BSD sysctl+proc example

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#include
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SYSCTL_DECL(_myctl);
SYSCTL_NODE(, OID_AUTO, myctl, CTLFLAG_RW, 0, "A new tree entry");

static int procfs_dotest(PFS_FILL_ARGS)
{
   int error=0;
   const char *pp;
          
   if (uio == NULL) {
        printf("NULL Pointer\n");
        return (EOPNOTSUPP);
    }
    printf("Check Operation\n");
 
    if (uio->uio_rw == UIO_READ) {
        printf("read\n");
        sbuf_printf(sb, "cur pid: %ld\n", (long)td->td_proc->p_pid);
    } else {      
        printf("write\n");
        sbuf_trim(sb);
        sbuf_finish(sb);
        pp = sbuf_data(sb);
        printf("In: %s\n",pp);
    }       
   return (error);
}

static int
procfstest_attr(PFS_ATTR_ARGS)
{
    /* XXX inefficient, split into separate functions */
    vap->va_mode = 0666;
    return 0;
}

static int
procfstest_init(PFS_INIT_ARGS)
{
    struct pfs_node *root;
  
    root = pi->pi_root;
    pfs_create_file(root, "dotest", &procfs_dotest,
        procfstest_attr, NULL, NULL, PFS_RDWR|PFS_RAWWR);
     return 0;
}

static int
procfstest_uninit(PFS_INIT_ARGS)
{
    /* nothing to do, pseudofs will GC */
    return (0);
}


static int
sysctl_int_sample(SYSCTL_HANDLER_ARGS)
{
    static int sysctl_args = 0;
    int error;    

    error = sysctl_handle_int(oidp, &sysctl_args, 0, req);
    if (error != 0 || req->newptr == NULL) { 
        return sysctl_args; 
    } 
    printf("sysctlarg= %d\n",sysctl_args);

    return 0;
}


static int
myctl_modevent(module_t mod, int type, void *unused)
{
 switch (type) {
  case MOD_LOAD:
   printf("Load\n");
     sysctl_register_oid(&sysctl___myctl);
   break;
 
  case MOD_UNLOAD:
   printf("Unload\n");
     sysctl_unregister_oid(&sysctl___myctl);
   break;
 
  default:
   return EINVAL;
 }
 return 0;
}


static moduledata_t myctl_mod = {
    "mysys",
    myctl_modevent,
    0
};

SYSCTL_PROC(_myctl, OID_AUTO, test_my_sysctl, CTLTYPE_INT|CTLFLAG_RW,
             0, 0,
             sysctl_int_sample, "I", "test sysctl ");


DECLARE_MODULE(myctlmod, myctl_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
MODULE_VERSION(myctlmod, 1); 
PSEUDOFS(procfstest, 1);
MODULE_DEPEND(procfstest, procfs, 1, 1, 1);

///////////////////////////////////
////////Test Code
///////////////////////////////////
#include
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#include

int main(int argc,char* argv[] )
{
    int data=0,newdata=8;;
    size_t i=sizeof(data);
    sysctlbyname("myctl.test_my_sysctl",&data,&i,&newdata,sizeof(newdata));
    return 0;
}