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1.1 root 1: /* $Header: /a/guest/moore/talk/RCS/table.c,v 1.9 83/07/06 00:11:38 moore Exp $ */
2:
3: /* routines to handle insertion, deletion, etc on the table
4: of requests kept by the daemon. Nothing fancy here, linear
5: search on a double-linked list. A time is kept with each
6: entry so that overly old invitations can be eliminated.
7:
8: Consider this a mis-guided attempt at modularity
9: */
10:
11: #include "ctl.h"
12: #include <sys/time.h>
13:
14: #define MAX_ID 16000 /* << 2^15 so I don't have sign troubles */
15:
16: #define NIL ( (TABLE_ENTRY *) 0)
17:
18: extern int debug;
19: struct timeval tp;
20: struct timezone *txp;
21:
22: typedef struct table_entry TABLE_ENTRY;
23:
24: struct table_entry {
25: CTL_MSG request;
26: long time;
27: TABLE_ENTRY *next;
28: TABLE_ENTRY *last;
29: };
30:
31: TABLE_ENTRY *table = NIL;
32: CTL_MSG *find_request();
33: CTL_MSG *find_match();
34: char *malloc();
35:
36: /*
37: * Look in the table for an invitation that matches the current
38: * request looking for an invitation
39: */
40:
41: CTL_MSG *find_match(request)
42: CTL_MSG *request;
43: {
44: TABLE_ENTRY *ptr;
45: long current_time;
46:
47: gettimeofday(&tp, &txp);
48: current_time = tp.tv_sec;
49:
50: ptr = table;
51:
52: if (debug) {
53: printf("Entering Look-Up with : \n");
54: print_request(request);
55: }
56:
57: while (ptr != NIL) {
58:
59: if ( (ptr->time - current_time) > MAX_LIFE ) {
60: /* the entry is too old */
61: if (debug) printf("Deleting expired entry : \n");
62: if (debug) print_request(&ptr->request);
63: delete(ptr);
64: ptr = ptr->next;
65: continue;
66: }
67:
68: if (debug) print_request(&ptr->request);
69:
70: if ( strcmp(request->l_name, ptr->request.r_name) == 0 &&
71: strcmp(request->r_name, ptr->request.l_name) == 0 &&
72: ptr->request.type == LEAVE_INVITE ) {
73: return(&ptr->request);
74: }
75:
76: ptr = ptr->next;
77: }
78:
79: return((CTL_MSG *) 0);
80: }
81:
82: /*
83: * look for an identical request, as opposed to a complimentary
84: * one as find_match does
85: */
86:
87: CTL_MSG *find_request(request)
88: CTL_MSG *request;
89: {
90: TABLE_ENTRY *ptr;
91: long current_time;
92:
93: gettimeofday(&tp, &txp);
94: current_time = tp.tv_sec;
95:
96: /* See if this is a repeated message, and check for
97: out of date entries in the table while we are it.
98: */
99:
100: ptr = table;
101:
102: if (debug) {
103: printf("Entering find_request with : \n");
104: print_request(request);
105: }
106:
107: while (ptr != NIL) {
108:
109: if ( (ptr->time - current_time) > MAX_LIFE ) {
110: /* the entry is too old */
111: if (debug) printf("Deleting expired entry : \n");
112: if (debug) print_request(&ptr->request);
113: delete(ptr);
114: ptr = ptr->next;
115: continue;
116: }
117:
118: if (debug) print_request(&ptr->request);
119:
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:
125: /* update the time if we 'touch' it */
126: ptr->time = current_time;
127: return(&ptr->request);
128: }
129:
130: ptr = ptr->next;
131: }
132:
133: return((CTL_MSG *) 0);
134: }
135:
136: insert_table(request, response)
137: CTL_MSG *request;
138: CTL_RESPONSE *response;
139: {
140: TABLE_ENTRY *ptr;
141: long current_time;
142:
143: gettimeofday(&tp, &txp);
144: current_time = tp.tv_sec;
145:
146: response->id_num = request->id_num = new_id();
147:
148: /* insert a new entry into the top of the list */
149:
150: ptr = (TABLE_ENTRY *) malloc(sizeof(TABLE_ENTRY));
151:
152: if (ptr == NIL) {
153: print_error("malloc in insert_table");
154: }
155:
156: ptr->time = current_time;
157: ptr->request = *request;
158:
159: ptr->next = table;
160: if (ptr->next != NIL) {
161: ptr->next->last = ptr;
162: }
163: ptr->last = NIL;
164: table = ptr;
165: }
166:
167: /* generate a unique non-zero sequence number */
168:
169: new_id()
170: {
171: static int current_id = 0;
172:
173: current_id = (current_id + 1) % MAX_ID;
174:
175: /* 0 is reserved, helps to pick up bugs */
176:
177: if (current_id == 0) current_id = 1;
178:
179: return(current_id);
180: }
181:
182: /* delete the invitation with id 'id_num' */
183:
184: delete_invite(id_num)
185: int id_num;
186: {
187: TABLE_ENTRY *ptr;
188:
189: ptr = table;
190:
191: if (debug) printf("Entering delete_invite with %d\n", id_num);
192:
193: while (ptr != NIL && ptr->request.id_num != id_num) {
194: if (debug) print_request(&ptr->request);
195: ptr = ptr->next;
196: }
197:
198: if (ptr != NIL) {
199: delete(ptr);
200: return(SUCCESS);
201: }
202:
203: return(NOT_HERE);
204: }
205:
206: /* classic delete from a double-linked list */
207:
208: delete(ptr)
209: TABLE_ENTRY *ptr;
210: {
211: if (debug) printf("Deleting : ");
212: if (debug) print_request(&ptr->request);
213:
214: if (table == ptr) {
215: table = ptr->next;
216: } else if (ptr->last != NIL) {
217: ptr->last->next = ptr->next;
218: }
219:
220: if (ptr->next != NIL) {
221: ptr->next->last = ptr->last;
222: }
223:
224: free((char *) ptr);
225: }
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