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


bsdmalloc - memory allocator


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

char *malloc(sizeunsigned size;

int free( ptrchar *ptr;

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


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.


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().


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

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

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


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.


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


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)