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New pyrepl gives a traceback on exit with "dumb" terminal #119102

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New pyrepl gives a traceback on exit with "dumb" terminal#119102
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3.13only security fixestopic-replRelated to the interactive shelltype-bugAn unexpected behavior, bug, or error

Description

@dgrisby
dgrisby
opened on May 16, 2024

Bug report

Bug description:

I was experimenting with terminal types:

$ export TERM=dumb
$ python3
Python 3.13.0b1 (main, May 12 2024, 23:38:03) [GCC 13.2.1 20240316 (Red Hat 13.2.1-7)] on linux
Type "help", "copyright", "credits" or "license" for more information.
warning: can't use pyrepl: terminal doesn't have the required clear capability
>>> quit
Use quit() or Ctrl-D (i.e. EOF) to exit
>>> quit()
Exception ignored in atexit callback <function register_readline.<locals>.write_history at 0x7f7204f537e0>:
Traceback (most recent call last):
  File "<frozen site>", line 530, in write_history
  File "/home/duncan/py313inst/lib/python3.13/_pyrepl/readline.py", line 361, in write_history_file
    history = self.get_reader().get_trimmed_history(maxlength)
  File "/home/duncan/py313inst/lib/python3.13/_pyrepl/readline.py", line 277, in get_reader
    console = UnixConsole(self.f_in, self.f_out, encoding=ENCODING)
  File "/home/duncan/omni/py313inst/lib/python3.13/_pyrepl/unix_console.py", line 170, in __init__
    self._clear = _my_getstr("clear")
  File "/home/duncan/py313inst/lib/python3.13/_pyrepl/unix_console.py", line 163, in _my_getstr
    raise InvalidTerminal(
_pyrepl.unix_console.InvalidTerminal: terminal doesn't have the required clear capability

It notices that the terminal is unsuitable, but then tries to use it on exit.

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Linked PRs

Activity

  1. dgrisby
    added
    type-bugAn unexpected behavior, bug, or error
    on May 16, 2024
  2. Eclips4
    added
    topic-replRelated to the interactive shell
    on May 16, 2024
  3. AlexWaygood
    added
    3.13only security fixes
    on May 16, 2024

  4. danielhollas commented on May 17, 2024

    @danielhollas
    danielhollas
    on May 17, 2024
    Contributor

    Looks like the write_history callback is registered in site.py here:

    cpython/Lib/site.py

    Line 525 in 65de194

    def write_history(): 

            def write_history():
            try:
                if os.getenv("PYTHON_BASIC_REPL"):
                    readline.write_history_file(history)
                else:
                    _pyrepl.readline.write_history_file(history)
            except (FileNotFoundError, PermissionError):
                # home directory does not exist or is not writable
                # https://bugs.python.org/issue19891
                pass

    It clearly needs to get more clever to detect whether pyrepl is actually in use.

    Maybe it can just look at the _pyrepl.__main__.CAN_USE_PYREPL global.

  5. eugenetriguba commented on May 20, 2024

    @eugenetriguba
    eugenetriguba
    on May 20, 2024
    Contributor

    @danielhollas CAN_USE_PYREPL just checks whether we're on a Windows system, so I wouldn't think checking that would help in this case.

    Maybe: We set PYTHON_BASIC_REPL to true if TERM is set to "dumb"?

  6. danielhollas commented on May 20, 2024

    @danielhollas
    danielhollas
    on May 20, 2024
    Contributor

    @eugenetriguba if you look at the _pyrepl/__main__.py, CAN_USE_PYREPL is indeed checking for windows at import, but then later it is set to False if for any reason the new repl cannot be used, on line 41.

    I tried to fix this by checking CAN_USE_PYREPL in the write_history callback function but couldn't make it work -- accessing CAN_USE_PYREPL from __main__ module seems to be cursed, and moving it to __init__ did not help.

  7. danielhollas commented on May 20, 2024

    @danielhollas
    danielhollas
    on May 20, 2024
    Contributor

    Maybe: We set PYTHON_BASIC_REPL to true if TERM is set to "dumb"?

    The following patch indeed fixes the issue, happy to make a PR if this seems like a right approach

    diff --git a/Lib/_pyrepl/__main__.py b/Lib/_pyrepl/__main__.py
index c598019e7c..40cdd6d9fe 100644
--- a/Lib/_pyrepl/__main__.py
+++ b/Lib/_pyrepl/__main__.py
@@ -39,6 +39,7 @@ def interactive_console(mainmodule=None, quiet=False, pythonstartup=False):
         trace(msg)
         print(msg, file=sys.stderr)
         CAN_USE_PYREPL = False
+        os.environ["PYTHON_BASIC_REPL"] = "true"
     if run_interactive is None:
         return sys._baserepl()
     return run_interactive(mainmodule)

  8. mi1acl commented on May 20, 2024

    @mi1acl
    mi1acl
    on May 20, 2024

    @danielhollas I worked with @lysnikolaou during PyCon sprints on this one, we came to the same conclusion but he said this is not the best practice to export the env variable to the system. He said he will take a deeper look as to why this might be happening

  9. vstinner commented on May 20, 2024

    @vstinner
    vstinner
    on May 20, 2024
    Member

    Maybe add a site._CAN_USE_PYREPL constant and modify _pyrepl/__main__.py to set site._CAN_USE_PYREPL?

  10. mi1acl commented on May 20, 2024

    @mi1acl
    mi1acl
    on May 20, 2024

    I can do this if it's ok

  11. vstinner
    added 3 commits that reference this issue on May 20, 2024

    pythongh-119102: Fix REPL for dumb terminal

    b07fabe

    pythongh-119102: Fix REPL for dumb terminal

    18582fe

    pythongh-119102: Fix REPL for dumb terminal

    161f8b9

  12. vstinner commented on May 20, 2024

    @vstinner
    vstinner
    on May 20, 2024
    Member

    I proposed PR gh-119269 to fix this issue.

  13. vstinner
    added 2 commits that reference this issue on May 21, 2024

    pythongh-119102: Fix REPL for dumb terminal

    37dc157

    gh-119102: Fix REPL for dumb terminal (#119269)

    73f4a58
  14. miss-islington
    added a commit that references this issue on May 21, 2024

    pythongh-119102: Fix REPL for dumb terminal (pythonGH-119269)

    35c9446
  15. vstinner
    added a commit that references this issue on May 21, 2024

    [3.13] gh-119102: Fix REPL for dumb terminal (GH-119269) (#119308)

    f028451

  16. lysnikolaou commented on May 21, 2024

    @lysnikolaou
    lysnikolaou
    on May 21, 2024
    Member

    Leaving this open since #119269 did not fix the problem.

  17. vstinner
    added 2 commits that reference this issue on May 21, 2024

    pythongh-119102: Fix REPL for dumb terminal

    4908d3f

    pythongh-119102: Fix REPL for dumb terminal

    b2549d1

  18. vstinner commented on May 21, 2024

    @vstinner
    vstinner
    on May 21, 2024
    Member

    Please check my second fix: PR gh-119332.

  19. vstinner
    added a commit that references this issue on May 21, 2024

    gh-119102: Fix REPL for dumb terminal (#119332)

    de8f530
  20. miss-islington
    added a commit that references this issue on May 21, 2024

    pythongh-119102: Fix REPL for dumb terminal (pythonGH-119332)

    bb5c037
  21. lysnikolaou
    added a commit that references this issue on May 22, 2024

    [3.13] gh-119102: Fix REPL for dumb terminal (GH-119332) (#119359)

    f371565

  22. vstinner commented on May 22, 2024

    @vstinner
    vstinner
    on May 22, 2024
    Member

    This time, it should be fixed.

  23. vstinner
    closed this as completedon May 22, 2024
  24. estyxx
    added 2 commits that reference this issue on Jul 17, 2024

    pythongh-119102: Fix REPL for dumb terminal (python#119269)

    c620799

    pythongh-119102: Fix REPL for dumb terminal (python#119332)

    d25ceee
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