minix/servers/rs/rs.c
2005-08-25 12:33:09 +00:00

135 lines
4.6 KiB
C

/* Reincarnation Server. This servers starts new system services and detects
* they are exiting. In case of errors, system services can be restarted.
*
* Created:
* Jul 22, 2005 by Jorrit N. Herder
*/
#include "rs.h"
/* Set debugging level to 0, 1, or 2 to see no, some, all debug output. */
#define DEBUG_LEVEL 1
#define DPRINTF if (DEBUG_LEVEL > 0) printf
/* Allocate 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 init_server, (void) );
FORWARD _PROTOTYPE(void get_work, (void) );
FORWARD _PROTOTYPE(void reply, (int whom, int result) );
/*===========================================================================*
* main *
*===========================================================================*/
PUBLIC int main(void)
{
/* This is the main routine of this service. The main loop consists of
* three major activities: getting new work, processing the work, and
* sending the reply. The loop never terminates, unless a panic occurs.
*/
int result;
sigset_t sigset;
/* Initialize the server, then go to work. */
init_server();
/* Main loop - get work and do it, forever. */
while (TRUE) {
/* Wait for incoming message, sets 'callnr' and 'who'. */
get_work();
switch (callnr) {
case SYS_SIG:
/* Signals are passed by means of a notification message from SYSTEM.
* Extract the map of pending signals from the notification argument.
*/
sigset = (sigset_t) m_in.NOTIFY_ARG;
if (sigismember(&sigset, SIGCHLD)) {
/* A child of this server exited. Take action. */
do_exit(&m_in);
}
if (sigismember(&sigset, SIGUSR1)) {
do_start(&m_in);
}
if (sigismember(&sigset, SIGTERM)) {
/* Nothing to do on shutdown. */
}
if (sigismember(&sigset, SIGKSTOP)) {
/* Nothing to do on shutdown. */
}
continue;
case SRV_UP:
result = do_start(&m_in);
break;
case SRV_DOWN:
result = do_stop(&m_in);
break;
default:
printf("Warning, RS got unexpected request %d from %d\n",
m_in.m_type, m_in.m_source);
result = EINVAL;
}
/* Finally send reply message, unless disabled. */
if (result != EDONTREPLY) {
reply(who, result);
}
}
}
/*===========================================================================*
* init_server *
*===========================================================================*/
PRIVATE void init_server(void)
{
/* Initialize the reincarnation server. */
struct sigaction sa;
/* Install signal handlers. Ask PM to transform signal into message. */
sa.sa_handler = SIG_MESS;
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
if (sigaction(SIGCHLD, &sa, NULL)<0) panic("RS","sigaction failed", errno);
if (sigaction(SIGTERM, &sa, NULL)<0) panic("RS","sigaction failed", errno);
if (sigaction(SIGABRT, &sa, NULL)<0) panic("RS","sigaction failed", errno);
if (sigaction(SIGHUP, &sa, NULL)<0) panic("RS","sigaction failed", errno);
}
/*===========================================================================*
* get_work *
*===========================================================================*/
PRIVATE void get_work()
{
int status = 0;
status = receive(ANY, &m_in); /* this blocks until message arrives */
if (OK != status)
panic("RS","failed to receive message!", 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)
panic("RS", "unable to send reply!", send_status);
}