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cmaloney opened this issue Jun 10, 2025 · 0 comments
Open

Running python REPL under another program + Ctrl-C results in an exception traceback #135329

cmaloney opened this issue Jun 10, 2025 · 0 comments
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stdlib Python modules in the Lib dir topic-repl Related to the interactive shell type-bug An unexpected behavior, bug, or error

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@cmaloney
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cmaloney commented Jun 10, 2025 •
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Bug report

Bug description:

Running python REPL under another program (strace ./build/python in my case), then pressing Ctrl-C on Linux results in an infinite stream of exception tracebacks.

Tested on Python 3.13 branch and main

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/build/python/cpython/Lib/_pyrepl/readline.py", line 394, in multiline_input
    return reader.readline()
           ~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 742, in readline
    self.prepare()
    ~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/historical_reader.py", line 306, in prepare
    super().prepare()
    ~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 594, in prepare
    self.restore()
    ~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 608, in restore
    self.console.restore()
    ~~~~~~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/unix_console.py", line 371, in restore
    tcsetattr(self.input_fd, termios.TCSADRAIN, self.__svtermstate)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python/cpython/Lib/_pyrepl/fancy_termios.py", line 57, in tcsetattr
    termios.tcsetattr(fd, when, attrs.as_list())
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
termios.error: (5, 'Input/output error')
Traceback (most recent call last):
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 585, in prepare
    self.console.prepare()
    ~~~~~~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/unix_console.py", line 339, in prepare
    tcsetattr(self.input_fd, termios.TCSADRAIN, raw)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python/cpython/Lib/_pyrepl/fancy_termios.py", line 57, in tcsetattr
    termios.tcsetattr(fd, when, attrs.as_list())
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
termios.error: (5, 'Input/output error')

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/build/python/cpython/Lib/_pyrepl/readline.py", line 394, in multiline_input
    return reader.readline()
           ~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 742, in readline
    self.prepare()
    ~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/historical_reader.py", line 306, in prepare
    super().prepare()
    ~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 594, in prepare
    self.restore()
    ~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 608, in restore
    self.console.restore()
    ~~~~~~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/unix_console.py", line 371, in restore
    tcsetattr(self.input_fd, termios.TCSADRAIN, self.__svtermstate)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python/cpython/Lib/_pyrepl/fancy_termios.py", line 57, in tcsetattr
    termios.tcsetattr(fd, when, attrs.as_list())
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
termios.error: (5, 'Input/output error')
Traceback (most recent call last):
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 585, in prepare
    self.console.prepare()
    ~~~~~~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/unix_console.py", line 339, in prepare
    tcsetattr(self.input_fd, termios.TCSADRAIN, raw)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python/cpython/Lib/_pyrepl/fancy_termios.py", line 57, in tcsetattr
    termios.tcsetattr(fd, when, attrs.as_list())
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
termios.error: (5, 'Input/output error')

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/build/python/cpython/Lib/_pyrepl/readline.py", line 394, in multiline_input
    return reader.readline()
           ~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 742, in readline
    self.prepare()
    ~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/historical_reader.py", line 306, in prepare
    super().prepare()
    ~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 594, in prepare
    self.restore()
    ~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 608, in restore
    self.console.restore()
    ~~~~~~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/unix_console.py", line 371, in restore
    tcsetattr(self.input_fd, termios.TCSADRAIN, self.__svtermstate)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python/cpython/Lib/_pyrepl/fancy_termios.py", line 57, in tcsetattr
    termios.tcsetattr(fd, when, attrs.as_list())
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
termios.error: (5, 'Input/output error')
Traceback (most recent call last):
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 585, in prepare
    self.console.prepare()
    ~~~~~~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/unix_console.py", line 339, in prepare
    tcsetattr(self.input_fd, termios.TCSADRAIN, raw)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python/cpython/Lib/_pyrepl/fancy_termios.py", line 57, in tcsetattr
    termios.tcsetattr(fd, when, attrs.as_list())
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
termios.error: (5, 'Input/output error')

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/build/python/cpython/Lib/_pyrepl/readline.py", line 394, in multiline_input
    return reader.readline()
           ~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 742, in readline
    self.prepare()
    ~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/historical_reader.py", line 306, in prepare
    super().prepare()
    ~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 594, in prepare
    self.restore()
    ~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 608, in restore
    self.console.restore()
    ~~~~~~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/unix_console.py", line 371, in restore
    tcsetattr(self.input_fd, termios.TCSADRAIN, self.__svtermstate)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python/cpython/Lib/_pyrepl/fancy_termios.py", line 57, in tcsetattr
    termios.tcsetattr(fd, when, attrs.as_list())
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
termios.error: (5, 'Input/output error')
Traceback (most recent call last):
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 585, in prepare
    self.console.prepare()
    ~~~~~~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/unix_console.py", line 339, in prepare
    tcsetattr(self.input_fd, termios.TCSADRAIN, raw)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python/cpython/Lib/_pyrepl/fancy_termios.py", line 57, in tcsetattr
    termios.tcsetattr(fd, when, attrs.as_list())
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
termios.error: (5, 'Input/output error')

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/build/python/cpython/Lib/_pyrepl/readline.py", line 394, in multiline_input
    return reader.readline()
           ~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 742, in readline
    self.prepare()
    ~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/historical_reader.py", line 306, in prepare
    super().prepare()
    ~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 594, in prepare
    self.restore()
    ~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 608, in restore
    self.console.restore()
    ~~~~~~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/unix_console.py", line 371, in restore
    tcsetattr(self.input_fd, termios.TCSADRAIN, self.__svtermstate)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python/cpython/Lib/_pyrepl/fancy_termios.py", line 57, in tcsetattr
    termios.tcsetattr(fd, when, attrs.as_list())
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
termios.error: (5, 'Input/output error')
Traceback (most recent call last):
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 585, in prepare
    self.console.prepare()
    ~~~~~~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/unix_console.py", line 339, in prepare
    tcsetattr(self.input_fd, termios.TCSADRAIN, raw)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python/cpython/Lib/_pyrepl/fancy_termios.py", line 57, in tcsetattr
    termios.tcsetattr(fd, when, attrs.as_list())
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
termios.error: (5, 'Input/output error')

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/build/python/cpython/Lib/_pyrepl/readline.py", line 394, in multiline_input
    return reader.readline()
           ~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 742, in readline
    self.prepare()
    ~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/historical_reader.py", line 306, in prepare
    super().prepare()
    ~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 594, in prepare
    self.restore()
    ~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 608, in restore
    self.console.restore()
    ~~~~~~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/unix_console.py", line 371, in restore
    tcsetattr(self.input_fd, termios.TCSADRAIN, self.__svtermstate)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python/cpython/Lib/_pyrepl/fancy_termios.py", line 57, in tcsetattr
    termios.tcsetattr(fd, when, attrs.as_list())
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
termios.error: (5, 'Input/output error')
Traceback (most recent call last):
  File "/build/python/cpython/Lib/_pyrepl/reader.py", line 585, in prepare
    self.console.prepare()
    ~~~~~~~~~~~~~~~~~~~~^^
  File "/build/python/cpython/Lib/_pyrepl/unix_console.py", line 339, in prepare
    tcsetattr(self.input_fd, termios.TCSADRAIN, raw)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python/cpython/Lib/_pyrepl/fancy_termios.py", line 57, in tcsetattr
    termios.tcsetattr(fd, when, attrs.as_list())
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
termios.error: (5, 'Input/output error')

CPython versions tested on:

3.13

Operating systems tested on:

Linux
@cmaloney cmaloney added the type-bug An unexpected behavior, bug, or error label Jun 10, 2025
@picnixz picnixz added stdlib Python modules in the Lib dir topic-repl Related to the interactive shell labels Jun 10, 2025
dura0ok added a commit to dura0ok/cpython that referenced this issue Jun 10, 2025
@dura0ok
pythongh-135329: prevent infinite traceback loop on Ctrl-C under exte…
4eb8fa5 
…rnal programs

When running Python REPL under another program (e.g., strace) and pressing Ctrl-C,
termios raises `EIO` during terminal state restoration, causing infinite exception tracebacks.

This patch catches `termios.error` with `errno.EIO` in `reader.prepare()` to avoid
recursive failure loops when restoring console state.
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