src/include/postgres.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * postgres.h
   4  *        Primary include file for PostgreSQL server .c files
   5  *
   6  * This should be the first file included by PostgreSQL backend modules.
   7  * Client-side code should include postgres_fe.h instead.
   8  *
   9  *
  10  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  11  * Portions Copyright (c) 1995, Regents of the University of California
  12  *
  13  * $PostgreSQL$
  14  *
  15  *-------------------------------------------------------------------------
  16  */
  17 /*
  18  *----------------------------------------------------------------
  19  *       TABLE OF CONTENTS
  20  *
  21  *              When adding stuff to this file, please try to put stuff
  22  *              into the relevant section, or add new sections as appropriate.
  23  *
  24  *        section       description
  25  *        -------       ------------------------------------------------
  26  *              1)              variable-length datatypes (TOAST support)
  27  *              2)              datum type + support macros
  28  *              3)              exception handling definitions
  29  *
  30  *       NOTES
  31  *
  32  *      In general, this file should contain declarations that are widely needed
  33  *      in the backend environment, but are of no interest outside the backend.
  34  *
  35  *      Simple type definitions live in c.h, where they are shared with
  36  *      postgres_fe.h.  We do that since those type definitions are needed by
  37  *      frontend modules that want to deal with binary data transmission to or
  38  *      from the backend.  Type definitions in this file should be for
  39  *      representations that never escape the backend, such as Datum or
  40  *      TOASTed varlena objects.
  41  *
  42  *----------------------------------------------------------------
  43  */
  44 #ifndef POSTGRES_H
  45 #define POSTGRES_H
  46
  47 #include "c.h"
  48 #include "utils/elog.h"
  49 #include "utils/palloc.h"
  50
  51 /* ----------------------------------------------------------------
  52  *                              Section 1:      variable-length datatypes (TOAST support)
  53  * ----------------------------------------------------------------
  54  */
  55
  56 /*
  57  * struct varatt_external is a "TOAST pointer", that is, the information
  58  * needed to fetch a stored-out-of-line Datum.  The data is compressed
  59  * if and only if va_extsize < va_rawsize - VARHDRSZ.  This struct must not
  60  * contain any padding, because we sometimes compare pointers using memcmp.
  61  *
  62  * Note that this information is stored unaligned within actual tuples, so
  63  * you need to memcpy from the tuple into a local struct variable before
  64  * you can look at these fields!  (The reason we use memcmp is to avoid
  65  * having to do that just to detect equality of two TOAST pointers...)
  66  */
  67 struct varatt_external
  68 {
  69         int32           va_rawsize;             /* Original data size (includes header) */
  70         int32           va_extsize;             /* External saved size (doesn't) */
  71         Oid                     va_valueid;             /* Unique ID of value within TOAST table */
  72         Oid                     va_toastrelid;  /* RelID of TOAST table containing it */
  73 };
  74
  75 /*
  76  * These structs describe the header of a varlena object that may have been
  77  * TOASTed.  Generally, don't reference these structs directly, but use the
  78  * macros below.
  79  *
  80  * We use separate structs for the aligned and unaligned cases because the
  81  * compiler might otherwise think it could generate code that assumes
  82  * alignment while touching fields of a 1-byte-header varlena.
  83  */
  84 typedef union
  85 {
  86         struct                                          /* Normal varlena (4-byte length) */
  87         {
  88                 uint32          va_header;
  89                 char            va_data[1];
  90         }                       va_4byte;
  91         struct                                          /* Compressed-in-line format */
  92         {
  93                 uint32          va_header;
  94                 uint32          va_rawsize; /* Original data size (excludes header) */
  95                 char            va_data[1]; /* Compressed data */
  96         }                       va_compressed;
  97 } varattrib_4b;
  98
  99 typedef struct
 100 {
 101         uint8           va_header;
 102         char            va_data[1];             /* Data begins here */
 103 } varattrib_1b;
 104
 105 typedef struct
 106 {
 107         uint8           va_header;              /* Always 0x80 or 0x01 */
 108         uint8           va_len_1be;             /* Physical length of datum */
 109         char            va_data[1];             /* Data (for now always a TOAST pointer) */
 110 } varattrib_1b_e;
 111
 112 /*
 113  * Bit layouts for varlena headers on big-endian machines:
 114  *
 115  * 00xxxxxx 4-byte length word, aligned, uncompressed data (up to 1G)
 116  * 01xxxxxx 4-byte length word, aligned, *compressed* data (up to 1G)
 117  * 10000000 1-byte length word, unaligned, TOAST pointer
 118  * 1xxxxxxx 1-byte length word, unaligned, uncompressed data (up to 126b)
 119  *
 120  * Bit layouts for varlena headers on little-endian machines:
 121  *
 122  * xxxxxx00 4-byte length word, aligned, uncompressed data (up to 1G)
 123  * xxxxxx10 4-byte length word, aligned, *compressed* data (up to 1G)
 124  * 00000001 1-byte length word, unaligned, TOAST pointer
 125  * xxxxxxx1 1-byte length word, unaligned, uncompressed data (up to 126b)
 126  *
 127  * The "xxx" bits are the length field (which includes itself in all cases).
 128  * In the big-endian case we mask to extract the length, in the little-endian
 129  * case we shift.  Note that in both cases the flag bits are in the physically
 130  * first byte.  Also, it is not possible for a 1-byte length word to be zero;
 131  * this lets us disambiguate alignment padding bytes from the start of an
 132  * unaligned datum.  (We now *require* pad bytes to be filled with zero!)
 133  */
 134
 135 /*
 136  * Endian-dependent macros.  These are considered internal --- use the
 137  * external macros below instead of using these directly.
 138  *
 139  * Note: IS_1B is true for external toast records but VARSIZE_1B will return 0
 140  * for such records. Hence you should usually check for IS_EXTERNAL before
 141  * checking for IS_1B.
 142  */
 143
 144 #ifdef WORDS_BIGENDIAN
 145
 146 #define VARATT_IS_4B(PTR) \
 147         ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x00)
 148 #define VARATT_IS_4B_U(PTR) \
 149         ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x00)
 150 #define VARATT_IS_4B_C(PTR) \
 151         ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x40)
 152 #define VARATT_IS_1B(PTR) \
 153         ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x80)
 154 #define VARATT_IS_1B_E(PTR) \
 155         ((((varattrib_1b *) (PTR))->va_header) == 0x80)
 156 #define VARATT_NOT_PAD_BYTE(PTR) \
 157         (*((uint8 *) (PTR)) != 0)
 158
 159 /* VARSIZE_4B() should only be used on known-aligned data */
 160 #define VARSIZE_4B(PTR) \
 161         (((varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF)
 162 #define VARSIZE_1B(PTR) \
 163         (((varattrib_1b *) (PTR))->va_header & 0x7F)
 164 #define VARSIZE_1B_E(PTR) \
 165         (((varattrib_1b_e *) (PTR))->va_len_1be)
 166
 167 #define SET_VARSIZE_4B(PTR,len) \
 168         (((varattrib_4b *) (PTR))->va_4byte.va_header = (len) & 0x3FFFFFFF)
 169 #define SET_VARSIZE_4B_C(PTR,len) \
 170         (((varattrib_4b *) (PTR))->va_4byte.va_header = ((len) & 0x3FFFFFFF) | 0x40000000)
 171 #define SET_VARSIZE_1B(PTR,len) \
 172         (((varattrib_1b *) (PTR))->va_header = (len) | 0x80)
 173 #define SET_VARSIZE_1B_E(PTR,len) \
 174         (((varattrib_1b_e *) (PTR))->va_header = 0x80, \
 175          ((varattrib_1b_e *) (PTR))->va_len_1be = (len))
 176 #else                                                   /* !WORDS_BIGENDIAN */
 177
 178 #define VARATT_IS_4B(PTR) \
 179         ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x00)
 180 #define VARATT_IS_4B_U(PTR) \
 181         ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x00)
 182 #define VARATT_IS_4B_C(PTR) \
 183         ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x02)
 184 #define VARATT_IS_1B(PTR) \
 185         ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x01)
 186 #define VARATT_IS_1B_E(PTR) \
 187         ((((varattrib_1b *) (PTR))->va_header) == 0x01)
 188 #define VARATT_NOT_PAD_BYTE(PTR) \
 189         (*((uint8 *) (PTR)) != 0)
 190
 191 /* VARSIZE_4B() should only be used on known-aligned data */
 192 #define VARSIZE_4B(PTR) \
 193         ((((varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF)
 194 #define VARSIZE_1B(PTR) \
 195         ((((varattrib_1b *) (PTR))->va_header >> 1) & 0x7F)
 196 #define VARSIZE_1B_E(PTR) \
 197         (((varattrib_1b_e *) (PTR))->va_len_1be)
 198
 199 #define SET_VARSIZE_4B(PTR,len) \
 200         (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2))
 201 #define SET_VARSIZE_4B_C(PTR,len) \
 202         (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2) | 0x02)
 203 #define SET_VARSIZE_1B(PTR,len) \
 204         (((varattrib_1b *) (PTR))->va_header = (((uint8) (len)) << 1) | 0x01)
 205 #define SET_VARSIZE_1B_E(PTR,len) \
 206         (((varattrib_1b_e *) (PTR))->va_header = 0x01, \
 207          ((varattrib_1b_e *) (PTR))->va_len_1be = (len))
 208 #endif   /* WORDS_BIGENDIAN */
 209
 210 #define VARHDRSZ_SHORT                  1
 211 #define VARATT_SHORT_MAX                0x7F
 212 #define VARATT_CAN_MAKE_SHORT(PTR) \
 213         (VARATT_IS_4B_U(PTR) && \
 214          (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX)
 215 #define VARATT_CONVERTED_SHORT_SIZE(PTR) \
 216         (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT)
 217
 218 #define VARHDRSZ_EXTERNAL               2
 219
 220 #define VARDATA_4B(PTR)         (((varattrib_4b *) (PTR))->va_4byte.va_data)
 221 #define VARDATA_4B_C(PTR)       (((varattrib_4b *) (PTR))->va_compressed.va_data)
 222 #define VARDATA_1B(PTR)         (((varattrib_1b *) (PTR))->va_data)
 223 #define VARDATA_1B_E(PTR)       (((varattrib_1b_e *) (PTR))->va_data)
 224
 225 #define VARRAWSIZE_4B_C(PTR) \
 226         (((varattrib_4b *) (PTR))->va_compressed.va_rawsize)
 227
 228 /* Externally visible macros */
 229
 230 /*
 231  * VARDATA, VARSIZE, and SET_VARSIZE are the recommended API for most code
 232  * for varlena datatypes.  Note that they only work on untoasted,
 233  * 4-byte-header Datums!
 234  *
 235  * Code that wants to use 1-byte-header values without detoasting should
 236  * use VARSIZE_ANY/VARSIZE_ANY_EXHDR/VARDATA_ANY.  The other macros here
 237  * should usually be used only by tuple assembly/disassembly code and
 238  * code that specifically wants to work with still-toasted Datums.
 239  *
 240  * WARNING: It is only safe to use VARDATA_ANY() -- typically with
 241  * PG_DETOAST_DATUM_PACKED() -- if you really don't care about the alignment.
 242  * Either because you're working with something like text where the alignment
 243  * doesn't matter or because you're not going to access its constituent parts
 244  * and just use things like memcpy on it anyways.
 245  */
 246 #define VARDATA(PTR)                                            VARDATA_4B(PTR)
 247 #define VARSIZE(PTR)                                            VARSIZE_4B(PTR)
 248
 249 #define VARSIZE_SHORT(PTR)                                      VARSIZE_1B(PTR)
 250 #define VARDATA_SHORT(PTR)                                      VARDATA_1B(PTR)
 251
 252 #define VARSIZE_EXTERNAL(PTR)                           VARSIZE_1B_E(PTR)
 253 #define VARDATA_EXTERNAL(PTR)                           VARDATA_1B_E(PTR)
 254
 255 #define VARATT_IS_COMPRESSED(PTR)                       VARATT_IS_4B_C(PTR)
 256 #define VARATT_IS_EXTERNAL(PTR)                         VARATT_IS_1B_E(PTR)
 257 #define VARATT_IS_SHORT(PTR)                            VARATT_IS_1B(PTR)
 258 #define VARATT_IS_EXTENDED(PTR)                         (!VARATT_IS_4B_U(PTR))
 259
 260 #define SET_VARSIZE(PTR, len)                           SET_VARSIZE_4B(PTR, len)
 261 #define SET_VARSIZE_SHORT(PTR, len)                     SET_VARSIZE_1B(PTR, len)
 262 #define SET_VARSIZE_COMPRESSED(PTR, len)        SET_VARSIZE_4B_C(PTR, len)
 263 #define SET_VARSIZE_EXTERNAL(PTR, len)          SET_VARSIZE_1B_E(PTR, len)
 264
 265 #define VARSIZE_ANY(PTR) \
 266         (VARATT_IS_1B_E(PTR) ? VARSIZE_1B_E(PTR) : \
 267          (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR) : \
 268           VARSIZE_4B(PTR)))
 269
 270 #define VARSIZE_ANY_EXHDR(PTR) \
 271         (VARATT_IS_1B_E(PTR) ? VARSIZE_1B_E(PTR)-VARHDRSZ_EXTERNAL : \
 272          (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR)-VARHDRSZ_SHORT : \
 273           VARSIZE_4B(PTR)-VARHDRSZ))
 274
 275 /* caution: this will not work on an external or compressed-in-line Datum */
 276 /* caution: this will return a possibly unaligned pointer */
 277 #define VARDATA_ANY(PTR) \
 278          (VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR))
 279
 280
 281 /* ----------------------------------------------------------------
 282  *                              Section 2:      datum type + support macros
 283  * ----------------------------------------------------------------
 284  */
 285
 286 /*
 287  * Port Notes:
 288  *      Postgres makes the following assumption about machines:
 289  *
 290  *      sizeof(Datum) == sizeof(long) >= sizeof(void *) >= 4
 291  *
 292  *      Postgres also assumes that
 293  *
 294  *      sizeof(char) == 1
 295  *
 296  *      and that
 297  *
 298  *      sizeof(short) == 2
 299  *
 300  * When a type narrower than Datum is stored in a Datum, we place it in the
 301  * low-order bits and are careful that the DatumGetXXX macro for it discards
 302  * the unused high-order bits (as opposed to, say, assuming they are zero).
 303  * This is needed to support old-style user-defined functions, since depending
 304  * on architecture and compiler, the return value of a function returning char
 305  * or short may contain garbage when called as if it returned Datum.
 306  */
 307
 308 typedef unsigned long Datum;    /* XXX sizeof(long) >= sizeof(void *) */
 309
 310 #define SIZEOF_DATUM SIZEOF_UNSIGNED_LONG
 311
 312 typedef Datum *DatumPtr;
 313
 314 #define GET_1_BYTE(datum)       (((Datum) (datum)) & 0x000000ff)
 315 #define GET_2_BYTES(datum)      (((Datum) (datum)) & 0x0000ffff)
 316 #define GET_4_BYTES(datum)      (((Datum) (datum)) & 0xffffffff)
 317 #if SIZEOF_DATUM == 8
 318 #define GET_8_BYTES(datum)      ((Datum) (datum))
 319 #endif
 320 #define SET_1_BYTE(value)       (((Datum) (value)) & 0x000000ff)
 321 #define SET_2_BYTES(value)      (((Datum) (value)) & 0x0000ffff)
 322 #define SET_4_BYTES(value)      (((Datum) (value)) & 0xffffffff)
 323 #if SIZEOF_DATUM == 8
 324 #define SET_8_BYTES(value)      ((Datum) (value))
 325 #endif
 326
 327 /*
 328  * DatumGetBool
 329  *              Returns boolean value of a datum.
 330  *
 331  * Note: any nonzero value will be considered TRUE, but we ignore bits to
 332  * the left of the width of bool, per comment above.
 333  */
 334
 335 #define DatumGetBool(X) ((bool) (((bool) (X)) != 0))
 336
 337 /*
 338  * BoolGetDatum
 339  *              Returns datum representation for a boolean.
 340  *
 341  * Note: any nonzero value will be considered TRUE.
 342  */
 343
 344 #define BoolGetDatum(X) ((Datum) ((X) ? 1 : 0))
 345
 346 /*
 347  * DatumGetChar
 348  *              Returns character value of a datum.
 349  */
 350
 351 #define DatumGetChar(X) ((char) GET_1_BYTE(X))
 352
 353 /*
 354  * CharGetDatum
 355  *              Returns datum representation for a character.
 356  */
 357
 358 #define CharGetDatum(X) ((Datum) SET_1_BYTE(X))
 359
 360 /*
 361  * Int8GetDatum
 362  *              Returns datum representation for an 8-bit integer.
 363  */
 364
 365 #define Int8GetDatum(X) ((Datum) SET_1_BYTE(X))
 366
 367 /*
 368  * DatumGetUInt8
 369  *              Returns 8-bit unsigned integer value of a datum.
 370  */
 371
 372 #define DatumGetUInt8(X) ((uint8) GET_1_BYTE(X))
 373
 374 /*
 375  * UInt8GetDatum
 376  *              Returns datum representation for an 8-bit unsigned integer.
 377  */
 378
 379 #define UInt8GetDatum(X) ((Datum) SET_1_BYTE(X))
 380
 381 /*
 382  * DatumGetInt16
 383  *              Returns 16-bit integer value of a datum.
 384  */
 385
 386 #define DatumGetInt16(X) ((int16) GET_2_BYTES(X))
 387
 388 /*
 389  * Int16GetDatum
 390  *              Returns datum representation for a 16-bit integer.
 391  */
 392
 393 #define Int16GetDatum(X) ((Datum) SET_2_BYTES(X))
 394
 395 /*
 396  * DatumGetUInt16
 397  *              Returns 16-bit unsigned integer value of a datum.
 398  */
 399
 400 #define DatumGetUInt16(X) ((uint16) GET_2_BYTES(X))
 401
 402 /*
 403  * UInt16GetDatum
 404  *              Returns datum representation for a 16-bit unsigned integer.
 405  */
 406
 407 #define UInt16GetDatum(X) ((Datum) SET_2_BYTES(X))
 408
 409 /*
 410  * DatumGetInt32
 411  *              Returns 32-bit integer value of a datum.
 412  */
 413
 414 #define DatumGetInt32(X) ((int32) GET_4_BYTES(X))
 415
 416 /*
 417  * Int32GetDatum
 418  *              Returns datum representation for a 32-bit integer.
 419  */
 420
 421 #define Int32GetDatum(X) ((Datum) SET_4_BYTES(X))
 422
 423 /*
 424  * DatumGetUInt32
 425  *              Returns 32-bit unsigned integer value of a datum.
 426  */
 427
 428 #define DatumGetUInt32(X) ((uint32) GET_4_BYTES(X))
 429
 430 /*
 431  * UInt32GetDatum
 432  *              Returns datum representation for a 32-bit unsigned integer.
 433  */
 434
 435 #define UInt32GetDatum(X) ((Datum) SET_4_BYTES(X))
 436
 437 /*
 438  * DatumGetObjectId
 439  *              Returns object identifier value of a datum.
 440  */
 441
 442 #define DatumGetObjectId(X) ((Oid) GET_4_BYTES(X))
 443
 444 /*
 445  * ObjectIdGetDatum
 446  *              Returns datum representation for an object identifier.
 447  */
 448
 449 #define ObjectIdGetDatum(X) ((Datum) SET_4_BYTES(X))
 450
 451 /*
 452  * DatumGetTransactionId
 453  *              Returns transaction identifier value of a datum.
 454  */
 455
 456 #define DatumGetTransactionId(X) ((TransactionId) GET_4_BYTES(X))
 457
 458 /*
 459  * TransactionIdGetDatum
 460  *              Returns datum representation for a transaction identifier.
 461  */
 462
 463 #define TransactionIdGetDatum(X) ((Datum) SET_4_BYTES((X)))
 464
 465 /*
 466  * DatumGetCommandId
 467  *              Returns command identifier value of a datum.
 468  */
 469
 470 #define DatumGetCommandId(X) ((CommandId) GET_4_BYTES(X))
 471
 472 /*
 473  * CommandIdGetDatum
 474  *              Returns datum representation for a command identifier.
 475  */
 476
 477 #define CommandIdGetDatum(X) ((Datum) SET_4_BYTES(X))
 478
 479 /*
 480  * DatumGetPointer
 481  *              Returns pointer value of a datum.
 482  */
 483
 484 #define DatumGetPointer(X) ((Pointer) (X))
 485
 486 /*
 487  * PointerGetDatum
 488  *              Returns datum representation for a pointer.
 489  */
 490
 491 #define PointerGetDatum(X) ((Datum) (X))
 492
 493 /*
 494  * DatumGetCString
 495  *              Returns C string (null-terminated string) value of a datum.
 496  *
 497  * Note: C string is not a full-fledged Postgres type at present,
 498  * but type input functions use this conversion for their inputs.
 499  */
 500
 501 #define DatumGetCString(X) ((char *) DatumGetPointer(X))
 502
 503 /*
 504  * CStringGetDatum
 505  *              Returns datum representation for a C string (null-terminated string).
 506  *
 507  * Note: C string is not a full-fledged Postgres type at present,
 508  * but type output functions use this conversion for their outputs.
 509  * Note: CString is pass-by-reference; caller must ensure the pointed-to
 510  * value has adequate lifetime.
 511  */
 512
 513 #define CStringGetDatum(X) PointerGetDatum(X)
 514
 515 /*
 516  * DatumGetName
 517  *              Returns name value of a datum.
 518  */
 519
 520 #define DatumGetName(X) ((Name) DatumGetPointer(X))
 521
 522 /*
 523  * NameGetDatum
 524  *              Returns datum representation for a name.
 525  *
 526  * Note: Name is pass-by-reference; caller must ensure the pointed-to
 527  * value has adequate lifetime.
 528  */
 529
 530 #define NameGetDatum(X) PointerGetDatum(X)
 531
 532 /*
 533  * DatumGetInt64
 534  *              Returns 64-bit integer value of a datum.
 535  *
 536  * Note: this macro hides whether int64 is pass by value or by reference.
 537  */
 538
 539 #ifdef USE_FLOAT8_BYVAL
 540 #define DatumGetInt64(X) ((int64) GET_8_BYTES(X))
 541 #else
 542 #define DatumGetInt64(X) (* ((int64 *) DatumGetPointer(X)))
 543 #endif
 544
 545 /*
 546  * Int64GetDatum
 547  *              Returns datum representation for a 64-bit integer.
 548  *
 549  * Note: if int64 is pass by reference, this function returns a reference
 550  * to palloc'd space.
 551  */
 552
 553 #ifdef USE_FLOAT8_BYVAL
 554 #define Int64GetDatum(X) ((Datum) SET_8_BYTES(X))
 555 #else
 556 extern Datum Int64GetDatum(int64 X);
 557 #endif
 558
 559 /*
 560  * DatumGetFloat4
 561  *              Returns 4-byte floating point value of a datum.
 562  *
 563  * Note: this macro hides whether float4 is pass by value or by reference.
 564  */
 565
 566 #ifdef USE_FLOAT4_BYVAL
 567 extern float4 DatumGetFloat4(Datum X);
 568 #else
 569 #define DatumGetFloat4(X) (* ((float4 *) DatumGetPointer(X)))
 570 #endif
 571
 572 /*
 573  * Float4GetDatum
 574  *              Returns datum representation for a 4-byte floating point number.
 575  *
 576  * Note: if float4 is pass by reference, this function returns a reference
 577  * to palloc'd space.
 578  */
 579
 580 extern Datum Float4GetDatum(float4 X);
 581
 582 /*
 583  * DatumGetFloat8
 584  *              Returns 8-byte floating point value of a datum.
 585  *
 586  * Note: this macro hides whether float8 is pass by value or by reference.
 587  */
 588
 589 #ifdef USE_FLOAT8_BYVAL
 590 extern float8 DatumGetFloat8(Datum X);
 591 #else
 592 #define DatumGetFloat8(X) (* ((float8 *) DatumGetPointer(X)))
 593 #endif
 594
 595 /*
 596  * Float8GetDatum
 597  *              Returns datum representation for an 8-byte floating point number.
 598  *
 599  * Note: if float8 is pass by reference, this function returns a reference
 600  * to palloc'd space.
 601  */
 602
 603 extern Datum Float8GetDatum(float8 X);
 604
 605
 606 /*
 607  * Int64GetDatumFast
 608  * Float8GetDatumFast
 609  * Float4GetDatumFast
 610  *
 611  * These macros are intended to allow writing code that does not depend on
 612  * whether int64, float8, float4 are pass-by-reference types, while not
 613  * sacrificing performance when they are.  The argument must be a variable
 614  * that will exist and have the same value for as long as the Datum is needed.
 615  * In the pass-by-ref case, the address of the variable is taken to use as
 616  * the Datum.  In the pass-by-val case, these will be the same as the non-Fast
 617  * macros.
 618  */
 619
 620 #ifdef USE_FLOAT8_BYVAL
 621 #define Int64GetDatumFast(X)  Int64GetDatum(X)
 622 #define Float8GetDatumFast(X) Float8GetDatum(X)
 623 #else
 624 #define Int64GetDatumFast(X)  PointerGetDatum(&(X))
 625 #define Float8GetDatumFast(X) PointerGetDatum(&(X))
 626 #endif
 627
 628 #ifdef USE_FLOAT4_BYVAL
 629 #define Float4GetDatumFast(X) Float4GetDatum(X)
 630 #else
 631 #define Float4GetDatumFast(X) PointerGetDatum(&(X))
 632 #endif
 633
 634
 635 /* ----------------------------------------------------------------
 636  *                              Section 3:      exception handling definitions
 637  *                                                      Assert, Trap, etc macros
 638  * ----------------------------------------------------------------
 639  */
 640
 641 extern PGDLLIMPORT bool assert_enabled;
 642
 643 /*
 644  * USE_ASSERT_CHECKING, if defined, turns on all the assertions.
 645  * - plai  9/5/90
 646  *
 647  * It should _NOT_ be defined in releases or in benchmark copies
 648  */
 649
 650 /*
 651  * Trap
 652  *              Generates an exception if the given condition is true.
 653  */
 654 #define Trap(condition, errorType) \
 655         do { \
 656                 if ((assert_enabled) && (condition)) \
 657                         ExceptionalCondition(CppAsString(condition), (errorType), \
 658                                                                  __FILE__, __LINE__); \
 659         } while (0)
 660
 661 /*
 662  *      TrapMacro is the same as Trap but it's intended for use in macros:
 663  *
 664  *              #define foo(x) (AssertMacro(x != 0) && bar(x))
 665  *
 666  *      Isn't CPP fun?
 667  */
 668 #define TrapMacro(condition, errorType) \
 669         ((bool) ((! assert_enabled) || ! (condition) || \
 670                          (ExceptionalCondition(CppAsString(condition), (errorType), \
 671                                                                    __FILE__, __LINE__))))
 672
 673 #ifndef USE_ASSERT_CHECKING
 674 #define Assert(condition)
 675 #define AssertMacro(condition)  ((void)true)
 676 #define AssertArg(condition)
 677 #define AssertState(condition)
 678 #else
 679 #define Assert(condition) \
 680                 Trap(!(condition), "FailedAssertion")
 681
 682 #define AssertMacro(condition) \
 683                 ((void) TrapMacro(!(condition), "FailedAssertion"))
 684
 685 #define AssertArg(condition) \
 686                 Trap(!(condition), "BadArgument")
 687
 688 #define AssertState(condition) \
 689                 Trap(!(condition), "BadState")
 690 #endif   /* USE_ASSERT_CHECKING */
 691
 692 extern int ExceptionalCondition(const char *conditionName,
 693                                          const char *errorType,
 694                                          const char *fileName, int lineNumber);
 695
 696 #endif   /* POSTGRES_H */