src/backend/commands/proclang.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * proclang.c
   4  *        PostgreSQL PROCEDURAL LANGUAGE support code.
   5  *
   6  *-------------------------------------------------------------------------
   7  */
   8 #include <ctype.h>
   9
  10 #include "postgres.h"
  11
  12 #include "access/heapam.h"
  13 #include "catalog/catname.h"
  14 #include "catalog/indexing.h"
  15 #include "catalog/pg_language.h"
  16 #include "catalog/pg_proc.h"
  17 #include "catalog/pg_shadow.h"
  18 #include "commands/proclang.h"
  19 #include "fmgr.h"
  20 #include "utils/syscache.h"
  21
  22
  23 static void
  24 case_translate_language_name(const char *input, char *output)
  25 {
  26 /*-------------------------------------------------------------------------
  27   Translate the input language name to lower case, except if it's C,
  28   translate to upper case.
  29 --------------------------------------------------------------------------*/
  30         int                     i;
  31
  32         for (i = 0; i < NAMEDATALEN && input[i]; ++i)
  33                 output[i] = tolower(input[i]);
  34
  35         output[i] = '\0';
  36
  37         if (strcmp(output, "c") == 0)
  38                 output[0] = 'C';
  39 }
  40
  41
  42 /* ---------------------------------------------------------------------
  43  * CREATE PROCEDURAL LANGUAGE
  44  * ---------------------------------------------------------------------
  45  */
  46 void
  47 CreateProceduralLanguage(CreatePLangStmt *stmt)
  48 {
  49         char            languageName[NAMEDATALEN];
  50         HeapTuple       langTup;
  51         HeapTuple       procTup;
  52
  53         Oid                     typev[8];
  54         char            nulls[Natts_pg_language];
  55         Datum           values[Natts_pg_language];
  56         Relation        rel;
  57         HeapTuple       tup;
  58         TupleDesc       tupDesc;
  59
  60         int                     i;
  61
  62         /* ----------------
  63          * Check permission
  64          * ----------------
  65          */
  66         if (!superuser())
  67         {
  68                 elog(ERROR, "Only users with Postgres superuser privilege are "
  69                          "permitted to create procedural languages");
  70         }
  71
  72         /* ----------------
  73          * Translate the language name and check that
  74          * this language doesn't already exist
  75          * ----------------
  76          */
  77         case_translate_language_name(stmt->plname, languageName);
  78
  79         langTup = SearchSysCacheTuple(LANGNAME,
  80                                                                   PointerGetDatum(languageName),
  81                                                                   0, 0, 0);
  82         if (HeapTupleIsValid(langTup))
  83                 elog(ERROR, "Language %s already exists", languageName);
  84
  85         /* ----------------
  86          * Lookup the PL handler function and check that it is
  87          * of return type Opaque
  88          * ----------------
  89          */
  90         memset(typev, 0, sizeof(typev));
  91         procTup = SearchSysCacheTuple(PROCNAME,
  92                                                                   PointerGetDatum(stmt->plhandler),
  93                                                                   Int32GetDatum(0),
  94                                                                   PointerGetDatum(typev),
  95                                                                   0);
  96         if (!HeapTupleIsValid(procTup))
  97         {
  98                 elog(ERROR, "PL handler function %s() doesn't exist",
  99                          stmt->plhandler);
 100         }
 101         if (((Form_pg_proc) GETSTRUCT(procTup))->prorettype != InvalidOid)
 102         {
 103                 elog(ERROR, "PL handler function %s() isn't of return type Opaque",
 104                          stmt->plhandler);
 105         }
 106
 107         /* ----------------
 108          * Insert the new language into pg_language
 109          * ----------------
 110          */
 111         for (i = 0; i < Natts_pg_language; i++)
 112         {
 113                 nulls[i] = ' ';
 114                 values[i] = (Datum) NULL;
 115         }
 116
 117         i = 0;
 118         values[i++] = PointerGetDatum(languageName);
 119         values[i++] = Int8GetDatum((bool) 1);
 120         values[i++] = Int8GetDatum(stmt->pltrusted);
 121         values[i++] = ObjectIdGetDatum(procTup->t_data->t_oid);
 122         values[i++] = (Datum) fmgr(F_TEXTIN, stmt->plcompiler);
 123
 124         rel = heap_openr(LanguageRelationName, RowExclusiveLock);
 125
 126         tupDesc = rel->rd_att;
 127         tup = heap_formtuple(tupDesc, values, nulls);
 128
 129         heap_insert(rel, tup);
 130
 131         if (RelationGetForm(rel)->relhasindex)
 132         {
 133                 Relation        idescs[Num_pg_language_indices];
 134
 135                 CatalogOpenIndices(Num_pg_language_indices, Name_pg_language_indices, idescs);
 136                 CatalogIndexInsert(idescs, Num_pg_language_indices, rel, tup);
 137                 CatalogCloseIndices(Num_pg_language_indices, idescs);
 138         }
 139
 140         heap_close(rel, RowExclusiveLock);
 141 }
 142
 143
 144 /* ---------------------------------------------------------------------
 145  * DROP PROCEDURAL LANGUAGE
 146  * ---------------------------------------------------------------------
 147  */
 148 void
 149 DropProceduralLanguage(DropPLangStmt *stmt)
 150 {
 151         char            languageName[NAMEDATALEN];
 152         HeapTuple       langTup;
 153         Relation        rel;
 154
 155         /* ----------------
 156          * Check permission
 157          * ----------------
 158          */
 159         if (!superuser())
 160         {
 161                 elog(ERROR, "Only users with Postgres superuser privilege are "
 162                          "permitted to drop procedural languages");
 163         }
 164
 165         /* ----------------
 166          * Translate the language name, check that
 167          * this language exist and is a PL
 168          * ----------------
 169          */
 170         case_translate_language_name(stmt->plname, languageName);
 171
 172         rel = heap_openr(LanguageRelationName, RowExclusiveLock);
 173
 174         langTup = SearchSysCacheTupleCopy(LANGNAME,
 175                                                                           PointerGetDatum(languageName),
 176                                                                           0, 0, 0);
 177         if (!HeapTupleIsValid(langTup))
 178                 elog(ERROR, "Language %s doesn't exist", languageName);
 179
 180         if (!((Form_pg_language) GETSTRUCT(langTup))->lanispl)
 181                 elog(ERROR, "Language %s isn't a created procedural language",
 182                          languageName);
 183
 184         heap_delete(rel, &langTup->t_self, NULL);
 185
 186         heap_freetuple(langTup);
 187         heap_close(rel, RowExclusiveLock);
 188 }