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) 1996-2017, 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 * 3) exception handling backend support
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 traditional "TOAST pointer", that is, the
58 * information needed to fetch a Datum stored out-of-line in a TOAST table.
59 * The data is compressed if and only if va_extsize < va_rawsize - VARHDRSZ.
60 * This struct must not contain any padding, because we sometimes compare
61 * these pointers using memcmp.
62 *
63 * Note that this information is stored unaligned within actual tuples, so
64 * you need to memcpy from the tuple into a local struct variable before
65 * you can look at these fields! (The reason we use memcmp is to avoid
66 * having to do that just to detect equality of two TOAST pointers...)
67 */
68 typedef struct varatt_external
69 {
70 int32 va_rawsize; /* Original data size (includes header) */
71 int32 va_extsize; /* External saved size (doesn't) */
72 Oid va_valueid; /* Unique ID of value within TOAST table */
73 Oid va_toastrelid; /* RelID of TOAST table containing it */
74 } varatt_external;
75
76 /*
77 * struct varatt_indirect is a "TOAST pointer" representing an out-of-line
78 * Datum that's stored in memory, not in an external toast relation.
79 * The creator of such a Datum is entirely responsible that the referenced
80 * storage survives for as long as referencing pointer Datums can exist.
81 *
82 * Note that just as for struct varatt_external, this struct is stored
83 * unaligned within any containing tuple.
84 */
85 typedef struct varatt_indirect
86 {
87 struct varlena *pointer; /* Pointer to in-memory varlena */
88 } varatt_indirect;
89
90 /*
91 * struct varatt_expanded is a "TOAST pointer" representing an out-of-line
92 * Datum that is stored in memory, in some type-specific, not necessarily
93 * physically contiguous format that is convenient for computation not
94 * storage. APIs for this, in particular the definition of struct
95 * ExpandedObjectHeader, are in src/include/utils/expandeddatum.h.
96 *
97 * Note that just as for struct varatt_external, this struct is stored
98 * unaligned within any containing tuple.
99 */
100 typedef struct ExpandedObjectHeader ExpandedObjectHeader;
101
102 typedef struct varatt_expanded
103 {
104 ExpandedObjectHeader *eohptr;
105 } varatt_expanded;
106
107 /*
108 * Type tag for the various sorts of "TOAST pointer" datums. The peculiar
109 * value for VARTAG_ONDISK comes from a requirement for on-disk compatibility
110 * with a previous notion that the tag field was the pointer datum's length.
111 */
112 typedef enum vartag_external
113 {
114 VARTAG_INDIRECT = 1,
115 VARTAG_EXPANDED_RO = 2,
116 VARTAG_EXPANDED_RW = 3,
117 VARTAG_ONDISK = 18
118 } vartag_external;
119
120 /* this test relies on the specific tag values above */
121 #define VARTAG_IS_EXPANDED(tag) \
122 (((tag) & ~1) == VARTAG_EXPANDED_RO)
123
124 #define VARTAG_SIZE(tag) \
125 ((tag) == VARTAG_INDIRECT ? sizeof(varatt_indirect) : \
126 VARTAG_IS_EXPANDED(tag) ? sizeof(varatt_expanded) : \
127 (tag) == VARTAG_ONDISK ? sizeof(varatt_external) : \
128 TrapMacro(true, "unrecognized TOAST vartag"))
129
130 /*
131 * These structs describe the header of a varlena object that may have been
132 * TOASTed. Generally, don't reference these structs directly, but use the
133 * macros below.
134 *
135 * We use separate structs for the aligned and unaligned cases because the
136 * compiler might otherwise think it could generate code that assumes
137 * alignment while touching fields of a 1-byte-header varlena.
138 */
139 typedef union
140 {
141 struct /* Normal varlena (4-byte length) */
142 {
143 uint32 va_header;
144 char va_data[FLEXIBLE_ARRAY_MEMBER];
145 } va_4byte;
146 struct /* Compressed-in-line format */
147 {
148 uint32 va_header;
149 uint32 va_rawsize; /* Original data size (excludes header) */
150 char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */
151 } va_compressed;
152 } varattrib_4b;
153
154 typedef struct
155 {
156 uint8 va_header;
157 char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Data begins here */
158 } varattrib_1b;
159
160 /* TOAST pointers are a subset of varattrib_1b with an identifying tag byte */
161 typedef struct
162 {
163 uint8 va_header; /* Always 0x80 or 0x01 */
164 uint8 va_tag; /* Type of datum */
165 char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Type-specific data */
166 } varattrib_1b_e;
167
168 /*
169 * Bit layouts for varlena headers on big-endian machines:
170 *
171 * 00xxxxxx 4-byte length word, aligned, uncompressed data (up to 1G)
172 * 01xxxxxx 4-byte length word, aligned, *compressed* data (up to 1G)
173 * 10000000 1-byte length word, unaligned, TOAST pointer
174 * 1xxxxxxx 1-byte length word, unaligned, uncompressed data (up to 126b)
175 *
176 * Bit layouts for varlena headers on little-endian machines:
177 *
178 * xxxxxx00 4-byte length word, aligned, uncompressed data (up to 1G)
179 * xxxxxx10 4-byte length word, aligned, *compressed* data (up to 1G)
180 * 00000001 1-byte length word, unaligned, TOAST pointer
181 * xxxxxxx1 1-byte length word, unaligned, uncompressed data (up to 126b)
182 *
183 * The "xxx" bits are the length field (which includes itself in all cases).
184 * In the big-endian case we mask to extract the length, in the little-endian
185 * case we shift. Note that in both cases the flag bits are in the physically
186 * first byte. Also, it is not possible for a 1-byte length word to be zero;
187 * this lets us disambiguate alignment padding bytes from the start of an
188 * unaligned datum. (We now *require* pad bytes to be filled with zero!)
189 *
190 * In TOAST pointers the va_tag field (see varattrib_1b_e) is used to discern
191 * the specific type and length of the pointer datum.
192 */
193
194 /*
195 * Endian-dependent macros. These are considered internal --- use the
196 * external macros below instead of using these directly.
197 *
198 * Note: IS_1B is true for external toast records but VARSIZE_1B will return 0
199 * for such records. Hence you should usually check for IS_EXTERNAL before
200 * checking for IS_1B.
201 */
202
203 #ifdef WORDS_BIGENDIAN
204
205 #define VARATT_IS_4B(PTR) \
206 ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x00)
207 #define VARATT_IS_4B_U(PTR) \
208 ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x00)
209 #define VARATT_IS_4B_C(PTR) \
210 ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x40)
211 #define VARATT_IS_1B(PTR) \
212 ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x80)
213 #define VARATT_IS_1B_E(PTR) \
214 ((((varattrib_1b *) (PTR))->va_header) == 0x80)
215 #define VARATT_NOT_PAD_BYTE(PTR) \
216 (*((uint8 *) (PTR)) != 0)
217
218 /* VARSIZE_4B() should only be used on known-aligned data */
219 #define VARSIZE_4B(PTR) \
220 (((varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF)
221 #define VARSIZE_1B(PTR) \
222 (((varattrib_1b *) (PTR))->va_header & 0x7F)
223 #define VARTAG_1B_E(PTR) \
224 (((varattrib_1b_e *) (PTR))->va_tag)
225
226 #define SET_VARSIZE_4B(PTR,len) \
227 (((varattrib_4b *) (PTR))->va_4byte.va_header = (len) & 0x3FFFFFFF)
228 #define SET_VARSIZE_4B_C(PTR,len) \
229 (((varattrib_4b *) (PTR))->va_4byte.va_header = ((len) & 0x3FFFFFFF) | 0x40000000)
230 #define SET_VARSIZE_1B(PTR,len) \
231 (((varattrib_1b *) (PTR))->va_header = (len) | 0x80)
232 #define SET_VARTAG_1B_E(PTR,tag) \
233 (((varattrib_1b_e *) (PTR))->va_header = 0x80, \
234 ((varattrib_1b_e *) (PTR))->va_tag = (tag))
235 #else /* !WORDS_BIGENDIAN */
236
237 #define VARATT_IS_4B(PTR) \
238 ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x00)
239 #define VARATT_IS_4B_U(PTR) \
240 ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x00)
241 #define VARATT_IS_4B_C(PTR) \
242 ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x02)
243 #define VARATT_IS_1B(PTR) \
244 ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x01)
245 #define VARATT_IS_1B_E(PTR) \
246 ((((varattrib_1b *) (PTR))->va_header) == 0x01)
247 #define VARATT_NOT_PAD_BYTE(PTR) \
248 (*((uint8 *) (PTR)) != 0)
249
250 /* VARSIZE_4B() should only be used on known-aligned data */
251 #define VARSIZE_4B(PTR) \
252 ((((varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF)
253 #define VARSIZE_1B(PTR) \
254 ((((varattrib_1b *) (PTR))->va_header >> 1) & 0x7F)
255 #define VARTAG_1B_E(PTR) \
256 (((varattrib_1b_e *) (PTR))->va_tag)
257
258 #define SET_VARSIZE_4B(PTR,len) \
259 (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2))
260 #define SET_VARSIZE_4B_C(PTR,len) \
261 (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2) | 0x02)
262 #define SET_VARSIZE_1B(PTR,len) \
263 (((varattrib_1b *) (PTR))->va_header = (((uint8) (len)) << 1) | 0x01)
264 #define SET_VARTAG_1B_E(PTR,tag) \
265 (((varattrib_1b_e *) (PTR))->va_header = 0x01, \
266 ((varattrib_1b_e *) (PTR))->va_tag = (tag))
267 #endif /* WORDS_BIGENDIAN */
268
269 #define VARHDRSZ_SHORT offsetof(varattrib_1b, va_data)
270 #define VARATT_SHORT_MAX 0x7F
271 #define VARATT_CAN_MAKE_SHORT(PTR) \
272 (VARATT_IS_4B_U(PTR) && \
273 (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX)
274 #define VARATT_CONVERTED_SHORT_SIZE(PTR) \
275 (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT)
276
277 #define VARHDRSZ_EXTERNAL offsetof(varattrib_1b_e, va_data)
278
279 #define VARDATA_4B(PTR) (((varattrib_4b *) (PTR))->va_4byte.va_data)
280 #define VARDATA_4B_C(PTR) (((varattrib_4b *) (PTR))->va_compressed.va_data)
281 #define VARDATA_1B(PTR) (((varattrib_1b *) (PTR))->va_data)
282 #define VARDATA_1B_E(PTR) (((varattrib_1b_e *) (PTR))->va_data)
283
284 #define VARRAWSIZE_4B_C(PTR) \
285 (((varattrib_4b *) (PTR))->va_compressed.va_rawsize)
286
287 /* Externally visible macros */
288
289 /*
290 * In consumers oblivious to data alignment, call PG_DETOAST_DATUM_PACKED(),
291 * VARDATA_ANY(), VARSIZE_ANY() and VARSIZE_ANY_EXHDR(). Elsewhere, call
292 * PG_DETOAST_DATUM(), VARDATA() and VARSIZE(). Directly fetching an int16,
293 * int32 or wider field in the struct representing the datum layout requires
294 * aligned data. memcpy() is alignment-oblivious, as are most operations on
295 * datatypes, such as text, whose layout struct contains only char fields.
296 *
297 * Code assembling a new datum should call VARDATA() and SET_VARSIZE().
298 * (Datums begin life untoasted.)
299 *
300 * Other macros here should usually be used only by tuple assembly/disassembly
301 * code and code that specifically wants to work with still-toasted Datums.
302 */
303 #define VARDATA(PTR) VARDATA_4B(PTR)
304 #define VARSIZE(PTR) VARSIZE_4B(PTR)
305
306 #define VARSIZE_SHORT(PTR) VARSIZE_1B(PTR)
307 #define VARDATA_SHORT(PTR) VARDATA_1B(PTR)
308
309 #define VARTAG_EXTERNAL(PTR) VARTAG_1B_E(PTR)
310 #define VARSIZE_EXTERNAL(PTR) (VARHDRSZ_EXTERNAL + VARTAG_SIZE(VARTAG_EXTERNAL(PTR)))
311 #define VARDATA_EXTERNAL(PTR) VARDATA_1B_E(PTR)
312
313 #define VARATT_IS_COMPRESSED(PTR) VARATT_IS_4B_C(PTR)
314 #define VARATT_IS_EXTERNAL(PTR) VARATT_IS_1B_E(PTR)
315 #define VARATT_IS_EXTERNAL_ONDISK(PTR) \
316 (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_ONDISK)
317 #define VARATT_IS_EXTERNAL_INDIRECT(PTR) \
318 (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_INDIRECT)
319 #define VARATT_IS_EXTERNAL_EXPANDED_RO(PTR) \
320 (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RO)
321 #define VARATT_IS_EXTERNAL_EXPANDED_RW(PTR) \
322 (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RW)
323 #define VARATT_IS_EXTERNAL_EXPANDED(PTR) \
324 (VARATT_IS_EXTERNAL(PTR) && VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))
325 #define VARATT_IS_SHORT(PTR) VARATT_IS_1B(PTR)
326 #define VARATT_IS_EXTENDED(PTR) (!VARATT_IS_4B_U(PTR))
327
328 #define SET_VARSIZE(PTR, len) SET_VARSIZE_4B(PTR, len)
329 #define SET_VARSIZE_SHORT(PTR, len) SET_VARSIZE_1B(PTR, len)
330 #define SET_VARSIZE_COMPRESSED(PTR, len) SET_VARSIZE_4B_C(PTR, len)
331
332 #define SET_VARTAG_EXTERNAL(PTR, tag) SET_VARTAG_1B_E(PTR, tag)
333
334 #define VARSIZE_ANY(PTR) \
335 (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR) : \
336 (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR) : \
337 VARSIZE_4B(PTR)))
338
339 /* Size of a varlena data, excluding header */
340 #define VARSIZE_ANY_EXHDR(PTR) \
341 (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR)-VARHDRSZ_EXTERNAL : \
342 (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR)-VARHDRSZ_SHORT : \
343 VARSIZE_4B(PTR)-VARHDRSZ))
344
345 /* caution: this will not work on an external or compressed-in-line Datum */
346 /* caution: this will return a possibly unaligned pointer */
347 #define VARDATA_ANY(PTR) \
348 (VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR))
349
350
351 /* ----------------------------------------------------------------
352 * Section 2: datum type + support macros
353 * ----------------------------------------------------------------
354 */
355
356 /*
357 * Port Notes:
358 * Postgres makes the following assumptions about datatype sizes:
359 *
360 * sizeof(Datum) == sizeof(void *) == 4 or 8
361 * sizeof(char) == 1
362 * sizeof(short) == 2
363 *
364 * When a type narrower than Datum is stored in a Datum, we place it in the
365 * low-order bits and are careful that the DatumGetXXX macro for it discards
366 * the unused high-order bits (as opposed to, say, assuming they are zero).
367 * This is needed to support old-style user-defined functions, since depending
368 * on architecture and compiler, the return value of a function returning char
369 * or short may contain garbage when called as if it returned Datum.
370 */
371
372 typedef uintptr_t Datum;
373
374 #define SIZEOF_DATUM SIZEOF_VOID_P
375
376 typedef Datum *DatumPtr;
377
378 #define GET_1_BYTE(datum) (((Datum) (datum)) & 0x000000ff)
379 #define GET_2_BYTES(datum) (((Datum) (datum)) & 0x0000ffff)
380 #define GET_4_BYTES(datum) (((Datum) (datum)) & 0xffffffff)
381 #if SIZEOF_DATUM == 8
382 #define GET_8_BYTES(datum) ((Datum) (datum))
383 #endif
384 #define SET_1_BYTE(value) (((Datum) (value)) & 0x000000ff)
385 #define SET_2_BYTES(value) (((Datum) (value)) & 0x0000ffff)
386 #define SET_4_BYTES(value) (((Datum) (value)) & 0xffffffff)
387 #if SIZEOF_DATUM == 8
388 #define SET_8_BYTES(value) ((Datum) (value))
389 #endif
390
391 /*
392 * DatumGetBool
393 * Returns boolean value of a datum.
394 *
395 * Note: any nonzero value will be considered TRUE, but we ignore bits to
396 * the left of the width of bool, per comment above.
397 */
398
399 #define DatumGetBool(X) ((bool) (GET_1_BYTE(X) != 0))
400
401 /*
402 * BoolGetDatum
403 * Returns datum representation for a boolean.
404 *
405 * Note: any nonzero value will be considered TRUE.
406 */
407
408 #define BoolGetDatum(X) ((Datum) ((X) ? 1 : 0))
409
410 /*
411 * DatumGetChar
412 * Returns character value of a datum.
413 */
414
415 #define DatumGetChar(X) ((char) GET_1_BYTE(X))
416
417 /*
418 * CharGetDatum
419 * Returns datum representation for a character.
420 */
421
422 #define CharGetDatum(X) ((Datum) SET_1_BYTE(X))
423
424 /*
425 * Int8GetDatum
426 * Returns datum representation for an 8-bit integer.
427 */
428
429 #define Int8GetDatum(X) ((Datum) SET_1_BYTE(X))
430
431 /*
432 * DatumGetUInt8
433 * Returns 8-bit unsigned integer value of a datum.
434 */
435
436 #define DatumGetUInt8(X) ((uint8) GET_1_BYTE(X))
437
438 /*
439 * UInt8GetDatum
440 * Returns datum representation for an 8-bit unsigned integer.
441 */
442
443 #define UInt8GetDatum(X) ((Datum) SET_1_BYTE(X))
444
445 /*
446 * DatumGetInt16
447 * Returns 16-bit integer value of a datum.
448 */
449
450 #define DatumGetInt16(X) ((int16) GET_2_BYTES(X))
451
452 /*
453 * Int16GetDatum
454 * Returns datum representation for a 16-bit integer.
455 */
456
457 #define Int16GetDatum(X) ((Datum) SET_2_BYTES(X))
458
459 /*
460 * DatumGetUInt16
461 * Returns 16-bit unsigned integer value of a datum.
462 */
463
464 #define DatumGetUInt16(X) ((uint16) GET_2_BYTES(X))
465
466 /*
467 * UInt16GetDatum
468 * Returns datum representation for a 16-bit unsigned integer.
469 */
470
471 #define UInt16GetDatum(X) ((Datum) SET_2_BYTES(X))
472
473 /*
474 * DatumGetInt32
475 * Returns 32-bit integer value of a datum.
476 */
477
478 #define DatumGetInt32(X) ((int32) GET_4_BYTES(X))
479
480 /*
481 * Int32GetDatum
482 * Returns datum representation for a 32-bit integer.
483 */
484
485 #define Int32GetDatum(X) ((Datum) SET_4_BYTES(X))
486
487 /*
488 * DatumGetUInt32
489 * Returns 32-bit unsigned integer value of a datum.
490 */
491
492 #define DatumGetUInt32(X) ((uint32) GET_4_BYTES(X))
493
494 /*
495 * UInt32GetDatum
496 * Returns datum representation for a 32-bit unsigned integer.
497 */
498
499 #define UInt32GetDatum(X) ((Datum) SET_4_BYTES(X))
500
501 /*
502 * DatumGetObjectId
503 * Returns object identifier value of a datum.
504 */
505
506 #define DatumGetObjectId(X) ((Oid) GET_4_BYTES(X))
507
508 /*
509 * ObjectIdGetDatum
510 * Returns datum representation for an object identifier.
511 */
512
513 #define ObjectIdGetDatum(X) ((Datum) SET_4_BYTES(X))
514
515 /*
516 * DatumGetTransactionId
517 * Returns transaction identifier value of a datum.
518 */
519
520 #define DatumGetTransactionId(X) ((TransactionId) GET_4_BYTES(X))
521
522 /*
523 * TransactionIdGetDatum
524 * Returns datum representation for a transaction identifier.
525 */
526
527 #define TransactionIdGetDatum(X) ((Datum) SET_4_BYTES((X)))
528
529 /*
530 * MultiXactIdGetDatum
531 * Returns datum representation for a multixact identifier.
532 */
533
534 #define MultiXactIdGetDatum(X) ((Datum) SET_4_BYTES((X)))
535
536 /*
537 * DatumGetCommandId
538 * Returns command identifier value of a datum.
539 */
540
541 #define DatumGetCommandId(X) ((CommandId) GET_4_BYTES(X))
542
543 /*
544 * CommandIdGetDatum
545 * Returns datum representation for a command identifier.
546 */
547
548 #define CommandIdGetDatum(X) ((Datum) SET_4_BYTES(X))
549
550 /*
551 * DatumGetPointer
552 * Returns pointer value of a datum.
553 */
554
555 #define DatumGetPointer(X) ((Pointer) (X))
556
557 /*
558 * PointerGetDatum
559 * Returns datum representation for a pointer.
560 */
561
562 #define PointerGetDatum(X) ((Datum) (X))
563
564 /*
565 * DatumGetCString
566 * Returns C string (null-terminated string) value of a datum.
567 *
568 * Note: C string is not a full-fledged Postgres type at present,
569 * but type input functions use this conversion for their inputs.
570 */
571
572 #define DatumGetCString(X) ((char *) DatumGetPointer(X))
573
574 /*
575 * CStringGetDatum
576 * Returns datum representation for a C string (null-terminated string).
577 *
578 * Note: C string is not a full-fledged Postgres type at present,
579 * but type output functions use this conversion for their outputs.
580 * Note: CString is pass-by-reference; caller must ensure the pointed-to
581 * value has adequate lifetime.
582 */
583
584 #define CStringGetDatum(X) PointerGetDatum(X)
585
586 /*
587 * DatumGetName
588 * Returns name value of a datum.
589 */
590
591 #define DatumGetName(X) ((Name) DatumGetPointer(X))
592
593 /*
594 * NameGetDatum
595 * Returns datum representation for a name.
596 *
597 * Note: Name is pass-by-reference; caller must ensure the pointed-to
598 * value has adequate lifetime.
599 */
600
601 #define NameGetDatum(X) CStringGetDatum(NameStr(*(X)))
602
603 /*
604 * DatumGetInt64
605 * Returns 64-bit integer value of a datum.
606 *
607 * Note: this macro hides whether int64 is pass by value or by reference.
608 */
609
610 #ifdef USE_FLOAT8_BYVAL
611 #define DatumGetInt64(X) ((int64) GET_8_BYTES(X))
612 #else
613 #define DatumGetInt64(X) (* ((int64 *) DatumGetPointer(X)))
614 #endif
615
616 /*
617 * Int64GetDatum
618 * Returns datum representation for a 64-bit integer.
619 *
620 * Note: if int64 is pass by reference, this function returns a reference
621 * to palloc'd space.
622 */
623
624 #ifdef USE_FLOAT8_BYVAL
625 #define Int64GetDatum(X) ((Datum) SET_8_BYTES(X))
626 #else
627 extern Datum Int64GetDatum(int64 X);
628 #endif
629
630 /*
631 * DatumGetUInt64
632 * Returns 64-bit unsigned integer value of a datum.
633 *
634 * Note: this macro hides whether int64 is pass by value or by reference.
635 */
636
637 #ifdef USE_FLOAT8_BYVAL
638 #define DatumGetUInt64(X) ((uint64) GET_8_BYTES(X))
639 #else
640 #define DatumGetUInt64(X) (* ((uint64 *) DatumGetPointer(X)))
641 #endif
642
643 /*
644 * UInt64GetDatum
645 * Returns datum representation for a 64-bit unsigned integer.
646 *
647 * Note: if int64 is pass by reference, this function returns a reference
648 * to palloc'd space.
649 */
650
651 #ifdef USE_FLOAT8_BYVAL
652 #define UInt64GetDatum(X) ((Datum) SET_8_BYTES(X))
653 #else
654 #define UInt64GetDatum(X) Int64GetDatum((int64) (X))
655 #endif
656
657 /*
658 * Float <-> Datum conversions
659 *
660 * These have to be implemented as inline functions rather than macros, when
661 * passing by value, because many machines pass int and float function
662 * parameters/results differently; so we need to play weird games with unions.
663 */
664
665 /*
666 * DatumGetFloat4
667 * Returns 4-byte floating point value of a datum.
668 *
669 * Note: this macro hides whether float4 is pass by value or by reference.
670 */
671
672 #ifdef USE_FLOAT4_BYVAL
673 static inline float4
DatumGetFloat4(Datum X)674 DatumGetFloat4(Datum X)
675 {
676 union
677 {
678 int32 value;
679 float4 retval;
680 } myunion;
681
682 myunion.value = DatumGetInt32(X);
683 return myunion.retval;
684 }
685 #else
686 #define DatumGetFloat4(X) (* ((float4 *) DatumGetPointer(X)))
687 #endif
688
689 /*
690 * Float4GetDatum
691 * Returns datum representation for a 4-byte floating point number.
692 *
693 * Note: if float4 is pass by reference, this function returns a reference
694 * to palloc'd space.
695 */
696 #ifdef USE_FLOAT4_BYVAL
697 static inline Datum
Float4GetDatum(float4 X)698 Float4GetDatum(float4 X)
699 {
700 union
701 {
702 float4 value;
703 int32 retval;
704 } myunion;
705
706 myunion.value = X;
707 return Int32GetDatum(myunion.retval);
708 }
709 #else
710 extern Datum Float4GetDatum(float4 X);
711 #endif
712
713 /*
714 * DatumGetFloat8
715 * Returns 8-byte floating point value of a datum.
716 *
717 * Note: this macro hides whether float8 is pass by value or by reference.
718 */
719
720 #ifdef USE_FLOAT8_BYVAL
721 static inline float8
DatumGetFloat8(Datum X)722 DatumGetFloat8(Datum X)
723 {
724 union
725 {
726 int64 value;
727 float8 retval;
728 } myunion;
729
730 myunion.value = DatumGetInt64(X);
731 return myunion.retval;
732 }
733 #else
734 #define DatumGetFloat8(X) (* ((float8 *) DatumGetPointer(X)))
735 #endif
736
737 /*
738 * Float8GetDatum
739 * Returns datum representation for an 8-byte floating point number.
740 *
741 * Note: if float8 is pass by reference, this function returns a reference
742 * to palloc'd space.
743 */
744
745 #ifdef USE_FLOAT8_BYVAL
746 static inline Datum
Float8GetDatum(float8 X)747 Float8GetDatum(float8 X)
748 {
749 union
750 {
751 float8 value;
752 int64 retval;
753 } myunion;
754
755 myunion.value = X;
756 return Int64GetDatum(myunion.retval);
757 }
758 #else
759 extern Datum Float8GetDatum(float8 X);
760 #endif
761
762
763 /*
764 * Int64GetDatumFast
765 * Float8GetDatumFast
766 * Float4GetDatumFast
767 *
768 * These macros are intended to allow writing code that does not depend on
769 * whether int64, float8, float4 are pass-by-reference types, while not
770 * sacrificing performance when they are. The argument must be a variable
771 * that will exist and have the same value for as long as the Datum is needed.
772 * In the pass-by-ref case, the address of the variable is taken to use as
773 * the Datum. In the pass-by-val case, these will be the same as the non-Fast
774 * macros.
775 */
776
777 #ifdef USE_FLOAT8_BYVAL
778 #define Int64GetDatumFast(X) Int64GetDatum(X)
779 #define Float8GetDatumFast(X) Float8GetDatum(X)
780 #else
781 #define Int64GetDatumFast(X) PointerGetDatum(&(X))
782 #define Float8GetDatumFast(X) PointerGetDatum(&(X))
783 #endif
784
785 #ifdef USE_FLOAT4_BYVAL
786 #define Float4GetDatumFast(X) Float4GetDatum(X)
787 #else
788 #define Float4GetDatumFast(X) PointerGetDatum(&(X))
789 #endif
790
791
792 /* ----------------------------------------------------------------
793 * Section 3: exception handling backend support
794 * ----------------------------------------------------------------
795 */
796
797 /*
798 * Backend only infrastructure for the assertion-related macros in c.h.
799 *
800 * ExceptionalCondition must be present even when assertions are not enabled.
801 */
802 extern void ExceptionalCondition(const char *conditionName,
803 const char *errorType,
804 const char *fileName, int lineNumber) pg_attribute_noreturn();
805
806 #endif /* POSTGRES_H */
807