guix/gnu/packages/patches/python-2.7-getentropy-on-old-kernels.patch

This patch resolves a compatibility issue when compiled against glibc
2.25
and run runder kernels < 3.17:

https://bugzilla.redhat.com/show_bug.cgi?id=1410175

Upstream bug URLs:

https://bugs.python.org/issue29157
https://bugs.python.org/issue29188

Patch adapted from upstream source repository:

https://github.com/python/cpython/commit/01bdbad3e951014c58581635b94b22868537901c

From 01bdbad3e951014c58581635b94b22868537901c Mon Sep 17 00:00:00 2001
From: Victor Stinner <victor.stinner@gmail.com>
Date: Mon, 9 Jan 2017 11:10:41 +0100
Subject: [PATCH] Don't use getentropy() on Linux

Issue #29188: Support glibc 2.24 on Linux: don't use getentropy() function but
read from /dev/urandom to get random bytes, for example in os.urandom().  On
Linux, getentropy() is implemented which getrandom() is blocking mode, whereas
os.urandom() should not block.
---
 Misc/NEWS       |  5 +++++
 Python/random.c | 11 +++++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/Python/random.c b/Python/random.c
index 57c41ffcd6..000cb36938 100644
--- a/Python/random.c
+++ b/Python/random.c
@@ -97,8 +97,15 @@ win32_urandom(unsigned char *buffer, Py_ssize_t size, int raise)
 }
 
 /* Issue #25003: Don't use getentropy() on Solaris (available since
- * Solaris 11.3), it is blocking whereas os.urandom() should not block. */
-#elif defined(HAVE_GETENTROPY) && !defined(sun)
+   Solaris 11.3), it is blocking whereas os.urandom() should not block.
+
+   Issue #29188: Don't use getentropy() on Linux since the glibc 2.24
+   implements it with the getrandom() syscall which can fail with ENOSYS,
+   and this error is not supported in py_getentropy() and getrandom() is called
+   with flags=0 which blocks until system urandom is initialized, which is not
+   the desired behaviour to seed the Python hash secret nor for os.urandom():
+   see the PEP 524 which was only implemented in Python 3.6. */
+#elif defined(HAVE_GETENTROPY) && !defined(sun) && !defined(linux)
 #define PY_GETENTROPY 1
 
 /* Fill buffer with size pseudo-random bytes generated by getentropy().
-- 
2.12.0