[Enhancement]: Access to pipe file to user for the mod_user_pipe plugin

[sosie-js]

Is there a way to make the pipe file accessible when controling using python as it is relocated and unaccessible to user, I got when using pyaudiacity

PermissionError: [Errno 13] Permission denied: '/tmp/snap-private-tmp/snap.audacity/tmp/audacity_script_pipe.to.1000'

I modified pyaudacity main file

with

       USE_SNAP=True
        snap_tmp = ""
        if USE_SNAP:
            snap_tmp="/tmp/snap-private-tmp/snap.audacity"
        write_pipe_name = snap_tmp+"/tmp/audacity_script_pipe.to." + str(os.getuid())
        read_pipe_name = snap_tmp+"/tmp/audacity_script_pipe.from." + str(os.getuid())
        eol = "\n"

and I had also to do extra sudo chown on linux behind:

sudo chown  `whoami`:root /tmp/snap-private-tmp
sudo chown  `whoami`:root /tmp/snap-private-tmp/snap.audacity
sudo chown  -R  `whoami`:root /tmp/snap-private-tmp/snap.audacity/tmp

What changes would you like?

Access or relocating possibily to user home writable.

[sosie-js]

Here is the bash script audacity_snap.sh I use now:

#!/bin/bash
#requires user sudo belong sudoers
# usermod -a -G sudo <user> + REBOOT
snap run audacity&
sudo chown  `whoami`:root /tmp/snap-private-tmp
sudo chown  `whoami`:root /tmp/snap-private-tmp/snap.audacity
sudo chown  -R  `whoami`:root /tmp/snap-private-tmp/snap.audacity/tmp

[frenchwr]

Hi @sosie-js , this may be tricky with the Audacity snap because snaps are designed with security in mind.

I can look into it, but I first want to make sure I'm understanding correctly: are you saying with the bash script you pasted in your latest comment that you are able to successfully control the Audacity snap using pyaudacity? Or is that just your latest unsuccessful attempt?

[sosie-js]

Hi @frenchwr

The script works fine, I use it to control indeed audacity with a patched pyaudacity to support snap as I told you.
, but it requires to type passwd each time.

if /tmp is a tmpfs your snaps /tmp’s will then live in ram too, that means run faster but limited to ram.
with big projects that can be a limitation...

Other approach is to relocate outside /tmp why not /var/tmp/audacity-whoami like normal audacity run?

If we take this approach, some then suggest to use fstab rule to make this permanent but will not work
as"-whoami" is not handled

$ tail -n 1 /etc/fstab 
/tmp    /var/tmp/audacity  auto    bind    0    0

and extra
$ sudo update-initramfs -u -k all

thus solution is maybe udev hotplug style getting things complicated imho.

[frenchwr]

Hi @sosie-js ,

Thanks for the details. That's helpful context.

Access or relocating possibily to user home writable.

From my reading of mod-script-pipe used by pyaudacity, it looks like the named pipes it creates always go to something like:

/tmp/audacity_script_pipe.to
/tmp/audacity_script_pipe.from

In the case of the audacity snap, /tmp inside the snap happens to be an area that is accessible from the host only at /tmp/snap-private-tmp and by design that is owned by root. It is not possible to map paths on the host to some path inside the snap. Snaps are containers, and by design are meant to be isolated a user's host environment.

There are ways to grant a snap application to certain host paths (e.g. a user's home directory) using snapd interfaces, but I don't think that would help in your case because mod-script-pipe will still be writing to /tmp.

All that's to say, I think the approach you are using is the best you will be able to do using the Audacity snap. You might consider trying a non-containerized packaging format of Audacity to control with pyaudacity. I see there is an apt package (apt install audacity). You could also try building from source if you want the latest version.

[sosie-js]

Well, it is just of matter of changing a path fifotmpl[] when snap version of PipeServer.cpp in the source directory modules/scripting/mod-script-pipe/.
For example for 3.7.5 this is https://github.com/audacity/audacity/blob/release-3.7.5/modules/scripting/mod-script-pipe/PipeServer.cpp
before building the snap version, no?
substitute /tmp/ by example
~/snap/audacity/ <-- created by snap so accessible no?
or ~/.local/share/audacity/
or /var/tmp/audacity/

Need a patch system on your side...

[frenchwr]

Yes, you're right. However, we generally avoid carrying patches of upstream source code, as one of our (the snapcrafters team) goals is to align with upstream and eventually transfer ownership of the snap packaging to upstream.

In my opinion, the best solution would be to ask upstream if they would consider setting fifotmpl based on an environment variable.

[sosie-js]

@frenchwr Great idea, can be also an audacity param set in audacity config file. so i put it on the pipe of Audacity discussions :

[sosie-js]

I think we can handle this by audacity by an extra package detection on python side, please if someone can complete code on Mac and Windows, that would be great !

# -*- coding: utf-8 -*-

##################################
# package detection for misc audacity, partcularly snap
##################################


import psutil
import platform

import sys

#OS detection
if platform.system() == "Linux" :
    os_name = "Linux"
if platform.system() == "Darwin":
    os_name = "Mac"       
if platform.system() == "Windows":
    os_name = "Windows"       

def which_pkgversion() :
    
    from io import open
    import pathlib
    from pathlib import Path
    home_dir = Path.home()
    # Platform specific constants
    if sys.platform == 'win32':
        audacitycfg=pathlib.Path(home_dir,"AppData\\Roaming\\audacity\\audacity.cfg").resolve()
    elif sys.platform == 'darwin': #macOS 
        audacitycfg=pathlib.Path(home_dir,"Library/Application Support/audacity/audacity.cfg").resolve()
    else: # Linux 
        audacitycfg=pathlib.Path(home_dir,".config/audacity/audacity.cfg").resolve()

    lines = open(audacitycfg).read().splitlines()
    AUDACITY_VERSION={}
    for line in lines:
        if "Major" in line:
            AUDACITY_VERSION["Major"]=int(line.split("=")[1])
        if "Minor" in line:
            AUDACITY_VERSION["Minor"]=int(line.split("=")[1])
        if "Micro=" in line:
            AUDACITY_VERSION["Micro"]=int(line.split("=")[1])
    return AUDACITY_VERSION


def which_pkgbuild(name):

    pkgbuild="none"
    process_count = 0

    for p in psutil.process_iter():

        if name in p.name().lower():
            path=p.exe()
            process_count += 1
            break; 

    if process_count > 0:
        #print(path)
        if os_name == "Linux" :
            if "/snap/" in path:
                pkgbuild = "snap"
            else:
                pkgbuild = "system"
        else :
            raise Error("FIXME Baby, i have not "+os_name) 
    return pkgbuild


if os_name == "Windows":
    name = "audacity.exe"
else:
    name = "audacity"
pkgbuild=which_pkgbuild(name) 

if pkgbuild == "none" :
    print("audacity is not running")
else:
    pkgversion = which_pkgversion() 
    print(pkgbuild + " version of audacity " + str(pkgversion)+ " running on "+os_name)