1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Simple pointer stack
4 *
5 * (c) 2010 Arnaldo Carvalho de Melo <acme@redhat.com>
6 */
7
8 #include "pstack.h"
9 #include "debug.h"
10 #include <linux/kernel.h>
11 #include <linux/zalloc.h>
12 #include <stdlib.h>
13 #include <string.h>
14
15 struct pstack {
16 unsigned short top;
17 unsigned short max_nr_entries;
18 void *entries[];
19 };
20
21 struct pstack *pstack__new(unsigned short max_nr_entries)
22 {
23 struct pstack *pstack = zalloc((sizeof(*pstack) +
24 max_nr_entries * sizeof(void *)));
25 if (pstack != NULL)
26 pstack->max_nr_entries = max_nr_entries;
27 return pstack;
28 }
29
30 void pstack__delete(struct pstack *pstack)
31 {
32 free(pstack);
33 }
34
35 bool pstack__empty(const struct pstack *pstack)
36 {
37 return pstack->top == 0;
38 }
39
40 void pstack__remove(struct pstack *pstack, void *key)
41 {
42 unsigned short i = pstack->top, last_index = pstack->top - 1;
43
44 while (i-- != 0) {
45 if (pstack->entries[i] == key) {
46 if (i < last_index)
47 memmove(pstack->entries + i,
48 pstack->entries + i + 1,
49 (last_index - i) * sizeof(void *));
50 --pstack->top;
51 return;
52 }
53 }
54 pr_err("%s: %p not on the pstack!\n", __func__, key);
55 }
56
57 void pstack__push(struct pstack *pstack, void *key)
58 {
59 if (pstack->top == pstack->max_nr_entries) {
60 pr_err("%s: top=%d, overflow!\n", __func__, pstack->top);
61 return;
62 }
63 pstack->entries[pstack->top++] = key;
64 }
65
66 void *pstack__pop(struct pstack *pstack)
67 {
68 void *ret;
69
70 if (pstack->top == 0) {
71 pr_err("%s: underflow!\n", __func__);
72 return NULL;
73 }
74
75 ret = pstack->entries[--pstack->top];
76 pstack->entries[pstack->top] = NULL;
77 return ret;
78 }
79
80 void *pstack__peek(struct pstack *pstack)
81 {
82 if (pstack->top == 0)
83 return NULL;
84 return pstack->entries[pstack->top - 1];
85 }
86
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.