summaryrefslogtreecommitdiffstats
path: root/src/fe_utils/string_utils.c
blob: b4bba26934bdbd56469414c4ccc6d690cccdfb89 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
/*-------------------------------------------------------------------------
 *
 * String-processing utility routines for frontend code
 *
 * Assorted utility functions that are useful in constructing SQL queries
 * and interpreting backend output.
 *
 *
 * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/fe_utils/string_utils.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres_fe.h"

#include <ctype.h>

#include "common/keywords.h"
#include "fe_utils/string_utils.h"

static PQExpBuffer defaultGetLocalPQExpBuffer(void);

/* Globals exported by this file */
int			quote_all_identifiers = 0;
PQExpBuffer (*getLocalPQExpBuffer) (void) = defaultGetLocalPQExpBuffer;


/*
 * Returns a temporary PQExpBuffer, valid until the next call to the function.
 * This is used by fmtId and fmtQualifiedId.
 *
 * Non-reentrant and non-thread-safe but reduces memory leakage. You can
 * replace this with a custom version by setting the getLocalPQExpBuffer
 * function pointer.
 */
static PQExpBuffer
defaultGetLocalPQExpBuffer(void)
{
	static PQExpBuffer id_return = NULL;

	if (id_return)				/* first time through? */
	{
		/* same buffer, just wipe contents */
		resetPQExpBuffer(id_return);
	}
	else
	{
		/* new buffer */
		id_return = createPQExpBuffer();
	}

	return id_return;
}

/*
 *	Quotes input string if it's not a legitimate SQL identifier as-is.
 *
 *	Note that the returned string must be used before calling fmtId again,
 *	since we re-use the same return buffer each time.
 */
const char *
fmtId(const char *rawid)
{
	PQExpBuffer id_return = getLocalPQExpBuffer();

	const char *cp;
	bool		need_quotes = false;

	/*
	 * These checks need to match the identifier production in scan.l. Don't
	 * use islower() etc.
	 */
	if (quote_all_identifiers)
		need_quotes = true;
	/* slightly different rules for first character */
	else if (!((rawid[0] >= 'a' && rawid[0] <= 'z') || rawid[0] == '_'))
		need_quotes = true;
	else
	{
		/* otherwise check the entire string */
		for (cp = rawid; *cp; cp++)
		{
			if (!((*cp >= 'a' && *cp <= 'z')
				  || (*cp >= '0' && *cp <= '9')
				  || (*cp == '_')))
			{
				need_quotes = true;
				break;
			}
		}
	}

	if (!need_quotes)
	{
		/*
		 * Check for keyword.  We quote keywords except for unreserved ones.
		 * (In some cases we could avoid quoting a col_name or type_func_name
		 * keyword, but it seems much harder than it's worth to tell that.)
		 *
		 * Note: ScanKeywordLookup() does case-insensitive comparison, but
		 * that's fine, since we already know we have all-lower-case.
		 */
		int			kwnum = ScanKeywordLookup(rawid, &ScanKeywords);

		if (kwnum >= 0 && ScanKeywordCategories[kwnum] != UNRESERVED_KEYWORD)
			need_quotes = true;
	}

	if (!need_quotes)
	{
		/* no quoting needed */
		appendPQExpBufferStr(id_return, rawid);
	}
	else
	{
		appendPQExpBufferChar(id_return, '"');
		for (cp = rawid; *cp; cp++)
		{
			/*
			 * Did we find a double-quote in the string? Then make this a
			 * double double-quote per SQL99. Before, we put in a
			 * backslash/double-quote pair. - thomas 2000-08-05
			 */
			if (*cp == '"')
				appendPQExpBufferChar(id_return, '"');
			appendPQExpBufferChar(id_return, *cp);
		}
		appendPQExpBufferChar(id_return, '"');
	}

	return id_return->data;
}

/*
 * fmtQualifiedId - construct a schema-qualified name, with quoting as needed.
 *
 * Like fmtId, use the result before calling again.
 *
 * Since we call fmtId and it also uses getLocalPQExpBuffer() we cannot
 * use that buffer until we're finished with calling fmtId().
 */
const char *
fmtQualifiedId(const char *schema, const char *id)
{
	PQExpBuffer id_return;
	PQExpBuffer lcl_pqexp = createPQExpBuffer();

	/* Some callers might fail to provide a schema name */
	if (schema && *schema)
	{
		appendPQExpBuffer(lcl_pqexp, "%s.", fmtId(schema));
	}
	appendPQExpBufferStr(lcl_pqexp, fmtId(id));

	id_return = getLocalPQExpBuffer();

	appendPQExpBufferStr(id_return, lcl_pqexp->data);
	destroyPQExpBuffer(lcl_pqexp);

	return id_return->data;
}


/*
 * Format a Postgres version number (in the PG_VERSION_NUM integer format
 * returned by PQserverVersion()) as a string.  This exists mainly to
 * encapsulate knowledge about two-part vs. three-part version numbers.
 *
 * For reentrancy, caller must supply the buffer the string is put in.
 * Recommended size of the buffer is 32 bytes.
 *
 * Returns address of 'buf', as a notational convenience.
 */
char *
formatPGVersionNumber(int version_number, bool include_minor,
					  char *buf, size_t buflen)
{
	if (version_number >= 100000)
	{
		/* New two-part style */
		if (include_minor)
			snprintf(buf, buflen, "%d.%d", version_number / 10000,
					 version_number % 10000);
		else
			snprintf(buf, buflen, "%d", version_number / 10000);
	}
	else
	{
		/* Old three-part style */
		if (include_minor)
			snprintf(buf, buflen, "%d.%d.%d", version_number / 10000,
					 (version_number / 100) % 100,
					 version_number % 100);
		else
			snprintf(buf, buflen, "%d.%d", version_number / 10000,
					 (version_number / 100) % 100);
	}
	return buf;
}


/*
 * Convert a string value to an SQL string literal and append it to
 * the given buffer.  We assume the specified client_encoding and
 * standard_conforming_strings settings.
 *
 * This is essentially equivalent to libpq's PQescapeStringInternal,
 * except for the output buffer structure.  We need it in situations
 * where we do not have a PGconn available.  Where we do,
 * appendStringLiteralConn is a better choice.
 */
void
appendStringLiteral(PQExpBuffer buf, const char *str,
					int encoding, bool std_strings)
{
	size_t		length = strlen(str);
	const char *source = str;
	char	   *target;

	if (!enlargePQExpBuffer(buf, 2 * length + 2))
		return;

	target = buf->data + buf->len;
	*target++ = '\'';

	while (*source != '\0')
	{
		char		c = *source;
		int			len;
		int			i;

		/* Fast path for plain ASCII */
		if (!IS_HIGHBIT_SET(c))
		{
			/* Apply quoting if needed */
			if (SQL_STR_DOUBLE(c, !std_strings))
				*target++ = c;
			/* Copy the character */
			*target++ = c;
			source++;
			continue;
		}

		/* Slow path for possible multibyte characters */
		len = PQmblen(source, encoding);

		/* Copy the character */
		for (i = 0; i < len; i++)
		{
			if (*source == '\0')
				break;
			*target++ = *source++;
		}

		/*
		 * If we hit premature end of string (ie, incomplete multibyte
		 * character), try to pad out to the correct length with spaces. We
		 * may not be able to pad completely, but we will always be able to
		 * insert at least one pad space (since we'd not have quoted a
		 * multibyte character).  This should be enough to make a string that
		 * the server will error out on.
		 */
		if (i < len)
		{
			char	   *stop = buf->data + buf->maxlen - 2;

			for (; i < len; i++)
			{
				if (target >= stop)
					break;
				*target++ = ' ';
			}
			break;
		}
	}

	/* Write the terminating quote and NUL character. */
	*target++ = '\'';
	*target = '\0';

	buf->len = target - buf->data;
}


/*
 * Convert a string value to an SQL string literal and append it to
 * the given buffer.  Encoding and string syntax rules are as indicated
 * by current settings of the PGconn.
 */
void
appendStringLiteralConn(PQExpBuffer buf, const char *str, PGconn *conn)
{
	size_t		length = strlen(str);

	/*
	 * XXX This is a kluge to silence escape_string_warning in our utility
	 * programs.  It should go away someday.
	 */
	if (strchr(str, '\\') != NULL && PQserverVersion(conn) >= 80100)
	{
		/* ensure we are not adjacent to an identifier */
		if (buf->len > 0 && buf->data[buf->len - 1] != ' ')
			appendPQExpBufferChar(buf, ' ');
		appendPQExpBufferChar(buf, ESCAPE_STRING_SYNTAX);
		appendStringLiteral(buf, str, PQclientEncoding(conn), false);
		return;
	}
	/* XXX end kluge */

	if (!enlargePQExpBuffer(buf, 2 * length + 2))
		return;
	appendPQExpBufferChar(buf, '\'');
	buf->len += PQescapeStringConn(conn, buf->data + buf->len,
								   str, length, NULL);
	appendPQExpBufferChar(buf, '\'');
}


/*
 * Convert a string value to a dollar quoted literal and append it to
 * the given buffer. If the dqprefix parameter is not NULL then the
 * dollar quote delimiter will begin with that (after the opening $).
 *
 * No escaping is done at all on str, in compliance with the rules
 * for parsing dollar quoted strings.  Also, we need not worry about
 * encoding issues.
 */
void
appendStringLiteralDQ(PQExpBuffer buf, const char *str, const char *dqprefix)
{
	static const char suffixes[] = "_XXXXXXX";
	int			nextchar = 0;
	PQExpBuffer delimBuf = createPQExpBuffer();

	/* start with $ + dqprefix if not NULL */
	appendPQExpBufferChar(delimBuf, '$');
	if (dqprefix)
		appendPQExpBufferStr(delimBuf, dqprefix);

	/*
	 * Make sure we choose a delimiter which (without the trailing $) is not
	 * present in the string being quoted. We don't check with the trailing $
	 * because a string ending in $foo must not be quoted with $foo$.
	 */
	while (strstr(str, delimBuf->data) != NULL)
	{
		appendPQExpBufferChar(delimBuf, suffixes[nextchar++]);
		nextchar %= sizeof(suffixes) - 1;
	}

	/* add trailing $ */
	appendPQExpBufferChar(delimBuf, '$');

	/* quote it and we are all done */
	appendPQExpBufferStr(buf, delimBuf->data);
	appendPQExpBufferStr(buf, str);
	appendPQExpBufferStr(buf, delimBuf->data);

	destroyPQExpBuffer(delimBuf);
}


/*
 * Convert a bytea value (presented as raw bytes) to an SQL string literal
 * and append it to the given buffer.  We assume the specified
 * standard_conforming_strings setting.
 *
 * This is needed in situations where we do not have a PGconn available.
 * Where we do, PQescapeByteaConn is a better choice.
 */
void
appendByteaLiteral(PQExpBuffer buf, const unsigned char *str, size_t length,
				   bool std_strings)
{
	const unsigned char *source = str;
	char	   *target;

	static const char hextbl[] = "0123456789abcdef";

	/*
	 * This implementation is hard-wired to produce hex-format output. We do
	 * not know the server version the output will be loaded into, so making
	 * an intelligent format choice is impossible.  It might be better to
	 * always use the old escaped format.
	 */
	if (!enlargePQExpBuffer(buf, 2 * length + 5))
		return;

	target = buf->data + buf->len;
	*target++ = '\'';
	if (!std_strings)
		*target++ = '\\';
	*target++ = '\\';
	*target++ = 'x';

	while (length-- > 0)
	{
		unsigned char c = *source++;

		*target++ = hextbl[(c >> 4) & 0xF];
		*target++ = hextbl[c & 0xF];
	}

	/* Write the terminating quote and NUL character. */
	*target++ = '\'';
	*target = '\0';

	buf->len = target - buf->data;
}


/*
 * Append the given string to the shell command being built in the buffer,
 * with shell-style quoting as needed to create exactly one argument.
 *
 * Forbid LF or CR characters, which have scant practical use beyond designing
 * security breaches.  The Windows command shell is unusable as a conduit for
 * arguments containing LF or CR characters.  A future major release should
 * reject those characters in CREATE ROLE and CREATE DATABASE, because use
 * there eventually leads to errors here.
 *
 * appendShellString() simply prints an error and dies if LF or CR appears.
 * appendShellStringNoError() omits those characters from the result, and
 * returns false if there were any.
 */
void
appendShellString(PQExpBuffer buf, const char *str)
{
	if (!appendShellStringNoError(buf, str))
	{
		fprintf(stderr,
				_("shell command argument contains a newline or carriage return: \"%s\"\n"),
				str);
		exit(EXIT_FAILURE);
	}
}

bool
appendShellStringNoError(PQExpBuffer buf, const char *str)
{
#ifdef WIN32
	int			backslash_run_length = 0;
#endif
	bool		ok = true;
	const char *p;

	/*
	 * Don't bother with adding quotes if the string is nonempty and clearly
	 * contains only safe characters.
	 */
	if (*str != '\0' &&
		strspn(str, "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_./:") == strlen(str))
	{
		appendPQExpBufferStr(buf, str);
		return ok;
	}

#ifndef WIN32
	appendPQExpBufferChar(buf, '\'');
	for (p = str; *p; p++)
	{
		if (*p == '\n' || *p == '\r')
		{
			ok = false;
			continue;
		}

		if (*p == '\'')
			appendPQExpBufferStr(buf, "'\"'\"'");
		else
			appendPQExpBufferChar(buf, *p);
	}
	appendPQExpBufferChar(buf, '\'');
#else							/* WIN32 */

	/*
	 * A Windows system() argument experiences two layers of interpretation.
	 * First, cmd.exe interprets the string.  Its behavior is undocumented,
	 * but a caret escapes any byte except LF or CR that would otherwise have
	 * special meaning.  Handling of a caret before LF or CR differs between
	 * "cmd.exe /c" and other modes, and it is unusable here.
	 *
	 * Second, the new process parses its command line to construct argv (see
	 * https://msdn.microsoft.com/en-us/library/17w5ykft.aspx).  This treats
	 * backslash-double quote sequences specially.
	 */
	appendPQExpBufferStr(buf, "^\"");
	for (p = str; *p; p++)
	{
		if (*p == '\n' || *p == '\r')
		{
			ok = false;
			continue;
		}

		/* Change N backslashes before a double quote to 2N+1 backslashes. */
		if (*p == '"')
		{
			while (backslash_run_length)
			{
				appendPQExpBufferStr(buf, "^\\");
				backslash_run_length--;
			}
			appendPQExpBufferStr(buf, "^\\");
		}
		else if (*p == '\\')
			backslash_run_length++;
		else
			backslash_run_length = 0;

		/*
		 * Decline to caret-escape the most mundane characters, to ease
		 * debugging and lest we approach the command length limit.
		 */
		if (!((*p >= 'a' && *p <= 'z') ||
			  (*p >= 'A' && *p <= 'Z') ||
			  (*p >= '0' && *p <= '9')))
			appendPQExpBufferChar(buf, '^');
		appendPQExpBufferChar(buf, *p);
	}

	/*
	 * Change N backslashes at end of argument to 2N backslashes, because they
	 * precede the double quote that terminates the argument.
	 */
	while (backslash_run_length)
	{
		appendPQExpBufferStr(buf, "^\\");
		backslash_run_length--;
	}
	appendPQExpBufferStr(buf, "^\"");
#endif							/* WIN32 */

	return ok;
}


/*
 * Append the given string to the buffer, with suitable quoting for passing
 * the string as a value in a keyword/value pair in a libpq connection string.
 */
void
appendConnStrVal(PQExpBuffer buf, const char *str)
{
	const char *s;
	bool		needquotes;

	/*
	 * If the string is one or more plain ASCII characters, no need to quote
	 * it. This is quite conservative, but better safe than sorry.
	 */
	needquotes = true;
	for (s = str; *s; s++)
	{
		if (!((*s >= 'a' && *s <= 'z') || (*s >= 'A' && *s <= 'Z') ||
			  (*s >= '0' && *s <= '9') || *s == '_' || *s == '.'))
		{
			needquotes = true;
			break;
		}
		needquotes = false;
	}

	if (needquotes)
	{
		appendPQExpBufferChar(buf, '\'');
		while (*str)
		{
			/* ' and \ must be escaped by to \' and \\ */
			if (*str == '\'' || *str == '\\')
				appendPQExpBufferChar(buf, '\\');

			appendPQExpBufferChar(buf, *str);
			str++;
		}
		appendPQExpBufferChar(buf, '\'');
	}
	else
		appendPQExpBufferStr(buf, str);
}


/*
 * Append a psql meta-command that connects to the given database with the
 * then-current connection's user, host and port.
 */
void
appendPsqlMetaConnect(PQExpBuffer buf, const char *dbname)
{
	const char *s;
	bool complex;

	/*
	 * If the name is plain ASCII characters, emit a trivial "\connect "foo"".
	 * For other names, even many not technically requiring it, skip to the
	 * general case.  No database has a zero-length name.
	 */
	complex = false;

	for (s = dbname; *s; s++)
	{
		if (*s == '\n' || *s == '\r')
		{
			fprintf(stderr,
					_("database name contains a newline or carriage return: \"%s\"\n"),
					dbname);
			exit(EXIT_FAILURE);
		}

		if (!((*s >= 'a' && *s <= 'z') || (*s >= 'A' && *s <= 'Z') ||
			  (*s >= '0' && *s <= '9') || *s == '_' || *s == '.'))
		{
			complex = true;
		}
	}

	appendPQExpBufferStr(buf, "\\connect ");
	if (complex)
	{
		PQExpBufferData connstr;

		initPQExpBuffer(&connstr);
		appendPQExpBufferStr(&connstr, "dbname=");
		appendConnStrVal(&connstr, dbname);

		appendPQExpBufferStr(buf, "-reuse-previous=on ");

		/*
		 * As long as the name does not contain a newline, SQL identifier
		 * quoting satisfies the psql meta-command parser.  Prefer not to
		 * involve psql-interpreted single quotes, which behaved differently
		 * before PostgreSQL 9.2.
		 */
		appendPQExpBufferStr(buf, fmtId(connstr.data));

		termPQExpBuffer(&connstr);
	}
	else
		appendPQExpBufferStr(buf, fmtId(dbname));
	appendPQExpBufferChar(buf, '\n');
}


/*
 * Deconstruct the text representation of a 1-dimensional Postgres array
 * into individual items.
 *
 * On success, returns true and sets *itemarray and *nitems to describe
 * an array of individual strings.  On parse failure, returns false;
 * *itemarray may exist or be NULL.
 *
 * NOTE: free'ing itemarray is sufficient to deallocate the working storage.
 */
bool
parsePGArray(const char *atext, char ***itemarray, int *nitems)
{
	int			inputlen;
	char	  **items;
	char	   *strings;
	int			curitem;

	/*
	 * We expect input in the form of "{item,item,item}" where any item is
	 * either raw data, or surrounded by double quotes (in which case embedded
	 * characters including backslashes and quotes are backslashed).
	 *
	 * We build the result as an array of pointers followed by the actual
	 * string data, all in one malloc block for convenience of deallocation.
	 * The worst-case storage need is not more than one pointer and one
	 * character for each input character (consider "{,,,,,,,,,,}").
	 */
	*itemarray = NULL;
	*nitems = 0;
	inputlen = strlen(atext);
	if (inputlen < 2 || atext[0] != '{' || atext[inputlen - 1] != '}')
		return false;			/* bad input */
	items = (char **) malloc(inputlen * (sizeof(char *) + sizeof(char)));
	if (items == NULL)
		return false;			/* out of memory */
	*itemarray = items;
	strings = (char *) (items + inputlen);

	atext++;					/* advance over initial '{' */
	curitem = 0;
	while (*atext != '}')
	{
		if (*atext == '\0')
			return false;		/* premature end of string */
		items[curitem] = strings;
		while (*atext != '}' && *atext != ',')
		{
			if (*atext == '\0')
				return false;	/* premature end of string */
			if (*atext != '"')
				*strings++ = *atext++;	/* copy unquoted data */
			else
			{
				/* process quoted substring */
				atext++;
				while (*atext != '"')
				{
					if (*atext == '\0')
						return false;	/* premature end of string */
					if (*atext == '\\')
					{
						atext++;
						if (*atext == '\0')
							return false;	/* premature end of string */
					}
					*strings++ = *atext++;	/* copy quoted data */
				}
				atext++;
			}
		}
		*strings++ = '\0';
		if (*atext == ',')
			atext++;
		curitem++;
	}
	if (atext[1] != '\0')
		return false;			/* bogus syntax (embedded '}') */
	*nitems = curitem;
	return true;
}


/*
 * Format a reloptions array and append it to the given buffer.
 *
 * "prefix" is prepended to the option names; typically it's "" or "toast.".
 *
 * Returns false if the reloptions array could not be parsed (in which case
 * nothing will have been appended to the buffer), or true on success.
 *
 * Note: this logic should generally match the backend's flatten_reloptions()
 * (in adt/ruleutils.c).
 */
bool
appendReloptionsArray(PQExpBuffer buffer, const char *reloptions,
					  const char *prefix, int encoding, bool std_strings)
{
	char	  **options;
	int			noptions;
	int			i;

	if (!parsePGArray(reloptions, &options, &noptions))
	{
		if (options)
			free(options);
		return false;
	}

	for (i = 0; i < noptions; i++)
	{
		char	   *option = options[i];
		char	   *name;
		char	   *separator;
		char	   *value;

		/*
		 * Each array element should have the form name=value.  If the "=" is
		 * missing for some reason, treat it like an empty value.
		 */
		name = option;
		separator = strchr(option, '=');
		if (separator)
		{
			*separator = '\0';
			value = separator + 1;
		}
		else
			value = "";

		if (i > 0)
			appendPQExpBufferStr(buffer, ", ");
		appendPQExpBuffer(buffer, "%s%s=", prefix, fmtId(name));

		/*
		 * In general we need to quote the value; but to avoid unnecessary
		 * clutter, do not quote if it is an identifier that would not need
		 * quoting.  (We could also allow numbers, but that is a bit trickier
		 * than it looks --- for example, are leading zeroes significant?  We
		 * don't want to assume very much here about what custom reloptions
		 * might mean.)
		 */
		if (strcmp(fmtId(value), value) == 0)
			appendPQExpBufferStr(buffer, value);
		else
			appendStringLiteral(buffer, value, encoding, std_strings);
	}

	if (options)
		free(options);

	return true;
}


/*
 * processSQLNamePattern
 *
 * Scan a wildcard-pattern string and generate appropriate WHERE clauses
 * to limit the set of objects returned.  The WHERE clauses are appended
 * to the already-partially-constructed query in buf.  Returns whether
 * any clause was added.
 *
 * conn: connection query will be sent to (consulted for escaping rules).
 * buf: output parameter.
 * pattern: user-specified pattern option, or NULL if none ("*" is implied).
 * have_where: true if caller already emitted "WHERE" (clauses will be ANDed
 * onto the existing WHERE clause).
 * force_escape: always quote regexp special characters, even outside
 * double quotes (else they are quoted only between double quotes).
 * schemavar: name of query variable to match against a schema-name pattern.
 * Can be NULL if no schema.
 * namevar: name of query variable to match against an object-name pattern.
 * altnamevar: NULL, or name of an alternative variable to match against name.
 * visibilityrule: clause to use if we want to restrict to visible objects
 * (for example, "pg_catalog.pg_table_is_visible(p.oid)").  Can be NULL.
 *
 * Formatting note: the text already present in buf should end with a newline.
 * The appended text, if any, will end with one too.
 */
bool
processSQLNamePattern(PGconn *conn, PQExpBuffer buf, const char *pattern,
					  bool have_where, bool force_escape,
					  const char *schemavar, const char *namevar,
					  const char *altnamevar, const char *visibilityrule)
{
	PQExpBufferData schemabuf;
	PQExpBufferData namebuf;
	int			encoding = PQclientEncoding(conn);
	bool		inquotes;
	const char *cp;
	int			i;
	bool		added_clause = false;

#define WHEREAND() \
	(appendPQExpBufferStr(buf, have_where ? "  AND " : "WHERE "), \
	 have_where = true, added_clause = true)

	if (pattern == NULL)
	{
		/* Default: select all visible objects */
		if (visibilityrule)
		{
			WHEREAND();
			appendPQExpBuffer(buf, "%s\n", visibilityrule);
		}
		return added_clause;
	}

	initPQExpBuffer(&schemabuf);
	initPQExpBuffer(&namebuf);

	/*
	 * Parse the pattern, converting quotes and lower-casing unquoted letters.
	 * Also, adjust shell-style wildcard characters into regexp notation.
	 *
	 * We surround the pattern with "^(...)$" to force it to match the whole
	 * string, as per SQL practice.  We have to have parens in case the string
	 * contains "|", else the "^" and "$" will be bound into the first and
	 * last alternatives which is not what we want.
	 *
	 * Note: the result of this pass is the actual regexp pattern(s) we want
	 * to execute.  Quoting/escaping into SQL literal format will be done
	 * below using appendStringLiteralConn().
	 */
	appendPQExpBufferStr(&namebuf, "^(");

	inquotes = false;
	cp = pattern;

	while (*cp)
	{
		char		ch = *cp;

		if (ch == '"')
		{
			if (inquotes && cp[1] == '"')
			{
				/* emit one quote, stay in inquotes mode */
				appendPQExpBufferChar(&namebuf, '"');
				cp++;
			}
			else
				inquotes = !inquotes;
			cp++;
		}
		else if (!inquotes && isupper((unsigned char) ch))
		{
			appendPQExpBufferChar(&namebuf,
								  pg_tolower((unsigned char) ch));
			cp++;
		}
		else if (!inquotes && ch == '*')
		{
			appendPQExpBufferStr(&namebuf, ".*");
			cp++;
		}
		else if (!inquotes && ch == '?')
		{
			appendPQExpBufferChar(&namebuf, '.');
			cp++;
		}
		else if (!inquotes && ch == '.')
		{
			/* Found schema/name separator, move current pattern to schema */
			resetPQExpBuffer(&schemabuf);
			appendPQExpBufferStr(&schemabuf, namebuf.data);
			resetPQExpBuffer(&namebuf);
			appendPQExpBufferStr(&namebuf, "^(");
			cp++;
		}
		else if (ch == '$')
		{
			/*
			 * Dollar is always quoted, whether inside quotes or not. The
			 * reason is that it's allowed in SQL identifiers, so there's a
			 * significant use-case for treating it literally, while because
			 * we anchor the pattern automatically there is no use-case for
			 * having it possess its regexp meaning.
			 */
			appendPQExpBufferStr(&namebuf, "\\$");
			cp++;
		}
		else
		{
			/*
			 * Ordinary data character, transfer to pattern
			 *
			 * Inside double quotes, or at all times if force_escape is true,
			 * quote regexp special characters with a backslash to avoid
			 * regexp errors.  Outside quotes, however, let them pass through
			 * as-is; this lets knowledgeable users build regexp expressions
			 * that are more powerful than shell-style patterns.
			 */
			if ((inquotes || force_escape) &&
				strchr("|*+?()[]{}.^$\\", ch))
				appendPQExpBufferChar(&namebuf, '\\');
			i = PQmblen(cp, encoding);
			while (i-- && *cp)
			{
				appendPQExpBufferChar(&namebuf, *cp);
				cp++;
			}
		}
	}

	/*
	 * Now decide what we need to emit.  We may run under a hostile
	 * search_path, so qualify EVERY name.  Note there will be a leading "^("
	 * in the patterns in any case.
	 *
	 * We want the regex matches to use the database's default collation where
	 * collation-sensitive behavior is required (for example, which characters
	 * match '\w').  That happened by default before PG v12, but if the server
	 * is >= v12 then we need to force it through explicit COLLATE clauses,
	 * otherwise the "C" collation attached to "name" catalog columns wins.
	 */
	if (namebuf.len > 2)
	{
		/* We have a name pattern, so constrain the namevar(s) */

		appendPQExpBufferStr(&namebuf, ")$");
		/* Optimize away a "*" pattern */
		if (strcmp(namebuf.data, "^(.*)$") != 0)
		{
			WHEREAND();
			if (altnamevar)
			{
				appendPQExpBuffer(buf,
								  "(%s OPERATOR(pg_catalog.~) ", namevar);
				appendStringLiteralConn(buf, namebuf.data, conn);
				if (PQserverVersion(conn) >= 120000)
					appendPQExpBufferStr(buf, " COLLATE pg_catalog.default");
				appendPQExpBuffer(buf,
								  "\n        OR %s OPERATOR(pg_catalog.~) ",
								  altnamevar);
				appendStringLiteralConn(buf, namebuf.data, conn);
				if (PQserverVersion(conn) >= 120000)
					appendPQExpBufferStr(buf, " COLLATE pg_catalog.default");
				appendPQExpBufferStr(buf, ")\n");
			}
			else
			{
				appendPQExpBuffer(buf, "%s OPERATOR(pg_catalog.~) ", namevar);
				appendStringLiteralConn(buf, namebuf.data, conn);
				if (PQserverVersion(conn) >= 120000)
					appendPQExpBufferStr(buf, " COLLATE pg_catalog.default");
				appendPQExpBufferChar(buf, '\n');
			}
		}
	}

	if (schemabuf.len > 2)
	{
		/* We have a schema pattern, so constrain the schemavar */

		appendPQExpBufferStr(&schemabuf, ")$");
		/* Optimize away a "*" pattern */
		if (strcmp(schemabuf.data, "^(.*)$") != 0 && schemavar)
		{
			WHEREAND();
			appendPQExpBuffer(buf, "%s OPERATOR(pg_catalog.~) ", schemavar);
			appendStringLiteralConn(buf, schemabuf.data, conn);
			if (PQserverVersion(conn) >= 120000)
				appendPQExpBufferStr(buf, " COLLATE pg_catalog.default");
			appendPQExpBufferChar(buf, '\n');
		}
	}
	else
	{
		/* No schema pattern given, so select only visible objects */
		if (visibilityrule)
		{
			WHEREAND();
			appendPQExpBuffer(buf, "%s\n", visibilityrule);
		}
	}

	termPQExpBuffer(&schemabuf);
	termPQExpBuffer(&namebuf);

	return added_clause;
#undef WHEREAND
}