FileSystem: improve exception throwing compatibility with JDK

h2/src/docsrc/html/changelog.html

@@ -23,6 +23,7 @@ Change Log
 </li><li>Follow JDBC specification on Procedures MetaData, use P0 as
     return type of procedure.
 </li><li>Issue 531: IDENTITY ignored for added column.
+</li><li>FileSystem: improve exception throwing compatibility with JDK
 </li></ul>
 
 <h2>Version 1.4.178 Beta (2014-05-02)</h2>

h2/src/main/org/h2/store/fs/FilePathDisk.java

@@ -18,6 +18,7 @@ import java.net.URL;
 import java.nio.ByteBuffer;
 import java.nio.channels.FileChannel;
 import java.nio.channels.FileLock;
+import java.nio.channels.NonWritableChannelException;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -395,10 +396,12 @@ class FileDisk extends FileBase {
 
     private final RandomAccessFile file;
     private final String name;
+    private final boolean readOnly;
 
     FileDisk(String fileName, String mode) throws FileNotFoundException {
         this.file = new RandomAccessFile(fileName, mode);
         this.name = fileName;
+        this.readOnly = mode.equals("r");
     }
 
     @Override
@@ -419,6 +422,10 @@ class FileDisk extends FileBase {
 
     @Override
     public FileChannel truncate(long newLength) throws IOException {
+    	// compatibility with JDK FileChannel#truncate
+    	if (readOnly) {
+    		throw new NonWritableChannelException();
+    	}
         if (newLength < file.length()) {
             file.setLength(newLength);
         }

h2/src/main/org/h2/store/fs/FilePathMem.java

@@ -12,6 +12,7 @@ import java.io.OutputStream;
 import java.nio.ByteBuffer;
 import java.nio.channels.FileChannel;
 import java.nio.channels.FileLock;
+import java.nio.channels.NonWritableChannelException;
 import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -264,6 +265,10 @@ class FileMem extends FileBase {
 
     @Override
     public FileChannel truncate(long newLength) throws IOException {
+    	// compatibility with JDK FileChannel#truncate
+    	if (readOnly) {
+    		throw new NonWritableChannelException();
+    	}
         if (newLength < size()) {
             data.touch(readOnly);
             pos = Math.min(pos, newLength);

h2/src/main/org/h2/store/fs/FilePathNio.java

@@ -82,28 +82,24 @@ class FileNio extends FileBase {
 
     @Override
     public FileChannel truncate(long newLength) throws IOException {
-        try {
-            long size = channel.size();
-            if (newLength < size) {
-                long pos = channel.position();
-                channel.truncate(newLength);
-                long newPos = channel.position();
-                if (pos < newLength) {
-                    // position should stay
-                    // in theory, this should not be needed
-                    if (newPos != pos) {
-                        channel.position(pos);
-                    }
-                } else if (newPos > newLength) {
-                    // looks like a bug in this FileChannel implementation, as
-                    // the documentation says the position needs to be changed
-                    channel.position(newLength);
+        long size = channel.size();
+        if (newLength < size) {
+            long pos = channel.position();
+            channel.truncate(newLength);
+            long newPos = channel.position();
+            if (pos < newLength) {
+                // position should stay
+                // in theory, this should not be needed
+                if (newPos != pos) {
+                    channel.position(pos);
                 }
+            } else if (newPos > newLength) {
+                // looks like a bug in this FileChannel implementation, as
+                // the documentation says the position needs to be changed
+                channel.position(newLength);
             }
-            return this;
-        } catch (NonWritableChannelException e) {
-            throw new IOException("read only");
         }
+        return this;
     }
 
     @Override

h2/src/main/org/h2/store/fs/FilePathNioMapped.java

@@ -16,6 +16,7 @@ import java.nio.ByteBuffer;
 import java.nio.MappedByteBuffer;
 import java.nio.channels.FileChannel;
 import java.nio.channels.FileLock;
+import java.nio.channels.NonWritableChannelException;
 
 import org.h2.engine.SysProperties;
 
@@ -203,6 +204,10 @@ class FileNioMapped extends FileBase {
 
     @Override
     public synchronized FileChannel truncate(long newLength) throws IOException {
+    	// compatibility with JDK FileChannel#truncate
+    	if (mode == MapMode.READ_ONLY) {
+    		throw new NonWritableChannelException();
+    	}
         if (newLength < size()) {
             setFileLength(newLength);
         }

h2/src/main/org/h2/store/fs/FilePathNioMem.java

@@ -12,6 +12,7 @@ import java.io.OutputStream;
 import java.nio.ByteBuffer;
 import java.nio.channels.FileChannel;
 import java.nio.channels.FileLock;
+import java.nio.channels.NonWritableChannelException;
 import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -256,6 +257,10 @@ class FileNioMem extends FileBase {
 
     @Override
     public FileChannel truncate(long newLength) throws IOException {
+    	// compatibility with JDK FileChannel#truncate
+    	if (readOnly) {
+    		throw new NonWritableChannelException();
+    	}
         if (newLength < size()) {
             data.touch(readOnly);
             pos = Math.min(pos, newLength);

h2/src/test/org/h2/test/unit/TestFileSystem.java

@@ -15,6 +15,7 @@ import java.nio.ByteBuffer;
 import java.nio.channels.FileChannel;
 import java.nio.channels.FileChannel.MapMode;
 import java.nio.channels.FileLock;
+import java.nio.channels.NonWritableChannelException;
 import java.sql.Connection;
 import java.sql.ResultSet;
 import java.sql.SQLException;
@@ -549,7 +550,7 @@ public class TestFileSystem extends TestBase {
                 fc.write(ByteBuffer.wrap(test, 0, 10));
             }
         };
-        new AssertThrows(IOException.class) {
+        new AssertThrows(NonWritableChannelException.class) {
             @Override
             public void test() throws Exception {
                 fc.truncate(10);