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postgres.h
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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 */
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 */
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  */
101 
102 typedef struct varatt_expanded
103 {
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 {
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  {
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 {
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 */
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
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
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
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
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 */
vartag_external
Definition: postgres.h:112
ExpandedObjectHeader * eohptr
Definition: postgres.h:104
Datum Float4GetDatum(float4 X)
Definition: fmgr.c:1798
struct varatt_expanded varatt_expanded
#define DatumGetInt32(X)
Definition: postgres.h:478
uint8 va_tag
Definition: postgres.h:164
unsigned char uint8
Definition: c.h:304
Oid va_toastrelid
Definition: postgres.h:73
int32 va_rawsize
Definition: postgres.h:70
unsigned int Oid
Definition: postgres_ext.h:31
signed int int32
Definition: c.h:294
struct varatt_external varatt_external
double float8
Definition: c.h:439
Datum Float8GetDatum(float8 X)
Definition: fmgr.c:1810
static struct @121 value
#define DatumGetInt64(X)
Definition: postgres.h:613
unsigned int uint32
Definition: c.h:306
uint8 va_header
Definition: postgres.h:156
Datum * DatumPtr
Definition: postgres.h:376
float float4
Definition: c.h:438
uint8 va_header
Definition: postgres.h:163
#define DatumGetFloat8(X)
Definition: postgres.h:734
uintptr_t Datum
Definition: postgres.h:372
void ExceptionalCondition(const char *conditionName, const char *errorType, const char *fileName, int lineNumber) pg_attribute_noreturn()
Definition: assert.c:26
int32 va_extsize
Definition: postgres.h:71
#define DatumGetFloat4(X)
Definition: postgres.h:686
uint32 va_header
Definition: postgres.h:143
struct varlena * pointer
Definition: postgres.h:87
#define pg_attribute_noreturn()
Definition: c.h:146
#define Int32GetDatum(X)
Definition: postgres.h:485
uint32 va_rawsize
Definition: postgres.h:149
Datum Int64GetDatum(int64 X)
Definition: fmgr.c:1786
Definition: c.h:497
struct varatt_indirect varatt_indirect