Add Database.getSystemTable method for accessing system tables

git-svn-id: https://svn.code.sf.net/p/jackcess/code/jackcess/trunk@380 f203690c-595d-4dc9-a70b-905162fa7fd2

src/changes/changes.xml

@@ -9,6 +9,9 @@
       <action dev="jahlborn" type="add">
         Add RowFilter contributed by Patricia Donaldson.
       </action>
+      <action dev="jahlborn" type="update">
+        Add Database.getSystemTable method for accessing system tables.
+      </action>
     </release>
     <release version="1.1.17" date="2008-09-23">
       <action dev="jahlborn" type="fix" issue="2043499">

src/java/com/healthmarketscience/jackcess/Column.java

@@ -430,8 +430,10 @@ public class Column implements Comparable<Column> {
       return readNumericValue(buffer);
     } else if (_type == DataType.GUID) {
       return readGUIDValue(buffer);
-    } else if (_type == DataType.UNKNOWN_0D) {
-      return null;
+    } else if ((_type == DataType.UNKNOWN_0D) || 
+               (_type == DataType.UNKNOWN_11)) {
+      // treat like "binary" data
+      return data;
     } else {
       throw new IOException("Unrecognized data type: " + _type);
     }
@@ -973,6 +975,7 @@ public class Column implements Comparable<Column> {
         break;
         
       case BINARY:
+      case UNKNOWN_0D:
         // should already be "encoded"
         break;
       default:

src/java/com/healthmarketscience/jackcess/DataType.java

@@ -122,9 +122,9 @@ public enum DataType {
   MEMO((byte) 0x0C, Types.LONGVARCHAR, null, true, true, 0, null, 0xFFFFFF,
        JetFormat.TEXT_FIELD_UNIT_SIZE),
   /**
-   * Unknown data.  Accepts {@code null}.
+   * Unknown data.  Handled like BINARY.
    */
-  UNKNOWN_0D((byte) 0x0D),
+  UNKNOWN_0D((byte) 0x0D, null, null, true, false, 0, 255, 255, 1),
   /**
    * Corresponds to a java String with the pattern
    * <code>"{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}"</code>.  Accepts any
@@ -140,7 +140,12 @@ public enum DataType {
    */
   // for some reason numeric is "var len" even though it has a fixed size...
   NUMERIC((byte) 0x10, Types.NUMERIC, 17, true, false, 17, 17, 17,
-          true, 0, 0, 28, 1, 18, 28, 1);
+          true, 0, 0, 28, 1, 18, 28, 1),
+  /**
+   * Unknown data (seems to be an alternative OLE type, used by
+   * MSysAccessObjects table).  Handled like a fixed length BINARY/OLE.
+   */
+  UNKNOWN_11((byte) 0x11, null, 3992);
 
   /** Map of SQL types to Access data types */
   private static Map<Integer, DataType> SQL_TYPES = new HashMap<Integer, DataType>();

src/java/com/healthmarketscience/jackcess/Database.java

@@ -237,8 +237,6 @@ public class Database
   private Table _systemCatalog;
   /** System access control entries table */
   private Table _accessControlEntries;
-  /** page number of the system relationships table */
-  private Integer _relationshipsPageNumber;
   /** System relationships table (initialized on first use) */
   private Table _relationships;
   /** SIDs to use for the ACEs added for new tables */
@@ -408,8 +406,6 @@ public class Database
           int pageNumber = (Integer)row.get(CAT_COL_ID);
           _accessControlEntries = readTable(TABLE_SYSTEM_ACES, pageNumber,
                                             defaultUseBigIndex());
-        } else if(TABLE_SYSTEM_RELATIONSHIPS.equals(name)) {
-          _relationshipsPageNumber = (Integer)row.get(CAT_COL_ID);
         }
       } else if (SYSTEM_OBJECT_NAME_TABLES.equals(name)) {
         _tableParentId = (Integer) row.get(CAT_COL_ID);
@@ -541,12 +537,10 @@ public class Database
   {
     // the relationships table does not get loaded until first accessed
     if(_relationships == null) {
-      if(_relationshipsPageNumber == null) {
+      _relationships = getSystemTable(TABLE_SYSTEM_RELATIONSHIPS);
+      if(_relationships == null) {
         throw new IOException("Could not find system relationships table");
       }
-      _relationships = readTable(TABLE_SYSTEM_RELATIONSHIPS,
-                                 _relationshipsPageNumber,
-                                 defaultUseBigIndex());
     }
 
     int nameCmp = table1.getName().compareTo(table2.getName());
@@ -574,6 +568,37 @@ public class Database
     return relationships;
   }
 
+  /**
+   * Returns a reference to <i>any</i> available table in this access
+   * database, including system tables.
+   * <p>
+   * Warning, this method is not designed for common use, only for the
+   * occassional time when access to a system table is necessary.  Messing
+   * with system tables can strip the paint off your house and give your whole
+   * family a permanent, orange afro.  You have been warned.
+   * 
+   * @param tableName Table name, may be a system table
+   * @return The table, or {@code null} if it doesn't exist
+   */
+  public Table getSystemTable(String tableName)
+    throws IOException
+  {
+    for(Map<String,Object> row :
+          Cursor.createCursor(_systemCatalog).iterable(
+              SYSTEM_CATALOG_COLUMNS))
+    {
+      String name = (String) row.get(CAT_COL_NAME);
+      if (tableName.equalsIgnoreCase(name) && 
+          TYPE_TABLE.equals(row.get(CAT_COL_TYPE))) {
+        Integer pageNumber = (Integer) row.get(CAT_COL_ID);
+        if(pageNumber != null) {
+          return readTable(name, pageNumber, defaultUseBigIndex());
+        }
+      }
+    }
+    return null;
+  }
+
   /**
    * Finds the relationships matching the given from and to tables from the
    * given cursor and adds them to the given list.

test/src/java/com/healthmarketscience/jackcess/DatabaseTest.java

@@ -896,6 +896,21 @@ public class DatabaseTest extends TestCase {
       }
     }
   }
+
+  public void testSystemTable() throws Exception
+  {
+    Database db = create();
+
+    assertNotNull(db.getSystemTable("MSysAccessObjects"));
+    assertNotNull(db.getSystemTable("MSysObjects"));
+    assertNotNull(db.getSystemTable("MSysQueries"));
+    assertNotNull(db.getSystemTable("MSysACES"));
+    assertNotNull(db.getSystemTable("MSysRelationships"));
+
+    assertNull(db.getSystemTable("MSysBogus"));
+
+    db.close();
+  }
     
   static Object[] createTestRow(String col1Val) {
     return new Object[] {col1Val, "R", "McCune", 1234, (byte) 0xad, 555.66d,