[Python-checkins] [python/cpython] bfa4fe: [2.7] bpo-29854: Fix segfault in call_readline() (...

[GitHub]

  Branch: refs/heads/2.7
  Home:   https://github.com/python/cpython
  Commit: bfa4fe4f39dd8b5ce1a0b649cedd36857859081a
      https://github.com/python/cpython/commit/bfa4fe4f39dd8b5ce1a0b649cedd36857859081a
  Author: Nir Soffer <nirsof at gmail.com>
  Date:   2017-07-11 (Tue, 11 Jul 2017)

  Changed paths:
    A Misc/NEWS.d/next/Library/2017-07-07-02-18-57.bpo-29854.J8wKb_.rst
    M Modules/readline.c

  Log Message:
  -----------
  [2.7] bpo-29854: Fix segfault in call_readline() (GH-728)

If history-length is set in .inputrc, and the history file is double the
history size (or more), history_get(N) returns NULL, and python
segfaults. Fix that by checking for NULL return value.

It seems that the root cause is incorrect handling of bigger history in
readline, but Python should not segfault even if readline returns
unexpected value.

This issue affects only GNU readline. When using libedit emulation
system history size option does not work.

This is a backport of the actual fix from master without the test, since
the test depends on new run_pty() helper which is not available in 2.7.