alloc.c
1/* $OpenBSD: alloc.c,v 1.19 2018/01/16 22:52:32 jca Exp $ */
2
3/* Public domain, like most of the rest of ksh */
4
5/*
6 * area-based allocation built on malloc/free
7 */
8
9#include <stdint.h>
10#include <stdlib.h>
11
12#include "sh.h"
13
14struct link {
15 struct link *prev;
16 struct link *next;
17};
18
19Area *
20ainit(Area *ap)
21{
22 ap->freelist = NULL;
23 return ap;
24}
25
26void
27afreeall(Area *ap)
28{
29 struct link *l, *l2;
30
31 for (l = ap->freelist; l != NULL; l = l2) {
32 l2 = l->next;
33 free(l);
34 }
35 ap->freelist = NULL;
36}
37
38#define L2P(l) ( (void *)(((char *)(l)) + sizeof(struct link)) )
39#define P2L(p) ( (struct link *)(((char *)(p)) - sizeof(struct link)) )
40
41void *
42alloc(size_t size, Area *ap)
43{
44 struct link *l;
45
46 /* ensure that we don't overflow by allocating space for link */
47 if (size > SIZE_MAX - sizeof(struct link))
48 internal_errorf("unable to allocate memory");
49
50 l = malloc(sizeof(struct link) + size);
51 if (l == NULL)
52 internal_errorf("unable to allocate memory");
53 l->next = ap->freelist;
54 l->prev = NULL;
55 if (ap->freelist)
56 ap->freelist->prev = l;
57 ap->freelist = l;
58
59 return L2P(l);
60}
61
62/*
63 * Copied from calloc().
64 *
65 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
66 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
67 */
68#define MUL_NO_OVERFLOW (1UL << (sizeof(size_t) * 4))
69
70void *
71areallocarray(void *ptr, size_t nmemb, size_t size, Area *ap)
72{
73 /* condition logic cloned from calloc() */
74 if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
75 nmemb > 0 && SIZE_MAX / nmemb < size) {
76 internal_errorf("unable to allocate memory");
77 }
78
79 return aresize(ptr, nmemb * size, ap);
80}
81
82void *
83aresize(void *ptr, size_t size, Area *ap)
84{
85 struct link *l, *l2, *lprev, *lnext;
86
87 if (ptr == NULL)
88 return alloc(size, ap);
89
90 /* ensure that we don't overflow by allocating space for link */
91 if (size > SIZE_MAX - sizeof(struct link))
92 internal_errorf("unable to allocate memory");
93
94 l = P2L(ptr);
95 lprev = l->prev;
96 lnext = l->next;
97
98 l2 = realloc(l, sizeof(struct link) + size);
99 if (l2 == NULL)
100 internal_errorf("unable to allocate memory");
101 if (lprev)
102 lprev->next = l2;
103 else
104 ap->freelist = l2;
105 if (lnext)
106 lnext->prev = l2;
107
108 return L2P(l2);
109}
110
111void
112afree(void *ptr, Area *ap)
113{
114 struct link *l;
115
116 if (!ptr)
117 return;
118
119 l = P2L(ptr);
120 if (l->prev)
121 l->prev->next = l->next;
122 else
123 ap->freelist = l->next;
124 if (l->next)
125 l->next->prev = l->prev;
126
127 free(l);
128}
