Make wxApp as a daemon in Linux

Thanks Devin Watson.

#include <wx/app.h>

class testwxdApp : public wxAppConsole
{
public:
    virtual bool OnInit();

private:
    void MakeDaemon();
};

IMPLEMENT_APP(testwxdApp);

bool testwxdApp::OnInit()
{
    // Make a daemon at very first
    MakeDaemon();

    // Daemon-specific initialization goes here

    return true;
}

void testwxdApp::MakeDaemon()
{
    // Our process ID and Session ID
    pid_t pid, sid;

    // Fork off the parent process
    pid = fork();
    if (pid < 0) {
        exit(EXIT_FAILURE);
    }
    // If we got a good PID, then we can exit the parent process
    if (pid > 0) {
        exit(EXIT_SUCCESS);
    }

    // Change the file mode mask
    umask(0);

    // Some logs may be opened here

    // Create a new SID for the child process
    sid = setsid();
    if (sid < 0) {
        // Log the failure
        exit(EXIT_FAILURE);
    }

    // Change the current working directory
    if ((chdir("/")) < 0) {
        // Log the failure
        exit(EXIT_FAILURE);
    }

    // Close out the standard file descriptors
    close(STDIN_FILENO);
    close(STDOUT_FILENO);
    close(STDERR_FILENO);
}