Question

I’m trying to write a c++ fastcgi program to be served by nginx. I’ve got the program compiling, and the hello world example works, but I can’t seem to get any of the environment variables (REQUEST_METHOD), etc. from nginx. As far as I can tell, I’m following tutorials and have the same configuration, so I’m really pulling out my hair here as to why it’s not working. Here’s my configuration:

location /cgi {
  fastcgi_pass 127.0.0.1:9000;
  fastcgi_index index.html;
  include /etc/nginx/fastcgi_params;
}

(the fastcgi_params is unchanged from the default nginx install).

Then the relevant code from the c++ program:

streambuf * cin_streambuf  = cin.rdbuf();
streambuf * cout_streambuf = cout.rdbuf();
streambuf * cerr_streambuf = cerr.rdbuf();

FCGX_Request request;

FCGX_Init();
FCGX_InitRequest (&request, 0, 0);

while (FCGX_Accept_r (&request) == 0)
{
  fcgi_streambuf cin_fcgi_streambuf (request.in);
  fcgi_streambuf cout_fcgi_streambuf (request.out);
  fcgi_streambuf cerr_fcgi_streambuf (request.err);

#if HAVE_IOSTREAM_WITHASSIGN_STREAMBUF
  cin  = &cin_fcgi_streambuf;
  cout = &cout_fcgi_streambuf;
  cerr = &cerr_fcgi_streambuf;
#else
  cin.rdbuf(&cin_fcgi_streambuf);
  cout.rdbuf(&cout_fcgi_streambuf);
  cerr.rdbuf(&cerr_fcgi_streambuf);
#endif

  //figure out what kind of request we have
  char * request_type = FCGX_GetParam("REQUEST_METHOD", request.envp);

  cout << "Content-type: text/html\r\n"
  "\r\n";
  cout << "Environment is: " << *request.envp;

}

The call to FCGX_GetParam returns null, and when I output the request.envp, the only variable shown is FCGI_ROLE=RESPONDER.

I’m using the following command to launch the process:

spawn-fcgi -p 9000 -n FCGI-App

Everything is running under Ubuntu 11.10.

Any ideas?

Answer 1

You are trying to print char **envp; with cout << *request.envp. This is expected to print only first string from the array, no surprise here.

Try the code form official FCGI example instead:

static void penv(const char * const * envp)
{
    cout << "<PRE>\n";
    for ( ; *envp; ++envp)
    {
        cout << *envp << "\n";
    }
    cout << "</PRE>\n";
}

...

penv(request.envp);