bsdmalloc(3X)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | WARNINGS | NOTES

NAME

bsdmalloc- memory allocator

SYNOPSIS

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

unsigned size;

char *malloc(size);


char *ptr;

int free( ptr);


char *ptr;
unsigned size;

char *realloc( ptr, 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 5.7  Last Revised 11 Feb 1993

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | WARNINGS | NOTES