter needs to know about that. All other processes build a filter chain reading from stdin and writing to stdout. It's cupsd's task to connect processes and pipes the right way.

taken from job.c of cups 1.3.11, lines 3382ff
   cupsdLogMessage(CUPSD_LOG_INFO, "[Job %d] Started filter %s (PID %d)",
                    job->id, command, pid);

    argv[6] = NULL;
    slot = !slot;
  }
This looks the same in job.c taken from 1.4.2 ( * "$Id: job.c 8801 2009-08-29 06:05:14Z mike $" )

IMHO backend hp is not compatible with current cups implementation.

Suggestion: move fputs(...) in front of if (fd != 0) { ... }:

      fputs("PAGE: 1 1\n", stderr);
      if (fd != 0)
      {
         /* start reading from beginning of given file */
         lseek(fd, 0, SEEK_SET);
      }

BR / Martin