Class CGIServlet.CGIRunner

  • Enclosing class:

    protected class CGIServlet.CGIRunner
    extends Object
    Encapsulates the knowledge of how to run a CGI script, given the script's desired environment and (optionally) input/output streams

    Exposes a run method used to actually invoke the CGI.

    The CGI environment and settings are derived from the information passed to the constructor.

    The input and output streams can be set by the setInput and setResponse methods, respectively.

    • Constructor Detail

      • CGIRunner

        protected CGIRunner​(String command,
                            Hashtable<String,​String> env,
                            File wd,
                            ArrayList<String> params)
        Creates a CGIRunner and initializes its environment, working directory, and query parameters.
        Input/output streams (optional) are set using the setInput and setResponse methods, respectively.
        command - string full path to command to be executed
        env - Hashtable with the desired script environment
        wd - File with the script's desired working directory
        params - ArrayList with the script's query command line parameters as strings
    • Method Detail

      • updateReadyStatus

        protected void updateReadyStatus()
        Checks and sets ready status
      • isReady

        protected boolean isReady()
        Gets ready status
        false if not ready (run will throw an exception), true if ready
      • setResponse

        protected void setResponse​(HttpServletResponse response)
        Sets HttpServletResponse object used to set headers and send output to
        response - HttpServletResponse to be used
      • setInput

        protected void setInput​(InputStream stdin)
        Sets standard input to be passed on to the invoked cgi script
        stdin - InputStream to be used
      • hashToStringArray

        protected String[] hashToStringArray​(Hashtable<String,​?> h)
                                      throws NullPointerException
        Converts a Hashtable to a String array by converting each key/value pair in the Hashtable to a String in the form "key=value" (hashkey + "=" + hash.get(hashkey).toString())
        h - Hashtable to convert
        converted string array
        NullPointerException - if a hash key has a null value
      • run

        protected void run()
                    throws IOException
        Executes a CGI script with the desired environment, current working directory, and input/output streams

        This implements the following CGI specification recommendations:

        • Servers SHOULD provide the "query" component of the script-URI as command-line arguments to scripts if it does not contain any unencoded "=" characters and the command-line arguments can be generated in an unambiguous manner.
        • Servers SHOULD set the AUTH_TYPE metavariable to the value of the "auth-scheme" token of the "Authorization" if it was supplied as part of the request header. See getCGIEnvironment method.
        • Where applicable, servers SHOULD set the current working directory to the directory in which the script is located before invoking it.
        • Server implementations SHOULD define their behavior for the following cases:
          • Allowed characters in pathInfo: This implementation does not allow ASCII NUL nor any character which cannot be URL-encoded according to internet standards;
          • Allowed characters in path segments: This implementation does not allow non-terminal NULL segments in the the path -- IOExceptions may be thrown;
          • "." and ".." path segments: This implementation does not allow "." and ".." in the the path, and such characters will result in an IOException being thrown (this should never happen since Tomcat normalises the requestURI before determining the contextPath, servletPath and pathInfo);
          • Implementation limitations: This implementation does not impose any limitations except as documented above. This implementation may be limited by the servlet container used to house this implementation. In particular, all the primary CGI variable values are derived either directly or indirectly from the container's implementation of the Servlet API methods.
        IOException - if problems during reading/writing occur
        See Also:
        Runtime.exec(String command, String[] envp, File dir)