| 1 | /* Reincarnation Server. This servers starts new system services and detects
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| 2 | * they are exiting. In case of errors, system services can be restarted.
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| 3 | *
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| 4 | * Created:
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| 5 | * Jul 22, 2005 by Jorrit N. Herder
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| 6 | */
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| 7 |
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| 8 | #include "rs.h"
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| 9 |
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| 10 | /* Set debugging level to 0, 1, or 2 to see no, some, all debug output. */
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| 11 | #define DEBUG_LEVEL 1
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| 12 | #define DPRINTF if (DEBUG_LEVEL > 0) printf
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| 13 |
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| 14 | /* Allocate space for the global variables. */
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| 15 | message m_in; /* the input message itself */
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| 16 | message m_out; /* the output message used for reply */
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| 17 | int who; /* caller's proc number */
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| 18 | int callnr; /* system call number */
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| 19 |
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| 20 | /* Declare some local functions. */
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| 21 | FORWARD _PROTOTYPE(void init_server, (void) );
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| 22 | FORWARD _PROTOTYPE(void get_work, (void) );
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| 23 | FORWARD _PROTOTYPE(void reply, (int whom, int result) );
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| 24 |
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| 25 | /*===========================================================================*
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| 26 | * main *
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| 27 | *===========================================================================*/
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| 28 | PUBLIC int main(void)
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| 29 | {
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| 30 | /* This is the main routine of this service. The main loop consists of
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| 31 | * three major activities: getting new work, processing the work, and
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| 32 | * sending the reply. The loop never terminates, unless a panic occurs.
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| 33 | */
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| 34 | int result;
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| 35 | sigset_t sigset;
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| 36 |
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| 37 | /* Initialize the server, then go to work. */
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| 38 | init_server();
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| 39 |
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| 40 | /* Main loop - get work and do it, forever. */
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| 41 | while (TRUE) {
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| 42 |
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| 43 | /* Wait for incoming message, sets 'callnr' and 'who'. */
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| 44 | get_work();
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| 45 |
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| 46 | switch (callnr) {
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| 47 | case SYS_SIG:
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| 48 | /* Signals are passed by means of a notification message from SYSTEM.
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| 49 | * Extract the map of pending signals from the notification argument.
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| 50 | */
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| 51 | sigset = (sigset_t) m_in.NOTIFY_ARG;
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| 52 |
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| 53 | if (sigismember(&sigset, SIGCHLD)) {
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| 54 | /* A child of this server exited. Take action. */
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| 55 | do_exit(&m_in);
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| 56 | }
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| 57 | if (sigismember(&sigset, SIGUSR1)) {
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| 58 | do_start(&m_in);
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| 59 | }
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| 60 | if (sigismember(&sigset, SIGTERM)) {
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| 61 | /* Nothing to do on shutdown. */
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| 62 | }
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| 63 | if (sigismember(&sigset, SIGKSTOP)) {
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| 64 | /* Nothing to do on shutdown. */
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| 65 | }
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| 66 | continue;
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| 67 | case SRV_UP:
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| 68 | result = do_start(&m_in);
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| 69 | break;
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| 70 | case SRV_DOWN:
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| 71 | result = do_stop(&m_in);
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| 72 | break;
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| 73 | default:
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| 74 | printf("Warning, RS got unexpected request %d from %d\n",
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| 75 | m_in.m_type, m_in.m_source);
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| 76 | result = EINVAL;
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| 77 | }
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| 78 |
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| 79 | /* Finally send reply message, unless disabled. */
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| 80 | if (result != EDONTREPLY) {
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| 81 | reply(who, result);
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| 82 | }
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| 83 | }
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| 84 | }
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| 85 |
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| 86 |
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| 87 | /*===========================================================================*
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| 88 | * init_server *
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| 89 | *===========================================================================*/
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| 90 | PRIVATE void init_server(void)
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| 91 | {
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| 92 | /* Initialize the reincarnation server. */
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| 93 | struct sigaction sa;
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| 94 |
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| 95 | /* Install signal handlers. Ask PM to transform signal into message. */
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| 96 | sa.sa_handler = SIG_MESS;
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| 97 | sigemptyset(&sa.sa_mask);
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| 98 | sa.sa_flags = 0;
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| 99 | if (sigaction(SIGCHLD, &sa, NULL)<0) panic("RS","sigaction failed", errno);
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| 100 | if (sigaction(SIGTERM, &sa, NULL)<0) panic("RS","sigaction failed", errno);
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| 101 | if (sigaction(SIGABRT, &sa, NULL)<0) panic("RS","sigaction failed", errno);
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| 102 | if (sigaction(SIGHUP, &sa, NULL)<0) panic("RS","sigaction failed", errno);
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| 103 | }
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| 104 |
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| 105 |
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| 106 | /*===========================================================================*
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| 107 | * get_work *
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| 108 | *===========================================================================*/
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| 109 | PRIVATE void get_work()
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| 110 | {
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| 111 | int status = 0;
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| 112 | status = receive(ANY, &m_in); /* this blocks until message arrives */
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| 113 | if (OK != status)
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| 114 | panic("RS","failed to receive message!", status);
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| 115 | who = m_in.m_source; /* message arrived! set sender */
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| 116 | callnr = m_in.m_type; /* set function call number */
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| 117 | }
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| 118 |
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| 119 |
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| 120 | /*===========================================================================*
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| 121 | * reply *
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| 122 | *===========================================================================*/
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| 123 | PRIVATE void reply(who, result)
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| 124 | int who; /* destination */
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| 125 | int result; /* report result to replyee */
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| 126 | {
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| 127 | int send_status;
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| 128 | m_out.m_type = result; /* build reply message */
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| 129 | send_status = send(who, &m_out); /* send the message */
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| 130 | if (OK != send_status)
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| 131 | panic("RS", "unable to send reply!", send_status);
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| 132 | }
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| 133 |
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| 134 |
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| 135 |
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