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) 1996-2020, PostgreSQL Global Development Group
11 * Portions Copyright (c) 1995, Regents of the University of California
12 *
13 * src/include/postgres.h
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 *
29 * NOTES
30 *
31 * In general, this file should contain declarations that are widely needed
32 * in the backend environment, but are of no interest outside the backend.
33 *
34 * Simple type definitions live in c.h, where they are shared with
35 * postgres_fe.h. We do that since those type definitions are needed by
36 * frontend modules that want to deal with binary data transmission to or
37 * from the backend. Type definitions in this file should be for
38 * representations that never escape the backend, such as Datum or
39 * TOASTed varlena objects.
40 *
41 *----------------------------------------------------------------
42 */
43 #ifndef POSTGRES_H
44 #define POSTGRES_H
45
46 #include "c.h"
47 #include "utils/elog.h"
48 #include "utils/palloc.h"
49
50 /* ----------------------------------------------------------------
51 * Section 1: variable-length datatypes (TOAST support)
52 * ----------------------------------------------------------------
53 */
54
55 /*
56 * struct varatt_external is a traditional "TOAST pointer", that is, the
57 * information needed to fetch a Datum stored out-of-line in a TOAST table.
58 * The data is compressed if and only if va_extsize < va_rawsize - VARHDRSZ.
59 * This struct must not contain any padding, because we sometimes compare
60 * these 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 typedef 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 } varatt_external;
74
75 /*
76 * struct varatt_indirect is a "TOAST pointer" representing an out-of-line
77 * Datum that's stored in memory, not in an external toast relation.
78 * The creator of such a Datum is entirely responsible that the referenced
79 * storage survives for as long as referencing pointer Datums can exist.
80 *
81 * Note that just as for struct varatt_external, this struct is stored
82 * unaligned within any containing tuple.
83 */
84 typedef struct varatt_indirect
85 {
86 struct varlena *pointer; /* Pointer to in-memory varlena */
87 } varatt_indirect;
88
89 /*
90 * struct varatt_expanded is a "TOAST pointer" representing an out-of-line
91 * Datum that is stored in memory, in some type-specific, not necessarily
92 * physically contiguous format that is convenient for computation not
93 * storage. APIs for this, in particular the definition of struct
94 * ExpandedObjectHeader, are in src/include/utils/expandeddatum.h.
95 *
96 * Note that just as for struct varatt_external, this struct is stored
97 * unaligned within any containing tuple.
98 */
99 typedef struct ExpandedObjectHeader ExpandedObjectHeader;
100
101 typedef struct varatt_expanded
102 {
103 ExpandedObjectHeader *eohptr;
104 } varatt_expanded;
105
106 /*
107 * Type tag for the various sorts of "TOAST pointer" datums. The peculiar
108 * value for VARTAG_ONDISK comes from a requirement for on-disk compatibility
109 * with a previous notion that the tag field was the pointer datum's length.
110 */
111 typedef enum vartag_external
112 {
113 VARTAG_INDIRECT = 1,
114 VARTAG_EXPANDED_RO = 2,
115 VARTAG_EXPANDED_RW = 3,
116 VARTAG_ONDISK = 18
117 } vartag_external;
118
119 /* this test relies on the specific tag values above */
120 #define VARTAG_IS_EXPANDED(tag) \
121 (((tag) & ~1) == VARTAG_EXPANDED_RO)
122
123 #define VARTAG_SIZE(tag) \
124 ((tag) == VARTAG_INDIRECT ? sizeof(varatt_indirect) : \
125 VARTAG_IS_EXPANDED(tag) ? sizeof(varatt_expanded) : \
126 (tag) == VARTAG_ONDISK ? sizeof(varatt_external) : \
127 TrapMacro(true, "unrecognized TOAST vartag"))
128
129 /*
130 * These structs describe the header of a varlena object that may have been
131 * TOASTed. Generally, don't reference these structs directly, but use the
132 * macros below.
133 *
134 * We use separate structs for the aligned and unaligned cases because the
135 * compiler might otherwise think it could generate code that assumes
136 * alignment while touching fields of a 1-byte-header varlena.
137 */
138 typedef union
139 {
140 struct /* Normal varlena (4-byte length) */
141 {
142 uint32 va_header;
143 char va_data[FLEXIBLE_ARRAY_MEMBER];
144 } va_4byte;
145 struct /* Compressed-in-line format */
146 {
147 uint32 va_header;
148 uint32 va_rawsize; /* Original data size (excludes header) */
149 char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */
150 } va_compressed;
151 } varattrib_4b;
152
153 typedef struct
154 {
155 uint8 va_header;
156 char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Data begins here */
157 } varattrib_1b;
158
159 /* TOAST pointers are a subset of varattrib_1b with an identifying tag byte */
160 typedef struct
161 {
162 uint8 va_header; /* Always 0x80 or 0x01 */
163 uint8 va_tag; /* Type of datum */
164 char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Type-specific data */
165 } varattrib_1b_e;
166
167 /*
168 * Bit layouts for varlena headers on big-endian machines:
169 *
170 * 00xxxxxx 4-byte length word, aligned, uncompressed data (up to 1G)
171 * 01xxxxxx 4-byte length word, aligned, *compressed* data (up to 1G)
172 * 10000000 1-byte length word, unaligned, TOAST pointer
173 * 1xxxxxxx 1-byte length word, unaligned, uncompressed data (up to 126b)
174 *
175 * Bit layouts for varlena headers on little-endian machines:
176 *
177 * xxxxxx00 4-byte length word, aligned, uncompressed data (up to 1G)
178 * xxxxxx10 4-byte length word, aligned, *compressed* data (up to 1G)
179 * 00000001 1-byte length word, unaligned, TOAST pointer
180 * xxxxxxx1 1-byte length word, unaligned, uncompressed data (up to 126b)
181 *
182 * The "xxx" bits are the length field (which includes itself in all cases).
183 * In the big-endian case we mask to extract the length, in the little-endian
184 * case we shift. Note that in both cases the flag bits are in the physically
185 * first byte. Also, it is not possible for a 1-byte length word to be zero;
186 * this lets us disambiguate alignment padding bytes from the start of an
187 * unaligned datum. (We now *require* pad bytes to be filled with zero!)
188 *
189 * In TOAST pointers the va_tag field (see varattrib_1b_e) is used to discern
190 * the specific type and length of the pointer datum.
191 */
192
193 /*
194 * Endian-dependent macros. These are considered internal --- use the
195 * external macros below instead of using these directly.
196 *
197 * Note: IS_1B is true for external toast records but VARSIZE_1B will return 0
198 * for such records. Hence you should usually check for IS_EXTERNAL before
199 * checking for IS_1B.
200 */
201
202 #ifdef WORDS_BIGENDIAN
203
204 #define VARATT_IS_4B(PTR) \
205 ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x00)
206 #define VARATT_IS_4B_U(PTR) \
207 ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x00)
208 #define VARATT_IS_4B_C(PTR) \
209 ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x40)
210 #define VARATT_IS_1B(PTR) \
211 ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x80)
212 #define VARATT_IS_1B_E(PTR) \
213 ((((varattrib_1b *) (PTR))->va_header) == 0x80)
214 #define VARATT_NOT_PAD_BYTE(PTR) \
215 (*((uint8 *) (PTR)) != 0)
216
217 /* VARSIZE_4B() should only be used on known-aligned data */
218 #define VARSIZE_4B(PTR) \
219 (((varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF)
220 #define VARSIZE_1B(PTR) \
221 (((varattrib_1b *) (PTR))->va_header & 0x7F)
222 #define VARTAG_1B_E(PTR) \
223 (((varattrib_1b_e *) (PTR))->va_tag)
224
225 #define SET_VARSIZE_4B(PTR,len) \
226 (((varattrib_4b *) (PTR))->va_4byte.va_header = (len) & 0x3FFFFFFF)
227 #define SET_VARSIZE_4B_C(PTR,len) \
228 (((varattrib_4b *) (PTR))->va_4byte.va_header = ((len) & 0x3FFFFFFF) | 0x40000000)
229 #define SET_VARSIZE_1B(PTR,len) \
230 (((varattrib_1b *) (PTR))->va_header = (len) | 0x80)
231 #define SET_VARTAG_1B_E(PTR,tag) \
232 (((varattrib_1b_e *) (PTR))->va_header = 0x80, \
233 ((varattrib_1b_e *) (PTR))->va_tag = (tag))
234 #else /* !WORDS_BIGENDIAN */
235
236 #define VARATT_IS_4B(PTR) \
237 ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x00)
238 #define VARATT_IS_4B_U(PTR) \
239 ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x00)
240 #define VARATT_IS_4B_C(PTR) \
241 ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x02)
242 #define VARATT_IS_1B(PTR) \
243 ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x01)
244 #define VARATT_IS_1B_E(PTR) \
245 ((((varattrib_1b *) (PTR))->va_header) == 0x01)
246 #define VARATT_NOT_PAD_BYTE(PTR) \
247 (*((uint8 *) (PTR)) != 0)
248
249 /* VARSIZE_4B() should only be used on known-aligned data */
250 #define VARSIZE_4B(PTR) \
251 ((((varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF)
252 #define VARSIZE_1B(PTR) \
253 ((((varattrib_1b *) (PTR))->va_header >> 1) & 0x7F)
254 #define VARTAG_1B_E(PTR) \
255 (((varattrib_1b_e *) (PTR))->va_tag)
256
257 #define SET_VARSIZE_4B(PTR,len) \
258 (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2))
259 #define SET_VARSIZE_4B_C(PTR,len) \
260 (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2) | 0x02)
261 #define SET_VARSIZE_1B(PTR,len) \
262 (((varattrib_1b *) (PTR))->va_header = (((uint8) (len)) << 1) | 0x01)
263 #define SET_VARTAG_1B_E(PTR,tag) \
264 (((varattrib_1b_e *) (PTR))->va_header = 0x01, \
265 ((varattrib_1b_e *) (PTR))->va_tag = (tag))
266 #endif /* WORDS_BIGENDIAN */
267
268 #define VARHDRSZ_SHORT offsetof(varattrib_1b, va_data)
269 #define VARATT_SHORT_MAX 0x7F
270 #define VARATT_CAN_MAKE_SHORT(PTR) \
271 (VARATT_IS_4B_U(PTR) && \
272 (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX)
273 #define VARATT_CONVERTED_SHORT_SIZE(PTR) \
274 (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT)
275
276 #define VARHDRSZ_EXTERNAL offsetof(varattrib_1b_e, va_data)
277
278 #define VARDATA_4B(PTR) (((varattrib_4b *) (PTR))->va_4byte.va_data)
279 #define VARDATA_4B_C(PTR) (((varattrib_4b *) (PTR))->va_compressed.va_data)
280 #define VARDATA_1B(PTR) (((varattrib_1b *) (PTR))->va_data)
281 #define VARDATA_1B_E(PTR) (((varattrib_1b_e *) (PTR))->va_data)
282
283 #define VARRAWSIZE_4B_C(PTR) \
284 (((varattrib_4b *) (PTR))->va_compressed.va_rawsize)
285
286 /* Externally visible macros */
287
288 /*
289 * In consumers oblivious to data alignment, call PG_DETOAST_DATUM_PACKED(),
290 * VARDATA_ANY(), VARSIZE_ANY() and VARSIZE_ANY_EXHDR(). Elsewhere, call
291 * PG_DETOAST_DATUM(), VARDATA() and VARSIZE(). Directly fetching an int16,
292 * int32 or wider field in the struct representing the datum layout requires
293 * aligned data. memcpy() is alignment-oblivious, as are most operations on
294 * datatypes, such as text, whose layout struct contains only char fields.
295 *
296 * Code assembling a new datum should call VARDATA() and SET_VARSIZE().
297 * (Datums begin life untoasted.)
298 *
299 * Other macros here should usually be used only by tuple assembly/disassembly
300 * code and code that specifically wants to work with still-toasted Datums.
301 */
302 #define VARDATA(PTR) VARDATA_4B(PTR)
303 #define VARSIZE(PTR) VARSIZE_4B(PTR)
304
305 #define VARSIZE_SHORT(PTR) VARSIZE_1B(PTR)
306 #define VARDATA_SHORT(PTR) VARDATA_1B(PTR)
307
308 #define VARTAG_EXTERNAL(PTR) VARTAG_1B_E(PTR)
309 #define VARSIZE_EXTERNAL(PTR) (VARHDRSZ_EXTERNAL + VARTAG_SIZE(VARTAG_EXTERNAL(PTR)))
310 #define VARDATA_EXTERNAL(PTR) VARDATA_1B_E(PTR)
311
312 #define VARATT_IS_COMPRESSED(PTR) VARATT_IS_4B_C(PTR)
313 #define VARATT_IS_EXTERNAL(PTR) VARATT_IS_1B_E(PTR)
314 #define VARATT_IS_EXTERNAL_ONDISK(PTR) \
315 (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_ONDISK)
316 #define VARATT_IS_EXTERNAL_INDIRECT(PTR) \
317 (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_INDIRECT)
318 #define VARATT_IS_EXTERNAL_EXPANDED_RO(PTR) \
319 (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RO)
320 #define VARATT_IS_EXTERNAL_EXPANDED_RW(PTR) \
321 (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RW)
322 #define VARATT_IS_EXTERNAL_EXPANDED(PTR) \
323 (VARATT_IS_EXTERNAL(PTR) && VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))
324 #define VARATT_IS_EXTERNAL_NON_EXPANDED(PTR) \
325 (VARATT_IS_EXTERNAL(PTR) && !VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))
326 #define VARATT_IS_SHORT(PTR) VARATT_IS_1B(PTR)
327 #define VARATT_IS_EXTENDED(PTR) (!VARATT_IS_4B_U(PTR))
328
329 #define SET_VARSIZE(PTR, len) SET_VARSIZE_4B(PTR, len)
330 #define SET_VARSIZE_SHORT(PTR, len) SET_VARSIZE_1B(PTR, len)
331 #define SET_VARSIZE_COMPRESSED(PTR, len) SET_VARSIZE_4B_C(PTR, len)
332
333 #define SET_VARTAG_EXTERNAL(PTR, tag) SET_VARTAG_1B_E(PTR, tag)
334
335 #define VARSIZE_ANY(PTR) \
336 (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR) : \
337 (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR) : \
338 VARSIZE_4B(PTR)))
339
340 /* Size of a varlena data, excluding header */
341 #define VARSIZE_ANY_EXHDR(PTR) \
342 (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR)-VARHDRSZ_EXTERNAL : \
343 (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR)-VARHDRSZ_SHORT : \
344 VARSIZE_4B(PTR)-VARHDRSZ))
345
346 /* caution: this will not work on an external or compressed-in-line Datum */
347 /* caution: this will return a possibly unaligned pointer */
348 #define VARDATA_ANY(PTR) \
349 (VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR))
350
351
352 /* ----------------------------------------------------------------
353 * Section 2: Datum type + support macros
354 * ----------------------------------------------------------------
355 */
356
357 /*
358 * A Datum contains either a value of a pass-by-value type or a pointer to a
359 * value of a pass-by-reference type. Therefore, we require:
360 *
361 * sizeof(Datum) == sizeof(void *) == 4 or 8
362 *
363 * The macros below and the analogous macros for other types should be used to
364 * convert between a Datum and the appropriate C type.
365 */
366
367 typedef uintptr_t Datum;
368
369 /*
370 * A NullableDatum is used in places where both a Datum and its nullness needs
371 * to be stored. This can be more efficient than storing datums and nullness
372 * in separate arrays, due to better spatial locality, even if more space may
373 * be wasted due to padding.
374 */
375 typedef struct NullableDatum
376 {
377 #define FIELDNO_NULLABLE_DATUM_DATUM 0
378 Datum value;
379 #define FIELDNO_NULLABLE_DATUM_ISNULL 1
380 bool isnull;
381 /* due to alignment padding this could be used for flags for free */
382 } NullableDatum;
383
384 #define SIZEOF_DATUM SIZEOF_VOID_P
385
386 /*
387 * DatumGetBool
388 * Returns boolean value of a datum.
389 *
390 * Note: any nonzero value will be considered true.
391 */
392
393 #define DatumGetBool(X) ((bool) ((X) != 0))
394
395 /*
396 * BoolGetDatum
397 * Returns datum representation for a boolean.
398 *
399 * Note: any nonzero value will be considered true.
400 */
401
402 #define BoolGetDatum(X) ((Datum) ((X) ? 1 : 0))
403
404 /*
405 * DatumGetChar
406 * Returns character value of a datum.
407 */
408
409 #define DatumGetChar(X) ((char) (X))
410
411 /*
412 * CharGetDatum
413 * Returns datum representation for a character.
414 */
415
416 #define CharGetDatum(X) ((Datum) (X))
417
418 /*
419 * Int8GetDatum
420 * Returns datum representation for an 8-bit integer.
421 */
422
423 #define Int8GetDatum(X) ((Datum) (X))
424
425 /*
426 * DatumGetUInt8
427 * Returns 8-bit unsigned integer value of a datum.
428 */
429
430 #define DatumGetUInt8(X) ((uint8) (X))
431
432 /*
433 * UInt8GetDatum
434 * Returns datum representation for an 8-bit unsigned integer.
435 */
436
437 #define UInt8GetDatum(X) ((Datum) (X))
438
439 /*
440 * DatumGetInt16
441 * Returns 16-bit integer value of a datum.
442 */
443
444 #define DatumGetInt16(X) ((int16) (X))
445
446 /*
447 * Int16GetDatum
448 * Returns datum representation for a 16-bit integer.
449 */
450
451 #define Int16GetDatum(X) ((Datum) (X))
452
453 /*
454 * DatumGetUInt16
455 * Returns 16-bit unsigned integer value of a datum.
456 */
457
458 #define DatumGetUInt16(X) ((uint16) (X))
459
460 /*
461 * UInt16GetDatum
462 * Returns datum representation for a 16-bit unsigned integer.
463 */
464
465 #define UInt16GetDatum(X) ((Datum) (X))
466
467 /*
468 * DatumGetInt32
469 * Returns 32-bit integer value of a datum.
470 */
471
472 #define DatumGetInt32(X) ((int32) (X))
473
474 /*
475 * Int32GetDatum
476 * Returns datum representation for a 32-bit integer.
477 */
478
479 #define Int32GetDatum(X) ((Datum) (X))
480
481 /*
482 * DatumGetUInt32
483 * Returns 32-bit unsigned integer value of a datum.
484 */
485
486 #define DatumGetUInt32(X) ((uint32) (X))
487
488 /*
489 * UInt32GetDatum
490 * Returns datum representation for a 32-bit unsigned integer.
491 */
492
493 #define UInt32GetDatum(X) ((Datum) (X))
494
495 /*
496 * DatumGetObjectId
497 * Returns object identifier value of a datum.
498 */
499
500 #define DatumGetObjectId(X) ((Oid) (X))
501
502 /*
503 * ObjectIdGetDatum
504 * Returns datum representation for an object identifier.
505 */
506
507 #define ObjectIdGetDatum(X) ((Datum) (X))
508
509 /*
510 * DatumGetTransactionId
511 * Returns transaction identifier value of a datum.
512 */
513
514 #define DatumGetTransactionId(X) ((TransactionId) (X))
515
516 /*
517 * TransactionIdGetDatum
518 * Returns datum representation for a transaction identifier.
519 */
520
521 #define TransactionIdGetDatum(X) ((Datum) (X))
522
523 /*
524 * MultiXactIdGetDatum
525 * Returns datum representation for a multixact identifier.
526 */
527
528 #define MultiXactIdGetDatum(X) ((Datum) (X))
529
530 /*
531 * DatumGetCommandId
532 * Returns command identifier value of a datum.
533 */
534
535 #define DatumGetCommandId(X) ((CommandId) (X))
536
537 /*
538 * CommandIdGetDatum
539 * Returns datum representation for a command identifier.
540 */
541
542 #define CommandIdGetDatum(X) ((Datum) (X))
543
544 /*
545 * DatumGetPointer
546 * Returns pointer value of a datum.
547 */
548
549 #define DatumGetPointer(X) ((Pointer) (X))
550
551 /*
552 * PointerGetDatum
553 * Returns datum representation for a pointer.
554 */
555
556 #define PointerGetDatum(X) ((Datum) (X))
557
558 /*
559 * DatumGetCString
560 * Returns C string (null-terminated string) value of a datum.
561 *
562 * Note: C string is not a full-fledged Postgres type at present,
563 * but type input functions use this conversion for their inputs.
564 */
565
566 #define DatumGetCString(X) ((char *) DatumGetPointer(X))
567
568 /*
569 * CStringGetDatum
570 * Returns datum representation for a C string (null-terminated string).
571 *
572 * Note: C string is not a full-fledged Postgres type at present,
573 * but type output functions use this conversion for their outputs.
574 * Note: CString is pass-by-reference; caller must ensure the pointed-to
575 * value has adequate lifetime.
576 */
577
578 #define CStringGetDatum(X) PointerGetDatum(X)
579
580 /*
581 * DatumGetName
582 * Returns name value of a datum.
583 */
584
585 #define DatumGetName(X) ((Name) DatumGetPointer(X))
586
587 /*
588 * NameGetDatum
589 * Returns datum representation for a name.
590 *
591 * Note: Name is pass-by-reference; caller must ensure the pointed-to
592 * value has adequate lifetime.
593 */
594
595 #define NameGetDatum(X) CStringGetDatum(NameStr(*(X)))
596
597 /*
598 * DatumGetInt64
599 * Returns 64-bit integer value of a datum.
600 *
601 * Note: this macro hides whether int64 is pass by value or by reference.
602 */
603
604 #ifdef USE_FLOAT8_BYVAL
605 #define DatumGetInt64(X) ((int64) (X))
606 #else
607 #define DatumGetInt64(X) (* ((int64 *) DatumGetPointer(X)))
608 #endif
609
610 /*
611 * Int64GetDatum
612 * Returns datum representation for a 64-bit integer.
613 *
614 * Note: if int64 is pass by reference, this function returns a reference
615 * to palloc'd space.
616 */
617
618 #ifdef USE_FLOAT8_BYVAL
619 #define Int64GetDatum(X) ((Datum) (X))
620 #else
621 extern Datum Int64GetDatum(int64 X);
622 #endif
623
624 /*
625 * DatumGetUInt64
626 * Returns 64-bit unsigned integer value of a datum.
627 *
628 * Note: this macro hides whether int64 is pass by value or by reference.
629 */
630
631 #ifdef USE_FLOAT8_BYVAL
632 #define DatumGetUInt64(X) ((uint64) (X))
633 #else
634 #define DatumGetUInt64(X) (* ((uint64 *) DatumGetPointer(X)))
635 #endif
636
637 /*
638 * UInt64GetDatum
639 * Returns datum representation for a 64-bit unsigned integer.
640 *
641 * Note: if int64 is pass by reference, this function returns a reference
642 * to palloc'd space.
643 */
644
645 #ifdef USE_FLOAT8_BYVAL
646 #define UInt64GetDatum(X) ((Datum) (X))
647 #else
648 #define UInt64GetDatum(X) Int64GetDatum((int64) (X))
649 #endif
650
651 /*
652 * Float <-> Datum conversions
653 *
654 * These have to be implemented as inline functions rather than macros, when
655 * passing by value, because many machines pass int and float function
656 * parameters/results differently; so we need to play weird games with unions.
657 */
658
659 /*
660 * DatumGetFloat4
661 * Returns 4-byte floating point value of a datum.
662 */
663 static inline float4
DatumGetFloat4(Datum X)664 DatumGetFloat4(Datum X)
665 {
666 union
667 {
668 int32 value;
669 float4 retval;
670 } myunion;
671
672 myunion.value = DatumGetInt32(X);
673 return myunion.retval;
674 }
675
676 /*
677 * Float4GetDatum
678 * Returns datum representation for a 4-byte floating point number.
679 */
680 static inline Datum
Float4GetDatum(float4 X)681 Float4GetDatum(float4 X)
682 {
683 union
684 {
685 float4 value;
686 int32 retval;
687 } myunion;
688
689 myunion.value = X;
690 return Int32GetDatum(myunion.retval);
691 }
692
693 /*
694 * DatumGetFloat8
695 * Returns 8-byte floating point value of a datum.
696 *
697 * Note: this macro hides whether float8 is pass by value or by reference.
698 */
699
700 #ifdef USE_FLOAT8_BYVAL
701 static inline float8
DatumGetFloat8(Datum X)702 DatumGetFloat8(Datum X)
703 {
704 union
705 {
706 int64 value;
707 float8 retval;
708 } myunion;
709
710 myunion.value = DatumGetInt64(X);
711 return myunion.retval;
712 }
713 #else
714 #define DatumGetFloat8(X) (* ((float8 *) DatumGetPointer(X)))
715 #endif
716
717 /*
718 * Float8GetDatum
719 * Returns datum representation for an 8-byte floating point number.
720 *
721 * Note: if float8 is pass by reference, this function returns a reference
722 * to palloc'd space.
723 */
724
725 #ifdef USE_FLOAT8_BYVAL
726 static inline Datum
Float8GetDatum(float8 X)727 Float8GetDatum(float8 X)
728 {
729 union
730 {
731 float8 value;
732 int64 retval;
733 } myunion;
734
735 myunion.value = X;
736 return Int64GetDatum(myunion.retval);
737 }
738 #else
739 extern Datum Float8GetDatum(float8 X);
740 #endif
741
742
743 /*
744 * Int64GetDatumFast
745 * Float8GetDatumFast
746 *
747 * These macros are intended to allow writing code that does not depend on
748 * whether int64 and float8 are pass-by-reference types, while not
749 * sacrificing performance when they are. The argument must be a variable
750 * that will exist and have the same value for as long as the Datum is needed.
751 * In the pass-by-ref case, the address of the variable is taken to use as
752 * the Datum. In the pass-by-val case, these will be the same as the non-Fast
753 * macros.
754 */
755
756 #ifdef USE_FLOAT8_BYVAL
757 #define Int64GetDatumFast(X) Int64GetDatum(X)
758 #define Float8GetDatumFast(X) Float8GetDatum(X)
759 #else
760 #define Int64GetDatumFast(X) PointerGetDatum(&(X))
761 #define Float8GetDatumFast(X) PointerGetDatum(&(X))
762 #endif
763
764 #endif /* POSTGRES_H */
765