1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
|
/**
* slibc — Yet another C library
* Copyright © 2015 Mattias Andrée (maandree@member.fsf.org)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <slibc-alloc.h>
#include <strings.h>
#include <sys/mman.h>
/**
* Create a new memory allocation on the heap.
* The allocation will not be initialised.
*
* @param size The size of the allocation.
* @return Pointer to the beginning of the new allocation.
* If `size` is zero, this function will either return
* `NULL` (that is what this implement does) or return
* a unique pointer that can later be freed with `free`.
* `NULL` is returned on error, and `errno` is set to
* indicate the error.
*
* @throws ENOMEM The process cannot allocate more memory.
*/
void* malloc(size_t size)
{
/* TODO implement implementation of malloc */
char* ptr;
if (size == 0)
return NULL;
ptr = mmap(NULL, sizeof(size_t) + size, (PROT_READ | PROT_WRITE),
(MAP_PRIVATE | MAP_ANONYMOUS), -1, 0);
*(size_t*)ptr = size;
return ptr + sizeof(size_t);
}
/**
* Variant of `malloc` that clears the allocation with zeroes.
*
* `p = calloc(n, m)` is equivalent to
* `(p = malloc(n * m), p ? (explicit_bzero(p, n * m), p) : NULL)`
*
* @param elem_count The number of elements to allocate.
* @param elem_size The size of each element.
* @return Pointer to the beginning of the new allocation.
* If `elem_count` or `elem_size` is zero, this function
* will either return `NULL` (that is what this implement
* does) or return a unique pointer that can later be
* freed with `free`. `NULL` is returned on error, and
* `errno` is set to indicate the error.
*
* @throws ENOMEM The process cannot allocate more memory.
*/
void* calloc(size_t elem_count, size_t elem_size)
{
void* ptr = malloc(elem_count * elem_size);
if (ptr != NULL)
explicit_bzero(ptr, elem_count * elem_size);
return ptr;
}
/**
* Variant of `malloc` that extends, or shrinks, an existing allocation,
* if beneficial and possible, or creates a new allocation with the new
* size, copies the data, and frees the old allocation.
*
* On error, `ptr` is not freed.
*
* @param ptr Pointer to the beginning of the old memory allocation.
* The process may crash if it does not point to the
* beginning of a memory allocation on the heap.
* However, if it is `NULL`, this function will behave
* like `malloc`.
* @param size The new allocation size. If zero, this function will
* behave like `free`, and will return `NULL`.
* @return Pointer to the beginning of the new allocation.
* If `size` is zero, `NULL` is returned. On error `NULL`
* is returned and `errno` is set to indicate the error.
*
* @throws ENOMEM The process cannot allocate more memory.
*/
void* realloc(void* ptr, size_t size)
{
return fast_realloc(ptr, size);
}
/**
* Free a memory allocation.
*
* @param ptr Pointer to the beginning of the memory allocation.
* The process may crash if it does not point to the
* beginning of a memory allocation on the heap.
* However, if it is `NULL`, nothing will happen.
*/
void free(void* ptr)
{
fast_free(ptr);
}
/**
* This function is identical to `free`.
* Any argument beyond the first argument, is ignored.
*
* This function uses variadic arguments because there
* there are multiple conflicting specifications for `cfree`.
*
* @param ptr Pointer to the beginning of the memory allocation.
* The process may crash if it does not point to the
* beginning of a memory allocation on the heap.
* However, if it is `NULL`, nothing will happen.
*/
void cfree(void* ptr, ...)
{
fast_free(ptr);
}
|
