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 commit is contained in:
Nir Soffer 2017-07-07 09:10:46 +03:00 committed by Berker Peksag
parent 25a4206c24
commit fae8f4a9cb
3 changed files with 48 additions and 7 deletions

View File

@ -9,7 +9,7 @@ import subprocess
import sys
import tempfile
import unittest
from test.support import import_module, unlink, TESTFN
from test.support import import_module, unlink, temp_dir, TESTFN
from test.support.script_helper import assert_python_ok
# Skip tests if there is no readline module
@ -210,13 +210,50 @@ print("history", ascii(readline.get_history_item(1)))
self.assertIn(b"result " + expected + b"\r\n", output)
self.assertIn(b"history " + expected + b"\r\n", output)
@unittest.skipIf(is_editline,
"editline history size configuration is broken")
def test_history_size(self):
history_size = 10
with temp_dir() as test_dir:
inputrc = os.path.join(test_dir, "inputrc")
with open(inputrc, "wb") as f:
f.write(b"set history-size %d\n" % history_size)
def run_pty(script, input=b"dummy input\r"):
history_file = os.path.join(test_dir, "history")
with open(history_file, "wb") as f:
# history_size * 2 items crashes readline
data = b"".join(b"item %d\n" % i
for i in range(history_size * 2))
f.write(data)
script = """
import os
import readline
history_file = os.environ["HISTORY_FILE"]
readline.read_history_file(history_file)
input()
readline.write_history_file(history_file)
"""
env = dict(os.environ)
env["INPUTRC"] = inputrc
env["HISTORY_FILE"] = history_file
run_pty(script, input=b"last input\r", env=env)
with open(history_file, "rb") as f:
lines = f.readlines()
self.assertEqual(len(lines), history_size)
self.assertEqual(lines[-1].strip(), b"last input")
def run_pty(script, input=b"dummy input\r", env=None):
pty = import_module('pty')
output = bytearray()
[master, slave] = pty.openpty()
args = (sys.executable, '-c', script)
proc = subprocess.Popen(args, stdin=slave, stdout=slave, stderr=slave)
proc = subprocess.Popen(args, stdin=slave, stdout=slave, stderr=slave, env=env)
os.close(slave)
with ExitStack() as cleanup:
cleanup.enter_context(proc)

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@ -0,0 +1,2 @@
Fix segfault in readline when using readline's history-size option. Patch
by Nir Soffer.

View File

@ -1347,15 +1347,17 @@ call_readline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
if (should_auto_add_history && n > 0) {
const char *line;
int length = _py_get_history_length();
if (length > 0)
if (length > 0) {
HIST_ENTRY *hist_ent;
#ifdef __APPLE__
if (using_libedit_emulation) {
/* handle older 0-based or newer 1-based indexing */
line = (const char *)history_get(length + libedit_history_start - 1)->line;
hist_ent = history_get(length + libedit_history_start - 1);
} else
#endif /* __APPLE__ */
line = (const char *)history_get(length)->line;
else
hist_ent = history_get(length);
line = hist_ent ? hist_ent->line : "";
} else
line = "";
if (strcmp(p, line))
add_history(p);