[SOLVED] Re: Cannot get pipes to work with glibmm
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::RefPtrGlib::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::coutbuf;
return true;
}
int main(int argc, char** argv)
{
Gtk::Main kit(argc,argv);
int fd_stdout, fd_stdin;
Glib::Pid pid;
std::vectorstd::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::slotvoid(),
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::slotbool,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::RefPtrGlib::IOChannel ch_stdin, ch_stdout;
std::vectorstd::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::slotvoid(),
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
Re: Cannot get pipes to work with glibmm
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::RefPtrGlib::IOChannel ch_stdin, ch_stdout;
std::vectorstd::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::slotvoid(),
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::cininput;
ch_stdin-write(input.append(\n));
ch_stdout-read_to_end(output);
std::coutoutputstd::endl;
}
}
Any idea what I am doing wrong?
Thanks!
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Cannot get pipes to work with glibmm
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::RefPtrGlib::IOChannel ch_stdin, ch_stdout;
std::vectorstd::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::slotvoid(),
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::cininput;
ch_stdin-write(input.append(\n));
ch_stdout-read_to_end(output);
std::coutoutputstd::endl;
}
}
Any idea what I am doing wrong?
Thanks!
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Glib::ustring, error while reading an utf-8 encoded file
Hi everybody,
I don't have experience about charset issues so I tried the following to
experiment:
(it's in C++ using glibmm and giomm but I guess the problem is not
related to that, it's just I don't understand something.)
*
#include giomm.h
#include iostream
#include glibmm.h
#include string
int main(int argc, char** argv)
{
Glib::init();
Gio::init();
if(argc!=2) return 1;
//open a file to read
Glib::RefPtrGio::File file=Gio::File::create_for_path(argv[1]);
Glib::RefPtrGio::DataInputStream
fin=Gio::DataInputStream::create(file-read());
std::string line;
//try to read.
try{
int i=1;
while(fin-read_line(line)){
std::couti: as-is: \line\std::endl;
std::couti: through Glib::ustring:
\Glib::ustring(line)\std::endl;
++i;
}
} catch(Glib::ConvertError error){
std::coutstd::endlGlib::ConvertError:
error.what()std::endl;
}
return 0;
}
***
Feading this utf-8 encoded file to the above program:
***
First line: plain text.
deuxième ligne: des accents ici et là...
***
results in:
1: as-is: First line: plain text.
1: through Glib::ustring: First line: plain text.
2: as-is: deuxième ligne: des accents ici et là...
2: through Glib::ustring:
Glib::ConvertError: Invalid byte sequence in conversion input
my locale is using utf-8 (fr_CH).
The question is: How to import the file content in an Glib::ustring when
already knowing its encoding (not necessarily utf-8 though)?
I'm writing an application which will likely have to deal with asian
characters so I need to find out!
Thanks a lot!
Bastien
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