1 /* $NetBSD: astack.c,v 1.1 2024/02/18 20:57:48 christos Exp $ */
2
3 /*
4 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
5 *
6 * SPDX-License-Identifier: MPL-2.0
7 *
8 * This Source Code Form is subject to the terms of the Mozilla Public
9 * License, v. 2.0. If a copy of the MPL was not distributed with this
10 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
11 *
12 * See the COPYRIGHT file distributed with this work for additional
13 * information regarding copyright ownership.
14 */
15
16 #include <inttypes.h>
17 #include <string.h>
18
19 #include <isc/astack.h>
20 #include <isc/atomic.h>
21 #include <isc/mem.h>
22 #include <isc/mutex.h>
23 #include <isc/types.h>
24 #include <isc/util.h>
25
26 struct isc_astack {
27 isc_mem_t *mctx;
28 size_t size;
29 size_t pos;
30 isc_mutex_t lock;
31 uintptr_t nodes[];
32 };
33
34 isc_astack_t *
isc_astack_new(isc_mem_t * mctx,size_t size)35 isc_astack_new(isc_mem_t *mctx, size_t size) {
36 isc_astack_t *stack = isc_mem_get(
37 mctx, sizeof(isc_astack_t) + size * sizeof(uintptr_t));
38
39 *stack = (isc_astack_t){
40 .size = size,
41 };
42 isc_mem_attach(mctx, &stack->mctx);
43 memset(stack->nodes, 0, size * sizeof(uintptr_t));
44 isc_mutex_init(&stack->lock);
45 return (stack);
46 }
47
48 bool
isc_astack_trypush(isc_astack_t * stack,void * obj)49 isc_astack_trypush(isc_astack_t *stack, void *obj) {
50 if (!isc_mutex_trylock(&stack->lock)) {
51 if (stack->pos >= stack->size) {
52 UNLOCK(&stack->lock);
53 return (false);
54 }
55 stack->nodes[stack->pos++] = (uintptr_t)obj;
56 UNLOCK(&stack->lock);
57 return (true);
58 } else {
59 return (false);
60 }
61 }
62
63 void *
isc_astack_pop(isc_astack_t * stack)64 isc_astack_pop(isc_astack_t *stack) {
65 LOCK(&stack->lock);
66 uintptr_t rv;
67 if (stack->pos == 0) {
68 rv = 0;
69 } else {
70 rv = stack->nodes[--stack->pos];
71 }
72 UNLOCK(&stack->lock);
73 return ((void *)rv);
74 }
75
76 void
isc_astack_destroy(isc_astack_t * stack)77 isc_astack_destroy(isc_astack_t *stack) {
78 LOCK(&stack->lock);
79 REQUIRE(stack->pos == 0);
80 UNLOCK(&stack->lock);
81
82 isc_mutex_destroy(&stack->lock);
83
84 isc_mem_putanddetach(&stack->mctx, stack,
85 sizeof(struct isc_astack) +
86 stack->size * sizeof(uintptr_t));
87 }
88