1 /* Auto-reallocating array for arbitrary member types. */
2 /*
3  * Copyright (c) 2020 Neels Hofmeyr <neels@hofmeyr.de>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #ifdef __linux__
19 /* stupid shims to compile and test on linux */
20 #include <strings.h>
21 static inline void *reallocarray(void *buf, size_t n, size_t member_size)
22 {
23 	return realloc(buf, n * member_size);
24 }
25 static inline void *recallocarray(void *buf, size_t oldn, size_t n,
26 				  size_t member_size)
27 {
28 	buf = reallocarray(buf, n, member_size);
29 	bzero(((char*)buf) + (oldn * member_size), (n - oldn) * member_size);
30 	return buf;
31 }
32 #endif
33 
34 
35 /* Usage:
36  *
37  * ARRAYLIST(any_type_t) list;
38  * // OR
39  * typedef ARRAYLIST(any_type_t) any_type_list_t;
40  * any_type_list_t list;
41  *
42  * // pass the number of (at first unused) members to add on each realloc:
43  * ARRAYLIST_INIT(list, 128);
44  * any_type_t *x;
45  * while (bar) {
46  *         // This enlarges the allocated array as needed;
47  *         // list.head may change due to realloc:
48  *         ARRAYLIST_ADD(x, list);
49  *         if (!x)
50  *                 abort();
51  *         *x = random_foo_value;
52  * }
53  * for (i = 0; i < list.len; i++)
54  *         printf("%s", foo_to_str(list.head[i]));
55  * ARRAYLIST_FREE(list);
56  */
57 #define ARRAYLIST(MEMBER_TYPE) \
58 	struct { \
59 		MEMBER_TYPE *head; \
60 		unsigned int len; \
61 		unsigned int allocated; \
62 		unsigned int alloc_blocksize; \
63 	}
64 
65 #define ARRAYLIST_INIT(ARRAY_LIST, ALLOC_BLOCKSIZE) do { \
66 		(ARRAY_LIST).head = NULL; \
67 		(ARRAY_LIST).len = 0; \
68 		(ARRAY_LIST).allocated = 0; \
69 		(ARRAY_LIST).alloc_blocksize = ALLOC_BLOCKSIZE; \
70 	} while(0)
71 
72 #define ARRAYLIST_ADD(NEW_ITEM_P, ARRAY_LIST) do { \
73 		if ((ARRAY_LIST).len && !(ARRAY_LIST).allocated) { \
74 			NEW_ITEM_P = NULL; \
75 			break; \
76 		} \
77 		if ((ARRAY_LIST).head == NULL \
78 		    || (ARRAY_LIST).allocated < (ARRAY_LIST).len + 1) { \
79 			(ARRAY_LIST).allocated += \
80 				(ARRAY_LIST).alloc_blocksize ? : 8; \
81 			(ARRAY_LIST).head = recallocarray((ARRAY_LIST).head, \
82 				(ARRAY_LIST).len, \
83 				(ARRAY_LIST).allocated, \
84 				sizeof(*(ARRAY_LIST).head)); \
85 		}; \
86 		if (!(ARRAY_LIST).head \
87 		    || (ARRAY_LIST).allocated < (ARRAY_LIST).len + 1) { \
88 			NEW_ITEM_P = NULL; \
89 			break; \
90 		} \
91 		(NEW_ITEM_P) = &(ARRAY_LIST).head[(ARRAY_LIST).len]; \
92 		(ARRAY_LIST).len++; \
93 	} while (0)
94 
95 #define ARRAYLIST_CLEAR(ARRAY_LIST) \
96 	(ARRAY_LIST).len = 0
97 
98 #define ARRAYLIST_FREE(ARRAY_LIST) \
99 	do { \
100 		if ((ARRAY_LIST).head && (ARRAY_LIST).allocated) \
101 			free((ARRAY_LIST).head); \
102 		ARRAYLIST_INIT(ARRAY_LIST, (ARRAY_LIST).alloc_blocksize); \
103 	} while(0)