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.Dd Aug 13, 2008
.Dt MALLOC_ZONE_MALLOC 3
.Os
.Sh NAME
.Nm malloc_create_zone ,
.Nm malloc_destroy_zone ,
.Nm malloc_default_zone ,
.Nm malloc_zone_from_ptr ,
.Nm malloc_zone_malloc ,
.Nm malloc_zone_calloc ,
.Nm malloc_zone_valloc ,
.Nm malloc_zone_realloc ,
.Nm malloc_zone_memalign ,
.Nm malloc_zone_free
.Nd zone-based memory allocation
.Sh SYNOPSIS
.In malloc/malloc.h
.Ft malloc_zone_t *
.Fo malloc_create_zone
.Fa "vm_size_t start_size"
.Fa "unsigned flags"
.Fc
.Ft void
.Fo malloc_destroy_zone
.Fa "malloc_zone_t *zone"
.Fc
.Ft malloc_zone_t *
.Fo malloc_default_zone
.Fa void
.Fc
.Ft malloc_zone_t *
.Fo malloc_zone_from_ptr
.Fa "const void *ptr"
.Fc
.Ft void *
.Fo malloc_zone_malloc
.Fa "malloc_zone_t *zone"
.Fa "size_t size"
.Fc
.Ft void *
.Fo malloc_zone_calloc
.Fa "malloc_zone_t *zone"
.Fa "size_t num_items"
.Fa "size_t size"
.Fc
.Ft void *
.Fo malloc_zone_valloc
.Fa "malloc_zone_t *zone"
.Fa "size_t size"
.Fc
.Ft void *
.Fo malloc_zone_realloc
.Fa "malloc_zone_t *zone"
.Fa "void *ptr"
.Fa "size_t size"
.Fc
.Ft void *
.Fo malloc_zone_memalign
.Fa "malloc_zone_t *zone"
.Fa "size_t alignment"
.Fa "size_t size"
.Fc
.Ft void
.Fo malloc_zone_free
.Fa "malloc_zone_t *zone"
.Fa "void *ptr"
.Fc
.Sh DESCRIPTION
The
.Fn malloc_create_zone
function creates a malloc zone, advising an initial allocation of
.Fa start_size
bytes, and specifying 
.Fa flags
that alter the standard behavior of the zone.
The returned malloc zone can be used to provide custom allocation and 
deallocation behavior, and to retrieve additional information about the
allocations in that zone.
.Pp
The
.Fn malloc_destroy_zone
function deallocates all memory associated with objects in 
.Fa zone
as well as 
.Fa zone
itself.
.Pp
The
.Fn malloc_default_zone
function returns the default system malloc zone, used by
.Xr malloc 3 ,
and
.Xr free 3 .
.Pp
The
.Fn malloc_zone_from_ptr
function returns a pointer to the malloc zone which contains
.Fa ptr
or NULL, if the pointer does not point to an allocated object in any current
malloc zone.
.Pp
The
.Fn malloc_zone_malloc ,
.Fn malloc_zone_calloc ,
.Fn malloc_zone_valloc ,
.Fn malloc_zone_realloc ,
.Fn malloc_zone_memalign ,
and
.Fn malloc_zone_free
perform the same task on
.Fa zone
as their non-prefixed variants, 
.Xr malloc 3 ,
.Xr calloc 3 ,
.Xr valloc 3 ,
.Xr realloc 3 ,
.Xr posix_memalign 3 ,
and 
.Xr free 3 perform on the default system malloc zone.
.Sh RETURN VALUES
The 
.Fn malloc_create_zone ,
.Fn malloc_default_zone ,
and
.Fn malloc_zone_from_ptr
functions return a pointer to a malloc_zone_t structure, or NULL if there was
an error.
.Pp
The 
.Fn malloc_zone_malloc ,
.Fn malloc_zone_calloc ,
.Fn malloc_zone_valloc ,
.Fn malloc_zone_realloc ,
and
.Fn malloc_zone_memalign
functions return a pointer to allocated memory.  If there is an error, they 
return a NULL pointer.  They are not required to set 
.Va errno .
.El
.Sh SEE ALSO
.Xr malloc 3 ,
.Xr posix_memalign 3