CUPS print file segmentation fault - c

Question

I am trying to make a CUPS print system. I want to get printer status, how many pages printed sofar etc.
To do that, I am executing example programs given in CUPS examples.
#include <cups/cups.h>
#include <stdio.h>
int main(){
int num_options;
cups_option_t *options;
cups_dest_t *dests;
int num_dests = cupsGetDests(&dests);
cups_dest_t *dest = cupsGetDest("name", NULL, num_dests, dests);
int job_id;
/* Print a single file */
job_id = cupsPrintFile(dest->name, "testfile.txt", "Test Print", num_options, options);
cupsFreeDests(num_dests, dests);
return 0;
}
I compile it using gcc myfile.c -o myout -lcups
When I try to execute ./myout
I am getting
Segmentation fault
I am using Raspberry-pi 3 board as my CUPS server.
Thanks in advance.

Answer 1

dest is pointing to non-valid address.
cups_dest_t *dest; // declared but not initialized or assigned afterwards
So dereferencing it ( cupsPrintFile(dest->name... ) is UB and can cause SegFault.
This is how you should have used it (taken from here):
#include <cups/cups.h>
cups_dest_t *dests;
int num_dests = cupsGetDests(&dests);
cups_dest_t *dest = cupsGetDest("name", NULL, num_dests, dests);
/* do something with dest */
cupsFreeDests(num_dests, dests);
Update:
Your code doesn't handle some of the variables (i.e. leaves them uninitialized - bad). The first one I see is cups_option_t *options;. Take care of all of your variables, and if that's not working - debug.
int main(){
int num_options;
cups_option_t *options; // add a call to "cupsAddOption("first", "value", num_options, &options);"
cups_dest_t *dests;
int num_dests = cupsGetDests(&dests);
cups_dest_t *dest = cupsGetDest("name", NULL, num_dests, dests);
int job_id;
/* Print a single file */
job_id = cupsPrintFile(dest->name, "testfile.txt", "Test Print", num_options, options); // options is used here but is uninitialized
cupsFreeDests(num_dests, dests);
return 0;
}