Process information in OpenBSD - unix

Question

I am new to OpenBSD. I have worked on Linux before. I am looking for the directory where I can find the information about the processes running currently. In Linux, we have /proc directory where the entire list is present. But I can not find a similar setup in OpenBSD 4.6. I know there are commands like ps, top and sysctl but I want to get that information through a C code.

Answer 1

procfs in the BSDs is either deprecated or removed altogether, sorry.
That being said, it's also quite usual to have the sources for your system under /usr/src, so you can look at them if you really need to.
Or you can just browse them on the web, eg http://bxr.su/o/bin/ps/ps.c

Answer 2

You can use sysctl to get the running processes in an array of kinfo_proc structures, this type is defined in:
/usr/include/sys/sysctl.h
The top command uses a function named getprocs that works this way, it's defined in:
/usr/src/usr.bin/top/machine.c
The next utility outputs information of all running processes using a slightly modified version of getprocs:
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <kvm.h>
#include <sys/sysctl.h>
#define TRUE 1
#define FALSE 0
struct kinfo_proc * getprocs( int * count, int threads )
{
struct kinfo_proc * procbase = NULL ;
unsigned int maxslp ;
size_t size = sizeof( maxslp ) ;
int maxslp_mib[] = { CTL_VM, VM_MAXSLP } ;
int mib[6] =
{
CTL_KERN,
KERN_PROC,
threads ? KERN_PROC_KTHREAD | KERN_PROC_SHOW_THREADS : KERN_PROC_KTHREAD,
0,
sizeof( struct kinfo_proc ),
0
} ;
if( sysctl( maxslp_mib, 2, &maxslp, &size, NULL, 0 ) == -1 )
{
perror( "list" ) ;
return NULL ;
}
retry:
if( sysctl( mib, 6, NULL, &size, NULL, 0 ) == -1 )
{
perror( "list" ) ;
return NULL ;
}
size = 5 * size / 4 ; /* extra slop */
procbase = (struct kinfo_proc *)malloc( size ) ;
if( procbase == NULL )
{
perror( "list" ) ;
return NULL ;
}
mib[5] = (int)( size / sizeof( struct kinfo_proc ) ) ;
if( sysctl( mib, 6, procbase, &size, NULL, 0 ) )
{
if( errno == ENOMEM )
{
free( procbase ) ;
goto retry;
}
perror( "list" ) ;
return NULL ;
}
*count = (int)( size / sizeof( struct kinfo_proc ) ) ;
return procbase ;
}
int showinfo( int threads )
{
struct kinfo_proc * list, * proc ;
int count, i ;
if( ( list = getprocs( &count, threads ) ) == NULL )
{
return 1 ;
}
proc = list ;
if( threads )
{
for( i = 0 ; i < count ; ++i, ++proc )
{
if( proc->p_tid != -1 )
{
printf( "%s: pid: %d (tid: %d)\n", proc->p_comm, proc->p_pid, proc->p_tid ) ;
}
}
}
else
{
for( i = 0 ; i < count ; ++i, ++proc )
{
printf( "%s: pid: %d\n", proc->p_comm, proc->p_pid ) ;
}
}
return 0 ;
}
int main( int argc, char * argv[] )
{
if( argc == 1 )
{
return showinfo( FALSE ) ;
}
else if( argc == 2 && ( !strcmp( argv[1], "-t" ) || !strcmp( argv[1], "--threads" ) ) )
{
return showinfo( TRUE ) ;
}
else
{
printf( "Usage:\n" ) ;
printf( " list [-h] [-t]\n\n" ) ;
printf( "Options:\n" ) ;
printf( " -h, --help Print this information\n" ) ;
printf( " -t, --threads Show threads\n\n" ) ;
return 0 ;
}
}