有趣的宏定义

pkcs11.h文件：

#include "pkcs11t.h"

#define __PASTE(x,y) x##y


/* ==============================================================
 * Define the "extern" form of all the entry points.
 * ==============================================================
 */

#define CK_NEED_ARG_LIST 1
#define CK_PKCS11_FUNCTION_INFO(name) \
  extern CK_DECLARE_FUNCTION(CK_RV, name)

/* pkcs11f.h has all the information about the Cryptoki
 * function prototypes. */
#include "pkcs11f.h"

#undef CK_NEED_ARG_LIST
#undef CK_PKCS11_FUNCTION_INFO


/* ==============================================================
 * Define the typedef form of all the entry points. That is, for
 * each Cryptoki function C_XXX, define a type CK_C_XXX which is
 * a pointer to that kind of function.
 * ==============================================================
 */

#define CK_NEED_ARG_LIST 1
#define CK_PKCS11_FUNCTION_INFO(name) \
  typedef CK_DECLARE_FUNCTION_POINTER(CK_RV, __PASTE(CK_,name))

/* pkcs11f.h has all the information about the Cryptoki
 * function prototypes. */
#include "pkcs11f.h"

#undef CK_NEED_ARG_LIST
#undef CK_PKCS11_FUNCTION_INFO


/* ==============================================================
 * Define structed vector of entry points. A CK_FUNCTION_LIST
 * contains a CK_VERSION indicating a library's Cryptoki version
 * and then a whole slew of function pointers to the routines in
 * the library. This type was declared, but not defined, in
 * pkcs11t.h.
 * ==============================================================
 */

#define CK_PKCS11_FUNCTION_INFO(name) \
  __PASTE(CK_,name) name;

struct CK_FUNCTION_LIST {

  CK_VERSION version; /* Cryptoki version */

/* Pile all the function pointers into the CK_FUNCTION_LIST. */
/* pkcs11f.h has all the information about the Cryptoki
 * function prototypes. */
#include "pkcs11f.h"

};

#undef CK_PKCS11_FUNCTION_INFO


#undef __PASTE

#ifdef __cplusplus
}
#endif

#endif

pkcs11f.h文件：

/* C_Initialize initializes the Cryptoki library. */
CK_PKCS11_FUNCTION_INFO(C_Initialize)
#ifdef CK_NEED_ARG_LIST
(
CK_VOID_PTR pInitArgs /* if this is not NULL_PTR, it gets
* cast to CK_C_INITIALIZE_ARGS_PTR
* and dereferenced */
);
#endif


/* C_Finalize indicates that an application is done with the
* Cryptoki library. */
CK_PKCS11_FUNCTION_INFO(C_Finalize)
#ifdef CK_NEED_ARG_LIST
(
CK_VOID_PTR pReserved /* reserved. Should be NULL_PTR */
);
#endif


/* C_GetInfo returns general information about Cryptoki. */
CK_PKCS11_FUNCTION_INFO(C_GetInfo)
#ifdef CK_NEED_ARG_LIST
(
CK_INFO_PTR pInfo /* location that receives information */
);
#endif


/* C_GetFunctionList returns the function list. */
CK_PKCS11_FUNCTION_INFO(C_GetFunctionList)
#ifdef CK_NEED_ARG_LIST
(
CK_FUNCTION_LIST_PTR_PTR ppFunctionList /* receives pointer to
* function list */
);
#endif



/* Slot and token management */

/* C_GetSlotList obtains a list of slots in the system. */
CK_PKCS11_FUNCTION_INFO(C_GetSlotList)
#ifdef CK_NEED_ARG_LIST
(
CK_BBOOL tokenPresent, /* only slots with tokens? */
CK_SLOT_ID_PTR pSlotList, /* receives array of slot IDs */
CK_ULONG_PTR pulCount /* receives number of slots */
);
#endif

pkcs11t.h文件：

#ifndef _PKCS11T_H_
#define _PKCS11T_H_ 1

#ifndef CK_DISABLE_TRUE_FALSE
#ifndef FALSE
#define FALSE 0
#endif

#ifndef TRUE
#define TRUE !(FALSE)
#endif
#endif

#define CK_TRUE 1
#define CK_FALSE 0

/* an unsigned 8-bit value */
typedef unsigned char CK_BYTE;

/* an unsigned 8-bit character */
typedef CK_BYTE CK_CHAR;

/* an 8-bit UTF-8 character */
typedef CK_BYTE CK_UTF8CHAR;

/* a BYTE-sized Boolean flag */
typedef CK_BYTE CK_BBOOL;

/* an unsigned value, at least 32 bits long */
typedef unsigned long int CK_ULONG;

/* a signed value, the same size as a CK_ULONG */
/* CK_LONG is new for v2.0 */
typedef long int CK_LONG;

/* at least 32 bits; each bit is a Boolean flag */
typedef CK_ULONG CK_FLAGS;


/* some special values for certain CK_ULONG variables */
#define CK_UNAVAILABLE_INFORMATION (~0UL)
#define CK_EFFECTIVELY_INFINITE 0


typedef CK_BYTE CK_PTR CK_BYTE_PTR;
typedef CK_CHAR CK_PTR CK_CHAR_PTR;
typedef CK_UTF8CHAR CK_PTR CK_UTF8CHAR_PTR;
typedef CK_ULONG CK_PTR CK_ULONG_PTR;
typedef void CK_PTR CK_VOID_PTR;

/* Pointer to a CK_VOID_PTR-- i.e., pointer to pointer to void */
typedef CK_VOID_PTR CK_PTR CK_VOID_PTR_PTR;


/* The following value is always invalid if used as a session */
/* handle or object handle */
#define CK_INVALID_HANDLE 0


typedef struct CK_VERSION {
  CK_BYTE major; /* integer portion of version number */
  CK_BYTE minor; /* 1/100ths portion of version number */
} CK_VERSION;

通过#define CK_PKCS11_FUNCTION_INFO(name)...

然后#include "pkcs11f.h"

然后再#undef CK_PKCS11_FUNCTION_INFO(name)

再#define CK_PKCS11_FUNCTION_INFO(name)...

再#include "pkc11f.h"

然后#undef CK_PKCS11_FUNCTION_INFO(name)

再#include "pkc11f.h"  .............

如此反复三次，使同一个头文件获得了不同的函数声明（有函数的声明，也有函数指针的声明，同时还定义了一个包含函数指针的结构体）。

真是妙啊！