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Member "bind-9.17.5/lib/isc/astack.c" (4 Sep 2020, 1814 Bytes) of package /linux/misc/dns/bind9/9.17.5/bind-9.17.5.tar.xz:


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    1 /*
    2  * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
    3  *
    4  * This Source Code Form is subject to the terms of the Mozilla Public
    5  * License, v. 2.0. If a copy of the MPL was not distributed with this
    6  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
    7  *
    8  * See the COPYRIGHT file distributed with this work for additional
    9  * information regarding copyright ownership.
   10  */
   11 
   12 #include <inttypes.h>
   13 #include <string.h>
   14 
   15 #include <isc/astack.h>
   16 #include <isc/atomic.h>
   17 #include <isc/mem.h>
   18 #include <isc/mutex.h>
   19 #include <isc/types.h>
   20 #include <isc/util.h>
   21 
   22 struct isc_astack {
   23     isc_mem_t *mctx;
   24     size_t size;
   25     size_t pos;
   26     isc_mutex_t lock;
   27     uintptr_t nodes[];
   28 };
   29 
   30 isc_astack_t *
   31 isc_astack_new(isc_mem_t *mctx, size_t size) {
   32     isc_astack_t *stack = isc_mem_get(
   33         mctx, sizeof(isc_astack_t) + size * sizeof(uintptr_t));
   34 
   35     *stack = (isc_astack_t){
   36         .size = size,
   37     };
   38     isc_mem_attach(mctx, &stack->mctx);
   39     memset(stack->nodes, 0, size * sizeof(uintptr_t));
   40     isc_mutex_init(&stack->lock);
   41     return (stack);
   42 }
   43 
   44 bool
   45 isc_astack_trypush(isc_astack_t *stack, void *obj) {
   46     if (!isc_mutex_trylock(&stack->lock)) {
   47         if (stack->pos >= stack->size) {
   48             UNLOCK(&stack->lock);
   49             return (false);
   50         }
   51         stack->nodes[stack->pos++] = (uintptr_t)obj;
   52         UNLOCK(&stack->lock);
   53         return (true);
   54     } else {
   55         return (false);
   56     }
   57 }
   58 
   59 void *
   60 isc_astack_pop(isc_astack_t *stack) {
   61     LOCK(&stack->lock);
   62     uintptr_t rv;
   63     if (stack->pos == 0) {
   64         rv = 0;
   65     } else {
   66         rv = stack->nodes[--stack->pos];
   67     }
   68     UNLOCK(&stack->lock);
   69     return ((void *)rv);
   70 }
   71 
   72 void
   73 isc_astack_destroy(isc_astack_t *stack) {
   74     LOCK(&stack->lock);
   75     REQUIRE(stack->pos == 0);
   76     UNLOCK(&stack->lock);
   77 
   78     isc_mutex_destroy(&stack->lock);
   79 
   80     isc_mem_putanddetach(&stack->mctx, stack,
   81                  sizeof(struct isc_astack) +
   82                      stack->size * sizeof(uintptr_t));
   83 }