xref: /PHP-7.2/Zend/zend_arena.h (revision 7a7ec01a)
1 /*
2    +----------------------------------------------------------------------+
3    | Zend Engine                                                          |
4    +----------------------------------------------------------------------+
5    | Copyright (c) 1998-2018 Zend Technologies Ltd. (http://www.zend.com) |
6    +----------------------------------------------------------------------+
7    | This source file is subject to version 2.00 of the Zend license,     |
8    | that is bundled with this package in the file LICENSE, and is        |
9    | available through the world-wide-web at the following url:           |
10    | http://www.zend.com/license/2_00.txt.                                |
11    | If you did not receive a copy of the Zend license and are unable to  |
12    | obtain it through the world-wide-web, please send a note to          |
13    | license@zend.com so we can mail you a copy immediately.              |
14    +----------------------------------------------------------------------+
15    | Authors: Dmitry Stogov <dmitry@zend.com>                             |
16    +----------------------------------------------------------------------+
17 */
18 
19 /* $Id:$ */
20 
21 #ifndef _ZEND_ARENA_H_
22 #define _ZEND_ARENA_H_
23 
24 #include "zend.h"
25 
26 typedef struct _zend_arena zend_arena;
27 
28 struct _zend_arena {
29 	char		*ptr;
30 	char		*end;
31 	zend_arena  *prev;
32 };
33 
zend_arena_create(size_t size)34 static zend_always_inline zend_arena* zend_arena_create(size_t size)
35 {
36 	zend_arena *arena = (zend_arena*)emalloc(size);
37 
38 	arena->ptr = (char*) arena + ZEND_MM_ALIGNED_SIZE(sizeof(zend_arena));
39 	arena->end = (char*) arena + size;
40 	arena->prev = NULL;
41 	return arena;
42 }
43 
zend_arena_destroy(zend_arena * arena)44 static zend_always_inline void zend_arena_destroy(zend_arena *arena)
45 {
46 	do {
47 		zend_arena *prev = arena->prev;
48 		efree(arena);
49 		arena = prev;
50 	} while (arena);
51 }
52 
53 #define ZEND_ARENA_ALIGNMENT 8U
54 
zend_arena_alloc(zend_arena ** arena_ptr,size_t size)55 static zend_always_inline void* zend_arena_alloc(zend_arena **arena_ptr, size_t size)
56 {
57 	zend_arena *arena = *arena_ptr;
58 	char *ptr = arena->ptr;
59 
60 	size = ZEND_MM_ALIGNED_SIZE(size);
61 
62 	if (EXPECTED(size <= (size_t)(arena->end - ptr))) {
63 		arena->ptr = ptr + size;
64 	} else {
65 		size_t arena_size =
66 			UNEXPECTED((size + ZEND_MM_ALIGNED_SIZE(sizeof(zend_arena))) > (size_t)(arena->end - (char*) arena)) ?
67 				(size + ZEND_MM_ALIGNED_SIZE(sizeof(zend_arena))) :
68 				(size_t)(arena->end - (char*) arena);
69 		zend_arena *new_arena = (zend_arena*)emalloc(arena_size);
70 
71 		ptr = (char*) new_arena + ZEND_MM_ALIGNED_SIZE(sizeof(zend_arena));
72 		new_arena->ptr = (char*) new_arena + ZEND_MM_ALIGNED_SIZE(sizeof(zend_arena)) + size;
73 		new_arena->end = (char*) new_arena + arena_size;
74 		new_arena->prev = arena;
75 		*arena_ptr = new_arena;
76 	}
77 
78 	return (void*) ptr;
79 }
80 
zend_arena_calloc(zend_arena ** arena_ptr,size_t count,size_t unit_size)81 static zend_always_inline void* zend_arena_calloc(zend_arena **arena_ptr, size_t count, size_t unit_size)
82 {
83 	int overflow;
84 	size_t size;
85 	void *ret;
86 
87 	size = zend_safe_address(unit_size, count, 0, &overflow);
88 	if (UNEXPECTED(overflow)) {
89 		zend_error(E_ERROR, "Possible integer overflow in zend_arena_calloc() (%zu * %zu)", unit_size, count);
90 	}
91 	ret = zend_arena_alloc(arena_ptr, size);
92 	memset(ret, 0, size);
93 	return ret;
94 }
95 
zend_arena_checkpoint(zend_arena * arena)96 static zend_always_inline void* zend_arena_checkpoint(zend_arena *arena)
97 {
98 	return arena->ptr;
99 }
100 
zend_arena_release(zend_arena ** arena_ptr,void * checkpoint)101 static zend_always_inline void zend_arena_release(zend_arena **arena_ptr, void *checkpoint)
102 {
103 	zend_arena *arena = *arena_ptr;
104 
105 	while (UNEXPECTED((char*)checkpoint > arena->end) ||
106 	       UNEXPECTED((char*)checkpoint <= (char*)arena)) {
107 		zend_arena *prev = arena->prev;
108 		efree(arena);
109 		*arena_ptr = arena = prev;
110 	}
111 	ZEND_ASSERT((char*)checkpoint > (char*)arena && (char*)checkpoint <= arena->end);
112 	arena->ptr = (char*)checkpoint;
113 }
114 
115 #endif /* _ZEND_ARENA_H_ */
116 
117 /*
118  * Local variables:
119  * tab-width: 4
120  * c-basic-offset: 4
121  * indent-tabs-mode: t
122  * End:
123  * vim600: sw=4 ts=4 fdm=marker
124  * vim<600: sw=4 ts=4
125  */
126