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[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.
This commit is contained in:
Nir Soffer 2017-07-11 00:06:57 +03:00 committed by Berker Peksag
parent 5d1554a2eb
commit bfa4fe4f39
2 changed files with 8 additions and 4 deletions
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2
Misc/NEWS.d/next/Library/2017-07-07-02-18-57.bpo-29854.J8wKb_.rst Normal file
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@ -0,0 +1,2 @@
Fix segfault in readline when using readline's history-size option. Patch
by Nir Soffer.

10
Modules/readline.c
View File

@ -1161,15 +1161,17 @@ call_readline(FILE *sys_stdin, FILE *sys_stdout, char *prompt)
if (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 = history_get(length + libedit_history_start - 1)->line;
hist_ent = history_get(length + libedit_history_start - 1);
} else
#endif /* __APPLE__ */
line = 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);