Hi Pavel, I tried to get this working on Ubuntu 16.04 and found the following:
- The compilation failed unless I added the '-fPIC' flag (as suggested by gcc). - The example code in the TerminalEmulator class comment references ProcessEndpoint, but the class doesn't exist. Pharo 7.0 Build information: Pharo-7.0+alpha.build.674.sha.57447e756fa6fcf1877f9d0d1cda235b3b63c807 (64 Bit) Cheers, Alistair On 5 March 2018 at 10:29, Pavel Krivanek <pavel.kriva...@gmail.com> wrote: > Hi, > > Guille is working on the Iceberg improvements and he wanted to be able to > open a terminal window on top of the repository and interact with it via the > command line. So we looked at this issue because I already in December made > some experiments with the terminal emulation in Pharo. > > In past, the Squeak had a working terminal emulation that used > PseudoTTYPlugin. The VM is not built with this code for a long time but I > tried to replace it with a small C library and then wrote an FFI interface > to it. Together with that, I ported most of the old code Squeak code to > Pharo. > > With Guille we tried to avoid usage of such external library and wrote an > FFI interface to all the required LibC functions. We were successful but we > realized that there are several issues that are limiting us. > > When you want to execute a separate process for the program that you want to > open in terminal (typically the Bash), you need to redirect the standard IO > files, create a fork of your process, do some additional initialization in > it and call 'exec' on it. In the parent process, you change redirected IO > files back to the original values. > > But the problem is that between the FFI calls from Smalltalk the VM can do a > lot of things including garbage collection etc. On OS X the fork() function > has the following limitation described in man: > > "There are limits to what you can do in the child process. To be totally > safe you should restrict your yourself to only executing async-signal safe > operations until such time as one of the exec functions is called. All > APIs, including global data symbols, in any framework or library should be > assumed to be unsafe after a fork() unless explicitly documented to be safe > or async-signal safe. If you need to use these frameworks in the child > process, you must exec. In this > situation it is reasonable to exec your-self. yourself." > > > As the result in most cases (but not all) the fork() and exec() pair from > the Smalltalk side fails on OS X. Linux does not have this limitation > however even there we found an issue. It is bound to the fact that fork() > makes a fork of all the parent process that uses the same resources. As soon > as Pharo is opened in a window and X11 is involved (the window wants to be > repainted), it can lead to the VM crash. > > So we learned that unfortunately we currently cannot use image-only FFI code > for this task. We need a C library or VM plugin. > > The repository of the terminal emulator is here: > https://github.com/pavel-krivanek/terminal > > and can be loaded using the following code: > > Metacello new > baseline: 'TerminalEmulator'; > repository: 'github://pavel-krivanek/terminal/src'; > load. > > #TerminalEmulator asClass compileLibrary. > > > It compiles and links the small library with only one function using the GCC > so the machine needs to have a proper development environment. > > The terminal emulator is in very early stage and has a lot of issues like > processes cleanup, drawing, keyboard input etc. etc. If you are interested > in it, feel free to contribute. > > Cheers, > -- Pavel > > > > > > >
