minix/kernel/dummy.c
2005-04-21 14:53:53 +00:00

86 lines
2.9 KiB
C

/* A dummy task. Used to safely remove old tasks, and get notices if they get
* called by accident (i.e., because of some bug...).
*
* Created:
* Jul 27, 2004 by Jorrit N. Herder
*/
#include "kernel.h"
#include "proc.h"
#include <minix/com.h>
/* Allocated space for the global variables. */
message m_in; /* the input message itself */
message m_out; /* the output message used for reply */
int who; /* caller's proc number */
int callnr; /* system call number */
/* Declare some local functions. */
FORWARD _PROTOTYPE(void get_work, (void) );
FORWARD _PROTOTYPE(void reply, (int whom, int result) );
/*===========================================================================*
* dummy_task *
*===========================================================================*/
PUBLIC void dummy_task()
{
/* This is the main routine of this service. In principle this should block
* forever on getting new work - the dummy task is not supposed to be called.
* If new work is received, somehow, diagnostics are printed.
*/
int result;
/* kprintf("DUMMY: do nothing kernel task started (proc. nr %d).\n",
proc_number(proc_ptr)); */
/* Main loop - get work and do it, forever. */
while (TRUE) {
/* Wait for incoming message, sets 'callnr' and 'who'. */
get_work();
/* There is work to do! (re)set some variables first. */
result = EINVAL; /* illegal send to dummy task */
/* Print diagnostics: this was not supposed to happen. */
kprintf("Dummy task: request received from %d.\n", who);
/* Finally send reply message, unless disabled. */
if (result != EDONTREPLY) {
reply(who, result);
}
}
}
/*===========================================================================*
* get_work *
*===========================================================================*/
PRIVATE void get_work()
{
int status = 0;
status = receive(ANY, &m_in); /* this blocks until message arrives */
if (OK != status)
kprintf("Dummy task failed to receive message: %d", status);
who = m_in.m_source; /* message arrived! set sender */
callnr = m_in.m_type; /* set function call number */
}
/*===========================================================================*
* reply *
*===========================================================================*/
PRIVATE void reply(who, result)
int who; /* destination */
int result; /* report result to replyee */
{
int send_status;
m_out.m_type = result; /* build reply message */
send_status = send(who, &m_out); /* send the message */
if (OK != send_status)
kprintf("Dummy task unable to send reply: %d", send_status);
}