gspool_jobdata(3) retrieve the data for a job as a stream


#include <gspool.h>
#include <stdio.h>

FILE *gspool_jobdata(const int fd, const unsigned flags, const slotno_t slotno)

int gspool_jobdata(const int fd, const int outfile, int (*func)(int,void*,unsigned), const unsigned flags, const slotno_t slotno)


Unix and GNU/Linux

The function gspool_jobdata() is used to retrieve the job file of a job.

fd is a file descriptor previously returned by gspool_open. flags is zero, or "GSPOOL_FLAG_IGNORESEQ" to ignore changes since the job list was last read.

slotno is the slot number corresponding to the job previously returned by functions such as gspool_joblist or gspool_jobfindslot.

The result is a "FILE" pointer which can be used with all standard I/O input functions such as fgets(3), getc(3) etc. At the end of the data fclose(3) must be called. For reasons of sychronisation the file should be read to the end before other operations are attempted.

If an error is detected, gspool_jobdata returns "NULL" and an error code is placed in the external variable "gsapi_dataerror".


The second format of the gspool_jobdata function is for use by Windows programs, as there is no acceptable equivalent of the pipe(2) construct.

The second argument outfile is (possibly) a file handle to the file from to which the job data is passed as the first argument to func.

The third argument func is a function with the same specifications as "write", indeed it may very well be "write". The main reason for doing it this way is that some versions of Windows do strange things if "write" is invoked from within a DLL.

Other aspects of the interface are similar to the Unix routine, apart from the routine returning zero for success and an error code for failure rather than a "FILE*" or "NULL". For consistency with the Unix version, the external variable "gsapi_dataerror" is also assigned any error code returned.


If an error is detected the external variable "gsapi_dataerror" will be set to the error code. Error codes which might be returned are:
Invalid file descriptor
failure writing to network
failure reading from network
job not found
job does not belong to user
sequence error, job may be out of data
Invalid slot number


An example to retrieve the data for a job:

 int     fd, ret, ch;
 slotno_t slot, *list;
 FILE *inf;
 fd = gspool_open("myhost", (char *) 0, 0);
 if  (fd < 0) { /* error handling */
 /* Select a job slot and assign this to "slot" */
 inf = gspool_jobdata(fd, 0, slot);
 if (!inf)  { /* handle errors */
 while ((ch = getc(inf)) != EOF)


Copyright (c) 2009 Free Software Foundation, Inc. This is free software. You may redistribute copies of it under the terms of the GNU General Public License <>. There is NO WARRANTY, to the extent permitted by law.


John M Collins, Xi Software Ltd.