Program: 180206
Project: 180206
Buggy source:
public XmlNode parse(Reader reader) throws IOException {
  if (!(reader.markSupported())) {
    this.reader=new BufferedReader(reader);
  }
 else {
    this.reader=reader;
  }
  skipPrologs();
  while (true) {
    int index;
    String tagName;
    String currentTag=readTag().trim();
    if (currentTag.startsWith("String_Node_Str")) {
      tagName=currentTag.substring(2,currentTag.length() - 1);
      if (ignoreNamespaces) {
        tagName=stripNamespace(tagName);
      }
      if (currentElement == null) {
        throw new IOException("String_Node_Str" + tagName + "String_Node_Str");
      }
      if (!tagName.equals(currentElement.getName())) {
        throw new IOException("String_Node_Str" + currentElement.getName() + "String_Node_Str"+ tagName+ "String_Node_Str");
      }
      if (elements.empty()) {
        return currentElement;
      }
 else {
        currentElement=(XmlNode)elements.pop();
      }
    }
 else {
      index=currentTag.indexOf("String_Node_Str");
      if (index < 0) {
        if (currentTag.endsWith("String_Node_Str")) {
          tagName=currentTag.substring(1,currentTag.length() - 2);
          currentTag="String_Node_Str";
        }
 else {
          tagName=currentTag.substring(1,currentTag.length() - 1);
          if (ignoreNamespaces) {
            tagName=stripNamespace(tagName);
          }
          currentTag="String_Node_Str";
        }
      }
 else {
        tagName=currentTag.substring(1,index);
        if (ignoreNamespaces) {
          tagName=stripNamespace(tagName);
        }
        currentTag=currentTag.substring(index + 1);
      }
      XmlNode element=new XmlNode(tagName,"String_Node_Str");
      boolean isTagClosed=false;
      while (currentTag.length() > 0) {
        currentTag=currentTag.trim();
        if (currentTag.equals("String_Node_Str")) {
          isTagClosed=true;
          break;
        }
 else         if (currentTag.equals("String_Node_Str")) {
          break;
        }
        index=currentTag.indexOf("String_Node_Str");
        if (index < 0) {
          throw new IOException("String_Node_Str" + tagName + "String_Node_Str");
        }
        String attributeName=currentTag.substring(0,index);
        if (ignoreNamespaces) {
          attributeName=stripNamespace(attributeName);
        }
        currentTag=currentTag.substring(index + 1);
        String attributeValue;
        boolean isQuoted=true;
        if (currentTag.startsWith("String_Node_Str")) {
          index=currentTag.indexOf('"',1);
        }
 else         if (currentTag.startsWith("String_Node_Str")) {
          index=currentTag.indexOf('\'',1);
        }
 else {
          isQuoted=false;
          index=currentTag.indexOf(' ');
          if (index < 0) {
            index=currentTag.indexOf('>');
            if (index < 0) {
              index=currentTag.indexOf('/');
            }
          }
        }
        if (index < 0) {
          throw new IOException("String_Node_Str" + tagName + "String_Node_Str");
        }
        if (isQuoted) {
          attributeValue=currentTag.substring(1,index);
        }
 else {
          attributeValue=currentTag.substring(0,index);
        }
        element.setAttribute(attributeName,attributeValue);
        currentTag=currentTag.substring(index + 1);
      }
      if (!isTagClosed) {
        element.setValue(readText());
      }
      if (currentElement != null) {
        try {
          element.setParent(currentElement);
        }
 catch (        SelfReferenceException e) {
          throw new IOException(e.getMessage());
        }
      }
      if (!isTagClosed) {
        if (currentElement != null) {
          elements.push(currentElement);
        }
        currentElement=element;
      }
 else       if (currentElement == null) {
        return element;
      }
    }
  }
}

Fixed version (ground truth):
public XmlNode parse(Reader reader) throws IOException {
  if (!(reader.markSupported())) {
    this.reader=new BufferedReader(reader);
  }
 else {
    this.reader=reader;
  }
  skipPrologs();
  while (true) {
    int index;
    String tagName;
    String currentTag=readTag().trim();
    if (currentTag.startsWith("String_Node_Str")) {
      tagName=currentTag.substring(2,currentTag.length() - 1);
      if (ignoreNamespaces) {
        tagName=stripNamespace(tagName);
      }
      if (currentElement == null) {
        throw new IOException("String_Node_Str" + tagName + "String_Node_Str");
      }
      if (!tagName.equals(currentElement.getName())) {
        throw new IOException("String_Node_Str" + currentElement.getName() + "String_Node_Str"+ tagName+ "String_Node_Str");
      }
      if (elements.empty()) {
        return currentElement;
      }
 else {
        currentElement=(XmlNode)elements.pop();
      }
    }
 else {
      index=currentTag.indexOf("String_Node_Str");
      if (index < 0) {
        if (currentTag.endsWith("String_Node_Str")) {
          tagName=currentTag.substring(1,currentTag.length() - 2);
          currentTag="String_Node_Str";
        }
 else {
          tagName=currentTag.substring(1,currentTag.length() - 1);
          if (ignoreNamespaces) {
            tagName=stripNamespace(tagName);
          }
          currentTag="String_Node_Str";
        }
      }
 else {
        tagName=currentTag.substring(1,index);
        if (ignoreNamespaces) {
          tagName=stripNamespace(tagName);
        }
        currentTag=currentTag.substring(index + 1);
      }
      XmlNode element=new XmlNode(tagName);
      boolean isTagClosed=false;
      while (currentTag.length() > 0) {
        currentTag=currentTag.trim();
        if (currentTag.equals("String_Node_Str")) {
          isTagClosed=true;
          break;
        }
 else         if (currentTag.equals("String_Node_Str")) {
          break;
        }
        index=currentTag.indexOf("String_Node_Str");
        if (index < 0) {
          throw new IOException("String_Node_Str" + tagName + "String_Node_Str");
        }
        String attributeName=currentTag.substring(0,index);
        if (ignoreNamespaces) {
          attributeName=stripNamespace(attributeName);
        }
        currentTag=currentTag.substring(index + 1);
        String attributeValue;
        boolean isQuoted=true;
        if (currentTag.startsWith("String_Node_Str")) {
          index=currentTag.indexOf('"',1);
        }
 else         if (currentTag.startsWith("String_Node_Str")) {
          index=currentTag.indexOf('\'',1);
        }
 else {
          isQuoted=false;
          index=currentTag.indexOf(' ');
          if (index < 0) {
            index=currentTag.indexOf('>');
            if (index < 0) {
              index=currentTag.indexOf('/');
            }
          }
        }
        if (index < 0) {
          throw new IOException("String_Node_Str" + tagName + "String_Node_Str");
        }
        if (isQuoted) {
          attributeValue=currentTag.substring(1,index);
        }
 else {
          attributeValue=currentTag.substring(0,index);
        }
        element.setAttribute(attributeName,attributeValue);
        currentTag=currentTag.substring(index + 1);
      }
      if (!isTagClosed) {
        element.setValue(readText());
      }
      if (currentElement != null) {
        try {
          element.setParent(currentElement);
        }
 catch (        SelfReferenceException e) {
          throw new IOException(e.getMessage());
        }
      }
      if (!isTagClosed) {
        if (currentElement != null) {
          elements.push(currentElement);
        }
        currentElement=element;
      }
 else       if (currentElement == null) {
        return element;
      }
    }
  }
}