text: /*-------------------------------------------------------------------------
   *
   * fmgr.h
   *	  Definitions for the Postgres function manager and function-call
   *	  interface.
   *
   * This file must be included by all Postgres modules that either define
   * or call fmgr-callable functions.
   *
   *
   * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   * $PostgreSQL$
   *
   *-------------------------------------------------------------------------
   */
  #ifndef FMGR_H
  #define FMGR_H
  
  /* We don't want to include primnodes.h here, so make a stub reference */
  typedef struct Node *fmNodePtr;
  
  /* Likewise, avoid including stringinfo.h here */
  typedef struct StringInfoData *fmStringInfo;
  
  
  /*
   * All functions that can be called directly by fmgr must have this signature.
   * (Other functions can be called by using a handler that does have this
   * signature.)
   */
  
  typedef struct FunctionCallInfoData *FunctionCallInfo;
  
  typedef Datum (*PGFunction) (FunctionCallInfo fcinfo);
  
  /*
   * This struct holds the system-catalog information that must be looked up
   * before a function can be called through fmgr.  If the same function is
   * to be called multiple times, the lookup need be done only once and the
   * info struct saved for re-use.
   */
  typedef struct FmgrInfo
  {
  	PGFunction	fn_addr;		/* pointer to function or handler to be called */
  	Oid			fn_oid;			/* OID of function (NOT of handler, if any) */
  	short		fn_nargs;		/* 0..FUNC_MAX_ARGS, or -1 if variable arg
  								 * count */
  	bool		fn_strict;		/* function is "strict" (NULL in => NULL out) */
  	bool		fn_retset;		/* function returns a set */
  	unsigned char fn_stats;		/* collect stats if track_functions > this */
  	void	   *fn_extra;		/* extra space for use by handler */
  	MemoryContext fn_mcxt;		/* memory context to store fn_extra in */
  	fmNodePtr	fn_expr;		/* expression parse tree for call, or NULL */
  } FmgrInfo;
  
  /*
   * This struct is the data actually passed to an fmgr-called function.
   */
  typedef struct FunctionCallInfoData
  {
  	FmgrInfo   *flinfo;			/* ptr to lookup info used for this call */
  	fmNodePtr	context;		/* pass info about context of call */
  	fmNodePtr	resultinfo;		/* pass or return extra info about result */
  	bool		isnull;			/* function must set true if result is NULL */
  	short		nargs;			/* # arguments actually passed */
  	Datum		arg[FUNC_MAX_ARGS];		/* Arguments passed to function */
  	bool		argnull[FUNC_MAX_ARGS]; /* T if arg[i] is actually NULL */
  } FunctionCallInfoData;
  
  /*
   * This routine fills a FmgrInfo struct, given the OID
   * of the function to be called.
   */
  extern void fmgr_info(Oid functionId, FmgrInfo *finfo);
  
  /*
   * Same, when the FmgrInfo struct is in a memory context longer-lived than
   * CurrentMemoryContext.  The specified context will be set as fn_mcxt
   * and used to hold all subsidiary data of finfo.
   */
  extern void fmgr_info_cxt(Oid functionId, FmgrInfo *finfo,
  			  MemoryContext mcxt);
  
  /*
   * Copy an FmgrInfo struct
   */
  extern void fmgr_info_copy(FmgrInfo *dstinfo, FmgrInfo *srcinfo,
  			   MemoryContext destcxt);
  
  /*
   * This macro initializes all the fields of a FunctionCallInfoData except
   * for the arg[] and argnull[] arrays.	Performance testing has shown that
   * the fastest way to set up argnull[] for small numbers of arguments is to
   * explicitly set each required element to false, so we don't try to zero
   * out the argnull[] array in the macro.
   */
  #define InitFunctionCallInfoData(Fcinfo, Flinfo, Nargs, Context, Resultinfo) \
  	do { \
  		(Fcinfo).flinfo = (Flinfo); \
  		(Fcinfo).context = (Context); \
  		(Fcinfo).resultinfo = (Resultinfo); \
  		(Fcinfo).isnull = false; \
  		(Fcinfo).nargs = (Nargs); \
  	} while (0)
  
  /*
   * This macro invokes a function given a filled-in FunctionCallInfoData
   * struct.	The macro result is the returned Datum --- but note that
   * caller must still check fcinfo->isnull!	Also, if function is strict,
   * it is caller's responsibility to verify that no null arguments are present
   * before calling.
   */
  #define FunctionCallInvoke(fcinfo)	((* (fcinfo)->flinfo->fn_addr) (fcinfo))
  
  
  /*-------------------------------------------------------------------------
   *		Support macros to ease writing fmgr-compatible functions
   *
   * A C-coded fmgr-compatible function should be declared as
   *
   *		Datum
   *		function_name(PG_FUNCTION_ARGS)
   *		{
   *			...
   *		}
   *
   * It should access its arguments using appropriate PG_GETARG_xxx macros
   * and should return its result using PG_RETURN_xxx.
   *
   *-------------------------------------------------------------------------
   */
  
  /* Standard parameter list for fmgr-compatible functions */
  #define PG_FUNCTION_ARGS	FunctionCallInfo fcinfo
  
  /*
   * Get number of arguments passed to function.
   */
  #define PG_NARGS() (fcinfo->nargs)
  
  /*
   * If function is not marked "proisstrict" in pg_proc, it must check for
   * null arguments using this macro.  Do not try to GETARG a null argument!
   */
  #define PG_ARGISNULL(n)  (fcinfo->argnull[n])
  
  /*
   * Support for fetching detoasted copies of toastable datatypes (all of
   * which are varlena types).  pg_detoast_datum() gives you either the input
   * datum (if not toasted) or a detoasted copy allocated with palloc().
   * pg_detoast_datum_copy() always gives you a palloc'd copy --- use it
   * if you need a modifiable copy of the input.	Caller is expected to have
   * checked for null inputs first, if necessary.
   *
   * pg_detoast_datum_packed() will return packed (1-byte header) datums
   * unmodified.	It will still expand an externally toasted or compressed datum.
   * The resulting datum can be accessed using VARSIZE_ANY() and VARDATA_ANY()
   * (beware of multiple evaluations in those macros!)
   *
   * WARNING: It is only safe to use pg_detoast_datum_packed() and
   * VARDATA_ANY() if you really don't care about the alignment. Either because
   * you're working with something like text where the alignment doesn't matter
   * or because you're not going to access its constituent parts and just use
   * things like memcpy on it anyways.
   *
   * Note: it'd be nice if these could be macros, but I see no way to do that
   * without evaluating the arguments multiple times, which is NOT acceptable.
   */
  extern struct varlena *pg_detoast_datum(struct varlena * datum);
  extern struct varlena *pg_detoast_datum_copy(struct varlena * datum);
  extern struct varlena *pg_detoast_datum_slice(struct varlena * datum,
  					   int32 first, int32 count);
  extern struct varlena *pg_detoast_datum_packed(struct varlena * datum);
  
  #define PG_DETOAST_DATUM(datum) \
  	pg_detoast_datum((struct varlena *) DatumGetPointer(datum))
  #define PG_DETOAST_DATUM_COPY(datum) \
  	pg_detoast_datum_copy((struct varlena *) DatumGetPointer(datum))
  #define PG_DETOAST_DATUM_SLICE(datum,f,c) \
  		pg_detoast_datum_slice((struct varlena *) DatumGetPointer(datum), \
  		(int32) (f), (int32) (c))
  /* WARNING -- unaligned pointer */
  #define PG_DETOAST_DATUM_PACKED(datum) \
  	pg_detoast_datum_packed((struct varlena *) DatumGetPointer(datum))
  
  /*
   * Support for cleaning up detoasted copies of inputs.	This must only
   * be used for pass-by-ref datatypes, and normally would only be used
   * for toastable types.  If the given pointer is different from the
   * original argument, assume it's a palloc'd detoasted copy, and pfree it.
   * NOTE: most functions on toastable types do not have to worry about this,
   * but we currently require that support functions for indexes not leak
   * memory.
   */
  #define PG_FREE_IF_COPY(ptr,n) \
  	do { \
  		if ((Pointer) (ptr) != PG_GETARG_POINTER(n)) \
  			pfree(ptr); \
  	} while (0)
  
  /* Macros for fetching arguments of standard types */
  
  #define PG_GETARG_DATUM(n)	 (fcinfo->arg[n])
  #define PG_GETARG_INT32(n)	 DatumGetInt32(PG_GETARG_DATUM(n))
  #define PG_GETARG_UINT32(n)  DatumGetUInt32(PG_GETARG_DATUM(n))
  #define PG_GETARG_INT16(n)	 DatumGetInt16(PG_GETARG_DATUM(n))
  #define PG_GETARG_UINT16(n)  DatumGetUInt16(PG_GETARG_DATUM(n))
  #define PG_GETARG_CHAR(n)	 DatumGetChar(PG_GETARG_DATUM(n))
  #define PG_GETARG_BOOL(n)	 DatumGetBool(PG_GETARG_DATUM(n))
  #define PG_GETARG_OID(n)	 DatumGetObjectId(PG_GETARG_DATUM(n))
  #define PG_GETARG_POINTER(n) DatumGetPointer(PG_GETARG_DATUM(n))
  #define PG_GETARG_CSTRING(n) DatumGetCString(PG_GETARG_DATUM(n))
  #define PG_GETARG_NAME(n)	 DatumGetName(PG_GETARG_DATUM(n))
  /* these macros hide the pass-by-reference-ness of the datatype: */
  #define PG_GETARG_FLOAT4(n)  DatumGetFloat4(PG_GETARG_DATUM(n))
  #define PG_GETARG_FLOAT8(n)  DatumGetFloat8(PG_GETARG_DATUM(n))
  #define PG_GETARG_INT64(n)	 DatumGetInt64(PG_GETARG_DATUM(n))
  /* use this if you want the raw, possibly-toasted input datum: */
  #define PG_GETARG_RAW_VARLENA_P(n)	((struct varlena *) PG_GETARG_POINTER(n))
  /* use this if you want the input datum de-toasted: */
  #define PG_GETARG_VARLENA_P(n) PG_DETOAST_DATUM(PG_GETARG_DATUM(n))
  /* and this if you can handle 1-byte-header datums: */
  #define PG_GETARG_VARLENA_PP(n) PG_DETOAST_DATUM_PACKED(PG_GETARG_DATUM(n))
  /* DatumGetFoo macros for varlena types will typically look like this: */
  #define DatumGetByteaP(X)			((bytea *) PG_DETOAST_DATUM(X))
  #define DatumGetByteaPP(X)			((bytea *) PG_DETOAST_DATUM_PACKED(X))
  #define DatumGetTextP(X)			((text *) PG_DETOAST_DATUM(X))
  #define DatumGetTextPP(X)			((text *) PG_DETOAST_DATUM_PACKED(X))
  #define DatumGetBpCharP(X)			((BpChar *) PG_DETOAST_DATUM(X))
  #define DatumGetBpCharPP(X)			((BpChar *) PG_DETOAST_DATUM_PACKED(X))
  #define DatumGetVarCharP(X)			((VarChar *) PG_DETOAST_DATUM(X))
  #define DatumGetVarCharPP(X)		((VarChar *) PG_DETOAST_DATUM_PACKED(X))
  #define DatumGetHeapTupleHeader(X)	((HeapTupleHeader) PG_DETOAST_DATUM(X))
  /* And we also offer variants that return an OK-to-write copy */
  #define DatumGetByteaPCopy(X)		((bytea *) PG_DETOAST_DATUM_COPY(X))
  #define DatumGetTextPCopy(X)		((text *) PG_DETOAST_DATUM_COPY(X))
  #define DatumGetBpCharPCopy(X)		((BpChar *) PG_DETOAST_DATUM_COPY(X))
  #define DatumGetVarCharPCopy(X)		((VarChar *) PG_DETOAST_DATUM_COPY(X))
  #define DatumGetHeapTupleHeaderCopy(X)	((HeapTupleHeader) PG_DETOAST_DATUM_COPY(X))
  /* Variants which return n bytes starting at pos. m */
  #define DatumGetByteaPSlice(X,m,n)	((bytea *) PG_DETOAST_DATUM_SLICE(X,m,n))
  #define DatumGetTextPSlice(X,m,n)	((text *) PG_DETOAST_DATUM_SLICE(X,m,n))
  #define DatumGetBpCharPSlice(X,m,n) ((BpChar *) PG_DETOAST_DATUM_SLICE(X,m,n))
  #define DatumGetVarCharPSlice(X,m,n) ((VarChar *) PG_DETOAST_DATUM_SLICE(X,m,n))
  /* GETARG macros for varlena types will typically look like this: */
  #define PG_GETARG_BYTEA_P(n)		DatumGetByteaP(PG_GETARG_DATUM(n))
  #define PG_GETARG_BYTEA_PP(n)		DatumGetByteaPP(PG_GETARG_DATUM(n))
  #define PG_GETARG_TEXT_P(n)			DatumGetTextP(PG_GETARG_DATUM(n))
  #define PG_GETARG_TEXT_PP(n)		DatumGetTextPP(PG_GETARG_DATUM(n))
  #define PG_GETARG_BPCHAR_P(n)		DatumGetBpCharP(PG_GETARG_DATUM(n))
  #define PG_GETARG_BPCHAR_PP(n)		DatumGetBpCharPP(PG_GETARG_DATUM(n))
  #define PG_GETARG_VARCHAR_P(n)		DatumGetVarCharP(PG_GETARG_DATUM(n))
  #define PG_GETARG_VARCHAR_PP(n)		DatumGetVarCharPP(PG_GETARG_DATUM(n))
  #define PG_GETARG_HEAPTUPLEHEADER(n)	DatumGetHeapTupleHeader(PG_GETARG_DATUM(n))
  /* And we also offer variants that return an OK-to-write copy */
  #define PG_GETARG_BYTEA_P_COPY(n)	DatumGetByteaPCopy(PG_GETARG_DATUM(n))
  #define PG_GETARG_TEXT_P_COPY(n)	DatumGetTextPCopy(PG_GETARG_DATUM(n))
  #define PG_GETARG_BPCHAR_P_COPY(n)	DatumGetBpCharPCopy(PG_GETARG_DATUM(n))
  #define PG_GETARG_VARCHAR_P_COPY(n) DatumGetVarCharPCopy(PG_GETARG_DATUM(n))
  #define PG_GETARG_HEAPTUPLEHEADER_COPY(n)	DatumGetHeapTupleHeaderCopy(PG_GETARG_DATUM(n))
  /* And a b-byte slice from position a -also OK to write */
  #define PG_GETARG_BYTEA_P_SLICE(n,a,b) DatumGetByteaPSlice(PG_GETARG_DATUM(n),a,b)
  #define PG_GETARG_TEXT_P_SLICE(n,a,b)  DatumGetTextPSlice(PG_GETARG_DATUM(n),a,b)
  #define PG_GETARG_BPCHAR_P_SLICE(n,a,b) DatumGetBpCharPSlice(PG_GETARG_DATUM(n),a,b)
  #define PG_GETARG_VARCHAR_P_SLICE(n,a,b) DatumGetVarCharPSlice(PG_GETARG_DATUM(n),a,b)
  
  /* To return a NULL do this: */
  #define PG_RETURN_NULL()  \
  	do { fcinfo->isnull = true; return (Datum) 0; } while (0)
  
  /* A few internal functions return void (which is not the same as NULL!) */
  #define PG_RETURN_VOID()	 return (Datum) 0
  
  /* Macros for returning results of standard types */
  
  #define PG_RETURN_DATUM(x)	 return (x)
  #define PG_RETURN_INT32(x)	 return Int32GetDatum(x)
  #define PG_RETURN_UINT32(x)  return UInt32GetDatum(x)
  #define PG_RETURN_INT16(x)	 return Int16GetDatum(x)
  #define PG_RETURN_CHAR(x)	 return CharGetDatum(x)
  #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 PGDLLIMPORT in case they don't.
   */
  #define PG_FUNCTION_INFO_V1(funcname) \
  extern PGDLLIMPORT 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.
   *
   * Note: we compare magic blocks with memcmp(), so there had better not be
   * any alignment pad bytes in them.
   *
   * Note: when changing the contents of magic blocks, be sure to adjust the
   * incompatible_module_error() function in dfmgr.c.
   *-------------------------------------------------------------------------
   */
  
  /* 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 */
  	int			float4byval;	/* FLOAT4PASSBYVAL */
  	int			float8byval;	/* FLOAT8PASSBYVAL */
  } 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, \
  	FLOAT4PASSBYVAL, \
  	FLOAT8PASSBYVAL \
  }
  
  /*
   * 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 PGDLLIMPORT 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);
  extern bool get_fn_expr_arg_stable(FmgrInfo *flinfo, int argnum);
  extern bool get_call_expr_arg_stable(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);
  
  /*
   * Support for aggregate functions
   *
   * This is actually in executor/nodeAgg.c, but we declare it here since the
   * whole point is for callers of it to not be overly friendly with nodeAgg.
   */
  
  /* AggCheckCallContext can return one of the following codes, or 0: */
  #define AGG_CONTEXT_AGGREGATE	1		/* regular aggregate */
  #define AGG_CONTEXT_WINDOW		2		/* window function */
  
  extern int AggCheckCallContext(FunctionCallInfo fcinfo,
  					MemoryContext *aggcontext);
  
  
  /*
   * !!! 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 */
  