SQL/MED catalog manipulation facilities

This doesn't do any remote or external things yet, but it gives modules
like plproxy and dblink a standardized and future-proof system for
managing their connection information.

Martin Pihlak and Peter Eisentraut

src/include/foreign/foreign.h

@@ -0,0 +1,101 @@
+/*-------------------------------------------------------------------------
+ *
+ * foreign.h
+ *	  support for foreign-data wrappers, servers and user mappings.
+ *
+ *
+ * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
+ *
+ * $PostgreSQL: pgsql/src/include/foreign/foreign.h,v 1.1 2008/12/19 16:25:19 petere Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FOREIGN_H
+#define FOREIGN_H
+
+#include "nodes/parsenodes.h"
+#include "nodes/pg_list.h"
+
+
+/* Helper for obtaining username for user mapping */
+#define MappingUserName(userid) \
+	(OidIsValid(userid) ? GetUserNameFromId(userid) : "public")
+
+
+/*
+ * Generic option types for validation.
+ * NB! Thes are treated as flags, so use only powers of two here.
+ */
+typedef enum {
+	InvalidOpt = 0,
+	ServerOpt = 1,				/* options applicable to SERVER */
+	UserMappingOpt = 2,			/* options for USER MAPPING */
+	FdwOpt = 4,					/* options for FOREIGN DATA WRAPPER */
+} GenericOptionFlags;
+
+typedef struct ForeignDataWrapperLibrary ForeignDataWrapperLibrary;
+
+typedef struct ForeignDataWrapper
+{
+	Oid		fdwid;				/* FDW Oid */
+	Oid		owner;				/* FDW owner user Oid */
+	char   *fdwname;			/* Name of the FDW */
+	char   *fdwlibrary;			/* Library name */
+	List   *options;			/* fdwoptions as DefElem list */
+
+	ForeignDataWrapperLibrary *lib;	/* interface to the FDW functions */
+} ForeignDataWrapper;
+
+typedef struct ForeignServer
+{
+	Oid		serverid;			/* server Oid */
+	Oid		fdwid;				/* foreign-data wrapper */
+	Oid		owner;				/* server owner user Oid */
+	char	*servername;		/* name of the server */
+	char	*servertype;		/* server type, optional */
+	char	*serverversion;		/* server version, optional */
+	List	*options;			/* srvoptions as DefElem list */
+} ForeignServer;
+
+typedef struct UserMapping
+{
+	Oid		userid;				/* local user Oid */
+	Oid		serverid;			/* server Oid */
+	List	*options;			/* useoptions as DefElem list */
+} UserMapping;
+
+
+/*
+ * Foreign-data wrapper library function types.
+ */
+typedef void (*OptionListValidatorFunc)(ForeignDataWrapper *,
+										GenericOptionFlags,
+										List *);
+
+/*
+ * Interface functions to the foreign-data wrapper. This is decoupled
+ * from the FDW as there maybe several FDW-s accessing the same library.
+ */
+struct ForeignDataWrapperLibrary
+{
+	char 	   *libname;		/* name of the library file */
+
+	OptionListValidatorFunc	validateOptionList;
+};
+
+
+extern ForeignServer *GetForeignServer(Oid serverid);
+extern ForeignServer *GetForeignServerByName(const char *name, bool missing_ok);
+extern Oid GetForeignServerOidByName(const char *name, bool missing_ok);
+extern UserMapping *GetUserMapping(Oid userid, Oid serverid);
+extern ForeignDataWrapper *GetForeignDataWrapper(Oid fdwid);
+extern ForeignDataWrapper *GetForeignDataWrapperByName(const char *name,
+													   bool missing_ok);
+extern Oid GetForeignDataWrapperOidByName(const char *name, bool missing_ok);
+extern ForeignDataWrapperLibrary *GetForeignDataWrapperLibrary(const char *libname);
+
+/* Foreign data wrapper interface functions */
+extern void _pg_validateOptionList(ForeignDataWrapper *fdw,
+								   GenericOptionFlags flags, List *options);
+
+#endif /* FOREIGN_H */