1mapmalloc(3MALLOC) Memory Allocation Library Functions mapmalloc(3MALLOC)
2
3
4
6 mapmalloc - memory allocator
7
9 cc [ flag ... ] file ... -lmapmalloc [ library ... ]
10 #include <stdlib.h>
11
12 void *malloc(size_t size);
13
14
15 void *calloc(size_t nelem, size_t elsize);
16
17
18 void free(void * ptr);
19
20
21 void *realloc(void *ptr, size_t size);
22
23
25 The collection of malloc functions in this library use mmap(2) instead
26 of sbrk(2) for acquiring new heap space. The functions in this library
27 are intended to be used only if necessary, when applications must call
28 sbrk(), but need to call other library routines that might call malloc.
29 The algorithms used by these functions are not sophisticated. There is
30 no reclaiming of memory.
31
32
33 The malloc() and free() functions provide a simple general-purpose mem‐
34 ory allocation package.
35
36
37 The malloc() function returns a pointer to a block of at least size
38 bytes suitably aligned for any use.
39
40
41 The argument to free() is a pointer to a block previously allocated by
42 malloc(), calloc() or realloc(). If ptr is a NULL pointer, no action
43 occurs.
44
45
46 Undefined results will occur if the space assigned by malloc() is over‐
47 run or if some random number is handed to free().
48
49
50 The calloc() function allocates space for an array of nelem elements of
51 size elsize. The space is initialized to zeros.
52
53
54 The realloc() function changes the size of the block pointed to by ptr
55 to size bytes and returns a pointer to the (possibly moved) block. The
56 contents will be unchanged up to the lesser of the new and old sizes.
57 If the new size of the block requires movement of the block, the space
58 for the previous instantiation of the block is freed. If the new size
59 is larger, the contents of the newly allocated portion of the block are
60 unspecified. If ptr is NULL, realloc() behaves like malloc() for the
61 specified size. If size is 0 and ptr is not a null pointer, the space
62 pointed to is freed.
63
64
65 Each of the allocation functions returns a pointer to space suitably
66 aligned (after possible pointer coercion) for storage of any type of
67 object.
68
69
70 The malloc() and realloc() functions will fail if there is not enough
71 available memory.
72
73
74 Entry points for malloc_debug(), mallocmap(), mallopt(), mallinfo(),
75 memalign(), and valloc() are empty routines, and are provided only to
76 protect the user from mixing malloc() functions from different imple‐
77 mentations.
78
80 If there is no available memory, malloc(), realloc(), and calloc()
81 return a null pointer. When realloc() returns NULL, the block pointed
82 to by ptr is left intact. If size, nelem, or elsize is 0, a unique
83 pointer to the arena is returned.
84
86 See attributes(5) for descriptions of the following attributes:
87
88
89
90
91 ┌─────────────────────────────┬─────────────────────────────┐
92 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
93 ├─────────────────────────────┼─────────────────────────────┤
94 │MT-Level │Safe │
95 └─────────────────────────────┴─────────────────────────────┘
96
98 brk(2), getrlimit(2), mmap(2), realloc(3C), malloc(3MALLOC),
99 attributes(5)
100
101
102
103SunOS 5.11 20 Feb 2004 mapmalloc(3MALLOC)