As per the man page, pstat_getdisk() call returns the number of instances, which could be 0 upon successful completion, otherwise a value of -1 is returned.

Please have a look at this sample program ->

#include <stdio.h>
#include <sys/pstat.h>

int main()
{
int j = 0, ret;
struct pst_diskinfo sDiskData;

while(1)
{
ret = pstat_getdisk(&sDiskData, sizeof(sDiskData), 1, j);
if(ret<0)
{
printf("\nReturned with code %d \n",ret);
break;
}
printf("\n Ret Code : %d , Device Name : %s%d",ret,sDiskData.psd_drv_name.psd_name,sDiskData.psd_instance);
j++;
}
return 0;
}

On HP-UX 11.11 and 11.23, the call pstat_getdisk() returns series of ‘1’s then single ‘0’ and finally ‘-1’ and the program terminates successfully.

On HP-UX 11.31 the call pstat_getdisk() returns series of ‘1’s followed by series of ‘0’s and never returns ‘-1’, so the same program never terminates.

The workaround would be to replace the condition
if(ret<0)
with
if(ret==0)

But, will this call always returns ‘1’s followed by ‘0’s or there can be a case in which the call will return ‘0’ in between?

In another way, can we get an invalid index in between or all the valid disks are in sequence only?