Issue #18756: Improve error reporting in os.urandom() when the failure is due to something else than /dev/urandom not existing.
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index bdbeb01..ccc58d4 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -10,6 +10,10 @@
import signal
import subprocess
import time
+try:
+ import resource
+except ImportError:
+ resource = None
from test import test_support
import mmap
@@ -563,6 +567,20 @@
data2 = self.get_urandom_subprocess(16)
self.assertNotEqual(data1, data2)
+ @unittest.skipUnless(resource, "test requires the resource module")
+ def test_urandom_failure(self):
+ soft_limit, hard_limit = resource.getrlimit(resource.RLIMIT_NOFILE)
+ resource.setrlimit(resource.RLIMIT_NOFILE, (1, hard_limit))
+ try:
+ with self.assertRaises(OSError) as cm:
+ os.urandom(16)
+ self.assertEqual(cm.exception.errno, errno.EMFILE)
+ finally:
+ # We restore the old limit as soon as possible. If doing it
+ # using addCleanup(), code running in between would fail
+ # creating any file descriptor.
+ resource.setrlimit(resource.RLIMIT_NOFILE, (soft_limit, hard_limit))
+
def test_execvpe_with_bad_arglist(self):
self.assertRaises(ValueError, os.execvpe, 'notepad', [], None)
diff --git a/Misc/NEWS b/Misc/NEWS
index 2aad9bb..e5101f5 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -29,6 +29,10 @@
Library
-------
+- Issue #18756: Improve error reporting in os.urandom() when the failure
+ is due to something else than /dev/urandom not existing (for example,
+ exhausting the file descriptor limit).
+
- Fix tkinter regression introduced by the security fix in issue #16248.
- Issue #18676: Change 'positive' to 'non-negative' in queue.py put and get
diff --git a/Python/random.c b/Python/random.c
index 825260f..73e3cc3 100644
--- a/Python/random.c
+++ b/Python/random.c
@@ -165,8 +165,12 @@
Py_END_ALLOW_THREADS
if (fd < 0)
{
- PyErr_SetString(PyExc_NotImplementedError,
- "/dev/urandom (or equivalent) not found");
+ if (errno == ENOENT || errno == ENXIO ||
+ errno == ENODEV || errno == EACCES)
+ PyErr_SetString(PyExc_NotImplementedError,
+ "/dev/urandom (or equivalent) not found");
+ else
+ PyErr_SetFromErrno(PyExc_OSError);
return -1;
}