c.h

Go to the documentation of this file.

/*-------------------------------------------------------------------------
 *
 * 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) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/c.h
 *
 *-------------------------------------------------------------------------
 */
/* IWYU pragma: always_keep */
/*
 *----------------------------------------------------------------
 *   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)      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
 
/* IWYU pragma: begin_exports */
 
/*
 * These headers must be included before any system headers, because on some
 * platforms they affect the behavior of the system headers (for example, by
 * defining _FILE_OFFSET_BITS).
 */
#include "pg_config.h"
#include "pg_config_manual.h"   /* must be after pg_config.h */
#include "pg_config_os.h"       /* config from include/port/PORTNAME.h */
 
/* System header files that should be available everywhere in Postgres */
#include <assert.h>
#include <inttypes.h>
#include <stdalign.h>
#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 HAVE_XLOCALE_H
#include <xlocale.h>
#endif
#ifdef ENABLE_NLS
#include <libintl.h>
#endif
 
#ifdef __cplusplus
extern "C++"
{
/* This header is used in the definition of various C++ things below. */
#include <type_traits>
}
#endif
 
 /* Pull in fundamental symbols that we also expose to applications */
#include "postgres_ext.h"
 
/* Define before including zlib.h to add const decorations to zlib API. */
#ifdef HAVE_LIBZ
#define ZLIB_CONST
#endif
 
 
/* ----------------------------------------------------------------
 *              Section 1: compiler characteristics
 * ----------------------------------------------------------------
 */
 
/*
 * 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
 *
 * C23: https://en.cppreference.com/w/c/language/attributes.html
 * C++: https://en.cppreference.com/w/cpp/language/attributes.html
 * 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
 */
 
/*
 * 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.
 *
 * Note that __has_attribute only tells about GCC-style attributes, not C23 or
 * C++ attributes.
 */
#ifndef __has_attribute
#define __has_attribute(attribute) 0
#endif
 
/*
 * pg_attribute_unused() suppresses compiler warnings on unused entities.
 */
#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) || (defined(__cplusplus) && __cplusplus >= 201703L)
#define pg_attribute_unused() [[maybe_unused]]
#elif defined(__GNUC__)
#define pg_attribute_unused() __attribute__((unused))
#else
#define pg_attribute_unused()
#endif
 
/*
 * pg_fallthrough indicates that the fall through from the previous case is
 * intentional.
 */
#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) || (defined(__cplusplus) && __cplusplus >= 201703L)
#define pg_fallthrough [[fallthrough]]
#elif __has_attribute(fallthrough)
#define pg_fallthrough __attribute__((fallthrough))
#else
#define pg_fallthrough
#endif
 
/*
 * pg_nodiscard means the compiler should warn if the result of a function
 * call is ignored.
 */
#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) || (defined(__cplusplus) && __cplusplus >= 201703L)
#define pg_nodiscard [[nodiscard]]
#elif defined(__GNUC__)
#define pg_nodiscard __attribute__((warn_unused_result))
#else
#define pg_nodiscard
#endif
 
/*
 * pg_noreturn corresponds to the C11 noreturn/_Noreturn function specifier.
 * We can't use the standard name "noreturn" because some third-party code
 * uses __attribute__((noreturn)) in headers, which would get confused if
 * "noreturn" is defined to "_Noreturn", as is done by <stdnoreturn.h>.
 *
 * C23 attributes must be placed at the start of a declaration or statement.
 * C11 function specifiers go before the function name in a declaration, but
 * it is common style (and required for C23 compatibility) to put them before
 * the return type.
 */
#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) || defined(__cplusplus)
#define pg_noreturn [[noreturn]]
#else
#define pg_noreturn _Noreturn
#endif
 
/*
 * This macro will disable address safety instrumentation for a function
 * when running with "-fsanitize=address". Think twice before using this!
 */
#if defined(__clang__) || __GNUC__ >= 8
#define pg_attribute_no_sanitize_address() __attribute__((no_sanitize("address")))
#elif __has_attribute(no_sanitize_address)
/* This would work for clang, but it's deprecated. */
#define pg_attribute_no_sanitize_address() __attribute__((no_sanitize_address))
#else
#define pg_attribute_no_sanitize_address()
#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
 
/*
 * pg_attribute_nonnull means the compiler should warn if the function is
 * called with the listed arguments set to NULL.  If no arguments are
 * listed, the compiler should warn if any pointer arguments are set to NULL.
 */
#if __has_attribute (nonnull)
#define pg_attribute_nonnull(...) __attribute__((nonnull(__VA_ARGS__)))
#else
#define pg_attribute_nonnull(...)
#endif
 
/*
 * pg_attribute_target allows specifying different target options that the
 * function should be compiled with (e.g., for using special CPU instructions).
 * Note that there still needs to be a configure-time check to verify that a
 * specific target is understood by the compiler.
 */
#if __has_attribute (target)
#define pg_attribute_target(...) __attribute__((target(__VA_ARGS__)))
#else
#define pg_attribute_target(...)
#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
 
/*
 * Our C and C++ compilers may have different ideas about which printf
 * archetype best represents what src/port/snprintf.c can do.
 */
#ifndef __cplusplus
#define PG_PRINTF_ATTRIBUTE PG_C_PRINTF_ATTRIBUTE
#else
#define PG_PRINTF_ATTRIBUTE PG_CXX_PRINTF_ATTRIBUTE
#endif
 
/* GCC supports format attributes */
#if defined(__GNUC__)
#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 supports aligned and packed */
#if defined(__GNUC__)
#define pg_attribute_aligned(a) __attribute__((aligned(a)))
#define pg_attribute_packed() __attribute__((packed))
#elif defined(_MSC_VER)
/*
 * MSVC supports aligned.
 *
 * Packing is also possible but only by wrapping the entire struct definition
 * which doesn't fit into our current macro declarations.
 */
#define pg_attribute_aligned(a) __declspec(align(a))
#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.
 */
#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__) && defined(__OPTIMIZE__)
/* GCC supports 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 supports noinline via __attribute__ */
#if defined(__GNUC__)
#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
 
/*
 * Define a compiler-independent macro for determining if an expression is a
 * compile-time integer const.  We don't define this macro to return 0 when
 * unsupported due to the risk of users of the macro misbehaving if we return
 * 0 when the expression *is* an integer constant.  Callers may check if this
 * macro is defined by checking if HAVE_PG_INTEGER_CONSTANT_P is defined.
 */
#if defined(HAVE__BUILTIN_CONSTANT_P)
 
/* When __builtin_constant_p() is available, use it. */
#define pg_integer_constant_p(x) __builtin_constant_p(x)
#define HAVE_PG_INTEGER_CONSTANT_P
#elif defined(_MSC_VER) && defined(__STDC_VERSION__)
 
/*
 * With MSVC we can use a trick with _Generic to make this work.  This has
 * been borrowed from:
 * https://stackoverflow.com/questions/49480442/detecting-integer-constant-expressions-in-macros
 * and only works with integer constants.  Compilation will fail if given a
 * constant or variable of any type other than an integer.
 */
#define pg_integer_constant_p(x) \
    _Generic((1 ? ((void *) ((x) * (uintptr_t) 0)) : &(int) {1}), int *: 1, void *: 0)
#define HAVE_PG_INTEGER_CONSTANT_P
#endif
 
/*
 * pg_assume(expr) states that we assume `expr` to evaluate to true. In assert
 * enabled builds pg_assume() is turned into an assertion, in optimized builds
 * we try to clue the compiler into the fact that `expr` is true.
 *
 * This is useful for two purposes:
 *
 * 1) Avoid compiler warnings by telling the compiler about assumptions the
 *    code makes. This is particularly useful when building with optimizations
 *    and w/o assertions.
 *
 * 2) Help the compiler to generate more efficient code
 *
 * It is unspecified whether `expr` is evaluated, therefore it better be
 * side-effect free.
 */
#if defined(USE_ASSERT_CHECKING)
#define pg_assume(expr) Assert(expr)
#elif defined(HAVE__BUILTIN_UNREACHABLE)
#define pg_assume(expr) \
    do { \
        if (!(expr)) \
            __builtin_unreachable(); \
    } while (0)
#elif defined(_MSC_VER)
#define pg_assume(expr) __assume(expr)
#else
#define pg_assume(expr) ((void) 0)
#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.
 */
#ifdef __GNUC__
#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
 
/*
 * When we call clang to generate bitcode, we might be using configure results
 * from a different compiler, which might not be fully compatible with the
 * clang we are using.  The fully correct solution would be to run a separate
 * set of configure tests for that clang-for-bitcode, but that could be very
 * difficult to implement, and in practice clang supports most things other
 * compilers support.  So this section just contains some hardcoded ugliness
 * to override some configure results where it is necessary.
 */
#if defined(__clang__)
#if __clang_major__ < 19
#undef HAVE_TYPEOF_UNQUAL
#else
#undef typeof_unqual
#define typeof_unqual __typeof_unqual__
#endif
#endif                          /* __clang__ */
 
/*
 * Provide typeof in C++ for C++ compilers that don't support typeof natively.
 * It might be spelled __typeof__ instead of typeof, in which case
 * pg_cxx_typeof provides that mapping. If neither is supported, we can use
 * decltype, but to make it equivalent to C's typeof, we need to remove
 * references from the result [1]. Also ensure HAVE_TYPEOF is set so that
 * typeof-dependent code is always enabled in C++ mode.
 *
 * [1]: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2927.htm#existing-decltype
 */
#if defined(__cplusplus)
#undef typeof
#ifdef pg_cxx_typeof
#define typeof(x) pg_cxx_typeof(x)
#elif !defined(HAVE_CXX_TYPEOF)
#define typeof(x) std::remove_reference<decltype(x)>::type
#endif
#ifndef HAVE_TYPEOF
#define HAVE_TYPEOF 1
#endif
/*
 * and analogously for typeof_unqual
 */
#undef typeof_unqual
#ifdef pg_cxx_typeof_unqual
#define typeof_unqual(x) pg_cxx_typeof_unqual(x)
#elif !defined(HAVE_CXX_TYPEOF_UNQUAL)
#define typeof_unqual(x) std::remove_cv<std::remove_reference<decltype(x)>::type>::type
#endif
#ifndef HAVE_TYPEOF_UNQUAL
#define HAVE_TYPEOF_UNQUAL 1
#endif
#endif                          /* __cplusplus */
 
/*
 * 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)
 
/*
 * 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 */
 
/*
 * 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.
 *
 * PostgreSQL currently cannot deal with bool of size other than 1; there are
 * static assertions around the code to prevent that.
 */
 
#include <stdbool.h>
 
 
/* ----------------------------------------------------------------
 *              Section 3:  standard system types
 * ----------------------------------------------------------------
 */
 
/*
 * Pointer
 *      Variable holding address of any memory resident object.
 *      (obsolescent; use void * or char *)
 */
typedef void *Pointer;
 
/* Historical names for types in <stdint.h>. */
typedef int8_t int8;
typedef int16_t int16;
typedef int32_t int32;
typedef int64_t int64;
typedef uint8_t uint8;
typedef uint16_t uint16;
typedef uint32_t uint32;
typedef uint64_t uint64;
 
/*
 * 64-bit integers
 */
#define INT64CONST(x)  INT64_C(x)
#define UINT64CONST(x) UINT64_C(x)
 
/* snprintf format strings to use for 64-bit integers */
#define INT64_FORMAT "%" PRId64
#define UINT64_FORMAT "%" PRIu64
#define OID8_FORMAT "%" PRIu64
 
/*
 * 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
 
/* Historical names for limits in <stdint.h>. */
#define PG_INT8_MIN     INT8_MIN
#define PG_INT8_MAX     INT8_MAX
#define PG_UINT8_MAX    UINT8_MAX
#define PG_INT16_MIN    INT16_MIN
#define PG_INT16_MAX    INT16_MAX
#define PG_UINT16_MAX   UINT16_MAX
#define PG_INT32_MIN    INT32_MIN
#define PG_INT32_MAX    INT32_MAX
#define PG_UINT32_MAX   UINT32_MAX
#define PG_INT64_MIN    INT64_MIN
#define PG_INT64_MAX    INT64_MAX
#define PG_UINT64_MAX   UINT64_MAX
 
/*
 * 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;
 
/*
 * float8, int8, and related datatypes are now always pass-by-value.
 * We keep this symbol to avoid breaking extension code that may use it.
 */
#define FLOAT8PASSBYVAL true
 
/*
 * Oid, Oid8, 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 uint64 MultiXactOffset;
 
typedef uint32 CommandId;
 
#define FirstCommandId  ((CommandId) 0)
#define InvalidCommandId    (~(CommandId)0)
 
/* 8-byte Object ID */
typedef uint64 Oid8;
 
#define InvalidOid8     ((Oid8) 0)
#define OID8_MAX    UINT64_MAX
 
/* ----------------
 *      Variable-length datatypes all share the '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 varatt.h for details of the TOASTed form.
 * ----------------
 */
typedef struct varlena
{
    char        vl_len_[4];     /* Do not touch this field directly! */
    char        vl_dat[FLEXIBLE_ARRAY_MEMBER];  /* Data content is here */
} varlena;
 
#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 varlena bytea;
typedef varlena text;
typedef varlena BpChar;         /* blank-padded char, ie SQL char(n) */
typedef 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)
 
/*
 * 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 Oid8IsValid(objectId)  ((bool) ((objectId) != InvalidOid8))
 
#define RegProcedureIsValid(p)  OidIsValid(p)
 
 
/* ----------------------------------------------------------------
 *              Section 5:  lengthof, alignment
 * ----------------------------------------------------------------
 */
/*
 * 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 INT64ALIGN(LEN)         TYPEALIGN(ALIGNOF_INT64_T, (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 INT64ALIGN_DOWN(LEN)    TYPEALIGN_DOWN(ALIGNOF_INT64_T, (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)
 
#elif defined(FRONTEND)
 
#define Assert(p) assert(p)
#define AssertMacro(p)  ((void) assert(p))
 
#else                           /* USE_ASSERT_CHECKING && !FRONTEND */
 
/*
 * Assert
 *      Generates a fatal exception if the given condition is false.
 */
#define Assert(condition) \
    do { \
        if (!(condition)) \
            ExceptionalCondition(#condition, __FILE__, __LINE__); \
    } while (0)
 
/*
 * AssertMacro is the same as Assert but it's suitable for use in
 * expression-like macros, for example:
 *
 *      #define foo(x) (AssertMacro(x != 0), bar(x))
 */
#define AssertMacro(condition) \
    ((void) ((condition) || \
             (ExceptionalCondition(#condition, __FILE__, __LINE__), 0)))
 
#endif                          /* USE_ASSERT_CHECKING && !FRONTEND */
 
/*
 * Check that `ptr' is `bndr' aligned.
 */
#define AssertPointerAlignment(ptr, bndr) \
    Assert(TYPEALIGN(bndr, (uintptr_t)(ptr)) == (uintptr_t)(ptr))
 
/*
 * 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
pg_noreturn extern void ExceptionalCondition(const char *conditionName,
                                             const char *fileName, int lineNumber);
#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).
 */
 
/*
 * We require C11 and C++11, so static_assert() is expected to be there.
 * StaticAssertDecl() was previously used for portability, but it's now just a
 * plain wrapper and doesn't need to be used in new code.  static_assert() is
 * a "declaration", and so it must be placed where for example a variable
 * declaration would be valid.  As long as we compile with
 * -Wno-declaration-after-statement, that also means it cannot be placed after
 * statements in a function.
 */
#define StaticAssertDecl(condition, errmessage) \
    static_assert(condition, errmessage)
 
/*
 * StaticAssertStmt() was previously used to make static assertions work as a
 * statement, but its use is now deprecated.
 */
#define StaticAssertStmt(condition, errmessage) \
    do { static_assert(condition, errmessage); } while(0)
 
/*
 * StaticAssertExpr() is for use in an expression.
 *
 * See <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3715.pdf> for some
 * rationale for the precise behavior of this implementation.  See
 * <https://stackoverflow.com/questions/31311748> about the C++
 * implementation.
 *
 * For compilers that don't support this, 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
#if !defined(_MSC_VER) || _MSC_VER >= 1933
#define StaticAssertExpr(condition, errmessage) \
    ((void) sizeof(struct {static_assert(condition, errmessage); char a;}))
#else                           /* _MSC_VER < 1933 */
/*
 * This compiler is buggy and fails to compile the previous variant; use a
 * fallback implementation.
 */
#define StaticAssertExpr(condition, errmessage) \
    ((void) sizeof(struct { int static_assert_failure : (condition) ? 1 : -1; }))
#endif                          /* _MSC_VER < 1933 */
#else                           /* __cplusplus */
#define StaticAssertExpr(condition, errmessage) \
    ([]{static_assert(condition, errmessage);})
#endif
 
 
/*
 * Compile-time checks that a variable (or expression) has the specified type.
 *
 * StaticAssertVariableIsOfType() can be used as a declaration.
 * StaticAssertVariableIsOfTypeMacro() is intended for use in macros, eg
 *      #define foo(x) (StaticAssertVariableIsOfTypeMacro(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 StaticAssertVariableIsOfType(varname, typename) \
    StaticAssertDecl(__builtin_types_compatible_p(typeof(varname), typename), \
    CppAsString(varname) " does not have type " CppAsString(typename))
#define StaticAssertVariableIsOfTypeMacro(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 StaticAssertVariableIsOfType(varname, typename) \
    StaticAssertDecl(sizeof(varname) == sizeof(typename), \
    CppAsString(varname) " does not have type " CppAsString(typename))
#define StaticAssertVariableIsOfTypeMacro(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))
 
 
/* Get a bit mask of the bits set in non-size_t aligned addresses */
#define SIZE_T_ALIGN_MASK (sizeof(size_t) - 1)
 
/*
 * MemSet
 *  Exactly the same as standard library function memset(), but considerably
 *  faster for zeroing small size_t-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 size_t aligned yet */ \
        void   *_vstart = (void *) (start); \
        int     _val = (val); \
        Size    _len = (len); \
\
        if ((((uintptr_t) _vstart) & SIZE_T_ALIGN_MASK) == 0 && \
            (_len & SIZE_T_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) \
        { \
            size_t *_start = (size_t *) _vstart; \
            size_t *_stop = (size_t *) ((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 size_t-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 \
    { \
        size_t *_start = (size_t *) (start); \
        int     _val = (val); \
        Size    _len = (len); \
\
        if ((_len & SIZE_T_ALIGN_MASK) == 0 && \
            _val == 0 && \
            _len <= MEMSET_LOOP_LIMIT && \
            MEMSET_LOOP_LIMIT != 0) \
        { \
            size_t *_stop = (size_t *) ((char *) _start + _len); \
            while (_start < _stop) \
                *_start++ = 0; \
        } \
        else \
            memset(_start, _val, _len); \
    } 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
 * ----------------------------------------------------------------
 */
 
/*
 * 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.  Otherwise
 * the variable might be under-aligned, causing problems on alignment-picky
 * hardware.
 */
typedef struct PGAlignedBlock
{
    alignas(MAXIMUM_ALIGNOF) char data[BLCKSZ];
} PGAlignedBlock;
 
/*
 * alignas with extended alignments is buggy in g++ < 9.  As a simple
 * workaround, we disable these definitions in that case.
 *
 * <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89357>
 */
#if !(defined(__cplusplus) && defined(__GNUC__) && !defined(__clang__) && __GNUC__ < 9)
 
/*
 * Use this to declare a field or local variable holding a page buffer, if that
 * page might be accessed as a page or passed to an SMgr I/O function.  If
 * allocating using the MemoryContext API, the aligned allocation functions
 * should be used with PG_IO_ALIGN_SIZE.  This alignment may be more efficient
 * for I/O in general, but may be strictly required on some platforms when
 * using direct I/O.
 */
typedef struct PGIOAlignedBlock
{
    alignas(PG_IO_ALIGN_SIZE) char data[BLCKSZ];
} PGIOAlignedBlock;
 
/* Same, but for an XLOG_BLCKSZ-sized buffer */
typedef struct PGAlignedXLogBlock
{
    alignas(PG_IO_ALIGN_SIZE) char data[XLOG_BLCKSZ];
} PGAlignedXLogBlock;
 
#else                           /* (g++ < 9) */
 
/* Allow these types to be used as abstract types when using old g++ */
typedef struct PGIOAlignedBlock PGIOAlignedBlock;
typedef struct PGAlignedXLogBlock PGAlignedXLogBlock;
 
#endif                          /* !(g++ < 9) */
 
/* 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(__cplusplus)
#define unconstify(underlying_type, expr) const_cast<underlying_type>(expr)
#define unvolatize(underlying_type, expr) const_cast<underlying_type>(expr)
#else
#define unconstify(underlying_type, expr) \
    (StaticAssertVariableIsOfTypeMacro(expr, const underlying_type), \
     (underlying_type) (expr))
#define unvolatize(underlying_type, expr) \
    (StaticAssertVariableIsOfTypeMacro(expr, volatile underlying_type), \
     (underlying_type) (expr))
#endif
 
/*
 * SSE2 instructions are part of the spec for the 64-bit x86 ISA. We assume
 * that compilers targeting this architecture understand SSE2 intrinsics.
 */
#if (defined(__x86_64__) || defined(_M_AMD64))
#define USE_SSE2
 
/*
 * We use the Neon instructions if the compiler provides access to them (as
 * indicated by __ARM_NEON) and we are on aarch64.  While Neon support is
 * technically optional for aarch64, it appears that all available 64-bit
 * hardware does have it.  Neon exists in some 32-bit hardware too, but we
 * could not realistically use it there without a run-time check, which seems
 * not worth the trouble for now.
 */
#elif defined(__aarch64__) && defined(__ARM_NEON)
#define USE_NEON
#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 !HAVE_DECL_FDATASYNC
extern int  fdatasync(int fd);
#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.)
 */
#if SIZEOF_LONG == 8
#define strtoi64(str, endptr, base) ((int64) strtol(str, endptr, base))
#define strtou64(str, endptr, base) ((uint64) strtoul(str, endptr, base))
#elif SIZEOF_LONG_LONG == 8
#define strtoi64(str, endptr, base) ((int64) strtoll(str, endptr, base))
#define strtou64(str, endptr, base) ((uint64) strtoull(str, endptr, base))
#else
#error "cannot find integer type of the same size as int64_t"
#endif
 
/*
 * Similarly, wrappers around labs()/llabs() matching our int64.
 */
#if SIZEOF_LONG == 8
#define i64abs(i) ((int64) labs(i))
#elif SIZEOF_LONG_LONG == 8
#define i64abs(i) ((int64) llabs(i))
#else
#error "cannot find integer type of the same size as int64_t"
#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 or other
 * loadable modules.
 * If the compiler knows __attribute__((visibility("*"))), we use that,
 * unless we already have a platform-specific definition.  Otherwise,
 * no special marking is required.
 */
#ifndef PGDLLEXPORT
#ifdef HAVE_VISIBILITY_ATTRIBUTE
#define PGDLLEXPORT __attribute__((visibility("default")))
#else
#define PGDLLEXPORT
#endif
#endif
 
/*
 * Platform independent struct representing additional information about the
 * received signal.  If the system does not support the extended information,
 * or a field does not apply to the signal, the value is instead reset to the
 * documented default value.
 */
 
typedef struct pg_signal_info
{
    uint32_t    pid;            /* pid of sending process or 0 if unknown */
    uint32_t    uid;            /* uid of sending process; only meaningful
                                 * when pid is not 0 */
} pg_signal_info;
 
/*
 * The following is used as the arg list for signal handlers. These days we
 * use the same argument to all signal handlers and hide the difference
 * between platforms in wrapper functions.
 *
 * SIGNAL_ARGS just exists separately from the pqsignal() definition for
 * historical reasons.
 */
#define SIGNAL_ARGS  int postgres_signal_arg, const pg_signal_info *pg_siginfo
 
/*
 * 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 */
 
/* /port compatibility functions */
#include "port.h"
 
/*
 * char16_t and char32_t
 *      Unicode code points.
 *
 * uchar.h should always be available in C11, but it's not available on
 * Mac. However, these types are keywords in C++11, so when using C++, we
 * can't redefine the types.
 *
 * XXX: when uchar.h is available everywhere, we can remove this check and
 * just include uchar.h unconditionally.
 *
 * XXX: this section is out of place because uchar.h needs to be included
 * after port.h, due to an interaction with win32_port.h in some cases.
 */
#ifdef HAVE_UCHAR_H
#include <uchar.h>
#else
#ifndef __cplusplus
typedef uint16_t char16_t;
typedef uint32_t char32_t;
#endif
#endif
 
/* IWYU pragma: end_exports */
 
#endif                          /* C_H */