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