fmgr.h

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#define PG_RETURN_BOOL(x)	 return BoolGetDatum(x)
#define PG_RETURN_OID(x)	 return ObjectIdGetDatum(x)
#define PG_RETURN_POINTER(x) return PointerGetDatum(x)
#define PG_RETURN_CSTRING(x) return CStringGetDatum(x)
#define PG_RETURN_NAME(x)	 return NameGetDatum(x)
/* these macros hide the pass-by-reference-ness of the datatype: */
#define PG_RETURN_FLOAT4(x)  return Float4GetDatum(x)
#define PG_RETURN_FLOAT8(x)  return Float8GetDatum(x)
#define PG_RETURN_INT64(x)	 return Int64GetDatum(x)
/* RETURN macros for other pass-by-ref types will typically look like this: */
#define PG_RETURN_BYTEA_P(x)   PG_RETURN_POINTER(x)
#define PG_RETURN_TEXT_P(x)    PG_RETURN_POINTER(x)
#define PG_RETURN_BPCHAR_P(x)  PG_RETURN_POINTER(x)
#define PG_RETURN_VARCHAR_P(x) PG_RETURN_POINTER(x)
#define PG_RETURN_HEAPTUPLEHEADER(x)  PG_RETURN_POINTER(x)


/*-------------------------------------------------------------------------
 *		Support for detecting call convention of dynamically-loaded functions
 *
 * Dynamically loaded functions may use either the version-1 ("new style")
 * or version-0 ("old style") calling convention.  Version 1 is the call
 * convention defined in this header file; version 0 is the old "plain C"
 * convention.	A version-1 function must be accompanied by the macro call
 *
 *		PG_FUNCTION_INFO_V1(function_name);
 *
 * Note that internal functions do not need this decoration since they are
 * assumed to be version-1.
 *
 *-------------------------------------------------------------------------
 */

typedef struct
{
	int			api_version;	/* specifies call convention version number */
	/* More fields may be added later, for version numbers > 1. */
} Pg_finfo_record;

/* Expected signature of an info function */
typedef const Pg_finfo_record *(*PGFInfoFunction) (void);

/*
 *	Macro to build an info function associated with the given function name.
 *	Win32 loadable functions usually link with 'dlltool --export-all', but it
 *	doesn't hurt to add DLLIMPORT in case they don't.
 */
#define PG_FUNCTION_INFO_V1(funcname) \
extern DLLIMPORT const Pg_finfo_record * CppConcat(pg_finfo_,funcname)(void); \
const Pg_finfo_record * \
CppConcat(pg_finfo_,funcname) (void) \
{ \
	static const Pg_finfo_record my_finfo = { 1 }; \
	return &my_finfo; \
} \
extern int no_such_variable


/*-------------------------------------------------------------------------
 *		Support for verifying backend compatibility of loaded modules
 *
 * We require dynamically-loaded modules to include the macro call
 *		PG_MODULE_MAGIC;
 * so that we can check for obvious incompatibility, such as being compiled
 * for a different major PostgreSQL version.
 *
 * To compile with versions of PostgreSQL that do not support this,
 * you may put an #ifdef/#endif test around it.  Note that in a multiple-
 * source-file module, the macro call should only appear once.
 *
 * The specific items included in the magic block are intended to be ones that
 * are custom-configurable and especially likely to break dynamically loaded
 * modules if they were compiled with other values.  Also, the length field
 * can be used to detect definition changes.
 *-------------------------------------------------------------------------
 */

/* Definition of the magic block structure */
typedef struct
{
	int			len;			/* sizeof(this struct) */
	int			version;		/* PostgreSQL major version */
	int			funcmaxargs;	/* FUNC_MAX_ARGS */
	int			indexmaxkeys;	/* INDEX_MAX_KEYS */
	int			namedatalen;	/* NAMEDATALEN */
} Pg_magic_struct;

/* The actual data block contents */
#define PG_MODULE_MAGIC_DATA \
{ \
	sizeof(Pg_magic_struct), \
	PG_VERSION_NUM / 100, \
	FUNC_MAX_ARGS, \
	INDEX_MAX_KEYS, \
	NAMEDATALEN \
}

/*
 * Declare the module magic function.  It needs to be a function as the dlsym
 * in the backend is only guaranteed to work on functions, not data
 */
typedef const Pg_magic_struct *(*PGModuleMagicFunction) (void);

#define PG_MAGIC_FUNCTION_NAME Pg_magic_func
#define PG_MAGIC_FUNCTION_NAME_STRING "Pg_magic_func"

#define PG_MODULE_MAGIC \
extern DLLIMPORT const Pg_magic_struct *PG_MAGIC_FUNCTION_NAME(void); \
const Pg_magic_struct * \
PG_MAGIC_FUNCTION_NAME(void) \
{ \
	static const Pg_magic_struct Pg_magic_data = PG_MODULE_MAGIC_DATA; \
	return &Pg_magic_data; \
} \
extern int no_such_variable


/*-------------------------------------------------------------------------
 *		Support routines and macros for callers of fmgr-compatible functions
 *-------------------------------------------------------------------------
 */

/* These are for invocation of a specifically named function with a
 * directly-computed parameter list.  Note that neither arguments nor result
 * are allowed to be NULL.
 */
extern Datum DirectFunctionCall1(PGFunction func, Datum arg1);
extern Datum DirectFunctionCall2(PGFunction func, Datum arg1, Datum arg2);
extern Datum DirectFunctionCall3(PGFunction func, Datum arg1, Datum arg2,
					Datum arg3);
extern Datum DirectFunctionCall4(PGFunction func, Datum arg1, Datum arg2,
					Datum arg3, Datum arg4);
extern Datum DirectFunctionCall5(PGFunction func, Datum arg1, Datum arg2,
					Datum arg3, Datum arg4, Datum arg5);
extern Datum DirectFunctionCall6(PGFunction func, Datum arg1, Datum arg2,
					Datum arg3, Datum arg4, Datum arg5,
					Datum arg6);
extern Datum DirectFunctionCall7(PGFunction func, Datum arg1, Datum arg2,
					Datum arg3, Datum arg4, Datum arg5,
					Datum arg6, Datum arg7);
extern Datum DirectFunctionCall8(PGFunction func, Datum arg1, Datum arg2,
					Datum arg3, Datum arg4, Datum arg5,
					Datum arg6, Datum arg7, Datum arg8);
extern Datum DirectFunctionCall9(PGFunction func, Datum arg1, Datum arg2,
					Datum arg3, Datum arg4, Datum arg5,
					Datum arg6, Datum arg7, Datum arg8,
					Datum arg9);

/* These are for invocation of a previously-looked-up function with a
 * directly-computed parameter list.  Note that neither arguments nor result
 * are allowed to be NULL.
 */
extern Datum FunctionCall1(FmgrInfo *flinfo, Datum arg1);
extern Datum FunctionCall2(FmgrInfo *flinfo, Datum arg1, Datum arg2);
extern Datum FunctionCall3(FmgrInfo *flinfo, Datum arg1, Datum arg2,
			  Datum arg3);
extern Datum FunctionCall4(FmgrInfo *flinfo, Datum arg1, Datum arg2,
			  Datum arg3, Datum arg4);
extern Datum FunctionCall5(FmgrInfo *flinfo, Datum arg1, Datum arg2,
			  Datum arg3, Datum arg4, Datum arg5);
extern Datum FunctionCall6(FmgrInfo *flinfo, Datum arg1, Datum arg2,
			  Datum arg3, Datum arg4, Datum arg5,
			  Datum arg6);
extern Datum FunctionCall7(FmgrInfo *flinfo, Datum arg1, Datum arg2,
			  Datum arg3, Datum arg4, Datum arg5,
			  Datum arg6, Datum arg7);
extern Datum FunctionCall8(FmgrInfo *flinfo, Datum arg1, Datum arg2,
			  Datum arg3, Datum arg4, Datum arg5,
			  Datum arg6, Datum arg7, Datum arg8);
extern Datum FunctionCall9(FmgrInfo *flinfo, Datum arg1, Datum arg2,
			  Datum arg3, Datum arg4, Datum arg5,
			  Datum arg6, Datum arg7, Datum arg8,
			  Datum arg9);

/* These are for invocation of a function identified by OID with a
 * directly-computed parameter list.  Note that neither arguments nor result
 * are allowed to be NULL.	These are essentially FunctionLookup() followed
 * by FunctionCallN().	If the same function is to be invoked repeatedly,
 * do the FunctionLookup() once and then use FunctionCallN().
 */
extern Datum OidFunctionCall1(Oid functionId, Datum arg1);
extern Datum OidFunctionCall2(Oid functionId, Datum arg1, Datum arg2);
extern Datum OidFunctionCall3(Oid functionId, Datum arg1, Datum arg2,
				 Datum arg3);
extern Datum OidFunctionCall4(Oid functionId, Datum arg1, Datum arg2,
				 Datum arg3, Datum arg4);
extern Datum OidFunctionCall5(Oid functionId, Datum arg1, Datum arg2,
				 Datum arg3, Datum arg4, Datum arg5);
extern Datum OidFunctionCall6(Oid functionId, Datum arg1, Datum arg2,
				 Datum arg3, Datum arg4, Datum arg5,
				 Datum arg6);
extern Datum OidFunctionCall7(Oid functionId, Datum arg1, Datum arg2,
				 Datum arg3, Datum arg4, Datum arg5,
				 Datum arg6, Datum arg7);
extern Datum OidFunctionCall8(Oid functionId, Datum arg1, Datum arg2,
				 Datum arg3, Datum arg4, Datum arg5,
				 Datum arg6, Datum arg7, Datum arg8);
extern Datum OidFunctionCall9(Oid functionId, Datum arg1, Datum arg2,
				 Datum arg3, Datum arg4, Datum arg5,
				 Datum arg6, Datum arg7, Datum arg8,
				 Datum arg9);

/* Special cases for convenient invocation of datatype I/O functions. */
extern Datum InputFunctionCall(FmgrInfo *flinfo, char *str,
				  Oid typioparam, int32 typmod);
extern Datum OidInputFunctionCall(Oid functionId, char *str,
					 Oid typioparam, int32 typmod);
extern char *OutputFunctionCall(FmgrInfo *flinfo, Datum val);
extern char *OidOutputFunctionCall(Oid functionId, Datum val);
extern Datum ReceiveFunctionCall(FmgrInfo *flinfo, fmStringInfo buf,
					Oid typioparam, int32 typmod);
extern Datum OidReceiveFunctionCall(Oid functionId, fmStringInfo buf,
					   Oid typioparam, int32 typmod);
extern bytea *SendFunctionCall(FmgrInfo *flinfo, Datum val);
extern bytea *OidSendFunctionCall(Oid functionId, Datum val);


/*
 * Routines in fmgr.c
 */
extern const Pg_finfo_record *fetch_finfo_record(void *filehandle, char *funcname);
extern void clear_external_function_hash(void *filehandle);
extern Oid	fmgr_internal_function(const char *proname);
extern Oid	get_fn_expr_rettype(FmgrInfo *flinfo);
extern Oid	get_fn_expr_argtype(FmgrInfo *flinfo, int argnum);
extern Oid	get_call_expr_argtype(fmNodePtr expr, int argnum);

/*
 * Routines in dfmgr.c
 */
extern char *Dynamic_library_path;

extern PGFunction load_external_function(char *filename, char *funcname,
					   bool signalNotFound, void **filehandle);
extern PGFunction lookup_external_function(void *filehandle, char *funcname);
extern void load_file(const char *filename, bool restricted);
extern void **find_rendezvous_variable(const char *varName);


/*
 * !!! OLD INTERFACE !!!
 *
 * fmgr() is the only remaining vestige of the old-style caller support
 * functions.  It's no longer used anywhere in the Postgres distribution,
 * but we should leave it around for a release or two to ease the transition
 * for user-supplied C functions.  OidFunctionCallN() replaces it for new
 * code.
 */

/*
 * DEPRECATED, DO NOT USE IN NEW CODE
 */
extern char *fmgr(Oid procedureId,...);

#endif   /* FMGR_H */