[Termux] PermissionError: [Errno 13] Permission denied: '/proc/stat'

[babaric-dev]

Summary

• OS: Android 10
• Architecture: aarch64
• Psutil version: 5.9.4
• Python version: 3.11.1
• Type: core

Description

>>> import psutil
Traceback (most recent call last):
  File "/data/data/com.termux/files/usr/lib/python3.11/site-packages/psutil/_common.py", line 399, in wrapper
    return cache[key]
           ~~~~~^^^^^
KeyError: (('/proc',), frozenset())
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/data/data/com.termux/files/usr/lib/python3.11/site-packages/psutil/_pslinux.py", line 285, in <module>
    set_scputimes_ntuple("/proc")
  File "/data/data/com.termux/files/usr/lib/python3.11/site-packages/psutil/_common.py", line 401, in wrapper
    ret = cache[key] = fun(*args, **kwargs)                                       ^^^^^^^^^^^^^^^^^^^^
  File "/data/data/com.termux/files/usr/lib/python3.11/site-packages/psutil/_pslinux.py", line 268, in set_scputimes_ntuple
    with open_binary('%s/stat' % procfs_path) as f:                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/data/data/com.termux/files/usr/lib/python3.11/site-packages/psutil/_common.py", line 728, in open_binary
    return open(fname, "rb", buffering=FILE_READ_BUFFER_SIZE)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
PermissionError: [Errno 13] Permission denied: '/proc/stat'
>>>

From the error message above, 2 errors occured:

1. KeyError (IDK why this appears)
2. PermissionError (because of SeLinux restrictions on Android)

I want to focus on more about the second error. Because we never know which files are readable and which are not, we should handle exceptions raised by open(). We should add an try-except clause catching PermissionError. Another solution that I propose is to check whether the file is readable first before actually reading it. Both have their pros and cons, but I prefer the latter solution.

[giampaolo]

Please paste the full error here instead of opening two tickets.

[giampaolo]

The error originates from here and occurs at import time. It's just printed, meaning it does not crash the app.

KeyError before PermissionError is legitimate, although a bit confusing: it just means caching didn't happen yet. We may want to improve that though.

As for PermissionError, I don't think there's anything we can do. If a basic file like /proc/stat cannot be read, I imagine tools like htop or ps won't work as well (unless they have SUID permissions).

[giampaolo]

KeyError before PermissionError is legitimate, although a bit confusing: it just means caching didn't happen yet. We may want to improve that though.

This part is now solved by #2196. The KeyError part is no longer shown in traceback messages.

[babaric-dev]

A bit off-topic, but when will 5.9.5 be released?

[thewhiteh4t]

@giampaolo in version 5.9.5 specifically in termux, we cannot catch PermissionError ?

[thewhiteh4t]

[Ammar-Husain]

So How to get rid of this annoying error each time i run the code ?

[romanovj]

@Ammar-Husain you can copy /proc/stat with adb and then read it (you will need to setup adb)

/data/data/com.termux/files/usr/lib/python3.11/site-packages/psutil/_pslinux.py

function def set_scputimes_ntuple(procfs_path):

replace

with open_binary('%s/stat' ...

with

os.system('adb shell cp /proc/stat /sdcard/stat')
with open_binary('%s/stat' % "/sdcard" ) as f:

or just copy file once

[purarue]

Thought I would linkback to pipx issue discussing the traceback being printed

If psutil happens to be installed, since pipx uses userpath internally, which uses psutil in this function, every time I run pipx I see this traceback.

The actual code that uses psutil in userpath works fine on android:

>>> userpath.utils.get_parent_process_name()
'zsh'

would be nice to be able to silence the traceback without having to mess with adb or patching the psutil code, for now I've just been doing pipx ... 2>/dev/null but not the best solution

[giampaolo]

I have fixed this in becbe86. The error/exception is no longer printed on screen. It is only shown by using PSUTIL_DEBUG env var.

[thewhiteh4t]

works now, thanks a lot!!