Index: driver/utility.c
===================================================================
--- driver/utility.c	(revision 1012)
+++ driver/utility.c	(working copy)
@@ -571,7 +571,7 @@
 
   @return  The column size of the field
 */
-SQLLEN get_column_size(STMT *stmt __attribute__((unused)), MYSQL_FIELD *field,
+SQLLEN get_column_size(STMT *stmt, MYSQL_FIELD *field,
                        my_bool actual)
 {
   CHARSET_INFO *charset= get_charset(field->charsetnr, MYF(0));
@@ -643,7 +643,8 @@
   case MYSQL_TYPE_BLOB:
   case MYSQL_TYPE_GEOMETRY:
     if (field->charsetnr == 63)
-      return length;
+      return (stmt->dbc->flag && FLAG_COLUMN_SIZE_S32) ?
+              (length > INT_MAX32 ? INT_MAX32 : length) : length;
     else
       return length / mbmaxlen;
   }
Index: test/my_catalog.c
===================================================================
--- test/my_catalog.c	(revision 1012)
+++ test/my_catalog.c	(working copy)
@@ -1129,6 +1129,71 @@
 }
 
 
+/**
+ Bug #12805: LONGBLOB Problem
+*/
+DECLARE_TEST(t_bug12805)
+{
+  HDBC hdbc1;
+  HSTMT hstmt1;
+
+  SQLCHAR   conn[256], conn_out[256];
+  SQLSMALLINT conn_out_len;
+  SQLULEN length;
+
+  /* Limit column size to a signed 32-bit value */
+  sprintf(conn, "DRIVER=%s;USER=%s;PASSWORD=%s;"
+                "DATABASE=%s;SERVER=%s;OPTION=67108864",
+          mydriver, myuid, mypwd, mydb, myserver);
+
+  if (mysock != NULL)
+  {
+    strcat((char *)conn, ";SOCKET=");
+    strcat((char *)conn, (char *)mysock);
+  }
+
+  ok_env(henv, SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc1));
+
+  ok_con(hdbc1, SQLDriverConnect(hdbc1, NULL, conn, sizeof(conn), conn_out,
+                                 sizeof(conn_out), &conn_out_len,
+                                 SQL_DRIVER_NOPROMPT));
+  ok_con(hdbc1, SQLAllocStmt(hdbc1, &hstmt1));
+
+  ok_sql(hstmt1, "DROP TABLE IF EXISTS bug12805");
+  ok_sql(hstmt1, "CREATE TABLE bug12805("\
+                 "id INT PRIMARY KEY auto_increment,"\
+                 "longimagedata LONGBLOB NULL)");
+
+  ok_stmt(hstmt1, SQLColumns(hstmt1, NULL, 0, NULL, 0,
+                             (SQLCHAR *)"bug12805", SQL_NTS,
+                             (SQLCHAR *)"longimagedata", SQL_NTS));
+
+  ok_stmt(hstmt1, SQLFetch(hstmt1));
+  ok_stmt(hstmt1, SQLGetData(hstmt1, 7, SQL_C_ULONG, &length,
+                             sizeof(SQLULEN), NULL));
+  is_num(length, 2147483647);
+  ok_stmt(hstmt1, SQLFreeStmt(hstmt1, SQL_CLOSE));
+
+  ok_con(hdbc1, SQLDisconnect(hdbc1));
+  ok_con(hdbc1, SQLFreeConnect(hdbc1));
+
+  /* Check without the 32-bit signed flag */
+  ok_stmt(hstmt, SQLColumns(hstmt, NULL, 0, NULL, 0,
+                            (SQLCHAR *)"bug12805", SQL_NTS,
+                            (SQLCHAR *)"longimagedata", SQL_NTS));
+
+  ok_stmt(hstmt, SQLFetch(hstmt));
+  ok_stmt(hstmt, SQLGetData(hstmt, 7, SQL_C_ULONG, &length,
+                             sizeof(SQLULEN), NULL));
+  is_num(length, 4294967295);
+
+  ok_stmt(hstmt, SQLFreeStmt(hstmt, SQL_CLOSE));
+  ok_sql(hstmt, "DROP TABLE bug12805");
+
+  return OK;
+}
+
+
 BEGIN_TESTS
   ADD_TEST(my_columns_null)
   ADD_TEST(my_drop_table)
@@ -1151,6 +1216,7 @@
   ADD_TEST(t_bug26934)
   ADD_TEST(t_bug29888)
   ADD_TEST(t_bug14407)
+  ADD_TEST(t_bug12805)
 END_TESTS