Adding upstream version 15.5.upstream/15.5

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1417 insertions, 0 deletions

diff --git a/src/include/c.h b/src/include/c.h
new file mode 100644
index 0000000..ffcdb05
--- /dev/null
+++ b/src/include/c.h
@@ -0,0 +1,1417 @@
+/*-------------------------------------------------------------------------
+ *
+ * c.h
+ *	  Fundamental C definitions.  This is included by every .c file in
+ *	  PostgreSQL (via either postgres.h or postgres_fe.h, as appropriate).
+ *
+ *	  Note that the definitions here are not intended to be exposed to clients
+ *	  of the frontend interface libraries --- so we don't worry much about
+ *	  polluting the namespace with lots of stuff...
+ *
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/c.h
+ *
+ *-------------------------------------------------------------------------
+ */
+/*
+ *----------------------------------------------------------------
+ *	 TABLE OF CONTENTS
+ *
+ *		When adding stuff to this file, please try to put stuff
+ *		into the relevant section, or add new sections as appropriate.
+ *
+ *	  section	description
+ *	  -------	------------------------------------------------
+ *		0)		pg_config.h and standard system headers
+ *		1)		compiler characteristics
+ *		2)		bool, true, false
+ *		3)		standard system types
+ *		4)		IsValid macros for system types
+ *		5)		offsetof, lengthof, alignment
+ *		6)		assertions
+ *		7)		widely useful macros
+ *		8)		random stuff
+ *		9)		system-specific hacks
+ *
+ * NOTE: since this file is included by both frontend and backend modules,
+ * it's usually wrong to put an "extern" declaration here, unless it's
+ * ifdef'd so that it's seen in only one case or the other.
+ * typedefs and macros are the kind of thing that might go here.
+ *
+ *----------------------------------------------------------------
+ */
+#ifndef C_H
+#define C_H
+
+#include "postgres_ext.h"
+
+/* Must undef pg_config_ext.h symbols before including pg_config.h */
+#undef PG_INT64_TYPE
+
+#include "pg_config.h"
+#include "pg_config_manual.h"	/* must be after pg_config.h */
+#include "pg_config_os.h"		/* must be before any system header files */
+
+/* System header files that should be available everywhere in Postgres */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stddef.h>
+#include <stdarg.h>
+#ifdef HAVE_STRINGS_H
+#include <strings.h>
+#endif
+#include <stdint.h>
+#include <sys/types.h>
+#include <errno.h>
+#if defined(WIN32) || defined(__CYGWIN__)
+#include <fcntl.h>				/* ensure O_BINARY is available */
+#endif
+#include <locale.h>
+#ifdef ENABLE_NLS
+#include <libintl.h>
+#endif
+
+
+/* ----------------------------------------------------------------
+ *				Section 1: compiler characteristics
+ *
+ * type prefixes (const, signed, volatile, inline) are handled in pg_config.h.
+ * ----------------------------------------------------------------
+ */
+
+/*
+ * Disable "inline" if PG_FORCE_DISABLE_INLINE is defined.
+ * This is used to work around compiler bugs and might also be useful for
+ * investigatory purposes.
+ */
+#ifdef PG_FORCE_DISABLE_INLINE
+#undef inline
+#define inline
+#endif
+
+/*
+ * Attribute macros
+ *
+ * GCC: https://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
+ * GCC: https://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html
+ * Clang: https://clang.llvm.org/docs/AttributeReference.html
+ * Sunpro: https://docs.oracle.com/cd/E18659_01/html/821-1384/gjzke.html
+ * XLC: https://www.ibm.com/support/knowledgecenter/SSGH2K_13.1.2/com.ibm.xlc131.aix.doc/language_ref/function_attributes.html
+ * XLC: https://www.ibm.com/support/knowledgecenter/SSGH2K_13.1.2/com.ibm.xlc131.aix.doc/language_ref/type_attrib.html
+ */
+
+/*
+ * For compilers which don't support __has_attribute, we just define
+ * __has_attribute(x) to 0 so that we can define macros for various
+ * __attribute__s more easily below.
+ */
+#ifndef __has_attribute
+#define __has_attribute(attribute) 0
+#endif
+
+/* only GCC supports the unused attribute */
+#ifdef __GNUC__
+#define pg_attribute_unused() __attribute__((unused))
+#else
+#define pg_attribute_unused()
+#endif
+
+/*
+ * pg_nodiscard means the compiler should warn if the result of a function
+ * call is ignored.  The name "nodiscard" is chosen in alignment with
+ * (possibly future) C and C++ standards.  For maximum compatibility, use it
+ * as a function declaration specifier, so it goes before the return type.
+ */
+#ifdef __GNUC__
+#define pg_nodiscard __attribute__((warn_unused_result))
+#else
+#define pg_nodiscard
+#endif
+
+/*
+ * Place this macro before functions that should be allowed to make misaligned
+ * accesses.  Think twice before using it on non-x86-specific code!
+ * Testing can be done with "-fsanitize=alignment -fsanitize-trap=alignment"
+ * on clang, or "-fsanitize=alignment -fno-sanitize-recover=alignment" on gcc.
+ */
+#if __clang_major__ >= 7 || __GNUC__ >= 8
+#define pg_attribute_no_sanitize_alignment() __attribute__((no_sanitize("alignment")))
+#else
+#define pg_attribute_no_sanitize_alignment()
+#endif
+
+/*
+ * Append PG_USED_FOR_ASSERTS_ONLY to definitions of variables that are only
+ * used in assert-enabled builds, to avoid compiler warnings about unused
+ * variables in assert-disabled builds.
+ */
+#ifdef USE_ASSERT_CHECKING
+#define PG_USED_FOR_ASSERTS_ONLY
+#else
+#define PG_USED_FOR_ASSERTS_ONLY pg_attribute_unused()
+#endif
+
+/* GCC and XLC support format attributes */
+#if defined(__GNUC__) || defined(__IBMC__)
+#define pg_attribute_format_arg(a) __attribute__((format_arg(a)))
+#define pg_attribute_printf(f,a) __attribute__((format(PG_PRINTF_ATTRIBUTE, f, a)))
+#else
+#define pg_attribute_format_arg(a)
+#define pg_attribute_printf(f,a)
+#endif
+
+/* GCC, Sunpro and XLC support aligned, packed and noreturn */
+#if defined(__GNUC__) || defined(__SUNPRO_C) || defined(__IBMC__)
+#define pg_attribute_aligned(a) __attribute__((aligned(a)))
+#define pg_attribute_noreturn() __attribute__((noreturn))
+#define pg_attribute_packed() __attribute__((packed))
+#define HAVE_PG_ATTRIBUTE_NORETURN 1
+#else
+/*
+ * NB: aligned and packed are not given default definitions because they
+ * affect code functionality; they *must* be implemented by the compiler
+ * if they are to be used.
+ */
+#define pg_attribute_noreturn()
+#endif
+
+/*
+ * Use "pg_attribute_always_inline" in place of "inline" for functions that
+ * we wish to force inlining of, even when the compiler's heuristics would
+ * choose not to.  But, if possible, don't force inlining in unoptimized
+ * debug builds.
+ */
+#if (defined(__GNUC__) && __GNUC__ > 3 && defined(__OPTIMIZE__)) || defined(__SUNPRO_C) || defined(__IBMC__)
+/* GCC > 3, Sunpro and XLC support always_inline via __attribute__ */
+#define pg_attribute_always_inline __attribute__((always_inline)) inline
+#elif defined(_MSC_VER)
+/* MSVC has a special keyword for this */
+#define pg_attribute_always_inline __forceinline
+#else
+/* Otherwise, the best we can do is to say "inline" */
+#define pg_attribute_always_inline inline
+#endif
+
+/*
+ * Forcing a function not to be inlined can be useful if it's the slow path of
+ * a performance-critical function, or should be visible in profiles to allow
+ * for proper cost attribution.  Note that unlike the pg_attribute_XXX macros
+ * above, this should be placed before the function's return type and name.
+ */
+/* GCC, Sunpro and XLC support noinline via __attribute__ */
+#if (defined(__GNUC__) && __GNUC__ > 2) || defined(__SUNPRO_C) || defined(__IBMC__)
+#define pg_noinline __attribute__((noinline))
+/* msvc via declspec */
+#elif defined(_MSC_VER)
+#define pg_noinline __declspec(noinline)
+#else
+#define pg_noinline
+#endif
+
+/*
+ * For now, just define pg_attribute_cold and pg_attribute_hot to be empty
+ * macros on minGW 8.1.  There appears to be a compiler bug that results in
+ * compilation failure.  At this time, we still have at least one buildfarm
+ * animal running that compiler, so this should make that green again. It's
+ * likely this compiler is not popular enough to warrant keeping this code
+ * around forever, so let's just remove it once the last buildfarm animal
+ * upgrades.
+ */
+#if defined(__MINGW64__) && __GNUC__ == 8 && __GNUC_MINOR__ == 1
+
+#define pg_attribute_cold
+#define pg_attribute_hot
+
+#else
+/*
+ * Marking certain functions as "hot" or "cold" can be useful to assist the
+ * compiler in arranging the assembly code in a more efficient way.
+ */
+#if __has_attribute (cold)
+#define pg_attribute_cold __attribute__((cold))
+#else
+#define pg_attribute_cold
+#endif
+
+#if __has_attribute (hot)
+#define pg_attribute_hot __attribute__((hot))
+#else
+#define pg_attribute_hot
+#endif
+
+#endif							/* defined(__MINGW64__) && __GNUC__ == 8 &&
+								 * __GNUC_MINOR__ == 1 */
+/*
+ * Mark a point as unreachable in a portable fashion.  This should preferably
+ * be something that the compiler understands, to aid code generation.
+ * In assert-enabled builds, we prefer abort() for debugging reasons.
+ */
+#if defined(HAVE__BUILTIN_UNREACHABLE) && !defined(USE_ASSERT_CHECKING)
+#define pg_unreachable() __builtin_unreachable()
+#elif defined(_MSC_VER) && !defined(USE_ASSERT_CHECKING)
+#define pg_unreachable() __assume(0)
+#else
+#define pg_unreachable() abort()
+#endif
+
+/*
+ * Hints to the compiler about the likelihood of a branch. Both likely() and
+ * unlikely() return the boolean value of the contained expression.
+ *
+ * These should only be used sparingly, in very hot code paths. It's very easy
+ * to mis-estimate likelihoods.
+ */
+#if __GNUC__ >= 3
+#define likely(x)	__builtin_expect((x) != 0, 1)
+#define unlikely(x) __builtin_expect((x) != 0, 0)
+#else
+#define likely(x)	((x) != 0)
+#define unlikely(x) ((x) != 0)
+#endif
+
+/*
+ * CppAsString
+ *		Convert the argument to a string, using the C preprocessor.
+ * CppAsString2
+ *		Convert the argument to a string, after one round of macro expansion.
+ * CppConcat
+ *		Concatenate two arguments together, using the C preprocessor.
+ *
+ * Note: There used to be support here for pre-ANSI C compilers that didn't
+ * support # and ##.  Nowadays, these macros are just for clarity and/or
+ * backward compatibility with existing PostgreSQL code.
+ */
+#define CppAsString(identifier) #identifier
+#define CppAsString2(x)			CppAsString(x)
+#define CppConcat(x, y)			x##y
+
+/*
+ * VA_ARGS_NARGS
+ *		Returns the number of macro arguments it is passed.
+ *
+ * An empty argument still counts as an argument, so effectively, this is
+ * "one more than the number of commas in the argument list".
+ *
+ * This works for up to 63 arguments.  Internally, VA_ARGS_NARGS_() is passed
+ * 64+N arguments, and the C99 standard only requires macros to allow up to
+ * 127 arguments, so we can't portably go higher.  The implementation is
+ * pretty trivial: VA_ARGS_NARGS_() returns its 64th argument, and we set up
+ * the call so that that is the appropriate one of the list of constants.
+ * This idea is due to Laurent Deniau.
+ */
+#define VA_ARGS_NARGS(...) \
+	VA_ARGS_NARGS_(__VA_ARGS__, \
+				   63,62,61,60,                   \
+				   59,58,57,56,55,54,53,52,51,50, \
+				   49,48,47,46,45,44,43,42,41,40, \
+				   39,38,37,36,35,34,33,32,31,30, \
+				   29,28,27,26,25,24,23,22,21,20, \
+				   19,18,17,16,15,14,13,12,11,10, \
+				   9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
+#define VA_ARGS_NARGS_( \
+	_01,_02,_03,_04,_05,_06,_07,_08,_09,_10, \
+	_11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \
+	_21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \
+	_31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \
+	_41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \
+	_51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \
+	_61,_62,_63,  N, ...) \
+	(N)
+
+/*
+ * dummyret is used to set return values in macros that use ?: to make
+ * assignments.  gcc wants these to be void, other compilers like char
+ */
+#ifdef __GNUC__					/* GNU cc */
+#define dummyret	void
+#else
+#define dummyret	char
+#endif
+
+/*
+ * Generic function pointer.  This can be used in the rare cases where it's
+ * necessary to cast a function pointer to a seemingly incompatible function
+ * pointer type while avoiding gcc's -Wcast-function-type warnings.
+ */
+typedef void (*pg_funcptr_t) (void);
+
+/*
+ * We require C99, hence the compiler should understand flexible array
+ * members.  However, for documentation purposes we still consider it to be
+ * project style to write "field[FLEXIBLE_ARRAY_MEMBER]" not just "field[]".
+ * When computing the size of such an object, use "offsetof(struct s, f)"
+ * for portability.  Don't use "offsetof(struct s, f[0])", as this doesn't
+ * work with MSVC and with C++ compilers.
+ */
+#define FLEXIBLE_ARRAY_MEMBER	/* empty */
+
+/* Which __func__ symbol do we have, if any? */
+#ifdef HAVE_FUNCNAME__FUNC
+#define PG_FUNCNAME_MACRO	__func__
+#else
+#ifdef HAVE_FUNCNAME__FUNCTION
+#define PG_FUNCNAME_MACRO	__FUNCTION__
+#else
+#define PG_FUNCNAME_MACRO	NULL
+#endif
+#endif
+
+/*
+ * Does the compiler support #pragma GCC system_header? We optionally use it
+ * to avoid warnings that we can't fix (e.g. in the perl headers).
+ * See https://gcc.gnu.org/onlinedocs/cpp/System-Headers.html
+ *
+ * Headers for which we do not want to show compiler warnings can,
+ * conditionally, use #pragma GCC system_header to avoid warnings. Obviously
+ * this should only be used for external headers over which we do not have
+ * control.
+ *
+ * Support for the pragma is tested here, instead of during configure, as gcc
+ * also warns about the pragma being used in a .c file. It's surprisingly hard
+ * to get autoconf to use .h as the file-ending. Looks like gcc has
+ * implemented the pragma since the 2000, so this test should suffice.
+ *
+ *
+ * Alternatively, we could add the include paths for problematic headers with
+ * -isystem, but that is a larger hammer and is harder to search for.
+ *
+ * A more granular alternative would be to use #pragma GCC diagnostic
+ * push/ignored/pop, but gcc warns about unknown warnings being ignored, so
+ * every to-be-ignored-temporarily compiler warning would require its own
+ * pg_config.h symbol and #ifdef.
+ */
+#ifdef __GNUC__
+#define HAVE_PRAGMA_GCC_SYSTEM_HEADER	1
+#endif
+
+
+/* ----------------------------------------------------------------
+ *				Section 2:	bool, true, false
+ * ----------------------------------------------------------------
+ */
+
+/*
+ * bool
+ *		Boolean value, either true or false.
+ *
+ * We use stdbool.h if available and its bool has size 1.  That's useful for
+ * better compiler and debugger output and for compatibility with third-party
+ * libraries.  But PostgreSQL currently cannot deal with bool of other sizes;
+ * there are static assertions around the code to prevent that.
+ *
+ * For C++ compilers, we assume the compiler has a compatible built-in
+ * definition of bool.
+ *
+ * See also the version of this code in src/interfaces/ecpg/include/ecpglib.h.
+ */
+
+#ifndef __cplusplus
+
+#ifdef PG_USE_STDBOOL
+#include <stdbool.h>
+#else
+
+#ifndef bool
+typedef unsigned char bool;
+#endif
+
+#ifndef true
+#define true	((bool) 1)
+#endif
+
+#ifndef false
+#define false	((bool) 0)
+#endif
+
+#endif							/* not PG_USE_STDBOOL */
+#endif							/* not C++ */
+
+
+/* ----------------------------------------------------------------
+ *				Section 3:	standard system types
+ * ----------------------------------------------------------------
+ */
+
+/*
+ * Pointer
+ *		Variable holding address of any memory resident object.
+ *
+ *		XXX Pointer arithmetic is done with this, so it can't be void *
+ *		under "true" ANSI compilers.
+ */
+typedef char *Pointer;
+
+/*
+ * intN
+ *		Signed integer, EXACTLY N BITS IN SIZE,
+ *		used for numerical computations and the
+ *		frontend/backend protocol.
+ */
+#ifndef HAVE_INT8
+typedef signed char int8;		/* == 8 bits */
+typedef signed short int16;		/* == 16 bits */
+typedef signed int int32;		/* == 32 bits */
+#endif							/* not HAVE_INT8 */
+
+/*
+ * uintN
+ *		Unsigned integer, EXACTLY N BITS IN SIZE,
+ *		used for numerical computations and the
+ *		frontend/backend protocol.
+ */
+#ifndef HAVE_UINT8
+typedef unsigned char uint8;	/* == 8 bits */
+typedef unsigned short uint16;	/* == 16 bits */
+typedef unsigned int uint32;	/* == 32 bits */
+#endif							/* not HAVE_UINT8 */
+
+/*
+ * bitsN
+ *		Unit of bitwise operation, AT LEAST N BITS IN SIZE.
+ */
+typedef uint8 bits8;			/* >= 8 bits */
+typedef uint16 bits16;			/* >= 16 bits */
+typedef uint32 bits32;			/* >= 32 bits */
+
+/*
+ * 64-bit integers
+ */
+#ifdef HAVE_LONG_INT_64
+/* Plain "long int" fits, use it */
+
+#ifndef HAVE_INT64
+typedef long int int64;
+#endif
+#ifndef HAVE_UINT64
+typedef unsigned long int uint64;
+#endif
+#define INT64CONST(x)  (x##L)
+#define UINT64CONST(x) (x##UL)
+#elif defined(HAVE_LONG_LONG_INT_64)
+/* We have working support for "long long int", use that */
+
+#ifndef HAVE_INT64
+typedef long long int int64;
+#endif
+#ifndef HAVE_UINT64
+typedef unsigned long long int uint64;
+#endif
+#define INT64CONST(x)  (x##LL)
+#define UINT64CONST(x) (x##ULL)
+#else
+/* neither HAVE_LONG_INT_64 nor HAVE_LONG_LONG_INT_64 */
+#error must have a working 64-bit integer datatype
+#endif
+
+/* snprintf format strings to use for 64-bit integers */
+#define INT64_FORMAT "%" INT64_MODIFIER "d"
+#define UINT64_FORMAT "%" INT64_MODIFIER "u"
+
+/*
+ * 128-bit signed and unsigned integers
+ *		There currently is only limited support for such types.
+ *		E.g. 128bit literals and snprintf are not supported; but math is.
+ *		Also, because we exclude such types when choosing MAXIMUM_ALIGNOF,
+ *		it must be possible to coerce the compiler to allocate them on no
+ *		more than MAXALIGN boundaries.
+ */
+#if defined(PG_INT128_TYPE)
+#if defined(pg_attribute_aligned) || ALIGNOF_PG_INT128_TYPE <= MAXIMUM_ALIGNOF
+#define HAVE_INT128 1
+
+typedef PG_INT128_TYPE int128
+#if defined(pg_attribute_aligned)
+			pg_attribute_aligned(MAXIMUM_ALIGNOF)
+#endif
+		   ;
+
+typedef unsigned PG_INT128_TYPE uint128
+#if defined(pg_attribute_aligned)
+			pg_attribute_aligned(MAXIMUM_ALIGNOF)
+#endif
+		   ;
+
+#endif
+#endif
+
+/*
+ * stdint.h limits aren't guaranteed to have compatible types with our fixed
+ * width types. So just define our own.
+ */
+#define PG_INT8_MIN		(-0x7F-1)
+#define PG_INT8_MAX		(0x7F)
+#define PG_UINT8_MAX	(0xFF)
+#define PG_INT16_MIN	(-0x7FFF-1)
+#define PG_INT16_MAX	(0x7FFF)
+#define PG_UINT16_MAX	(0xFFFF)
+#define PG_INT32_MIN	(-0x7FFFFFFF-1)
+#define PG_INT32_MAX	(0x7FFFFFFF)
+#define PG_UINT32_MAX	(0xFFFFFFFFU)
+#define PG_INT64_MIN	(-INT64CONST(0x7FFFFFFFFFFFFFFF) - 1)
+#define PG_INT64_MAX	INT64CONST(0x7FFFFFFFFFFFFFFF)
+#define PG_UINT64_MAX	UINT64CONST(0xFFFFFFFFFFFFFFFF)
+
+/*
+ * We now always use int64 timestamps, but keep this symbol defined for the
+ * benefit of external code that might test it.
+ */
+#define HAVE_INT64_TIMESTAMP
+
+/*
+ * Size
+ *		Size of any memory resident object, as returned by sizeof.
+ */
+typedef size_t Size;
+
+/*
+ * Index
+ *		Index into any memory resident array.
+ *
+ * Note:
+ *		Indices are non negative.
+ */
+typedef unsigned int Index;
+
+/*
+ * Offset
+ *		Offset into any memory resident array.
+ *
+ * Note:
+ *		This differs from an Index in that an Index is always
+ *		non negative, whereas Offset may be negative.
+ */
+typedef signed int Offset;
+
+/*
+ * Common Postgres datatype names (as used in the catalogs)
+ */
+typedef float float4;
+typedef double float8;
+
+#ifdef USE_FLOAT8_BYVAL
+#define FLOAT8PASSBYVAL true
+#else
+#define FLOAT8PASSBYVAL false
+#endif
+
+/*
+ * Oid, RegProcedure, TransactionId, SubTransactionId, MultiXactId,
+ * CommandId
+ */
+
+/* typedef Oid is in postgres_ext.h */
+
+/*
+ * regproc is the type name used in the include/catalog headers, but
+ * RegProcedure is the preferred name in C code.
+ */
+typedef Oid regproc;
+typedef regproc RegProcedure;
+
+typedef uint32 TransactionId;
+
+typedef uint32 LocalTransactionId;
+
+typedef uint32 SubTransactionId;
+
+#define InvalidSubTransactionId		((SubTransactionId) 0)
+#define TopSubTransactionId			((SubTransactionId) 1)
+
+/* MultiXactId must be equivalent to TransactionId, to fit in t_xmax */
+typedef TransactionId MultiXactId;
+
+typedef uint32 MultiXactOffset;
+
+typedef uint32 CommandId;
+
+#define FirstCommandId	((CommandId) 0)
+#define InvalidCommandId	(~(CommandId)0)
+
+
+/* ----------------
+ *		Variable-length datatypes all share the 'struct varlena' header.
+ *
+ * NOTE: for TOASTable types, this is an oversimplification, since the value
+ * may be compressed or moved out-of-line.  However datatype-specific routines
+ * are mostly content to deal with de-TOASTed values only, and of course
+ * client-side routines should never see a TOASTed value.  But even in a
+ * de-TOASTed value, beware of touching vl_len_ directly, as its
+ * representation is no longer convenient.  It's recommended that code always
+ * use macros VARDATA_ANY, VARSIZE_ANY, VARSIZE_ANY_EXHDR, VARDATA, VARSIZE,
+ * and SET_VARSIZE instead of relying on direct mentions of the struct fields.
+ * See postgres.h for details of the TOASTed form.
+ * ----------------
+ */
+struct varlena
+{
+	char		vl_len_[4];		/* Do not touch this field directly! */
+	char		vl_dat[FLEXIBLE_ARRAY_MEMBER];	/* Data content is here */
+};
+
+#define VARHDRSZ		((int32) sizeof(int32))
+
+/*
+ * These widely-used datatypes are just a varlena header and the data bytes.
+ * There is no terminating null or anything like that --- the data length is
+ * always VARSIZE_ANY_EXHDR(ptr).
+ */
+typedef struct varlena bytea;
+typedef struct varlena text;
+typedef struct varlena BpChar;	/* blank-padded char, ie SQL char(n) */
+typedef struct varlena VarChar; /* var-length char, ie SQL varchar(n) */
+
+/*
+ * Specialized array types.  These are physically laid out just the same
+ * as regular arrays (so that the regular array subscripting code works
+ * with them).  They exist as distinct types mostly for historical reasons:
+ * they have nonstandard I/O behavior which we don't want to change for fear
+ * of breaking applications that look at the system catalogs.  There is also
+ * an implementation issue for oidvector: it's part of the primary key for
+ * pg_proc, and we can't use the normal btree array support routines for that
+ * without circularity.
+ */
+typedef struct
+{
+	int32		vl_len_;		/* these fields must match ArrayType! */
+	int			ndim;			/* always 1 for int2vector */
+	int32		dataoffset;		/* always 0 for int2vector */
+	Oid			elemtype;
+	int			dim1;
+	int			lbound1;
+	int16		values[FLEXIBLE_ARRAY_MEMBER];
+} int2vector;
+
+typedef struct
+{
+	int32		vl_len_;		/* these fields must match ArrayType! */
+	int			ndim;			/* always 1 for oidvector */
+	int32		dataoffset;		/* always 0 for oidvector */
+	Oid			elemtype;
+	int			dim1;
+	int			lbound1;
+	Oid			values[FLEXIBLE_ARRAY_MEMBER];
+} oidvector;
+
+/*
+ * Representation of a Name: effectively just a C string, but null-padded to
+ * exactly NAMEDATALEN bytes.  The use of a struct is historical.
+ */
+typedef struct nameData
+{
+	char		data[NAMEDATALEN];
+} NameData;
+typedef NameData *Name;
+
+#define NameStr(name)	((name).data)
+
+
+/* ----------------------------------------------------------------
+ *				Section 4:	IsValid macros for system types
+ * ----------------------------------------------------------------
+ */
+/*
+ * BoolIsValid
+ *		True iff bool is valid.
+ */
+#define BoolIsValid(boolean)	((boolean) == false || (boolean) == true)
+
+/*
+ * PointerIsValid
+ *		True iff pointer is valid.
+ */
+#define PointerIsValid(pointer) ((const void*)(pointer) != NULL)
+
+/*
+ * PointerIsAligned
+ *		True iff pointer is properly aligned to point to the given type.
+ */
+#define PointerIsAligned(pointer, type) \
+		(((uintptr_t)(pointer) % (sizeof (type))) == 0)
+
+#define OffsetToPointer(base, offset) \
+		((void *)((char *) base + offset))
+
+#define OidIsValid(objectId)  ((bool) ((objectId) != InvalidOid))
+
+#define RegProcedureIsValid(p)	OidIsValid(p)
+
+
+/* ----------------------------------------------------------------
+ *				Section 5:	offsetof, lengthof, alignment
+ * ----------------------------------------------------------------
+ */
+/*
+ * offsetof
+ *		Offset of a structure/union field within that structure/union.
+ *
+ *		XXX This is supposed to be part of stddef.h, but isn't on
+ *		some systems (like SunOS 4).
+ */
+#ifndef offsetof
+#define offsetof(type, field)	((long) &((type *)0)->field)
+#endif							/* offsetof */
+
+/*
+ * lengthof
+ *		Number of elements in an array.
+ */
+#define lengthof(array) (sizeof (array) / sizeof ((array)[0]))
+
+/* ----------------
+ * Alignment macros: align a length or address appropriately for a given type.
+ * The fooALIGN() macros round up to a multiple of the required alignment,
+ * while the fooALIGN_DOWN() macros round down.  The latter are more useful
+ * for problems like "how many X-sized structures will fit in a page?".
+ *
+ * NOTE: TYPEALIGN[_DOWN] will not work if ALIGNVAL is not a power of 2.
+ * That case seems extremely unlikely to be needed in practice, however.
+ *
+ * NOTE: MAXIMUM_ALIGNOF, and hence MAXALIGN(), intentionally exclude any
+ * larger-than-8-byte types the compiler might have.
+ * ----------------
+ */
+
+#define TYPEALIGN(ALIGNVAL,LEN)  \
+	(((uintptr_t) (LEN) + ((ALIGNVAL) - 1)) & ~((uintptr_t) ((ALIGNVAL) - 1)))
+
+#define SHORTALIGN(LEN)			TYPEALIGN(ALIGNOF_SHORT, (LEN))
+#define INTALIGN(LEN)			TYPEALIGN(ALIGNOF_INT, (LEN))
+#define LONGALIGN(LEN)			TYPEALIGN(ALIGNOF_LONG, (LEN))
+#define DOUBLEALIGN(LEN)		TYPEALIGN(ALIGNOF_DOUBLE, (LEN))
+#define MAXALIGN(LEN)			TYPEALIGN(MAXIMUM_ALIGNOF, (LEN))
+/* MAXALIGN covers only built-in types, not buffers */
+#define BUFFERALIGN(LEN)		TYPEALIGN(ALIGNOF_BUFFER, (LEN))
+#define CACHELINEALIGN(LEN)		TYPEALIGN(PG_CACHE_LINE_SIZE, (LEN))
+
+#define TYPEALIGN_DOWN(ALIGNVAL,LEN)  \
+	(((uintptr_t) (LEN)) & ~((uintptr_t) ((ALIGNVAL) - 1)))
+
+#define SHORTALIGN_DOWN(LEN)	TYPEALIGN_DOWN(ALIGNOF_SHORT, (LEN))
+#define INTALIGN_DOWN(LEN)		TYPEALIGN_DOWN(ALIGNOF_INT, (LEN))
+#define LONGALIGN_DOWN(LEN)		TYPEALIGN_DOWN(ALIGNOF_LONG, (LEN))
+#define DOUBLEALIGN_DOWN(LEN)	TYPEALIGN_DOWN(ALIGNOF_DOUBLE, (LEN))
+#define MAXALIGN_DOWN(LEN)		TYPEALIGN_DOWN(MAXIMUM_ALIGNOF, (LEN))
+#define BUFFERALIGN_DOWN(LEN)	TYPEALIGN_DOWN(ALIGNOF_BUFFER, (LEN))
+
+/*
+ * The above macros will not work with types wider than uintptr_t, like with
+ * uint64 on 32-bit platforms.  That's not problem for the usual use where a
+ * pointer or a length is aligned, but for the odd case that you need to
+ * align something (potentially) wider, use TYPEALIGN64.
+ */
+#define TYPEALIGN64(ALIGNVAL,LEN)  \
+	(((uint64) (LEN) + ((ALIGNVAL) - 1)) & ~((uint64) ((ALIGNVAL) - 1)))
+
+/* we don't currently need wider versions of the other ALIGN macros */
+#define MAXALIGN64(LEN)			TYPEALIGN64(MAXIMUM_ALIGNOF, (LEN))
+
+
+/* ----------------------------------------------------------------
+ *				Section 6:	assertions
+ * ----------------------------------------------------------------
+ */
+
+/*
+ * USE_ASSERT_CHECKING, if defined, turns on all the assertions.
+ * - plai  9/5/90
+ *
+ * It should _NOT_ be defined in releases or in benchmark copies
+ */
+
+/*
+ * Assert() can be used in both frontend and backend code. In frontend code it
+ * just calls the standard assert, if it's available. If use of assertions is
+ * not configured, it does nothing.
+ */
+#ifndef USE_ASSERT_CHECKING
+
+#define Assert(condition)	((void)true)
+#define AssertMacro(condition)	((void)true)
+#define AssertArg(condition)	((void)true)
+#define AssertState(condition)	((void)true)
+#define AssertPointerAlignment(ptr, bndr)	((void)true)
+#define Trap(condition, errorType)	((void)true)
+#define TrapMacro(condition, errorType) (true)
+
+#elif defined(FRONTEND)
+
+#include <assert.h>
+#define Assert(p) assert(p)
+#define AssertMacro(p)	((void) assert(p))
+#define AssertArg(condition) assert(condition)
+#define AssertState(condition) assert(condition)
+#define AssertPointerAlignment(ptr, bndr)	((void)true)
+
+#else							/* USE_ASSERT_CHECKING && !FRONTEND */
+
+/*
+ * Trap
+ *		Generates an exception if the given condition is true.
+ */
+#define Trap(condition, errorType) \
+	do { \
+		if (condition) \
+			ExceptionalCondition(#condition, (errorType), \
+								 __FILE__, __LINE__); \
+	} while (0)
+
+/*
+ *	TrapMacro is the same as Trap but it's intended for use in macros:
+ *
+ *		#define foo(x) (AssertMacro(x != 0), bar(x))
+ *
+ *	Isn't CPP fun?
+ */
+#define TrapMacro(condition, errorType) \
+	((bool) (! (condition) || \
+			 (ExceptionalCondition(#condition, (errorType), \
+								   __FILE__, __LINE__), 0)))
+
+#define Assert(condition) \
+	do { \
+		if (!(condition)) \
+			ExceptionalCondition(#condition, "FailedAssertion", \
+								 __FILE__, __LINE__); \
+	} while (0)
+
+#define AssertMacro(condition) \
+	((void) ((condition) || \
+			 (ExceptionalCondition(#condition, "FailedAssertion", \
+								   __FILE__, __LINE__), 0)))
+
+#define AssertArg(condition) \
+	do { \
+		if (!(condition)) \
+			ExceptionalCondition(#condition, "BadArgument", \
+								 __FILE__, __LINE__); \
+	} while (0)
+
+#define AssertState(condition) \
+	do { \
+		if (!(condition)) \
+			ExceptionalCondition(#condition, "BadState", \
+								 __FILE__, __LINE__); \
+	} while (0)
+
+/*
+ * Check that `ptr' is `bndr' aligned.
+ */
+#define AssertPointerAlignment(ptr, bndr) \
+	Trap(TYPEALIGN(bndr, (uintptr_t)(ptr)) != (uintptr_t)(ptr), \
+		 "UnalignedPointer")
+
+#endif							/* USE_ASSERT_CHECKING && !FRONTEND */
+
+/*
+ * ExceptionalCondition is compiled into the backend whether or not
+ * USE_ASSERT_CHECKING is defined, so as to support use of extensions
+ * that are built with that #define with a backend that isn't.  Hence,
+ * we should declare it as long as !FRONTEND.
+ */
+#ifndef FRONTEND
+extern void ExceptionalCondition(const char *conditionName,
+								 const char *errorType,
+								 const char *fileName, int lineNumber) pg_attribute_noreturn();
+#endif
+
+/*
+ * Macros to support compile-time assertion checks.
+ *
+ * If the "condition" (a compile-time-constant expression) evaluates to false,
+ * throw a compile error using the "errmessage" (a string literal).
+ *
+ * gcc 4.6 and up supports _Static_assert(), but there are bizarre syntactic
+ * placement restrictions.  Macros StaticAssertStmt() and StaticAssertExpr()
+ * make it safe to use as a statement or in an expression, respectively.
+ * The macro StaticAssertDecl() is suitable for use at file scope (outside of
+ * any function).
+ *
+ * Otherwise we fall back on a kluge that assumes the compiler will complain
+ * about a negative width for a struct bit-field.  This will not include a
+ * helpful error message, but it beats not getting an error at all.
+ */
+#ifndef __cplusplus
+#ifdef HAVE__STATIC_ASSERT
+#define StaticAssertStmt(condition, errmessage) \
+	do { _Static_assert(condition, errmessage); } while(0)
+#define StaticAssertExpr(condition, errmessage) \
+	((void) ({ StaticAssertStmt(condition, errmessage); true; }))
+#define StaticAssertDecl(condition, errmessage) \
+	_Static_assert(condition, errmessage)
+#else							/* !HAVE__STATIC_ASSERT */
+#define StaticAssertStmt(condition, errmessage) \
+	((void) sizeof(struct { int static_assert_failure : (condition) ? 1 : -1; }))
+#define StaticAssertExpr(condition, errmessage) \
+	StaticAssertStmt(condition, errmessage)
+#define StaticAssertDecl(condition, errmessage) \
+	extern void static_assert_func(int static_assert_failure[(condition) ? 1 : -1])
+#endif							/* HAVE__STATIC_ASSERT */
+#else							/* C++ */
+#if defined(__cpp_static_assert) && __cpp_static_assert >= 200410
+#define StaticAssertStmt(condition, errmessage) \
+	static_assert(condition, errmessage)
+#define StaticAssertExpr(condition, errmessage) \
+	({ static_assert(condition, errmessage); })
+#define StaticAssertDecl(condition, errmessage) \
+	static_assert(condition, errmessage)
+#else							/* !__cpp_static_assert */
+#define StaticAssertStmt(condition, errmessage) \
+	do { struct static_assert_struct { int static_assert_failure : (condition) ? 1 : -1; }; } while(0)
+#define StaticAssertExpr(condition, errmessage) \
+	((void) ({ StaticAssertStmt(condition, errmessage); }))
+#define StaticAssertDecl(condition, errmessage) \
+	extern void static_assert_func(int static_assert_failure[(condition) ? 1 : -1])
+#endif							/* __cpp_static_assert */
+#endif							/* C++ */
+
+
+/*
+ * Compile-time checks that a variable (or expression) has the specified type.
+ *
+ * AssertVariableIsOfType() can be used as a statement.
+ * AssertVariableIsOfTypeMacro() is intended for use in macros, eg
+ *		#define foo(x) (AssertVariableIsOfTypeMacro(x, int), bar(x))
+ *
+ * If we don't have __builtin_types_compatible_p, we can still assert that
+ * the types have the same size.  This is far from ideal (especially on 32-bit
+ * platforms) but it provides at least some coverage.
+ */
+#ifdef HAVE__BUILTIN_TYPES_COMPATIBLE_P
+#define AssertVariableIsOfType(varname, typename) \
+	StaticAssertStmt(__builtin_types_compatible_p(__typeof__(varname), typename), \
+	CppAsString(varname) " does not have type " CppAsString(typename))
+#define AssertVariableIsOfTypeMacro(varname, typename) \
+	(StaticAssertExpr(__builtin_types_compatible_p(__typeof__(varname), typename), \
+	 CppAsString(varname) " does not have type " CppAsString(typename)))
+#else							/* !HAVE__BUILTIN_TYPES_COMPATIBLE_P */
+#define AssertVariableIsOfType(varname, typename) \
+	StaticAssertStmt(sizeof(varname) == sizeof(typename), \
+	CppAsString(varname) " does not have type " CppAsString(typename))
+#define AssertVariableIsOfTypeMacro(varname, typename) \
+	(StaticAssertExpr(sizeof(varname) == sizeof(typename), \
+	 CppAsString(varname) " does not have type " CppAsString(typename)))
+#endif							/* HAVE__BUILTIN_TYPES_COMPATIBLE_P */
+
+
+/* ----------------------------------------------------------------
+ *				Section 7:	widely useful macros
+ * ----------------------------------------------------------------
+ */
+/*
+ * Max
+ *		Return the maximum of two numbers.
+ */
+#define Max(x, y)		((x) > (y) ? (x) : (y))
+
+/*
+ * Min
+ *		Return the minimum of two numbers.
+ */
+#define Min(x, y)		((x) < (y) ? (x) : (y))
+
+/*
+ * Abs
+ *		Return the absolute value of the argument.
+ */
+#define Abs(x)			((x) >= 0 ? (x) : -(x))
+
+
+/* Get a bit mask of the bits set in non-long aligned addresses */
+#define LONG_ALIGN_MASK (sizeof(long) - 1)
+
+/*
+ * MemSet
+ *	Exactly the same as standard library function memset(), but considerably
+ *	faster for zeroing small word-aligned structures (such as parsetree nodes).
+ *	This has to be a macro because the main point is to avoid function-call
+ *	overhead.   However, we have also found that the loop is faster than
+ *	native libc memset() on some platforms, even those with assembler
+ *	memset() functions.  More research needs to be done, perhaps with
+ *	MEMSET_LOOP_LIMIT tests in configure.
+ */
+#define MemSet(start, val, len) \
+	do \
+	{ \
+		/* must be void* because we don't know if it is integer aligned yet */ \
+		void   *_vstart = (void *) (start); \
+		int		_val = (val); \
+		Size	_len = (len); \
+\
+		if ((((uintptr_t) _vstart) & LONG_ALIGN_MASK) == 0 && \
+			(_len & LONG_ALIGN_MASK) == 0 && \
+			_val == 0 && \
+			_len <= MEMSET_LOOP_LIMIT && \
+			/* \
+			 *	If MEMSET_LOOP_LIMIT == 0, optimizer should find \
+			 *	the whole "if" false at compile time. \
+			 */ \
+			MEMSET_LOOP_LIMIT != 0) \
+		{ \
+			long *_start = (long *) _vstart; \
+			long *_stop = (long *) ((char *) _start + _len); \
+			while (_start < _stop) \
+				*_start++ = 0; \
+		} \
+		else \
+			memset(_vstart, _val, _len); \
+	} while (0)
+
+/*
+ * MemSetAligned is the same as MemSet except it omits the test to see if
+ * "start" is word-aligned.  This is okay to use if the caller knows a-priori
+ * that the pointer is suitably aligned (typically, because he just got it
+ * from palloc(), which always delivers a max-aligned pointer).
+ */
+#define MemSetAligned(start, val, len) \
+	do \
+	{ \
+		long   *_start = (long *) (start); \
+		int		_val = (val); \
+		Size	_len = (len); \
+\
+		if ((_len & LONG_ALIGN_MASK) == 0 && \
+			_val == 0 && \
+			_len <= MEMSET_LOOP_LIMIT && \
+			MEMSET_LOOP_LIMIT != 0) \
+		{ \
+			long *_stop = (long *) ((char *) _start + _len); \
+			while (_start < _stop) \
+				*_start++ = 0; \
+		} \
+		else \
+			memset(_start, _val, _len); \
+	} while (0)
+
+
+/*
+ * MemSetTest/MemSetLoop are a variant version that allow all the tests in
+ * MemSet to be done at compile time in cases where "val" and "len" are
+ * constants *and* we know the "start" pointer must be word-aligned.
+ * If MemSetTest succeeds, then it is okay to use MemSetLoop, otherwise use
+ * MemSetAligned.  Beware of multiple evaluations of the arguments when using
+ * this approach.
+ */
+#define MemSetTest(val, len) \
+	( ((len) & LONG_ALIGN_MASK) == 0 && \
+	(len) <= MEMSET_LOOP_LIMIT && \
+	MEMSET_LOOP_LIMIT != 0 && \
+	(val) == 0 )
+
+#define MemSetLoop(start, val, len) \
+	do \
+	{ \
+		long * _start = (long *) (start); \
+		long * _stop = (long *) ((char *) _start + (Size) (len)); \
+	\
+		while (_start < _stop) \
+			*_start++ = 0; \
+	} while (0)
+
+/*
+ * Macros for range-checking float values before converting to integer.
+ * We must be careful here that the boundary values are expressed exactly
+ * in the float domain.  PG_INTnn_MIN is an exact power of 2, so it will
+ * be represented exactly; but PG_INTnn_MAX isn't, and might get rounded
+ * off, so avoid using that.
+ * The input must be rounded to an integer beforehand, typically with rint(),
+ * else we might draw the wrong conclusion about close-to-the-limit values.
+ * These macros will do the right thing for Inf, but not necessarily for NaN,
+ * so check isnan(num) first if that's a possibility.
+ */
+#define FLOAT4_FITS_IN_INT16(num) \
+	((num) >= (float4) PG_INT16_MIN && (num) < -((float4) PG_INT16_MIN))
+#define FLOAT4_FITS_IN_INT32(num) \
+	((num) >= (float4) PG_INT32_MIN && (num) < -((float4) PG_INT32_MIN))
+#define FLOAT4_FITS_IN_INT64(num) \
+	((num) >= (float4) PG_INT64_MIN && (num) < -((float4) PG_INT64_MIN))
+#define FLOAT8_FITS_IN_INT16(num) \
+	((num) >= (float8) PG_INT16_MIN && (num) < -((float8) PG_INT16_MIN))
+#define FLOAT8_FITS_IN_INT32(num) \
+	((num) >= (float8) PG_INT32_MIN && (num) < -((float8) PG_INT32_MIN))
+#define FLOAT8_FITS_IN_INT64(num) \
+	((num) >= (float8) PG_INT64_MIN && (num) < -((float8) PG_INT64_MIN))
+
+
+/* ----------------------------------------------------------------
+ *				Section 8:	random stuff
+ * ----------------------------------------------------------------
+ */
+
+#ifdef HAVE_STRUCT_SOCKADDR_UN
+#define HAVE_UNIX_SOCKETS 1
+#endif
+
+/*
+ * Invert the sign of a qsort-style comparison result, ie, exchange negative
+ * and positive integer values, being careful not to get the wrong answer
+ * for INT_MIN.  The argument should be an integral variable.
+ */
+#define INVERT_COMPARE_RESULT(var) \
+	((var) = ((var) < 0) ? 1 : -(var))
+
+/*
+ * Use this, not "char buf[BLCKSZ]", to declare a field or local variable
+ * holding a page buffer, if that page might be accessed as a page and not
+ * just a string of bytes.  Otherwise the variable might be under-aligned,
+ * causing problems on alignment-picky hardware.  (In some places, we use
+ * this to declare buffers even though we only pass them to read() and
+ * write(), because copying to/from aligned buffers is usually faster than
+ * using unaligned buffers.)  We include both "double" and "int64" in the
+ * union to ensure that the compiler knows the value must be MAXALIGN'ed
+ * (cf. configure's computation of MAXIMUM_ALIGNOF).
+ */
+typedef union PGAlignedBlock
+{
+	char		data[BLCKSZ];
+	double		force_align_d;
+	int64		force_align_i64;
+} PGAlignedBlock;
+
+/* Same, but for an XLOG_BLCKSZ-sized buffer */
+typedef union PGAlignedXLogBlock
+{
+	char		data[XLOG_BLCKSZ];
+	double		force_align_d;
+	int64		force_align_i64;
+} PGAlignedXLogBlock;
+
+/* msb for char */
+#define HIGHBIT					(0x80)
+#define IS_HIGHBIT_SET(ch)		((unsigned char)(ch) & HIGHBIT)
+
+/*
+ * Support macros for escaping strings.  escape_backslash should be true
+ * if generating a non-standard-conforming string.  Prefixing a string
+ * with ESCAPE_STRING_SYNTAX guarantees it is non-standard-conforming.
+ * Beware of multiple evaluation of the "ch" argument!
+ */
+#define SQL_STR_DOUBLE(ch, escape_backslash)	\
+	((ch) == '\'' || ((ch) == '\\' && (escape_backslash)))
+
+#define ESCAPE_STRING_SYNTAX	'E'
+
+
+#define STATUS_OK				(0)
+#define STATUS_ERROR			(-1)
+#define STATUS_EOF				(-2)
+
+/*
+ * gettext support
+ */
+
+#ifndef ENABLE_NLS
+/* stuff we'd otherwise get from <libintl.h> */
+#define gettext(x) (x)
+#define dgettext(d,x) (x)
+#define ngettext(s,p,n) ((n) == 1 ? (s) : (p))
+#define dngettext(d,s,p,n) ((n) == 1 ? (s) : (p))
+#endif
+
+#define _(x) gettext(x)
+
+/*
+ *	Use this to mark string constants as needing translation at some later
+ *	time, rather than immediately.  This is useful for cases where you need
+ *	access to the original string and translated string, and for cases where
+ *	immediate translation is not possible, like when initializing global
+ *	variables.
+ *
+ *	https://www.gnu.org/software/gettext/manual/html_node/Special-cases.html
+ */
+#define gettext_noop(x) (x)
+
+/*
+ * To better support parallel installations of major PostgreSQL
+ * versions as well as parallel installations of major library soname
+ * versions, we mangle the gettext domain name by appending those
+ * version numbers.  The coding rule ought to be that wherever the
+ * domain name is mentioned as a literal, it must be wrapped into
+ * PG_TEXTDOMAIN().  The macros below do not work on non-literals; but
+ * that is somewhat intentional because it avoids having to worry
+ * about multiple states of premangling and postmangling as the values
+ * are being passed around.
+ *
+ * Make sure this matches the installation rules in nls-global.mk.
+ */
+#ifdef SO_MAJOR_VERSION
+#define PG_TEXTDOMAIN(domain) (domain CppAsString2(SO_MAJOR_VERSION) "-" PG_MAJORVERSION)
+#else
+#define PG_TEXTDOMAIN(domain) (domain "-" PG_MAJORVERSION)
+#endif
+
+/*
+ * Macro that allows to cast constness and volatile away from an expression, but doesn't
+ * allow changing the underlying type.  Enforcement of the latter
+ * currently only works for gcc like compilers.
+ *
+ * Please note IT IS NOT SAFE to cast constness away if the result will ever
+ * be modified (it would be undefined behaviour). Doing so anyway can cause
+ * compiler misoptimizations or runtime crashes (modifying readonly memory).
+ * It is only safe to use when the result will not be modified, but API
+ * design or language restrictions prevent you from declaring that
+ * (e.g. because a function returns both const and non-const variables).
+ *
+ * Note that this only works in function scope, not for global variables (it'd
+ * be nice, but not trivial, to improve that).
+ */
+#if defined(HAVE__BUILTIN_TYPES_COMPATIBLE_P)
+#define unconstify(underlying_type, expr) \
+	(StaticAssertExpr(__builtin_types_compatible_p(__typeof(expr), const underlying_type), \
+					  "wrong cast"), \
+	 (underlying_type) (expr))
+#define unvolatize(underlying_type, expr) \
+	(StaticAssertExpr(__builtin_types_compatible_p(__typeof(expr), volatile underlying_type), \
+					  "wrong cast"), \
+	 (underlying_type) (expr))
+#else
+#define unconstify(underlying_type, expr) \
+	((underlying_type) (expr))
+#define unvolatize(underlying_type, expr) \
+	((underlying_type) (expr))
+#endif
+
+/* ----------------------------------------------------------------
+ *				Section 9: system-specific hacks
+ *
+ *		This should be limited to things that absolutely have to be
+ *		included in every source file.  The port-specific header file
+ *		is usually a better place for this sort of thing.
+ * ----------------------------------------------------------------
+ */
+
+/*
+ *	NOTE:  this is also used for opening text files.
+ *	WIN32 treats Control-Z as EOF in files opened in text mode.
+ *	Therefore, we open files in binary mode on Win32 so we can read
+ *	literal control-Z.  The other affect is that we see CRLF, but
+ *	that is OK because we can already handle those cleanly.
+ */
+#if defined(WIN32) || defined(__CYGWIN__)
+#define PG_BINARY	O_BINARY
+#define PG_BINARY_A "ab"
+#define PG_BINARY_R "rb"
+#define PG_BINARY_W "wb"
+#else
+#define PG_BINARY	0
+#define PG_BINARY_A "a"
+#define PG_BINARY_R "r"
+#define PG_BINARY_W "w"
+#endif
+
+/*
+ * Provide prototypes for routines not present in a particular machine's
+ * standard C library.
+ */
+
+#if defined(HAVE_FDATASYNC) && !HAVE_DECL_FDATASYNC
+extern int	fdatasync(int fildes);
+#endif
+
+/* Older platforms may provide strto[u]ll functionality under other names */
+#if !defined(HAVE_STRTOLL) && defined(HAVE___STRTOLL)
+#define strtoll __strtoll
+#define HAVE_STRTOLL 1
+#endif
+
+#if !defined(HAVE_STRTOLL) && defined(HAVE_STRTOQ)
+#define strtoll strtoq
+#define HAVE_STRTOLL 1
+#endif
+
+#if !defined(HAVE_STRTOULL) && defined(HAVE___STRTOULL)
+#define strtoull __strtoull
+#define HAVE_STRTOULL 1
+#endif
+
+#if !defined(HAVE_STRTOULL) && defined(HAVE_STRTOUQ)
+#define strtoull strtouq
+#define HAVE_STRTOULL 1
+#endif
+
+#if defined(HAVE_STRTOLL) && !HAVE_DECL_STRTOLL
+extern long long strtoll(const char *str, char **endptr, int base);
+#endif
+
+#if defined(HAVE_STRTOULL) && !HAVE_DECL_STRTOULL
+extern unsigned long long strtoull(const char *str, char **endptr, int base);
+#endif
+
+/*
+ * Thin wrappers that convert strings to exactly 64-bit integers, matching our
+ * definition of int64.  (For the naming, compare that POSIX has
+ * strtoimax()/strtoumax() which return intmax_t/uintmax_t.)
+ */
+#ifdef HAVE_LONG_INT_64
+#define strtoi64(str, endptr, base) ((int64) strtol(str, endptr, base))
+#define strtou64(str, endptr, base) ((uint64) strtoul(str, endptr, base))
+#else
+#define strtoi64(str, endptr, base) ((int64) strtoll(str, endptr, base))
+#define strtou64(str, endptr, base) ((uint64) strtoull(str, endptr, base))
+#endif
+
+/*
+ * Use "extern PGDLLIMPORT ..." to declare variables that are defined
+ * in the core backend and need to be accessible by loadable modules.
+ * No special marking is required on most ports.
+ */
+#ifndef PGDLLIMPORT
+#define PGDLLIMPORT
+#endif
+
+/*
+ * Use "extern PGDLLEXPORT ..." to declare functions that are defined in
+ * loadable modules and need to be callable by the core backend.  (Usually,
+ * this is not necessary because our build process automatically exports
+ * such symbols, but sometimes manual marking is required.)
+ * No special marking is required on most ports.
+ */
+#ifndef PGDLLEXPORT
+#define PGDLLEXPORT
+#endif
+
+/*
+ * The following is used as the arg list for signal handlers.  Any ports
+ * that take something other than an int argument should override this in
+ * their pg_config_os.h file.  Note that variable names are required
+ * because it is used in both the prototypes as well as the definitions.
+ * Note also the long name.  We expect that this won't collide with
+ * other names causing compiler warnings.
+ */
+
+#ifndef SIGNAL_ARGS
+#define SIGNAL_ARGS  int postgres_signal_arg
+#endif
+
+/*
+ * When there is no sigsetjmp, its functionality is provided by plain
+ * setjmp.  We now support the case only on Windows.  However, it seems
+ * that MinGW-64 has some longstanding issues in its setjmp support,
+ * so on that toolchain we cheat and use gcc's builtins.
+ */
+#ifdef WIN32
+#ifdef __MINGW64__
+typedef intptr_t sigjmp_buf[5];
+#define sigsetjmp(x,y) __builtin_setjmp(x)
+#define siglongjmp __builtin_longjmp
+#else							/* !__MINGW64__ */
+#define sigjmp_buf jmp_buf
+#define sigsetjmp(x,y) setjmp(x)
+#define siglongjmp longjmp
+#endif							/* __MINGW64__ */
+#endif							/* WIN32 */
+
+/* EXEC_BACKEND defines */
+#ifdef EXEC_BACKEND
+#define NON_EXEC_STATIC
+#else
+#define NON_EXEC_STATIC static
+#endif
+
+/* /port compatibility functions */
+#include "port.h"
+
+#endif							/* C_H */