In CREATE CONVERSION, test that the given function is a valid conversion

function for the specified source and destination encodings. We do that by
calling the function with an empty string. If it can't perform the requested
conversion, it will throw an error.

Backport to 7.4 - 8.3. Per bug report #4680 by Denis Afonin.

diff --git a/src/backend/commands/conversioncmds.c b/src/backend/commands/conversioncmds.c
index 53b3f854ce64ca3f9d58bbb48bd16020005d68c1..bb430273b20e202f29f426d6b32d8e1e2bc3ac45 100644 (file)
--- a/src/backend/commands/conversioncmds.c
+++ b/src/backend/commands/conversioncmds.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/commands/conversioncmds.c,v 1.23 2005/10/15 02:49:15 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/commands/conversioncmds.c,v 1.23.2.1 2009/02/27 16:35:42 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -47,6 +47,7 @@ CreateConversionCommand(CreateConversionStmt *stmt)
        const char *to_encoding_name = stmt->to_encoding_name;
        List       *func_name = stmt->func_name;
        static Oid      funcargs[] = {INT4OID, INT4OID, CSTRINGOID, INTERNALOID, INT4OID};
+       char            result[1];
 
        /* Convert list of names to a name and namespace */
        namespaceId = QualifiedNameGetCreationNamespace(stmt->conversion_name,
@@ -86,6 +87,19 @@ CreateConversionCommand(CreateConversionStmt *stmt)
                aclcheck_error(aclresult, ACL_KIND_PROC,
                                           NameListToString(func_name));
 
+       /*
+        * Check that the conversion function is suitable for the requested
+        * source and target encodings. We do that by calling the function with
+        * an empty string; the conversion function should throw an error if it
+        * can't perform the requested conversion.
+        */
+       OidFunctionCall5(funcoid,
+                                        Int32GetDatum(from_encoding),
+                                        Int32GetDatum(to_encoding),
+                                        CStringGetDatum(""),
+                                        CStringGetDatum(result),
+                                        Int32GetDatum(0));
+
        /*
         * All seem ok, go ahead (possible failure would be a duplicate conversion
         * name)