BSDMALLOC(3MALLOC) Memory Allocation Library Functions BSDMALLOC(3MALLOC)

NAME

bsdmalloc - memory allocator

SYNOPSIS

cc [ flag ... ] file ... -lbsdmalloc [ library ... ]

char *malloc(sizeunsigned size;


int free( ptrchar *ptr;


char *realloc( ptr, sizechar *ptr;
unsigned size;

DESCRIPTION

These routines provide a general-purpose memory allocation package.
They maintain a table of free blocks for efficient allocation and
coalescing of free storage. When there is no suitable space already
free, the allocation routines call sbrk(2) to get more memory from
the system. Each of the allocation routines returns a pointer to
space suitably aligned for storage of any type of object. Each
returns a null pointer if the request cannot be completed.


The malloc() function returns a pointer to a block of at least size
bytes, which is appropriately aligned.


The free() function releases a previously allocated block. Its
argument is a pointer to a block previously allocated by malloc() or
realloc(). The free() function does not set errno.


The realloc() function changes the size of the block pointed to by
ptr to size bytes and returns a pointer to the (possibly moved)
block. The contents will be unchanged up to the lesser of the new and
old sizes. If the new size of the block requires movement of the
block, the space for the previous instantiation of the block is
freed. If the new size is larger, the contents of the newly allocated
portion of the block are unspecified. If ptr is NULL, realloc()
behaves like malloc() for the specified size. If size is 0 and ptr is
not a null pointer, the space pointed to is freed.

RETURN VALUES

The malloc() and realloc() functions return a null pointer if there
is not enough available memory. They return a non-null pointer if
size is 0. These pointers should not be dereferenced. When realloc()
returns NULL, the block pointed to by ptr is left intact. Always cast
the value returned by malloc() and realloc().

ERRORS

If malloc() or realloc() returns unsuccessfully, errno will be set
to indicate the following:

ENOMEM
size bytes of memory cannot be allocated because it exceeds
the physical limits of the system.


EAGAIN
There is not enough memory available at this point in time
to allocate size bytes of memory; but the application could
try again later.

USAGE

Using realloc() with a block freed before the most recent call to
malloc() or realloc() results in an error.


Comparative features of the various allocation libraries can be found
in the umem_alloc(3MALLOC) manual page.

SEE ALSO

brk(2), malloc(3C), malloc(3MALLOC), mapmalloc(3MALLOC),
umem_alloc(3MALLOC)

WARNINGS

Use of libbsdmalloc renders an application non-SCD compliant.


The libbsdmalloc routines are incompatible with the memory allocation
routines in the standard C-library (libc): malloc(3C), alloca(3C),
calloc(3C), free(3C), memalign(3C), realloc(3C), and valloc(3C).

March 21, 2005 BSDMALLOC(3MALLOC)