Program: 32932
Project: 32932
Buggy source:
private InputStream getStream(String URL,Boolean CheckPNG){
  boolean success=false;
  File cacheFile=new File(CACHE_DIR,MD5(URL));
  boolean alreadyCached=false;
  if (cacheFile.exists() && cacheFile.length() > 1) {
    alreadyCached=true;
    logger.info("String_Node_Str");
  }
  try {
    URL U=new URL(URL);
    C=(HttpURLConnection)U.openConnection();
    C.setReadTimeout(15000);
    C.setDoInput(true);
    C.setDoOutput(false);
    C.connect();
    logger.info("String_Node_Str" + C.getResponseCode());
    int respcode=C.getResponseCode() / 100;
    if (respcode != 4 && respcode != 5) {
      if (alreadyCached && C.getLastModified() == cacheFile.lastModified()) {
        logger.info("String_Node_Str");
        return getStreamFromCache(cacheFile);
      }
      if (C.getContentLength() <= 0) {
        return null;
      }
      InputStream IS=new BufferedInputStream(C.getInputStream());
      if (!CheckPNG) {
        success=true;
        saveToCache(IS,cacheFile);
        return IS;
      }
      IS.mark(C.getContentLength() + 10);
      byte[] ib=new byte[4];
      IS.read(ib);
      if (ib[1] == (byte)'P' && ib[2] == (byte)'N' && ib[3] == (byte)'G') {
        IS.reset();
        success=true;
        saveToCache(IS,cacheFile);
        return IS;
      }
    }
  }
 catch (  Exception ex) {
    success=false;
    logger.log(Level.WARNING,ex.getMessage());
    if (alreadyCached)     return getStreamFromCache(cacheFile);
  }
 finally {
    if (!success)     disconnect();
  }
  return null;
}

Fixed version (ground truth):
private InputStream getStream(String URL,Boolean CheckPNG){
  boolean success=false;
  File cacheFile=new File(CACHE_DIR,MD5(URL));
  boolean alreadyCached=false;
  if (cacheFile.exists() && cacheFile.length() > 1) {
    alreadyCached=true;
    logger.info("String_Node_Str" + cacheFile.lastModified() + "String_Node_Str"+ cacheFile.length()+ "String_Node_Str");
  }
  try {
    URL U=new URL(URL);
    C=(HttpURLConnection)U.openConnection();
    C.setReadTimeout(15000);
    C.setDoInput(true);
    C.setDoOutput(false);
    C.connect();
    logger.info("String_Node_Str" + C.getResponseCode());
    int respcode=C.getResponseCode() / 100;
    if (respcode != 4 && respcode != 5) {
      if (C.getContentLength() <= 0) {
        logger.info("String_Node_Str");
        return null;
      }
      logger.info("String_Node_Str" + C.getLastModified() + "String_Node_Str"+ C.getContentLength()+ "String_Node_Str");
      if (alreadyCached && C.getLastModified() == cacheFile.lastModified() && C.getContentLength() == cacheFile.length()) {
        logger.info("String_Node_Str");
        return getStreamFromCache(cacheFile);
      }
      InputStream IS=new BufferedInputStream(C.getInputStream());
      if (!CheckPNG) {
        success=true;
        saveToCache(IS,cacheFile);
        return IS;
      }
      IS.mark(C.getContentLength() + 10);
      byte[] ib=new byte[4];
      IS.read(ib);
      if (ib[1] == (byte)'P' && ib[2] == (byte)'N' && ib[3] == (byte)'G') {
        IS.reset();
        success=true;
        saveToCache(IS,cacheFile);
        return IS;
      }
    }
  }
 catch (  Exception ex) {
    success=false;
    logger.log(Level.WARNING,ex.getMessage());
    if (alreadyCached)     return getStreamFromCache(cacheFile);
  }
 finally {
    if (!success)     disconnect();
  }
  return null;
}