src/libpq/include/postgres.h

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/*-------------------------------------------------------------------------
 *
 * postgres.h
 *   Primary include file for PostgreSQL server .c files
 *
 * This should be the first file included by PostgreSQL backend modules.
 * Client-side code should include postgres_fe.h instead.
 *
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1995, Regents of the University of California
 *
 * $PostgreSQL: pgsql/src/include/postgres.h,v 1.71 2005/04/14 01:38:21 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
/*
 *----------------------------------------------------------------
 *  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
 *   ------- ------------------------------------------------
 *  1)  variable-length datatypes (TOAST support)
 *  2)  datum type + support macros
 *  3)  exception handling definitions
 *  4)  genbki macros used by catalog/pg_xxx.h files
 *
 *  NOTES
 *
 * In general, this file should contain declarations that are widely needed
 * in the backend environment, but are of no interest outside the backend.
 *
 * Simple type definitions live in c.h, where they are shared with
 * postgres_fe.h. We do that since those type definitions are needed by
 * frontend modules that want to deal with binary data transmission to or
 * from the backend.  Type definitions in this file should be for
 * representations that never escape the backend, such as Datum or
 * TOASTed varlena objects.
 *
 *----------------------------------------------------------------
 */
#ifndef POSTGRES_H
#define POSTGRES_H

#include "c.h"
#include "utils/elog.h"
#include "utils/palloc.h"

/* ----------------------------------------------------------------
 *    Section 1: variable-length datatypes (TOAST support)
 * ----------------------------------------------------------------
 */

/* ----------------
 * struct varattrib is the header of a varlena object that may have been
 * TOASTed.
 * ----------------
 */
typedef struct varattrib {
  int32  va_header;  /* External/compressed storage */
  /* flags and item size */
  union {
    struct {
      int32  va_rawsize;  /* Plain data size */
      char  va_data[1];  /* Compressed data */
    }   va_compressed;  /* Compressed stored attribute */

    struct {
      int32  va_rawsize;  /* Plain data size */
      int32  va_extsize;  /* External saved size */
      Oid   va_valueid;  /* Unique identifier of value */
      Oid   va_toastrelid; /* RelID where to find chunks */
    }   va_external; /* External stored attribute */

    char  va_data[1]; /* Plain stored attribute */
  }   va_content;
} varattrib;

#define VARATT_FLAG_EXTERNAL 0x80000000
#define VARATT_FLAG_COMPRESSED 0x40000000
#define VARATT_MASK_FLAGS  0xc0000000
#define VARATT_MASK_SIZE  0x3fffffff

#define VARATT_SIZEP(_PTR) (((varattrib *)(_PTR))->va_header)
#define VARATT_SIZE(PTR) (VARATT_SIZEP(PTR) & VARATT_MASK_SIZE)
#define VARATT_DATA(PTR) (((varattrib *)(PTR))->va_content.va_data)
#define VARATT_CDATA(PTR) (((varattrib *)(PTR))->va_content.va_compressed.va_data)

#define VARSIZE(__PTR)  VARATT_SIZE(__PTR)
#define VARDATA(__PTR)  VARATT_DATA(__PTR)

#define VARATT_IS_EXTENDED(PTR)  \
  ((VARATT_SIZEP(PTR) & VARATT_MASK_FLAGS) != 0)
#define VARATT_IS_EXTERNAL(PTR)  \
  ((VARATT_SIZEP(PTR) & VARATT_FLAG_EXTERNAL) != 0)
#define VARATT_IS_COMPRESSED(PTR) \
  ((VARATT_SIZEP(PTR) & VARATT_FLAG_COMPRESSED) != 0)


/* ----------------------------------------------------------------
 *    Section 2: datum type + support macros
 * ----------------------------------------------------------------
 */

/*
 * Port Notes:
 * Postgres makes the following assumption about machines:
 *
 * sizeof(Datum) == sizeof(long) >= sizeof(void *) >= 4
 *
 * Postgres also assumes that
 *
 * sizeof(char) == 1
 *
 * and that
 *
 * sizeof(short) == 2
 *
 * If your machine meets these requirements, Datums should also be checked
 * to see if the positioning is correct.
 */

typedef unsigned long Datum; /* XXX sizeof(long) >= sizeof(void *) */

#define SIZEOF_DATUM SIZEOF_UNSIGNED_LONG
typedef Datum *DatumPtr;

#define GET_1_BYTE(datum) (((Datum) (datum)) & 0x000000ff)
#define GET_2_BYTES(datum) (((Datum) (datum)) & 0x0000ffff)
#define GET_4_BYTES(datum) (((Datum) (datum)) & 0xffffffff)
#define SET_1_BYTE(value) (((Datum) (value)) & 0x000000ff)
#define SET_2_BYTES(value) (((Datum) (value)) & 0x0000ffff)
#define SET_4_BYTES(value) (((Datum) (value)) & 0xffffffff)

/*
 * DatumGetBool
 *  Returns boolean value of a datum.
 *
 * Note: any nonzero value will be considered TRUE.
 */

#define DatumGetBool(X) ((bool) (((Datum) (X)) != 0))

/*
 * BoolGetDatum
 *  Returns datum representation for a boolean.
 *
 * Note: any nonzero value will be considered TRUE.
 */

#define BoolGetDatum(X) ((Datum) ((X) ? 1 : 0))

/*
 * DatumGetChar
 *  Returns character value of a datum.
 */

#define DatumGetChar(X) ((char) GET_1_BYTE(X))

/*
 * CharGetDatum
 *  Returns datum representation for a character.
 */

#define CharGetDatum(X) ((Datum) SET_1_BYTE(X))

/*
 * Int8GetDatum
 *  Returns datum representation for an 8-bit integer.
 */

#define Int8GetDatum(X) ((Datum) SET_1_BYTE(X))

/*
 * DatumGetUInt8
 *  Returns 8-bit unsigned integer value of a datum.
 */

#define DatumGetUInt8(X) ((uint8) GET_1_BYTE(X))

/*
 * UInt8GetDatum
 *  Returns datum representation for an 8-bit unsigned integer.
 */

#define UInt8GetDatum(X) ((Datum) SET_1_BYTE(X))

/*
 * DatumGetInt16
 *  Returns 16-bit integer value of a datum.
 */

#define DatumGetInt16(X) ((int16) GET_2_BYTES(X))

/*
 * Int16GetDatum
 *  Returns datum representation for a 16-bit integer.
 */

#define Int16GetDatum(X) ((Datum) SET_2_BYTES(X))

/*
 * DatumGetUInt16
 *  Returns 16-bit unsigned integer value of a datum.
 */

#define DatumGetUInt16(X) ((uint16) GET_2_BYTES(X))

/*
 * UInt16GetDatum
 *  Returns datum representation for a 16-bit unsigned integer.
 */

#define UInt16GetDatum(X) ((Datum) SET_2_BYTES(X))

/*
 * DatumGetInt32
 *  Returns 32-bit integer value of a datum.
 */

#define DatumGetInt32(X) ((int32) GET_4_BYTES(X))

/*
 * Int32GetDatum
 *  Returns datum representation for a 32-bit integer.
 */

#define Int32GetDatum(X) ((Datum) SET_4_BYTES(X))

/*
 * DatumGetUInt32
 *  Returns 32-bit unsigned integer value of a datum.
 */

#define DatumGetUInt32(X) ((uint32) GET_4_BYTES(X))

/*
 * UInt32GetDatum
 *  Returns datum representation for a 32-bit unsigned integer.
 */

#define UInt32GetDatum(X) ((Datum) SET_4_BYTES(X))

/*
 * DatumGetObjectId
 *  Returns object identifier value of a datum.
 */

#define DatumGetObjectId(X) ((Oid) GET_4_BYTES(X))

/*
 * ObjectIdGetDatum
 *  Returns datum representation for an object identifier.
 */

#define ObjectIdGetDatum(X) ((Datum) SET_4_BYTES(X))

/*
 * DatumGetTransactionId
 *  Returns transaction identifier value of a datum.
 */

#define DatumGetTransactionId(X) ((TransactionId) GET_4_BYTES(X))

/*
 * TransactionIdGetDatum
 *  Returns datum representation for a transaction identifier.
 */

#define TransactionIdGetDatum(X) ((Datum) SET_4_BYTES((X)))

/*
 * DatumGetCommandId
 *  Returns command identifier value of a datum.
 */

#define DatumGetCommandId(X) ((CommandId) GET_4_BYTES(X))

/*
 * CommandIdGetDatum
 *  Returns datum representation for a command identifier.
 */

#define CommandIdGetDatum(X) ((Datum) SET_4_BYTES(X))

/*
 * DatumGetPointer
 *  Returns pointer value of a datum.
 */

#define DatumGetPointer(X) ((Pointer) (X))

/*
 * PointerGetDatum
 *  Returns datum representation for a pointer.
 */

#define PointerGetDatum(X) ((Datum) (X))

/*
 * DatumGetCString
 *  Returns C string (null-terminated string) value of a datum.
 *
 * Note: C string is not a full-fledged Postgres type at present,
 * but type input functions use this conversion for their inputs.
 */

#define DatumGetCString(X) ((char *) DatumGetPointer(X))

/*
 * CStringGetDatum
 *  Returns datum representation for a C string (null-terminated string).
 *
 * Note: C string is not a full-fledged Postgres type at present,
 * but type output functions use this conversion for their outputs.
 * Note: CString is pass-by-reference; caller must ensure the pointed-to
 * value has adequate lifetime.
 */

#define CStringGetDatum(X) PointerGetDatum(X)

/*
 * DatumGetName
 *  Returns name value of a datum.
 */

#define DatumGetName(X) ((Name) DatumGetPointer(X))

/*
 * NameGetDatum
 *  Returns datum representation for a name.
 *
 * Note: Name is pass-by-reference; caller must ensure the pointed-to
 * value has adequate lifetime.
 */

#define NameGetDatum(X) PointerGetDatum(X)

/*
 * DatumGetInt64
 *  Returns 64-bit integer value of a datum.
 *
 * Note: this macro hides the fact that int64 is currently a
 * pass-by-reference type. Someday it may be pass-by-value,
 * at least on some platforms.
 */

#define DatumGetInt64(X) (* ((int64 *) DatumGetPointer(X)))

/*
 * Int64GetDatum
 *  Returns datum representation for a 64-bit integer.
 *
 * Note: this routine returns a reference to palloc'd space.
 */

extern Datum Int64GetDatum( int64 X );

/*
 * DatumGetFloat4
 *  Returns 4-byte floating point value of a datum.
 *
 * Note: this macro hides the fact that float4 is currently a
 * pass-by-reference type. Someday it may be pass-by-value.
 */

#define DatumGetFloat4(X) (* ((float4 *) DatumGetPointer(X)))

/*
 * Float4GetDatum
 *  Returns datum representation for a 4-byte floating point number.
 *
 * Note: this routine returns a reference to palloc'd space.
 */

extern Datum Float4GetDatum( float4 X );

/*
 * DatumGetFloat8
 *  Returns 8-byte floating point value of a datum.
 *
 * Note: this macro hides the fact that float8 is currently a
 * pass-by-reference type. Someday it may be pass-by-value,
 * at least on some platforms.
 */

#define DatumGetFloat8(X) (* ((float8 *) DatumGetPointer(X)))

/*
 * Float8GetDatum
 *  Returns datum representation for an 8-byte floating point number.
 *
 * Note: this routine returns a reference to palloc'd space.
 */

extern Datum Float8GetDatum( float8 X );


/*
 * DatumGetFloat32
 *  Returns 32-bit floating point value of a datum.
 *  This is really a pointer, of course.
 *
 * XXX: this macro is now deprecated in favor of DatumGetFloat4.
 * It will eventually go away.
 */

#define DatumGetFloat32(X) ((float32) DatumGetPointer(X))

/*
 * Float32GetDatum
 *  Returns datum representation for a 32-bit floating point number.
 *  This is really a pointer, of course.
 *
 * XXX: this macro is now deprecated in favor of Float4GetDatum.
 * It will eventually go away.
 */

#define Float32GetDatum(X) PointerGetDatum(X)

/*
 * DatumGetFloat64
 *  Returns 64-bit floating point value of a datum.
 *  This is really a pointer, of course.
 *
 * XXX: this macro is now deprecated in favor of DatumGetFloat8.
 * It will eventually go away.
 */

#define DatumGetFloat64(X) ((float64) DatumGetPointer(X))

/*
 * Float64GetDatum
 *  Returns datum representation for a 64-bit floating point number.
 *  This is really a pointer, of course.
 *
 * XXX: this macro is now deprecated in favor of Float8GetDatum.
 * It will eventually go away.
 */

#define Float64GetDatum(X) PointerGetDatum(X)

/*
 * Int64GetDatumFast
 * Float4GetDatumFast
 * Float8GetDatumFast
 *
 * These macros are intended to allow writing code that does not depend on
 * whether int64, float4, float8 are pass-by-reference types, while not
 * sacrificing performance when they are.  The argument must be a variable
 * that will exist and have the same value for as long as the Datum is needed.
 * In the pass-by-ref case, the address of the variable is taken to use as
 * the Datum.  In the pass-by-val case, these will be the same as the non-Fast
 * macros.
 */

#define Int64GetDatumFast(X)  PointerGetDatum(&(X))
#define Float4GetDatumFast(X) PointerGetDatum(&(X))
#define Float8GetDatumFast(X) PointerGetDatum(&(X))


/* ----------------------------------------------------------------
 *    Section 3: exception handling definitions
 *       Assert, Trap, etc macros
 * ----------------------------------------------------------------
 */

extern DLLIMPORT bool assert_enabled;

/*
 * 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
 */

/*
 * Trap
 *  Generates an exception if the given condition is true.
 *
 */
#define Trap(condition, errorType) \
  do { \
    if ((assert_enabled) && (condition)) \
      ExceptionalCondition(CppAsString(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) ((! assert_enabled) || ! (condition) || \
           (ExceptionalCondition(CppAsString(condition), (errorType), \
                                 __FILE__, __LINE__))))

#ifndef USE_ASSERT_CHECKING
#define Assert(condition)
#define AssertMacro(condition) ((void)true)
#define AssertArg(condition)
#define AssertState(condition)
#define assert_enabled 0
#else
#define Assert(condition) \
  Trap(!(condition), "FailedAssertion")

#define AssertMacro(condition) \
  ((void) TrapMacro(!(condition), "FailedAssertion"))

#define AssertArg(condition) \
  Trap(!(condition), "BadArgument")

#define AssertState(condition) \
  Trap(!(condition), "BadState")
#endif   /* USE_ASSERT_CHECKING */

extern int ExceptionalCondition( char *conditionName, char *errorType,
                                   char *fileName, int lineNumber );

/* ----------------------------------------------------------------
 *    Section 4: genbki macros used by catalog/pg_xxx.h files
 * ----------------------------------------------------------------
 */
#define CATALOG(name,oid) typedef struct CppConcat(FormData_,name)

#define BKI_BOOTSTRAP
#define BKI_SHARED_RELATION
#define BKI_WITHOUT_OIDS

/* these need to expand into some harmless, repeatable declaration */
#define DATA(x)   extern int no_such_variable
#define DESCR(x)  extern int no_such_variable

typedef int4 aclitem;   /* PHONY definition for catalog use only */

#endif   /* POSTGRES_H */