fixes #127 Possible ArrayIndexOutOfBoundsException in MigrationReader.

Author: harawata

src/main/java/org/apache/ibatis/migration/MigrationReader.java

@@ -124,7 +124,7 @@ public int read(char[] cbuf, int off, int len) throws IOException {
                 if (bufferLen == 0) {
                   return -1;
                 } else {
-                  return readFromBuffer(cbuf, off, bufferLen);
+                  return readFromBuffer(cbuf, off, len);
                 }
               }
               break;

src/test/java/org/apache/ibatis/migration/MigrationReaderTest.java

@@ -22,6 +22,7 @@
 import java.io.InputStream;
 import java.io.Reader;
 import java.io.UnsupportedEncodingException;
+import java.util.Arrays;
 import java.util.Properties;
 
 import org.junit.After;
@@ -305,6 +306,27 @@ public void shouldRespectSpecifiedOffsetAndLength() throws Exception {
     }
   }
 
+  @Test
+  public void testReadWithBuffer() throws Exception {
+    // @formatter:off
+    String script = "long do part 123456789012345678901234567890\n"
+        + "--//@UNDO\n"
+        + "undo part\n";
+    // @formatter:on
+    MigrationReader reader = new MigrationReader(strToInputStream(script, charset), charset, false, null);
+    try {
+      StringBuilder buffer = new StringBuilder();
+      char[] cbuf = new char[30];
+      int res;
+      while ((res = reader.read(cbuf)) != -1) {
+        buffer.append(res == cbuf.length ? cbuf : Arrays.copyOf(cbuf, res));
+      }
+      assertEquals("long do part 123456789012345678901234567890\n", buffer.toString());
+    } finally {
+      reader.close();
+    }
+  }
+
   private String readAsString(Reader reader) throws IOException {
     try {
       StringBuilder buffer = new StringBuilder();