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schemacmds.c
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1 /*-------------------------------------------------------------------------
2  *
3  * schemacmds.c
4  * schema creation/manipulation commands
5  *
6  * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  *
10  * IDENTIFICATION
11  * src/backend/commands/schemacmds.c
12  *
13  *-------------------------------------------------------------------------
14  */
15 #include "postgres.h"
16 
17 #include "access/htup_details.h"
18 #include "access/table.h"
19 #include "access/xact.h"
20 #include "catalog/catalog.h"
21 #include "catalog/dependency.h"
22 #include "catalog/indexing.h"
23 #include "catalog/namespace.h"
24 #include "catalog/objectaccess.h"
25 #include "catalog/pg_authid.h"
26 #include "catalog/pg_namespace.h"
27 #include "commands/dbcommands.h"
28 #include "commands/event_trigger.h"
29 #include "commands/schemacmds.h"
30 #include "miscadmin.h"
31 #include "parser/parse_utilcmd.h"
32 #include "tcop/utility.h"
33 #include "utils/acl.h"
34 #include "utils/builtins.h"
35 #include "utils/rel.h"
36 #include "utils/syscache.h"
37 
38 static void AlterSchemaOwner_internal(HeapTuple tup, Relation rel, Oid newOwnerId);
39 
40 /*
41  * CREATE SCHEMA
42  *
43  * Note: caller should pass in location information for the whole
44  * CREATE SCHEMA statement, which in turn we pass down as the location
45  * of the component commands. This comports with our general plan of
46  * reporting location/len for the whole command even when executing
47  * a subquery.
48  */
49 Oid
50 CreateSchemaCommand(CreateSchemaStmt *stmt, const char *queryString,
51  int stmt_location, int stmt_len)
52 {
53  const char *schemaName = stmt->schemaname;
54  Oid namespaceId;
55  OverrideSearchPath *overridePath;
56  List *parsetree_list;
57  ListCell *parsetree_item;
58  Oid owner_uid;
59  Oid saved_uid;
60  int save_sec_context;
61  AclResult aclresult;
62  ObjectAddress address;
63 
64  GetUserIdAndSecContext(&saved_uid, &save_sec_context);
65 
66  /*
67  * Who is supposed to own the new schema?
68  */
69  if (stmt->authrole)
70  owner_uid = get_rolespec_oid(stmt->authrole, false);
71  else
72  owner_uid = saved_uid;
73 
74  /* fill schema name with the user name if not specified */
75  if (!schemaName)
76  {
77  HeapTuple tuple;
78 
79  tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(owner_uid));
80  if (!HeapTupleIsValid(tuple))
81  elog(ERROR, "cache lookup failed for role %u", owner_uid);
82  schemaName =
84  ReleaseSysCache(tuple);
85  }
86 
87  /*
88  * To create a schema, must have schema-create privilege on the current
89  * database and must be able to become the target role (this does not
90  * imply that the target role itself must have create-schema privilege).
91  * The latter provision guards against "giveaway" attacks. Note that a
92  * superuser will always have both of these privileges a fortiori.
93  */
94  aclresult = pg_database_aclcheck(MyDatabaseId, saved_uid, ACL_CREATE);
95  if (aclresult != ACLCHECK_OK)
98 
99  check_is_member_of_role(saved_uid, owner_uid);
100 
101  /* Additional check to protect reserved schema names */
102  if (!allowSystemTableMods && IsReservedName(schemaName))
103  ereport(ERROR,
104  (errcode(ERRCODE_RESERVED_NAME),
105  errmsg("unacceptable schema name \"%s\"", schemaName),
106  errdetail("The prefix \"pg_\" is reserved for system schemas.")));
107 
108  /*
109  * If if_not_exists was given and the schema already exists, bail out.
110  * (Note: we needn't check this when not if_not_exists, because
111  * NamespaceCreate will complain anyway.) We could do this before making
112  * the permissions checks, but since CREATE TABLE IF NOT EXISTS makes its
113  * creation-permission check first, we do likewise.
114  */
115  if (stmt->if_not_exists &&
117  {
118  ereport(NOTICE,
119  (errcode(ERRCODE_DUPLICATE_SCHEMA),
120  errmsg("schema \"%s\" already exists, skipping",
121  schemaName)));
122  return InvalidOid;
123  }
124 
125  /*
126  * If the requested authorization is different from the current user,
127  * temporarily set the current user so that the object(s) will be created
128  * with the correct ownership.
129  *
130  * (The setting will be restored at the end of this routine, or in case of
131  * error, transaction abort will clean things up.)
132  */
133  if (saved_uid != owner_uid)
134  SetUserIdAndSecContext(owner_uid,
135  save_sec_context | SECURITY_LOCAL_USERID_CHANGE);
136 
137  /* Create the schema's namespace */
138  namespaceId = NamespaceCreate(schemaName, owner_uid, false);
139 
140  /* Advance cmd counter to make the namespace visible */
142 
143  /*
144  * Temporarily make the new namespace be the front of the search path, as
145  * well as the default creation target namespace. This will be undone at
146  * the end of this routine, or upon error.
147  */
149  overridePath->schemas = lcons_oid(namespaceId, overridePath->schemas);
150  /* XXX should we clear overridePath->useTemp? */
151  PushOverrideSearchPath(overridePath);
152 
153  /*
154  * Report the new schema to possibly interested event triggers. Note we
155  * must do this here and not in ProcessUtilitySlow because otherwise the
156  * objects created below are reported before the schema, which would be
157  * wrong.
158  */
159  ObjectAddressSet(address, NamespaceRelationId, namespaceId);
161  (Node *) stmt);
162 
163  /*
164  * Examine the list of commands embedded in the CREATE SCHEMA command, and
165  * reorganize them into a sequentially executable order with no forward
166  * references. Note that the result is still a list of raw parsetrees ---
167  * we cannot, in general, run parse analysis on one statement until we
168  * have actually executed the prior ones.
169  */
170  parsetree_list = transformCreateSchemaStmt(stmt);
171 
172  /*
173  * Execute each command contained in the CREATE SCHEMA. Since the grammar
174  * allows only utility commands in CREATE SCHEMA, there is no need to pass
175  * them through parse_analyze() or the rewriter; we can just hand them
176  * straight to ProcessUtility.
177  */
178  foreach(parsetree_item, parsetree_list)
179  {
180  Node *stmt = (Node *) lfirst(parsetree_item);
181  PlannedStmt *wrapper;
182 
183  /* need to make a wrapper PlannedStmt */
184  wrapper = makeNode(PlannedStmt);
185  wrapper->commandType = CMD_UTILITY;
186  wrapper->canSetTag = false;
187  wrapper->utilityStmt = stmt;
188  wrapper->stmt_location = stmt_location;
189  wrapper->stmt_len = stmt_len;
190 
191  /* do this step */
192  ProcessUtility(wrapper,
193  queryString,
195  NULL,
196  NULL,
198  NULL);
199 
200  /* make sure later steps can see the object created here */
202  }
203 
204  /* Reset search path to normal state */
206 
207  /* Reset current user and security context */
208  SetUserIdAndSecContext(saved_uid, save_sec_context);
209 
210  return namespaceId;
211 }
212 
213 /*
214  * Guts of schema deletion.
215  */
216 void
218 {
219  Relation relation;
220  HeapTuple tup;
221 
222  relation = table_open(NamespaceRelationId, RowExclusiveLock);
223 
225  ObjectIdGetDatum(schemaOid));
226  if (!HeapTupleIsValid(tup)) /* should not happen */
227  elog(ERROR, "cache lookup failed for namespace %u", schemaOid);
228 
229  CatalogTupleDelete(relation, &tup->t_self);
230 
231  ReleaseSysCache(tup);
232 
233  table_close(relation, RowExclusiveLock);
234 }
235 
236 
237 /*
238  * Rename schema
239  */
241 RenameSchema(const char *oldname, const char *newname)
242 {
243  Oid nspOid;
244  HeapTuple tup;
245  Relation rel;
246  AclResult aclresult;
247  ObjectAddress address;
248  Form_pg_namespace nspform;
249 
250  rel = table_open(NamespaceRelationId, RowExclusiveLock);
251 
253  if (!HeapTupleIsValid(tup))
254  ereport(ERROR,
255  (errcode(ERRCODE_UNDEFINED_SCHEMA),
256  errmsg("schema \"%s\" does not exist", oldname)));
257 
258  nspform = (Form_pg_namespace) GETSTRUCT(tup);
259  nspOid = nspform->oid;
260 
261  /* make sure the new name doesn't exist */
262  if (OidIsValid(get_namespace_oid(newname, true)))
263  ereport(ERROR,
264  (errcode(ERRCODE_DUPLICATE_SCHEMA),
265  errmsg("schema \"%s\" already exists", newname)));
266 
267  /* must be owner */
268  if (!pg_namespace_ownercheck(nspOid, GetUserId()))
270  oldname);
271 
272  /* must have CREATE privilege on database */
274  if (aclresult != ACLCHECK_OK)
275  aclcheck_error(aclresult, OBJECT_DATABASE,
277 
278  if (!allowSystemTableMods && IsReservedName(newname))
279  ereport(ERROR,
280  (errcode(ERRCODE_RESERVED_NAME),
281  errmsg("unacceptable schema name \"%s\"", newname),
282  errdetail("The prefix \"pg_\" is reserved for system schemas.")));
283 
284  /* rename */
285  namestrcpy(&nspform->nspname, newname);
286  CatalogTupleUpdate(rel, &tup->t_self, tup);
287 
288  InvokeObjectPostAlterHook(NamespaceRelationId, nspOid, 0);
289 
290  ObjectAddressSet(address, NamespaceRelationId, nspOid);
291 
292  table_close(rel, NoLock);
293  heap_freetuple(tup);
294 
295  return address;
296 }
297 
298 void
299 AlterSchemaOwner_oid(Oid oid, Oid newOwnerId)
300 {
301  HeapTuple tup;
302  Relation rel;
303 
304  rel = table_open(NamespaceRelationId, RowExclusiveLock);
305 
307  if (!HeapTupleIsValid(tup))
308  elog(ERROR, "cache lookup failed for schema %u", oid);
309 
310  AlterSchemaOwner_internal(tup, rel, newOwnerId);
311 
312  ReleaseSysCache(tup);
313 
315 }
316 
317 
318 /*
319  * Change schema owner
320  */
322 AlterSchemaOwner(const char *name, Oid newOwnerId)
323 {
324  Oid nspOid;
325  HeapTuple tup;
326  Relation rel;
327  ObjectAddress address;
328  Form_pg_namespace nspform;
329 
330  rel = table_open(NamespaceRelationId, RowExclusiveLock);
331 
333  if (!HeapTupleIsValid(tup))
334  ereport(ERROR,
335  (errcode(ERRCODE_UNDEFINED_SCHEMA),
336  errmsg("schema \"%s\" does not exist", name)));
337 
338  nspform = (Form_pg_namespace) GETSTRUCT(tup);
339  nspOid = nspform->oid;
340 
341  AlterSchemaOwner_internal(tup, rel, newOwnerId);
342 
343  ObjectAddressSet(address, NamespaceRelationId, nspOid);
344 
345  ReleaseSysCache(tup);
346 
348 
349  return address;
350 }
351 
352 static void
354 {
355  Form_pg_namespace nspForm;
356 
357  Assert(tup->t_tableOid == NamespaceRelationId);
358  Assert(RelationGetRelid(rel) == NamespaceRelationId);
359 
360  nspForm = (Form_pg_namespace) GETSTRUCT(tup);
361 
362  /*
363  * If the new owner is the same as the existing owner, consider the
364  * command to have succeeded. This is for dump restoration purposes.
365  */
366  if (nspForm->nspowner != newOwnerId)
367  {
368  Datum repl_val[Natts_pg_namespace];
369  bool repl_null[Natts_pg_namespace];
370  bool repl_repl[Natts_pg_namespace];
371  Acl *newAcl;
372  Datum aclDatum;
373  bool isNull;
374  HeapTuple newtuple;
375  AclResult aclresult;
376 
377  /* Otherwise, must be owner of the existing object */
378  if (!pg_namespace_ownercheck(nspForm->oid, GetUserId()))
380  NameStr(nspForm->nspname));
381 
382  /* Must be able to become new owner */
383  check_is_member_of_role(GetUserId(), newOwnerId);
384 
385  /*
386  * must have create-schema rights
387  *
388  * NOTE: This is different from other alter-owner checks in that the
389  * current user is checked for create privileges instead of the
390  * destination owner. This is consistent with the CREATE case for
391  * schemas. Because superusers will always have this right, we need
392  * no special case for them.
393  */
395  ACL_CREATE);
396  if (aclresult != ACLCHECK_OK)
397  aclcheck_error(aclresult, OBJECT_DATABASE,
399 
400  memset(repl_null, false, sizeof(repl_null));
401  memset(repl_repl, false, sizeof(repl_repl));
402 
403  repl_repl[Anum_pg_namespace_nspowner - 1] = true;
404  repl_val[Anum_pg_namespace_nspowner - 1] = ObjectIdGetDatum(newOwnerId);
405 
406  /*
407  * Determine the modified ACL for the new owner. This is only
408  * necessary when the ACL is non-null.
409  */
410  aclDatum = SysCacheGetAttr(NAMESPACENAME, tup,
411  Anum_pg_namespace_nspacl,
412  &isNull);
413  if (!isNull)
414  {
415  newAcl = aclnewowner(DatumGetAclP(aclDatum),
416  nspForm->nspowner, newOwnerId);
417  repl_repl[Anum_pg_namespace_nspacl - 1] = true;
418  repl_val[Anum_pg_namespace_nspacl - 1] = PointerGetDatum(newAcl);
419  }
420 
421  newtuple = heap_modify_tuple(tup, RelationGetDescr(rel), repl_val, repl_null, repl_repl);
422 
423  CatalogTupleUpdate(rel, &newtuple->t_self, newtuple);
424 
425  heap_freetuple(newtuple);
426 
427  /* Update owner dependency reference */
428  changeDependencyOnOwner(NamespaceRelationId, nspForm->oid,
429  newOwnerId);
430  }
431 
432  InvokeObjectPostAlterHook(NamespaceRelationId,
433  nspForm->oid, 0);
434 }
ObjectAddress RenameSchema(const char *oldname, const char *newname)
Definition: schemacmds.c:241
static void AlterSchemaOwner_internal(HeapTuple tup, Relation rel, Oid newOwnerId)
Definition: schemacmds.c:353
Oid get_namespace_oid(const char *nspname, bool missing_ok)
Definition: namespace.c:3035
void table_close(Relation relation, LOCKMODE lockmode)
Definition: table.c:133
#define GETSTRUCT(TUP)
Definition: htup_details.h:655
FormData_pg_namespace * Form_pg_namespace
Definition: pg_namespace.h:51
void SetUserIdAndSecContext(Oid userid, int sec_context)
Definition: miscinit.c:492
#define RelationGetDescr(relation)
Definition: rel.h:448
Oid GetUserId(void)
Definition: miscinit.c:380
NameData rolname
Definition: pg_authid.h:34
#define DatumGetAclP(X)
Definition: acl.h:120
#define PointerGetDatum(X)
Definition: postgres.h:556
void AlterSchemaOwner_oid(Oid oid, Oid newOwnerId)
Definition: schemacmds.c:299
char * pstrdup(const char *in)
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Definition: schemacmds.c:217
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void ProcessUtility(PlannedStmt *pstmt, const char *queryString, ProcessUtilityContext context, ParamListInfo params, QueryEnvironment *queryEnv, DestReceiver *dest, char *completionTag)
Definition: utility.c:337
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Definition: list.c:490
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Definition: heaptuple.c:1338
unsigned int Oid
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Definition: dest.c:96
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Definition: plannodes.h:96
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Definition: pg_authid.h:56
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Definition: pg_shdepend.c:309
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Definition: aclchk.c:3352
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Definition: syscache.h:183
RoleSpec * authrole
Definition: parsenodes.h:1735
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Definition: postgres.h:507
#define ERROR
Definition: elog.h:43
#define ACL_CREATE
Definition: parsenodes.h:84
ItemPointerData t_self
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Definition: namespace.c:3352
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Definition: plannodes.h:95
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Definition: miscinit.c:485
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int errdetail(const char *fmt,...)
Definition: elog.c:955
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Definition: plannodes.h:92
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Definition: schemacmds.c:50
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Definition: mcxt.c:38
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Definition: elog.h:141
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Definition: syscache.c:1116
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Definition: plannodes.h:54
AclResult
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uintptr_t Datum
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Definition: xact.c:1005
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Definition: syscache.c:1164
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Definition: syscache.c:1377
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Definition: globals.c:85
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Definition: acl.c:5217
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Definition: miscadmin.h:299
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Definition: globals.c:120
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Definition: nodes.h:573
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Definition: htup.h:78
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Definition: aclchk.c:4641
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Definition: schemacmds.c:322
#define Assert(condition)
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Definition: pg_list.h:190
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