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variable.c
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1 /*-------------------------------------------------------------------------
2  *
3  * variable.c
4  * Routines for handling specialized SET variables.
5  *
6  *
7  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
8  * Portions Copyright (c) 1994, Regents of the University of California
9  *
10  *
11  * IDENTIFICATION
12  * src/backend/commands/variable.c
13  *
14  *-------------------------------------------------------------------------
15  */
16 
17 #include "postgres.h"
18 
19 #include <ctype.h>
20 
21 #include "access/htup_details.h"
22 #include "access/parallel.h"
23 #include "access/xact.h"
24 #include "access/xlog.h"
25 #include "catalog/pg_authid.h"
26 #include "commands/variable.h"
27 #include "miscadmin.h"
28 #include "utils/acl.h"
29 #include "utils/builtins.h"
30 #include "utils/syscache.h"
31 #include "utils/snapmgr.h"
32 #include "utils/timestamp.h"
33 #include "utils/varlena.h"
34 #include "mb/pg_wchar.h"
35 
36 /*
37  * DATESTYLE
38  */
39 
40 /*
41  * check_datestyle: GUC check_hook for datestyle
42  */
43 bool
44 check_datestyle(char **newval, void **extra, GucSource source)
45 {
46  int newDateStyle = DateStyle;
47  int newDateOrder = DateOrder;
48  bool have_style = false;
49  bool have_order = false;
50  bool ok = true;
51  char *rawstring;
52  int *myextra;
53  char *result;
54  List *elemlist;
55  ListCell *l;
56 
57  /* Need a modifiable copy of string */
58  rawstring = pstrdup(*newval);
59 
60  /* Parse string into list of identifiers */
61  if (!SplitIdentifierString(rawstring, ',', &elemlist))
62  {
63  /* syntax error in list */
64  GUC_check_errdetail("List syntax is invalid.");
65  pfree(rawstring);
66  list_free(elemlist);
67  return false;
68  }
69 
70  foreach(l, elemlist)
71  {
72  char *tok = (char *) lfirst(l);
73 
74  /* Ugh. Somebody ought to write a table driven version -- mjl */
75 
76  if (pg_strcasecmp(tok, "ISO") == 0)
77  {
78  if (have_style && newDateStyle != USE_ISO_DATES)
79  ok = false; /* conflicting styles */
80  newDateStyle = USE_ISO_DATES;
81  have_style = true;
82  }
83  else if (pg_strcasecmp(tok, "SQL") == 0)
84  {
85  if (have_style && newDateStyle != USE_SQL_DATES)
86  ok = false; /* conflicting styles */
87  newDateStyle = USE_SQL_DATES;
88  have_style = true;
89  }
90  else if (pg_strncasecmp(tok, "POSTGRES", 8) == 0)
91  {
92  if (have_style && newDateStyle != USE_POSTGRES_DATES)
93  ok = false; /* conflicting styles */
94  newDateStyle = USE_POSTGRES_DATES;
95  have_style = true;
96  }
97  else if (pg_strcasecmp(tok, "GERMAN") == 0)
98  {
99  if (have_style && newDateStyle != USE_GERMAN_DATES)
100  ok = false; /* conflicting styles */
101  newDateStyle = USE_GERMAN_DATES;
102  have_style = true;
103  /* GERMAN also sets DMY, unless explicitly overridden */
104  if (!have_order)
105  newDateOrder = DATEORDER_DMY;
106  }
107  else if (pg_strcasecmp(tok, "YMD") == 0)
108  {
109  if (have_order && newDateOrder != DATEORDER_YMD)
110  ok = false; /* conflicting orders */
111  newDateOrder = DATEORDER_YMD;
112  have_order = true;
113  }
114  else if (pg_strcasecmp(tok, "DMY") == 0 ||
115  pg_strncasecmp(tok, "EURO", 4) == 0)
116  {
117  if (have_order && newDateOrder != DATEORDER_DMY)
118  ok = false; /* conflicting orders */
119  newDateOrder = DATEORDER_DMY;
120  have_order = true;
121  }
122  else if (pg_strcasecmp(tok, "MDY") == 0 ||
123  pg_strcasecmp(tok, "US") == 0 ||
124  pg_strncasecmp(tok, "NONEURO", 7) == 0)
125  {
126  if (have_order && newDateOrder != DATEORDER_MDY)
127  ok = false; /* conflicting orders */
128  newDateOrder = DATEORDER_MDY;
129  have_order = true;
130  }
131  else if (pg_strcasecmp(tok, "DEFAULT") == 0)
132  {
133  /*
134  * Easiest way to get the current DEFAULT state is to fetch the
135  * DEFAULT string from guc.c and recursively parse it.
136  *
137  * We can't simply "return check_datestyle(...)" because we need
138  * to handle constructs like "DEFAULT, ISO".
139  */
140  char *subval;
141  void *subextra = NULL;
142 
143  subval = strdup(GetConfigOptionResetString("datestyle"));
144  if (!subval)
145  {
146  ok = false;
147  break;
148  }
149  if (!check_datestyle(&subval, &subextra, source))
150  {
151  free(subval);
152  ok = false;
153  break;
154  }
155  myextra = (int *) subextra;
156  if (!have_style)
157  newDateStyle = myextra[0];
158  if (!have_order)
159  newDateOrder = myextra[1];
160  free(subval);
161  free(subextra);
162  }
163  else
164  {
165  GUC_check_errdetail("Unrecognized key word: \"%s\".", tok);
166  pfree(rawstring);
167  list_free(elemlist);
168  return false;
169  }
170  }
171 
172  pfree(rawstring);
173  list_free(elemlist);
174 
175  if (!ok)
176  {
177  GUC_check_errdetail("Conflicting \"datestyle\" specifications.");
178  return false;
179  }
180 
181  /*
182  * Prepare the canonical string to return. GUC wants it malloc'd.
183  */
184  result = (char *) malloc(32);
185  if (!result)
186  return false;
187 
188  switch (newDateStyle)
189  {
190  case USE_ISO_DATES:
191  strcpy(result, "ISO");
192  break;
193  case USE_SQL_DATES:
194  strcpy(result, "SQL");
195  break;
196  case USE_GERMAN_DATES:
197  strcpy(result, "German");
198  break;
199  default:
200  strcpy(result, "Postgres");
201  break;
202  }
203  switch (newDateOrder)
204  {
205  case DATEORDER_YMD:
206  strcat(result, ", YMD");
207  break;
208  case DATEORDER_DMY:
209  strcat(result, ", DMY");
210  break;
211  default:
212  strcat(result, ", MDY");
213  break;
214  }
215 
216  free(*newval);
217  *newval = result;
218 
219  /*
220  * Set up the "extra" struct actually used by assign_datestyle.
221  */
222  myextra = (int *) malloc(2 * sizeof(int));
223  if (!myextra)
224  return false;
225  myextra[0] = newDateStyle;
226  myextra[1] = newDateOrder;
227  *extra = (void *) myextra;
228 
229  return true;
230 }
231 
232 /*
233  * assign_datestyle: GUC assign_hook for datestyle
234  */
235 void
236 assign_datestyle(const char *newval, void *extra)
237 {
238  int *myextra = (int *) extra;
239 
240  DateStyle = myextra[0];
241  DateOrder = myextra[1];
242 }
243 
244 
245 /*
246  * TIMEZONE
247  */
248 
249 /*
250  * check_timezone: GUC check_hook for timezone
251  */
252 bool
253 check_timezone(char **newval, void **extra, GucSource source)
254 {
255  pg_tz *new_tz;
256  long gmtoffset;
257  char *endptr;
258  double hours;
259 
260  if (pg_strncasecmp(*newval, "interval", 8) == 0)
261  {
262  /*
263  * Support INTERVAL 'foo'. This is for SQL spec compliance, not
264  * because it has any actual real-world usefulness.
265  */
266  const char *valueptr = *newval;
267  char *val;
269 
270  valueptr += 8;
271  while (isspace((unsigned char) *valueptr))
272  valueptr++;
273  if (*valueptr++ != '\'')
274  return false;
275  val = pstrdup(valueptr);
276  /* Check and remove trailing quote */
277  endptr = strchr(val, '\'');
278  if (!endptr || endptr[1] != '\0')
279  {
280  pfree(val);
281  return false;
282  }
283  *endptr = '\0';
284 
285  /*
286  * Try to parse it. XXX an invalid interval format will result in
287  * ereport(ERROR), which is not desirable for GUC. We did what we
288  * could to guard against this in flatten_set_variable_args, but a
289  * string coming in from postgresql.conf might contain anything.
290  */
292  CStringGetDatum(val),
294  Int32GetDatum(-1)));
295 
296  pfree(val);
297  if (interval->month != 0)
298  {
299  GUC_check_errdetail("Cannot specify months in time zone interval.");
300  pfree(interval);
301  return false;
302  }
303  if (interval->day != 0)
304  {
305  GUC_check_errdetail("Cannot specify days in time zone interval.");
306  pfree(interval);
307  return false;
308  }
309 
310  /* Here we change from SQL to Unix sign convention */
311  gmtoffset = -(interval->time / USECS_PER_SEC);
312  new_tz = pg_tzset_offset(gmtoffset);
313 
314  pfree(interval);
315  }
316  else
317  {
318  /*
319  * Try it as a numeric number of hours (possibly fractional).
320  */
321  hours = strtod(*newval, &endptr);
322  if (endptr != *newval && *endptr == '\0')
323  {
324  /* Here we change from SQL to Unix sign convention */
325  gmtoffset = -hours * SECS_PER_HOUR;
326  new_tz = pg_tzset_offset(gmtoffset);
327  }
328  else
329  {
330  /*
331  * Otherwise assume it is a timezone name, and try to load it.
332  */
333  new_tz = pg_tzset(*newval);
334 
335  if (!new_tz)
336  {
337  /* Doesn't seem to be any great value in errdetail here */
338  return false;
339  }
340 
341  if (!pg_tz_acceptable(new_tz))
342  {
343  GUC_check_errmsg("time zone \"%s\" appears to use leap seconds",
344  *newval);
345  GUC_check_errdetail("PostgreSQL does not support leap seconds.");
346  return false;
347  }
348  }
349  }
350 
351  /* Test for failure in pg_tzset_offset, which we assume is out-of-range */
352  if (!new_tz)
353  {
354  GUC_check_errdetail("UTC timezone offset is out of range.");
355  return false;
356  }
357 
358  /*
359  * Pass back data for assign_timezone to use
360  */
361  *extra = malloc(sizeof(pg_tz *));
362  if (!*extra)
363  return false;
364  *((pg_tz **) *extra) = new_tz;
365 
366  return true;
367 }
368 
369 /*
370  * assign_timezone: GUC assign_hook for timezone
371  */
372 void
373 assign_timezone(const char *newval, void *extra)
374 {
375  session_timezone = *((pg_tz **) extra);
376 }
377 
378 /*
379  * show_timezone: GUC show_hook for timezone
380  */
381 const char *
383 {
384  const char *tzn;
385 
386  /* Always show the zone's canonical name */
388 
389  if (tzn != NULL)
390  return tzn;
391 
392  return "unknown";
393 }
394 
395 
396 /*
397  * LOG_TIMEZONE
398  *
399  * For log_timezone, we don't support the interval-based methods of setting a
400  * zone, which are only there for SQL spec compliance not because they're
401  * actually useful.
402  */
403 
404 /*
405  * check_log_timezone: GUC check_hook for log_timezone
406  */
407 bool
408 check_log_timezone(char **newval, void **extra, GucSource source)
409 {
410  pg_tz *new_tz;
411 
412  /*
413  * Assume it is a timezone name, and try to load it.
414  */
415  new_tz = pg_tzset(*newval);
416 
417  if (!new_tz)
418  {
419  /* Doesn't seem to be any great value in errdetail here */
420  return false;
421  }
422 
423  if (!pg_tz_acceptable(new_tz))
424  {
425  GUC_check_errmsg("time zone \"%s\" appears to use leap seconds",
426  *newval);
427  GUC_check_errdetail("PostgreSQL does not support leap seconds.");
428  return false;
429  }
430 
431  /*
432  * Pass back data for assign_log_timezone to use
433  */
434  *extra = malloc(sizeof(pg_tz *));
435  if (!*extra)
436  return false;
437  *((pg_tz **) *extra) = new_tz;
438 
439  return true;
440 }
441 
442 /*
443  * assign_log_timezone: GUC assign_hook for log_timezone
444  */
445 void
446 assign_log_timezone(const char *newval, void *extra)
447 {
448  log_timezone = *((pg_tz **) extra);
449 }
450 
451 /*
452  * show_log_timezone: GUC show_hook for log_timezone
453  */
454 const char *
456 {
457  const char *tzn;
458 
459  /* Always show the zone's canonical name */
461 
462  if (tzn != NULL)
463  return tzn;
464 
465  return "unknown";
466 }
467 
468 
469 /*
470  * SET TRANSACTION READ ONLY and SET TRANSACTION READ WRITE
471  *
472  * We allow idempotent changes (r/w -> r/w and r/o -> r/o) at any time, and
473  * we also always allow changes from read-write to read-only. However,
474  * read-only may be changed to read-write only when in a top-level transaction
475  * that has not yet taken an initial snapshot. Can't do it in a hot standby
476  * slave, either.
477  *
478  * If we are not in a transaction at all, just allow the change; it means
479  * nothing since XactReadOnly will be reset by the next StartTransaction().
480  * The IsTransactionState() test protects us against trying to check
481  * RecoveryInProgress() in contexts where shared memory is not accessible.
482  * (Similarly, if we're restoring state in a parallel worker, just allow
483  * the change.)
484  */
485 bool
486 check_transaction_read_only(bool *newval, void **extra, GucSource source)
487 {
488  if (*newval == false && XactReadOnly && IsTransactionState() && !InitializingParallelWorker)
489  {
490  /* Can't go to r/w mode inside a r/o transaction */
491  if (IsSubTransaction())
492  {
493  GUC_check_errcode(ERRCODE_ACTIVE_SQL_TRANSACTION);
494  GUC_check_errmsg("cannot set transaction read-write mode inside a read-only transaction");
495  return false;
496  }
497  /* Top level transaction can't change to r/w after first snapshot. */
498  if (FirstSnapshotSet)
499  {
500  GUC_check_errcode(ERRCODE_ACTIVE_SQL_TRANSACTION);
501  GUC_check_errmsg("transaction read-write mode must be set before any query");
502  return false;
503  }
504  /* Can't go to r/w mode while recovery is still active */
505  if (RecoveryInProgress())
506  {
507  GUC_check_errcode(ERRCODE_FEATURE_NOT_SUPPORTED);
508  GUC_check_errmsg("cannot set transaction read-write mode during recovery");
509  return false;
510  }
511  }
512 
513  return true;
514 }
515 
516 /*
517  * SET TRANSACTION ISOLATION LEVEL
518  *
519  * We allow idempotent changes at any time, but otherwise this can only be
520  * changed in a toplevel transaction that has not yet taken a snapshot.
521  *
522  * As in check_transaction_read_only, allow it if not inside a transaction.
523  */
524 bool
525 check_XactIsoLevel(char **newval, void **extra, GucSource source)
526 {
527  int newXactIsoLevel;
528 
529  if (strcmp(*newval, "serializable") == 0)
530  {
531  newXactIsoLevel = XACT_SERIALIZABLE;
532  }
533  else if (strcmp(*newval, "repeatable read") == 0)
534  {
535  newXactIsoLevel = XACT_REPEATABLE_READ;
536  }
537  else if (strcmp(*newval, "read committed") == 0)
538  {
539  newXactIsoLevel = XACT_READ_COMMITTED;
540  }
541  else if (strcmp(*newval, "read uncommitted") == 0)
542  {
543  newXactIsoLevel = XACT_READ_UNCOMMITTED;
544  }
545  else if (strcmp(*newval, "default") == 0)
546  {
547  newXactIsoLevel = DefaultXactIsoLevel;
548  }
549  else
550  return false;
551 
552  if (newXactIsoLevel != XactIsoLevel && IsTransactionState())
553  {
554  if (FirstSnapshotSet)
555  {
556  GUC_check_errcode(ERRCODE_ACTIVE_SQL_TRANSACTION);
557  GUC_check_errmsg("SET TRANSACTION ISOLATION LEVEL must be called before any query");
558  return false;
559  }
560  /* We ignore a subtransaction setting it to the existing value. */
561  if (IsSubTransaction())
562  {
563  GUC_check_errcode(ERRCODE_ACTIVE_SQL_TRANSACTION);
564  GUC_check_errmsg("SET TRANSACTION ISOLATION LEVEL must not be called in a subtransaction");
565  return false;
566  }
567  /* Can't go to serializable mode while recovery is still active */
568  if (newXactIsoLevel == XACT_SERIALIZABLE && RecoveryInProgress())
569  {
570  GUC_check_errcode(ERRCODE_FEATURE_NOT_SUPPORTED);
571  GUC_check_errmsg("cannot use serializable mode in a hot standby");
572  GUC_check_errhint("You can use REPEATABLE READ instead.");
573  return false;
574  }
575  }
576 
577  *extra = malloc(sizeof(int));
578  if (!*extra)
579  return false;
580  *((int *) *extra) = newXactIsoLevel;
581 
582  return true;
583 }
584 
585 void
586 assign_XactIsoLevel(const char *newval, void *extra)
587 {
588  XactIsoLevel = *((int *) extra);
589 }
590 
591 const char *
593 {
594  /* We need this because we don't want to show "default". */
595  switch (XactIsoLevel)
596  {
598  return "read uncommitted";
599  case XACT_READ_COMMITTED:
600  return "read committed";
602  return "repeatable read";
603  case XACT_SERIALIZABLE:
604  return "serializable";
605  default:
606  return "bogus";
607  }
608 }
609 
610 /*
611  * SET TRANSACTION [NOT] DEFERRABLE
612  */
613 
614 bool
615 check_transaction_deferrable(bool *newval, void **extra, GucSource source)
616 {
617  if (IsSubTransaction())
618  {
619  GUC_check_errcode(ERRCODE_ACTIVE_SQL_TRANSACTION);
620  GUC_check_errmsg("SET TRANSACTION [NOT] DEFERRABLE cannot be called within a subtransaction");
621  return false;
622  }
623  if (FirstSnapshotSet)
624  {
625  GUC_check_errcode(ERRCODE_ACTIVE_SQL_TRANSACTION);
626  GUC_check_errmsg("SET TRANSACTION [NOT] DEFERRABLE must be called before any query");
627  return false;
628  }
629 
630  return true;
631 }
632 
633 /*
634  * Random number seed
635  *
636  * We can't roll back the random sequence on error, and we don't want
637  * config file reloads to affect it, so we only want interactive SET SEED
638  * commands to set it. We use the "extra" storage to ensure that rollbacks
639  * don't try to do the operation again.
640  */
641 
642 bool
643 check_random_seed(double *newval, void **extra, GucSource source)
644 {
645  *extra = malloc(sizeof(int));
646  if (!*extra)
647  return false;
648  /* Arm the assign only if source of value is an interactive SET */
649  *((int *) *extra) = (source >= PGC_S_INTERACTIVE);
650 
651  return true;
652 }
653 
654 void
655 assign_random_seed(double newval, void *extra)
656 {
657  /* We'll do this at most once for any setting of the GUC variable */
658  if (*((int *) extra))
660  *((int *) extra) = 0;
661 }
662 
663 const char *
665 {
666  return "unavailable";
667 }
668 
669 
670 /*
671  * SET CLIENT_ENCODING
672  */
673 
674 bool
675 check_client_encoding(char **newval, void **extra, GucSource source)
676 {
677  int encoding;
678  const char *canonical_name;
679 
680  /* Look up the encoding by name */
681  encoding = pg_valid_client_encoding(*newval);
682  if (encoding < 0)
683  return false;
684 
685  /* Get the canonical name (no aliases, uniform case) */
686  canonical_name = pg_encoding_to_char(encoding);
687 
688  /*
689  * If we are not within a transaction then PrepareClientEncoding will not
690  * be able to look up the necessary conversion procs. If we are still
691  * starting up, it will return "OK" anyway, and InitializeClientEncoding
692  * will fix things once initialization is far enough along. After
693  * startup, we'll fail. This would only happen if someone tries to change
694  * client_encoding in postgresql.conf and then SIGHUP existing sessions.
695  * It seems like a bad idea for client_encoding to change that way anyhow,
696  * so we don't go out of our way to support it.
697  *
698  * Note: in the postmaster, or any other process that never calls
699  * InitializeClientEncoding, PrepareClientEncoding will always succeed,
700  * and so will SetClientEncoding; but they won't do anything, which is OK.
701  */
702  if (PrepareClientEncoding(encoding) < 0)
703  {
704  if (IsTransactionState())
705  {
706  /* Must be a genuine no-such-conversion problem */
707  GUC_check_errcode(ERRCODE_FEATURE_NOT_SUPPORTED);
708  GUC_check_errdetail("Conversion between %s and %s is not supported.",
709  canonical_name,
711  }
712  else
713  {
714  /* Provide a useful complaint */
715  GUC_check_errdetail("Cannot change \"client_encoding\" now.");
716  }
717  return false;
718  }
719 
720  /*
721  * Replace the user-supplied string with the encoding's canonical name.
722  * This gets rid of aliases and case-folding variations.
723  *
724  * XXX Although canonicalizing seems like a good idea in the abstract, it
725  * breaks pre-9.1 JDBC drivers, which expect that if they send "UNICODE"
726  * as the client_encoding setting then it will read back the same way. As
727  * a workaround, don't replace the string if it's "UNICODE". Remove that
728  * hack when pre-9.1 JDBC drivers are no longer in use.
729  */
730  if (strcmp(*newval, canonical_name) != 0 &&
731  strcmp(*newval, "UNICODE") != 0)
732  {
733  free(*newval);
734  *newval = strdup(canonical_name);
735  if (!*newval)
736  return false;
737  }
738 
739  /*
740  * Save the encoding's ID in *extra, for use by assign_client_encoding.
741  */
742  *extra = malloc(sizeof(int));
743  if (!*extra)
744  return false;
745  *((int *) *extra) = encoding;
746 
747  return true;
748 }
749 
750 void
751 assign_client_encoding(const char *newval, void *extra)
752 {
753  int encoding = *((int *) extra);
754 
755  /*
756  * Parallel workers send data to the leader, not the client. They always
757  * send data using the database encoding.
758  */
759  if (IsParallelWorker())
760  {
761  /*
762  * During parallel worker startup, we want to accept the leader's
763  * client_encoding setting so that anyone who looks at the value in
764  * the worker sees the same value that they would see in the leader.
765  */
767  return;
768 
769  /*
770  * A change other than during startup, for example due to a SET clause
771  * attached to a function definition, should be rejected, as there is
772  * nothing we can do inside the worker to make it take effect.
773  */
774  ereport(ERROR,
775  (errcode(ERRCODE_INVALID_TRANSACTION_STATE),
776  errmsg("cannot change client_encoding in a parallel worker")));
777  }
778 
779  /* We do not expect an error if PrepareClientEncoding succeeded */
780  if (SetClientEncoding(encoding) < 0)
781  elog(LOG, "SetClientEncoding(%d) failed", encoding);
782 }
783 
784 
785 /*
786  * SET SESSION AUTHORIZATION
787  */
788 
789 typedef struct
790 {
791  /* This is the "extra" state for both SESSION AUTHORIZATION and ROLE */
795 
796 bool
797 check_session_authorization(char **newval, void **extra, GucSource source)
798 {
799  HeapTuple roleTup;
800  Oid roleid;
801  bool is_superuser;
802  role_auth_extra *myextra;
803 
804  /* Do nothing for the boot_val default of NULL */
805  if (*newval == NULL)
806  return true;
807 
808  if (!IsTransactionState())
809  {
810  /*
811  * Can't do catalog lookups, so fail. The result of this is that
812  * session_authorization cannot be set in postgresql.conf, which seems
813  * like a good thing anyway, so we don't work hard to avoid it.
814  */
815  return false;
816  }
817 
818  /* Look up the username */
819  roleTup = SearchSysCache1(AUTHNAME, PointerGetDatum(*newval));
820  if (!HeapTupleIsValid(roleTup))
821  {
822  GUC_check_errmsg("role \"%s\" does not exist", *newval);
823  return false;
824  }
825 
826  roleid = HeapTupleGetOid(roleTup);
827  is_superuser = ((Form_pg_authid) GETSTRUCT(roleTup))->rolsuper;
828 
829  ReleaseSysCache(roleTup);
830 
831  /* Set up "extra" struct for assign_session_authorization to use */
832  myextra = (role_auth_extra *) malloc(sizeof(role_auth_extra));
833  if (!myextra)
834  return false;
835  myextra->roleid = roleid;
836  myextra->is_superuser = is_superuser;
837  *extra = (void *) myextra;
838 
839  return true;
840 }
841 
842 void
843 assign_session_authorization(const char *newval, void *extra)
844 {
845  role_auth_extra *myextra = (role_auth_extra *) extra;
846 
847  /* Do nothing for the boot_val default of NULL */
848  if (!myextra)
849  return;
850 
851  SetSessionAuthorization(myextra->roleid, myextra->is_superuser);
852 }
853 
854 
855 /*
856  * SET ROLE
857  *
858  * The SQL spec requires "SET ROLE NONE" to unset the role, so we hardwire
859  * a translation of "none" to InvalidOid. Otherwise this is much like
860  * SET SESSION AUTHORIZATION.
861  */
862 extern char *role_string; /* in guc.c */
863 
864 bool
865 check_role(char **newval, void **extra, GucSource source)
866 {
867  HeapTuple roleTup;
868  Oid roleid;
869  bool is_superuser;
870  role_auth_extra *myextra;
871 
872  if (strcmp(*newval, "none") == 0)
873  {
874  /* hardwired translation */
875  roleid = InvalidOid;
876  is_superuser = false;
877  }
878  else
879  {
880  if (!IsTransactionState())
881  {
882  /*
883  * Can't do catalog lookups, so fail. The result of this is that
884  * role cannot be set in postgresql.conf, which seems like a good
885  * thing anyway, so we don't work hard to avoid it.
886  */
887  return false;
888  }
889 
890  /* Look up the username */
891  roleTup = SearchSysCache1(AUTHNAME, PointerGetDatum(*newval));
892  if (!HeapTupleIsValid(roleTup))
893  {
894  GUC_check_errmsg("role \"%s\" does not exist", *newval);
895  return false;
896  }
897 
898  roleid = HeapTupleGetOid(roleTup);
899  is_superuser = ((Form_pg_authid) GETSTRUCT(roleTup))->rolsuper;
900 
901  ReleaseSysCache(roleTup);
902 
903  /*
904  * Verify that session user is allowed to become this role, but skip
905  * this in parallel mode, where we must blindly recreate the parallel
906  * leader's state.
907  */
910  {
911  GUC_check_errcode(ERRCODE_INSUFFICIENT_PRIVILEGE);
912  GUC_check_errmsg("permission denied to set role \"%s\"",
913  *newval);
914  return false;
915  }
916  }
917 
918  /* Set up "extra" struct for assign_role to use */
919  myextra = (role_auth_extra *) malloc(sizeof(role_auth_extra));
920  if (!myextra)
921  return false;
922  myextra->roleid = roleid;
923  myextra->is_superuser = is_superuser;
924  *extra = (void *) myextra;
925 
926  return true;
927 }
928 
929 void
930 assign_role(const char *newval, void *extra)
931 {
932  role_auth_extra *myextra = (role_auth_extra *) extra;
933 
934  SetCurrentRoleId(myextra->roleid, myextra->is_superuser);
935 }
936 
937 const char *
939 {
940  /*
941  * Check whether SET ROLE is active; if not return "none". This is a
942  * kluge to deal with the fact that SET SESSION AUTHORIZATION logically
943  * resets SET ROLE to NONE, but we cannot set the GUC role variable from
944  * assign_session_authorization (because we haven't got enough info to
945  * call set_config_option).
946  */
948  return "none";
949 
950  /* Otherwise we can just use the GUC string */
951  return role_string ? role_string : "none";
952 }
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