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Annotation of 42BSD/ucb/talk/ctl_transact.c, revision 1.1

1.1     ! root        1: #include "talk_ctl.h"
        !             2: #include <sys/time.h>
        !             3: 
        !             4: #define CTL_WAIT 2     /* the amount of time to wait for a 
        !             5:                           response, in seconds */
        !             6: 
        !             7: 
        !             8:     /*
        !             9:      * SOCKDGRAM is unreliable, so we must repeat messages if we have
        !            10:      * not recieved an acknowledgement within a reasonable amount
        !            11:      * of time
        !            12:      */
        !            13: 
        !            14: ctl_transact(target, msg, type, response)
        !            15: struct in_addr target;
        !            16: CTL_MSG msg;
        !            17: int type;
        !            18: CTL_RESPONSE *response;
        !            19: {
        !            20:     struct sockaddr junk;
        !            21:     int read_mask;
        !            22:     int ctl_mask;
        !            23:     int nready;
        !            24:     int cc;
        !            25:     int junk_size;
        !            26:     struct timeval wait;
        !            27: 
        !            28:     wait.tv_sec = CTL_WAIT;
        !            29:     wait.tv_usec = 0;
        !            30: 
        !            31:     msg.type = type;
        !            32: 
        !            33:     daemon_addr.sin_addr = target;
        !            34:     daemon_addr.sin_port = daemon_port;
        !            35: 
        !            36:     ctl_mask = 1 << ctl_sockt;
        !            37: 
        !            38:        /*
        !            39:         * keep sending the message until a response of the right
        !            40:         * type is obtained
        !            41:         */
        !            42:     do {
        !            43:            /* keep sending the message until a response is obtained */
        !            44: 
        !            45:        do {
        !            46:            cc = sendto(ctl_sockt, (char *)&msg, sizeof(CTL_MSG), 0,
        !            47:                        &daemon_addr, sizeof(daemon_addr));
        !            48: 
        !            49:            if (cc != sizeof(CTL_MSG)) {
        !            50:                if (errno == EINTR) {
        !            51:                        /* we are returning from an interupt */
        !            52:                    continue;
        !            53:                } else {
        !            54:                    p_error("Error on write to talk daemon");
        !            55:                }
        !            56:            }
        !            57: 
        !            58:            read_mask = ctl_mask;
        !            59: 
        !            60:            while ((nready = select(32, &read_mask, 0, 0, &wait)) < 0) {
        !            61:                if (errno == EINTR) {
        !            62:                        /* we are returning from an interupt */
        !            63:                    continue;
        !            64:                } else {
        !            65:                    p_error("Error on waiting for response from daemon");
        !            66:                }
        !            67:            }
        !            68:        } while (nready == 0);
        !            69: 
        !            70:            /* keep reading while there are queued messages 
        !            71:               (this is not necessary, it just saves extra
        !            72:               request/acknowledgements being sent)
        !            73:             */
        !            74: 
        !            75:        do {
        !            76: 
        !            77:            junk_size = sizeof(junk);
        !            78:            cc = recvfrom(ctl_sockt, (char *) response,
        !            79:                           sizeof(CTL_RESPONSE), 0, &junk, &junk_size );
        !            80:            if (cc < 0) {
        !            81:                if (errno == EINTR) {
        !            82:                    continue;
        !            83:                }
        !            84:                p_error("Error on read from talk daemon");
        !            85:            }
        !            86: 
        !            87:            read_mask = ctl_mask;
        !            88: 
        !            89:                /* an immediate poll */
        !            90: 
        !            91:            timerclear(&wait);
        !            92:            nready = select(32, &read_mask, 0, 0, &wait);
        !            93: 
        !            94:        } while ( nready > 0 && response->type != type);
        !            95: 
        !            96:     } while (response->type != type);
        !            97: }

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