Manual page for bsdmalloc(3X)
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.
Created by unroff & hp-tools.
© by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97
