granicus.if.org Git - postgresql/blob - src/backend/commands/lockcmds.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * lockcmds.c
   4  *        Lock command support code
   5  *
   6  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $PostgreSQL: pgsql/src/backend/commands/lockcmds.c,v 1.12 2004/12/31 21:59:41 pgsql Exp $
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #include "postgres.h"
  16
  17 #include "access/heapam.h"
  18 #include "catalog/namespace.h"
  19 #include "commands/lockcmds.h"
  20 #include "miscadmin.h"
  21 #include "utils/acl.h"
  22 #include "utils/lsyscache.h"
  23
  24
  25 /*
  26  * LOCK TABLE
  27  */
  28 void
  29 LockTableCommand(LockStmt *lockstmt)
  30 {
  31         ListCell   *p;
  32
  33         /*
  34          * Iterate over the list and open, lock, and close the relations one
  35          * at a time
  36          */
  37
  38         foreach(p, lockstmt->relations)
  39         {
  40                 RangeVar   *relation = lfirst(p);
  41                 Oid                     reloid;
  42                 AclResult       aclresult;
  43                 Relation        rel;
  44
  45                 /*
  46                  * We don't want to open the relation until we've checked
  47                  * privilege. So, manually get the relation OID.
  48                  */
  49                 reloid = RangeVarGetRelid(relation, false);
  50
  51                 if (lockstmt->mode == AccessShareLock)
  52                         aclresult = pg_class_aclcheck(reloid, GetUserId(),
  53                                                                                   ACL_SELECT);
  54                 else
  55                         aclresult = pg_class_aclcheck(reloid, GetUserId(),
  56                                                                                   ACL_UPDATE | ACL_DELETE);
  57
  58                 if (aclresult != ACLCHECK_OK)
  59                         aclcheck_error(aclresult, ACL_KIND_CLASS,
  60                                                    get_rel_name(reloid));
  61
  62                 rel = conditional_relation_open(reloid, lockstmt->mode, lockstmt->nowait);
  63
  64                 /* Currently, we only allow plain tables to be locked */
  65                 if (rel->rd_rel->relkind != RELKIND_RELATION)
  66                         ereport(ERROR,
  67                                         (errcode(ERRCODE_WRONG_OBJECT_TYPE),
  68                                          errmsg("\"%s\" is not a table",
  69                                                         relation->relname)));
  70
  71                 relation_close(rel, NoLock);    /* close rel, keep lock */
  72         }
  73 }