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diff --git a/src/backend/lib/fstack.h b/src/backend/lib/fstack.h
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+/*-------------------------------------------------------------------------
+ *
+ * fstack.h--
+ *    Fixed format stack definitions.
+ *
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ * $Id: fstack.h,v 1.1.1.1 1996/07/09 06:21:29 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+/*
+ * Note:
+ *	Fixed format stacks assist in the construction of FIFO stacks of
+ *	fixed format structures.  Structures which are to be stackable
+ *	should contain a FixedItemData component.  A stack is initilized
+ *	with the offset of the FixedItemData component of the structure
+ *	it will hold.  By doing so, push and pop operations are simplified
+ *	for the callers.  All references to stackable items are pointers
+ *	to the base of the structure instead of pointers to the
+ *	FixedItemData component.
+ *
+ */
+#ifndef	FSTACK_H
+#define FSTACK_H
+
+#include "c.h"
+
+/*
+ * FixedItem --
+ *	Fixed format stackable item chain component.
+ *
+ * Note:
+ *	Structures must contain one FixedItemData component per stack in
+ *	which it will be an item.
+ */
+typedef struct FixedItemData	FixedItemData;
+typedef FixedItemData		*FixedItem;
+
+struct FixedItemData {
+	FixedItem	next;	/* next item or NULL */
+};
+
+/*
+ * FixedStack --
+ *	Fixed format stack.
+ */
+typedef struct FixedStackData {
+	FixedItem	top;	/* Top item on the stack or NULL */
+	Offset		offset;	/* Offset from struct base to item */
+	/* this could be signed short int! */
+} FixedStackData;
+
+typedef FixedStackData		*FixedStack;
+
+/*
+ * FixedStackInit --
+ *	Iniitializes stack for structures with given fixed component offset.
+ *
+ * Exceptions:
+ *	BadArg if stack is invalid pointer.
+ */
+extern void FixedStackInit(FixedStack stack, Offset offset);
+
+/*
+ * FixedStackPop --
+ *	Returns pointer to top structure on stack or NULL if empty stack.
+ *
+ * Exceptions:
+ *	BadArg if stack is invalid.
+ */
+Pointer FixedStackPop(FixedStack stack);
+
+/*
+ * FixedStackPush --
+ *	Places structure associated with pointer onto top of stack.
+ *
+ * Exceptions:
+ *	BadArg if stack is invalid.
+ *	BadArg if pointer is invalid.
+ */
+extern void FixedStackPush(FixedStack stack, Pointer pointer);
+
+/*
+ * FixedStackGetTop --
+ *	Returns pointer to top structure of a stack.  This item is not poped.
+ *
+ * Note:
+ *	This is not part of the normal stack interface.  It is intended for
+ *	 debugging use only.
+ *
+ * Exceptions:
+ *	BadArg if stack is invalid.
+ */
+extern Pointer FixedStackGetTop(FixedStack stack);
+
+/*
+ * FixedStackGetNext --
+ *	Returns pointer to next structure after pointer of a stack.
+ *
+ * Note:
+ *	This is not part of the normal stack interface.  It is intended for
+ *	 debugging use only.
+ *
+ * Exceptions:
+ *	BadArg if stack is invalid.
+ *	BadArg if pointer is invalid.
+ *	BadArg if stack does not contain pointer.
+ */
+extern Pointer FixedStackGetNext(FixedStack stack, Pointer pointer);
+
+#endif	/* FSTACK_H */