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Annotation of 43BSD/old/talk/table.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1983 Regents of the University of California.
        !             3:  * All rights reserved.  The Berkeley software License Agreement
        !             4:  * specifies the terms and conditions for redistribution.
        !             5:  */
        !             6: 
        !             7: #ifndef lint
        !             8: static char sccsid[] = "@(#)table.c    5.1 (Berkeley) 6/6/85";
        !             9: #endif not lint
        !            10: 
        !            11: /*
        !            12:  * Routines to handle insertion, deletion, etc on the table
        !            13:  * of requests kept by the daemon. Nothing fancy here, linear
        !            14:  * search on a double-linked list. A time is kept with each 
        !            15:  * entry so that overly old invitations can be eliminated.
        !            16:  *
        !            17:  * Consider this a mis-guided attempt at modularity
        !            18:  */
        !            19: #include <stdio.h>
        !            20: #include <sys/time.h>
        !            21: 
        !            22: #include "ctl.h"
        !            23: 
        !            24: #define MAX_ID 16000   /* << 2^15 so I don't have sign troubles */
        !            25: 
        !            26: #define NIL ((TABLE_ENTRY *)0)
        !            27: 
        !            28: extern int debug;
        !            29: struct timeval tp;
        !            30: struct timezone *txp;
        !            31: 
        !            32: typedef struct table_entry TABLE_ENTRY;
        !            33: 
        !            34: struct table_entry {
        !            35:        CTL_MSG request;
        !            36:        long    time;
        !            37:        TABLE_ENTRY *next;
        !            38:        TABLE_ENTRY *last;
        !            39: };
        !            40: 
        !            41: TABLE_ENTRY    *table = NIL;
        !            42: CTL_MSG *find_request();
        !            43: CTL_MSG *find_match();
        !            44: char   *malloc();
        !            45: 
        !            46: /*
        !            47:  * Look in the table for an invitation that matches the current
        !            48:  * request looking for an invitation
        !            49:  */
        !            50: CTL_MSG *
        !            51: find_match(request)
        !            52:        CTL_MSG *request;
        !            53: {
        !            54:        TABLE_ENTRY *ptr;
        !            55:        extern FILE *debugout;
        !            56:        long current_time;
        !            57: 
        !            58:        gettimeofday(&tp, &txp);
        !            59:        current_time = tp.tv_sec;
        !            60:        if (debug) {
        !            61:                fprintf(debugout, "Entering Look-Up with : \n");
        !            62:                print_request(request);
        !            63:        }
        !            64:        for (ptr = table; ptr != NIL; ptr = ptr->next) {
        !            65:                if ((ptr->time - current_time) > MAX_LIFE) {
        !            66:                        /* the entry is too old */
        !            67:                        if (debug) {
        !            68:                                fprintf(debugout
        !            69:                                        ,"Deleting expired entry : \n");
        !            70:                                print_request(&ptr->request);
        !            71:                        }
        !            72:                        delete(ptr);
        !            73:                        continue;
        !            74:                }
        !            75:                if (debug)
        !            76:                        print_request(&ptr->request);
        !            77:                if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
        !            78:                    strcmp(request->r_name, ptr->request.l_name) == 0 &&
        !            79:                     ptr->request.type == LEAVE_INVITE)
        !            80:                        return (&ptr->request);
        !            81:        }
        !            82:        return ((CTL_MSG *)0);
        !            83: }
        !            84: 
        !            85: /*
        !            86:  * Look for an identical request, as opposed to a complimentary
        !            87:  * one as find_match does 
        !            88:  */
        !            89: CTL_MSG *
        !            90: find_request(request)
        !            91:        CTL_MSG *request;
        !            92: {
        !            93:        TABLE_ENTRY *ptr;
        !            94:        extern FILE *debugout;
        !            95:        long current_time;
        !            96: 
        !            97:        gettimeofday(&tp, &txp);
        !            98:        current_time = tp.tv_sec;
        !            99:        /*
        !           100:         * See if this is a repeated message, and check for
        !           101:         * out of date entries in the table while we are it.
        !           102:         */
        !           103:        if (debug) {
        !           104:                fprintf(debugout, "Entering find_request with : \n");
        !           105:                print_request(request);
        !           106:        }
        !           107:        for (ptr = table; ptr != NIL; ptr = ptr->next) {
        !           108:                if ((ptr->time - current_time) > MAX_LIFE) {
        !           109:                        /* the entry is too old */
        !           110:                        if (debug) {
        !           111:                                fprintf(debugout
        !           112:                                        , "Deleting expired entry : \n");
        !           113:                                print_request(&ptr->request);
        !           114:                        }
        !           115:                        delete(ptr);
        !           116:                        continue;
        !           117:                }
        !           118:                if (debug)
        !           119:                        print_request(&ptr->request);
        !           120:                if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
        !           121:                    strcmp(request->l_name, ptr->request.l_name) == 0 &&
        !           122:                    request->type == ptr->request.type &&
        !           123:                    request->pid == ptr->request.pid) {
        !           124:                        /* update the time if we 'touch' it */
        !           125:                        ptr->time = current_time;
        !           126:                        return (&ptr->request);
        !           127:                }
        !           128:        }
        !           129:        return ((CTL_MSG *)0);
        !           130: }
        !           131: 
        !           132: insert_table(request, response)
        !           133:        CTL_MSG *request;
        !           134:        CTL_RESPONSE *response;
        !           135: {
        !           136:        TABLE_ENTRY *ptr;
        !           137:        long current_time;
        !           138: 
        !           139:        gettimeofday(&tp, &txp);
        !           140:        current_time = tp.tv_sec;
        !           141:        response->id_num = request->id_num = new_id();
        !           142:        /* insert a new entry into the top of the list */
        !           143:        ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
        !           144:        if (ptr == NIL) {
        !           145:                fprintf(stderr, "malloc in insert_table");
        !           146:                exit(1);
        !           147:        }
        !           148:        ptr->time = current_time;
        !           149:        ptr->request = *request;
        !           150:        ptr->next = table;
        !           151:        if (ptr->next != NIL)
        !           152:                ptr->next->last = ptr;
        !           153:        ptr->last = NIL;
        !           154:        table = ptr;
        !           155: }
        !           156: 
        !           157: /*
        !           158:  * Generate a unique non-zero sequence number
        !           159:  */
        !           160: new_id()
        !           161: {
        !           162:        static int current_id = 0;
        !           163: 
        !           164:        current_id = (current_id + 1) % MAX_ID;
        !           165:        /* 0 is reserved, helps to pick up bugs */
        !           166:        if (current_id == 0)
        !           167:                current_id = 1;
        !           168:        return (current_id);
        !           169: }
        !           170: 
        !           171: /*
        !           172:  * Delete the invitation with id 'id_num'
        !           173:  */
        !           174: delete_invite(id_num)
        !           175:        int id_num;
        !           176: {
        !           177:        TABLE_ENTRY *ptr;
        !           178:        extern FILE *debugout;
        !           179: 
        !           180:        ptr = table;
        !           181: 
        !           182:        if (debug)
        !           183:                fprintf(debugout,"Entering delete_invite with %d\n", id_num);
        !           184:        for (ptr = table; ptr != NIL; ptr = ptr->next) {
        !           185:                if (ptr->request.id_num == id_num)
        !           186:                        break;
        !           187:                if (debug)
        !           188:                        print_request(&ptr->request);
        !           189:        }
        !           190:        if (ptr != NIL) {
        !           191:                delete(ptr);
        !           192:                return (SUCCESS);
        !           193:        }
        !           194:        return (NOT_HERE);
        !           195: }
        !           196: 
        !           197: /*
        !           198:  * Classic delete from a double-linked list
        !           199:  */
        !           200: delete(ptr)
        !           201:        TABLE_ENTRY *ptr;
        !           202: {
        !           203:        extern FILE *debugout;
        !           204: 
        !           205:        if (debug) {
        !           206:                fprintf(debugout, "Deleting : ");
        !           207:                print_request(&ptr->request);
        !           208:        }
        !           209:        if (table == ptr)
        !           210:                table = ptr->next;
        !           211:        else if (ptr->last != NIL)
        !           212:                ptr->last->next = ptr->next;
        !           213:        if (ptr->next != NIL)
        !           214:                ptr->next->last = ptr->last;
        !           215:        free((char *)ptr);
        !           216: }

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