backend-proto.c

   1 /*
   2  * (c) 2010 Cyrill Gorcunov, gorcunov@gmail.com
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or (at
   7  * your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  17  *
  18  * backend protocol
  19  */
  20
  21 #include <unistd.h>
  22 #include <stdio.h>
  23 #include <stddef.h>
  24 #include <stdlib.h>
  25 #include <stdarg.h>
  26 #include <string.h>
  27 #include <errno.h>
  28 #include <limits.h>
  29 #include <sys/param.h>
  30 #include <sys/types.h>
  31
  32 #include <pthread.h>
  33
  34 #include "backend-proto.h"
  35 #include "util.h"
  36
  37 static pthread_rwlock_t rwlock = PTHREAD_RWLOCK_INITIALIZER;
  38 static struct backend_proto protocols[BACKEND_PROTO_MAX];
  39
  40 struct backend_proto *backend_proto_register(struct backend_proto *proto)
  41 {
  42         struct backend_proto *p = NULL;
  43         unsigned int i, j = -1U;
  44
  45         pthread_rwlock_rdlock(&rwlock);
  46
  47         for (i = 0; i < ARRAY_SIZE(protocols); i++) {
  48                 if (protocols[i].protocol == BACKEND_PROTO_NONE) {
  49                         if (j == -1U)
  50                                 j = i;
  51                 } else if (protocols[i].protocol == proto->protocol) {
  52                         p = &protocols[i];
  53                         goto unlock;
  54                 }
  55         }
  56         if (j != -1U) {
  57                 protocols[j] = *proto;
  58                 p = &protocols[i];
  59                 goto unlock;
  60         }
  61
  62 unlock:
  63         pthread_rwlock_unlock(&rwlock);
  64         return p;
  65 }
  66
  67 void backend_proto_unregister(struct backend_proto *proto)
  68 {
  69         unsigned int i;
  70
  71         pthread_rwlock_wrlock(&rwlock);
  72
  73         for (i = 0; i < ARRAY_SIZE(protocols); i++) {
  74                 if (protocols[i].protocol == proto->protocol) {
  75                         protocols[i].protocol = BACKEND_PROTO_NONE;
  76                         break;
  77                 }
  78         }
  79
  80         pthread_rwlock_unlock(&rwlock);
  81 }
  82
  83 struct backend_proto *backend_proto_find(enum backend_protocols proto)
  84 {
  85         struct backend_proto *p = NULL;
  86         unsigned int i;
  87
  88         pthread_rwlock_rdlock(&rwlock);
  89
  90         for (i = 0; i < ARRAY_SIZE(protocols); i++) {
  91                 if (protocols[i].protocol == proto) {
  92                         p = &protocols[i];
  93                         break;
  94                 }
  95         }
  96
  97         pthread_rwlock_unlock(&rwlock);
  98         return p;
  99 }