NAME

bsdmalloc, malloc, free, realloc − memory allocator

SYNOPSIS

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

char ∗malloc( size)
unsigned size;

int free( ptr)
char ∗ ptr;

char ∗realloc( ptr, size)
char ∗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 (see DIAGNOSTICS). 

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

free() releases a previously allocated block.  Its  argument is  a  pointer  to a block previously allocated by malloc() or realloc(). 

realloc() changes the size of the block referenced 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 unable to honor a reallocation request, realloc() leaves its first argument unaltered.  For backwards  compatibility, realloc() accepts a pointer to a block freed since the most recent  call  to malloc() or realloc(). 

RETURN VALUES

malloc() and realloc() return a null pointer if there is not enough available memory.  When realloc() returns NULL, the block pointed to by ptr is left intact. 

ERRORS

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

ENOMEM size bytes of memory exceeds the physical limits of your system, and cannot be allocated. 

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. 

SEE ALSO

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

WARNINGS

Use of libbsdmalloc renders an application non-SCD compliant. 

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). 

NOTES

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

malloc() and realloc() return a non-NULL pointer if size is 0. These pointers should not be dereferenced. 

Always cast the value returned by malloc() and realloc(). 

Comparative features of bsdmalloc(), malloc(3X), and malloc(3C):

• The bsdmalloc() routines afford better performance, but are space-inefficient. 

• The malloc(3X) routines are space-efficient, but have slower performance. 

• The standard, fully SCD-compliant malloc(3C) routines are a trade-off between performance and space-efficiency. 

free() does not set errno. 

SunOS 5.5.1  —  Last change: 11 Feb 1993