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Common Security: CDSA and CSSM, Version 2
Copyright © 1999 The Open Group
Application Memory Functions
Introduction
Memory management between applications and CSSM, and between
applications and add-in service providers, differs by necessity.
Before selecting and loading a particular version of CSSM,
applications are required to provide memory management functions as
input to each get-operation. These functions operate on heap space
owned by the application. Corresponding free-operations are provided
to relieve applications of the burden of walking complex data
structures. Once a version of CSSM has been selected and loaded by the
application, some memory structures can be allocated on CSSM's heap.
Corresponding free-operations are defined, but they must be used by
the application to free those structures when they are no longer
needed.
When a service provider is selected and attached using
CSSM_ModuleAttach(),
the application must provide a set of memory
management functions and heap space for data structures that will be
returned by the add-in module as part of its service. When requesting
specific services, an application can provide pre-allocated memory as
input for the function call. This requires that the application know
the memory size required by the service provider. This is not always
possible. Supplying a heap and memory management frees the application
from specifying memory block sizes. The memory that the application
receives is in its heap space. When the application no longer requires
the memory, it is responsible for freeing it.
A memory function table is passed from the application to add-in
service modules through the
CSSM_xxx_Attach
functions associated with each add-in.
CSSM_API_MEMORY_FUNCS Data Structure
This structure is used by applications to supply memory functions for
the CSSM and the add-in modules. The functions are used when memory
needs to be allocated by the CSSM or add-ins for returning data
structures to the applications.
typedef void * (CSSMAPI *CSSM_MALLOC)
( uint32 size,
void * allocref);
typedef void (CSSMAPI *CSSM_FREE)
(void * memblock,
void * allocref);
typedef void * (CSSMAPI *CSSM_REALLOC)
(void * memblock,
uint32 size,
void * allocref);
typedef void * (CSSMAPI *CSSM_CALLOC)
(uint32 num,
uint32 size,
void * allocref);
typedef struct cssm_memory_funcs {
CSSM_MALLOC malloc_func;
CSSM_FREE free_func;
CSSM_REALLOC realloc_func;
CSSM_CALLOC calloc_func;
void *AllocRef;
} CSSM_MEMORY_FUNCS, *CSSM_MEMORY_FUNCS_PTR;
Definition
- malloc_func
Pointer to function that returns a void pointer to the allocated
memory block of at least size bytes from heap AllocRef.
- free_func
Pointer to function that deallocates a previously-allocated memory
block (memblock) from heap AllocRef.
- realloc_func
Pointer to function that returns a void pointer to the reallocated
memory block (memblock) of at least size bytes from heap AllocRef.
- calloc_func
Pointer to function that returns a void pointer to an array of num
elements of length size initialized to zero from heap AllocRef.
- AllocRef
Indicates the memory heap the function operates on.
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