Exposes a run method used to actually invoke the CGI.

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

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

 protected  void doGet(HttpServletRequest req,
    HttpServletResponse res) throws ServletException, IOException 
{
        // Verify that we were not accessed using the invoker servlet
        if (req.getAttribute(Globals.INVOKED_ATTR) != null)
            throw new UnavailableException
                ("Cannot invoke CGIServlet through the invoker");
        CGIEnvironment cgiEnv = new CGIEnvironment(req, getServletContext());
        if (cgiEnv.isValid()) {
            CGIRunner cgi = new CGIRunner(cgiEnv.getCommand(),
                                          cgiEnv.getEnvironment(),
                                          cgiEnv.getWorkingDirectory(),
                                          cgiEnv.getParameters());
            //if POST, we need to cgi.setInput
            //REMIND: how does this interact with Servlet API 2.3's Filters?!
            if ("POST".equals(req.getMethod())) {
                cgi.setInput(req.getInputStream());
            }
            cgi.setResponse(res);
            cgi.run();
        }
        if (!cgiEnv.isValid()) {
            res.setStatus(404);
        }
        if (debug  >= 10) {
            ServletOutputStream out = res.getOutputStream();
            out.println("< HTML >< HEAD >< TITLE >$Name$< /TITLE >< /HEAD >");
            out.println("< BODY >$Header$< p >");
            if (cgiEnv.isValid()) {
                out.println(cgiEnv.toString());
            } else {
                out.println("< H3 >");
                out.println("CGI script not found or not specified.");
                out.println("< /H3 >");
                out.println("< H4 >");
                out.println("Check the < b >HttpServletRequest ");
                out.println("< a href=\"#pathInfo\" >pathInfo< /a >< /b > ");
                out.println("property to see if it is what you meant ");
                out.println("it to be.  You must specify an existant ");
                out.println("and executable file as part of the ");
                out.println("path-info.");
                out.println("< /H4 >");
                out.println("< H4 >");
                out.println("For a good discussion of how CGI scripts ");
                out.println("work and what their environment variables ");
                out.println("mean, please visit the < a ");
                out.println("href=\"http://cgi-spec.golux.com\" >CGI ");
                out.println("Specification page< /a >.");
                out.println("< /H4 >");
            }
            printServletEnvironment(out, req, res);
            out.println("< /BODY >< /HTML >");
        }
}

Provides CGI Gateway service

 protected  void doPost(HttpServletRequest req,
    HttpServletResponse res) throws IOException, ServletException 
{
        doGet(req, res);
}

Provides CGI Gateway service -- delegates to doGet

 public  void init(ServletConfig config) throws ServletException 
{
        super.init(config);
        // Verify that we were not accessed using the invoker servlet
        String servletName = getServletConfig().getServletName();
        if (servletName == null)
            servletName = "";
        if (servletName.startsWith("org.apache.catalina.INVOKER."))
            throw new UnavailableException
                ("Cannot invoke CGIServlet through the invoker");
        // Set our properties from the initialization parameters
        if (getServletConfig().getInitParameter("debug") != null)
            debug = Integer.parseInt(getServletConfig().getInitParameter("debug"));
        cgiPathPrefix = getServletConfig().getInitParameter("cgiPathPrefix");
        boolean passShellEnvironment = 
            Boolean.valueOf(getServletConfig().getInitParameter("passShellEnvironment")).booleanValue();
        if (passShellEnvironment) {
            shellEnv.putAll(System.getenv());
        }
        if (getServletConfig().getInitParameter("executable") != null) {
            cgiExecutable = getServletConfig().getInitParameter("executable");
        }
        if (getServletConfig().getInitParameter("parameterEncoding") != null) {
            parameterEncoding = getServletConfig().getInitParameter("parameterEncoding");
        }
        if (getServletConfig().getInitParameter("stderrTimeout") != null) {
            stderrTimeout = Long.parseLong(getServletConfig().getInitParameter(
                    "stderrTimeout"));
        }
}

Sets instance variables.

Modified from Craig R. McClanahan's InvokerServlet

 public static  void main(String[] args) 
{
        System.out.println("$Header$");
}

For future testing use only; does nothing right now

 protected  void printServletEnvironment(ServletOutputStream out,
    HttpServletRequest req,
    HttpServletResponse res) throws IOException 
{
        // Document the properties from ServletRequest
        out.println("< h1 >ServletRequest Properties< /h1 >");
        out.println("< ul >");
        Enumeration attrs = req.getAttributeNames();
        while (attrs.hasMoreElements()) {
            String attr = (String) attrs.nextElement();
            out.println("< li >< b >attribute< /b > " + attr + " = " +
                           req.getAttribute(attr));
        }
        out.println("< li >< b >characterEncoding< /b > = " +
                       req.getCharacterEncoding());
        out.println("< li >< b >contentLength< /b > = " +
                       req.getContentLength());
        out.println("< li >< b >contentType< /b > = " +
                       req.getContentType());
        Enumeration locales = req.getLocales();
        while (locales.hasMoreElements()) {
            Locale locale = (Locale) locales.nextElement();
            out.println("< li >< b >locale< /b > = " + locale);
        }
        Enumeration params = req.getParameterNames();
        while (params.hasMoreElements()) {
            String param = (String) params.nextElement();
            String values[] = req.getParameterValues(param);
            for (int i = 0; i <  values.length; i++)
                out.println("< li >< b >parameter< /b > " + param + " = " +
                               values[i]);
        }
        out.println("< li >< b >protocol< /b > = " + req.getProtocol());
        out.println("< li >< b >remoteAddr< /b > = " + req.getRemoteAddr());
        out.println("< li >< b >remoteHost< /b > = " + req.getRemoteHost());
        out.println("< li >< b >scheme< /b > = " + req.getScheme());
        out.println("< li >< b >secure< /b > = " + req.isSecure());
        out.println("< li >< b >serverName< /b > = " + req.getServerName());
        out.println("< li >< b >serverPort< /b > = " + req.getServerPort());
        out.println("< /ul >");
        out.println("< hr >");
        // Document the properties from HttpServletRequest
        out.println("< h1 >HttpServletRequest Properties< /h1 >");
        out.println("< ul >");
        out.println("< li >< b >authType< /b > = " + req.getAuthType());
        out.println("< li >< b >contextPath< /b > = " +
                       req.getContextPath());
        Cookie cookies[] = req.getCookies();
        if (cookies!=null) {
            for (int i = 0; i <  cookies.length; i++)
                out.println("< li >< b >cookie< /b > " + cookies[i].getName() +" = " +cookies[i].getValue());
        }
        Enumeration headers = req.getHeaderNames();
        while (headers.hasMoreElements()) {
            String header = (String) headers.nextElement();
            out.println("< li >< b >header< /b > " + header + " = " +
                           req.getHeader(header));
        }
        out.println("< li >< b >method< /b > = " + req.getMethod());
        out.println("< li >< a name=\"pathInfo\" >< b >pathInfo< /b >< /a > = "
                    + req.getPathInfo());
        out.println("< li >< b >pathTranslated< /b > = " +
                       req.getPathTranslated());
        out.println("< li >< b >queryString< /b > = " +
                       req.getQueryString());
        out.println("< li >< b >remoteUser< /b > = " +
                       req.getRemoteUser());
        out.println("< li >< b >requestedSessionId< /b > = " +
                       req.getRequestedSessionId());
        out.println("< li >< b >requestedSessionIdFromCookie< /b > = " +
                       req.isRequestedSessionIdFromCookie());
        out.println("< li >< b >requestedSessionIdFromURL< /b > = " +
                       req.isRequestedSessionIdFromURL());
        out.println("< li >< b >requestedSessionIdValid< /b > = " +
                       req.isRequestedSessionIdValid());
        out.println("< li >< b >requestURI< /b > = " +
                       req.getRequestURI());
        out.println("< li >< b >servletPath< /b > = " +
                       req.getServletPath());
        out.println("< li >< b >userPrincipal< /b > = " +
                       req.getUserPrincipal());
        out.println("< /ul >");
        out.println("< hr >");
        // Document the servlet request attributes
        out.println("< h1 >ServletRequest Attributes< /h1 >");
        out.println("< ul >");
        attrs = req.getAttributeNames();
        while (attrs.hasMoreElements()) {
            String attr = (String) attrs.nextElement();
            out.println("< li >< b >" + attr + "< /b > = " +
                           req.getAttribute(attr));
        }
        out.println("< /ul >");
        out.println("< hr >");
        // Process the current session (if there is one)
        HttpSession session = req.getSession(false);
        if (session != null) {
            // Document the session properties
            out.println("< h1 >HttpSession Properties< /h1 >");
            out.println("< ul >");
            out.println("< li >< b >id< /b > = " +
                           session.getId());
            out.println("< li >< b >creationTime< /b > = " +
                           new Date(session.getCreationTime()));
            out.println("< li >< b >lastAccessedTime< /b > = " +
                           new Date(session.getLastAccessedTime()));
            out.println("< li >< b >maxInactiveInterval< /b > = " +
                           session.getMaxInactiveInterval());
            out.println("< /ul >");
            out.println("< hr >");
            // Document the session attributes
            out.println("< h1 >HttpSession Attributes< /h1 >");
            out.println("< ul >");
            attrs = session.getAttributeNames();
            while (attrs.hasMoreElements()) {
                String attr = (String) attrs.nextElement();
                out.println("< li >< b >" + attr + "< /b > = " +
                               session.getAttribute(attr));
            }
            out.println("< /ul >");
            out.println("< hr >");
        }
        // Document the servlet configuration properties
        out.println("< h1 >ServletConfig Properties< /h1 >");
        out.println("< ul >");
        out.println("< li >< b >servletName< /b > = " +
                       getServletConfig().getServletName());
        out.println("< /ul >");
        out.println("< hr >");
        // Document the servlet configuration initialization parameters
        out.println("< h1 >ServletConfig Initialization Parameters< /h1 >");
        out.println("< ul >");
        params = getServletConfig().getInitParameterNames();
        while (params.hasMoreElements()) {
            String param = (String) params.nextElement();
            String value = getServletConfig().getInitParameter(param);
            out.println("< li >< b >" + param + "< /b > = " + value);
        }
        out.println("< /ul >");
        out.println("< hr >");
        // Document the servlet context properties
        out.println("< h1 >ServletContext Properties< /h1 >");
        out.println("< ul >");
        out.println("< li >< b >majorVersion< /b > = " +
                       getServletContext().getMajorVersion());
        out.println("< li >< b >minorVersion< /b > = " +
                       getServletContext().getMinorVersion());
        out.println("< li >< b >realPath('/')< /b > = " +
                       getServletContext().getRealPath("/"));
        out.println("< li >< b >serverInfo< /b > = " +
                       getServletContext().getServerInfo());
        out.println("< /ul >");
        out.println("< hr >");
        // Document the servlet context initialization parameters
        out.println("< h1 >ServletContext Initialization Parameters< /h1 >");
        out.println("< ul >");
        params = getServletContext().getInitParameterNames();
        while (params.hasMoreElements()) {
            String param = (String) params.nextElement();
            String value = getServletContext().getInitParameter(param);
            out.println("< li >< b >" + param + "< /b > = " + value);
        }
        out.println("< /ul >");
        out.println("< hr >");
        // Document the servlet context attributes
        out.println("< h1 >ServletContext Attributes< /h1 >");
        out.println("< ul >");
        attrs = getServletContext().getAttributeNames();
        while (attrs.hasMoreElements()) {
            String attr = (String) attrs.nextElement();
            out.println("< li >< b >" + attr + "< /b > = " +
                           getServletContext().getAttribute(attr));
        }
        out.println("< /ul >");
        out.println("< hr >");
}

Prints out important Servlet API and container information

Copied from SnoopAllServlet by Craig R. McClanahan