Hi,
Sorry to flood the list with my broken pipes stories but I finally found
a way to get this to work! hurray! Here is a solution.
The following code just spawn a shell to which you can send commands.
#include <glibmm.h>
#include <gtkmm/main.h>
#include <vector>
#include <string>
#include <iostream>
Glib::RefPtr<Glib::IOChannel> ch_stdout;
bool callback(Glib::IOCondition cond)
{
Glib::ustring buf;
ch_stdout->read_line(buf);
//ch_stdout->read_to_end(buf) would never
//return for an unknown reason
std::cout<<buf;
return true;
}
int main(int argc, char** argv)
{
Gtk::Main kit(argc,argv);
int fd_stdout, fd_stdin;
Glib::Pid pid;
std::vector<std::string> arguments;
arguments.push_back("sh");
Glib::spawn_async_with_pipes(Glib::get_current_dir(),arguments,
Glib::SPAWN_SEARCH_PATH |
Glib::SPAWN_CHILD_INHERITS_STDIN,
sigc::slot<void>(),
&pid,/*&fd_stdin*/0,&fd_stdout);
ch_stdout=Glib::IOChannel::create_from_fd(fd_stdout);
Glib::signal_io().connect(sigc::ptr_fun(callback),
ch_stdout,Glib::IO_IN);
kit.run();
return 0;
}
To summerize what I did to get it to work:
- The output Glib::IOChannel must be flushed for the data to be actually
written in the pipe (not shown in the example). I know this looks
trivial but it took me a while to figure it out since it's never
mentionned in the reference documentation.
- for the watch function, connect the input Glib::IOChannel directly
using:
Glib::signal_io().connect(const sigc::slot<bool,IOCondition>,
const IOChannel&,
IOCondition,
int);
rather than using the version taking the file descriptor instead of the
IOChannel.
- Read a line at a time in the callback function. If there is more to be
read, the callback function will be called again anyway.
I think this is quite weird that Glib::IOChannel::read_to_end can be in
a condition where it never returns and would call it a bug! Note that
this is not a c++ binding issue since trying to do the same in C did
produce the same result.
I hope this might be of use to someone!
Cheers!
Le dimanche 18 octobre 2009 à 19:32 +0200, Bastien Dalla Piazza a
écrit :
> Hi again, I partially solved my problem:
>
> One needs to call Glib::IOChannel::flush() after writing on outgoing
> pipe for the message to be passed.
> For the ingoing pipe, it is necessary to add a watch function using for
> instance
>
> Glib::io_signal().connect(sigc::mem_fun(&object,Object::callback),ingoing_fd,
> Glib::IO_IN);
>
> I'm running into an other problem: Using the abow call, the function
>
> bool Object::callback(Glib::IOCondition cond)
>
> will be called each time the Glib::IO_IN condition is set on the ingoing
> pipe, that is when there is something to read.
>
> But trying to read in the above callback function using
>
> Glib::IOChannel::read_to_end
>
> results in an infinite loop (at least it looks like it).
> The Glib::IOChannel::read_line still works so I tried the following
> workaround:
>
> Glib::ustring store,buf;
> while(ingoing->get_condition() & Glib::IO_IN){
> ingoing->readline(buf);
> store.append(buf);
> }
>
> The while loop seems to finish, but then my callback function keeps
> being called over and over again by the main loop (Gtk::Main::run()), as
> if the Glib::IO_IN condition was never unset although the above while
> loop did finish.
>
> Am I doing things in an unexpected way, or is it possible there is a bug
> in Glib::IOChannel ?
>
> Thanks!
>
> Le samedi 17 octobre 2009 à 17:37 +0200, Bastien Dalla Piazza a écrit :
> > Hi,
> >
> > I don't know if this is the correct mailing list so redirect me if not.
> >
> > In a Gtkmm project, I'm using Glib::spawn_async_with_pipes to execute
> > and control a child process (gnugo in the example). But I cannot get it
> > to work!
> > For example:
> > In the following code, I just redirect the gnugo stdin and stdout to my
> > program:
> >
> > #include <glibmm.h>
> > #include <vector>
> > #include <string>
> > #include <iostream>
> >
> > int main(int argc, char** argv)
> > {
> > Glib::init();
> >
> > int fd_stdin, fd_stdout; //file descriptors
> > Glib::Pid pid;
> > Glib::RefPtr<Glib::IOChannel> ch_stdin, ch_stdout;
> >
> > std::vector<std::string> arguments;
> > arguments.push_back("gnugo");
> > arguments.push_back("--mode");
> > arguments.push_back("gtp");
> >
> > /spawn gnugo
> > Glib::spawn_async_with_pipes(Glib::get_current_dir(),
> > arguments,Glib::SPAWN_SEARCH_PATH,
> > sigc::slot<void>(),
> > &pid,&fd_stdin,&fd_stdout);
> >
> > //create the IOChannel from the file descriptors
> > ch_stdin=Glib::IOChannel::create_from_fd(fd_stdin);
> > ch_stdout=Glib::IOChannel::create_from_fd(fd_stdout);
> >
> > Glib::ustring input,output;
> >
> > //a stupid loop to test whether the pipes work
> > while(true){
> > std::cin>>input;
> > ch_stdin->write(input.append("\n"));
> > ch_stdout->read_to_end(output);
> > std::cout<<output<<std::endl;
> > }
> > }
> >
> > Any idea what I am doing wrong?
> >
> > Thanks!
_______________________________________________
gtk-app-devel-list mailing list
gtk-app-devel-list@gnome.org
http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
