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 14 struct link { 15 struct link *prev; 16 struct link *next; 17 }; 18 19 Area * 20 ainit(Area *ap) 21 { 22 ap->freelist = NULL; 23 return ap; 24 } 25 26 void 27 afreeall(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 41 void * 42 alloc(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 70 void * 71 areallocarray(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 82 void * 83 aresize(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 } 110 111 void 112 afree(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 } 129