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# HG changeset patch
# User Benjamin Peterson <benjamin@python.org>
# Date 1409243400 14400
# Node ID 3e7f8855078855a9409bc2c1372de89cb021d6c8
# Parent 3f73c44b1fd1d442d6841493328e9756fb5e7ef5
PEP 466: backport persistent urandom fd (closes #21305)
Patch from Alex Gaynor.
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -536,6 +536,7 @@ Py_Finalize(void)
PyInt_Fini();
PyFloat_Fini();
PyDict_Fini();
+ _PyRandom_Fini();
#ifdef Py_USING_UNICODE
/* Cleanup Unicode implementation */
diff -up Python-2.7.5/Include/pythonrun.h.urandom Python-2.7.5/Include/pythonrun.h
--- Python-2.7.5/Include/pythonrun.h.urandom 2015-03-06 08:16:47.638584015 +0100
+++ Python-2.7.5/Include/pythonrun.h 2015-03-06 08:21:48.009485462 +0100
@@ -145,6 +145,7 @@ PyAPI_FUNC(void) PyInt_Fini(void);
PyAPI_FUNC(void) PyFloat_Fini(void);
PyAPI_FUNC(void) PyOS_FiniInterrupts(void);
PyAPI_FUNC(void) PyByteArray_Fini(void);
+PyAPI_FUNC(void) _PyRandom_Fini(void);
/* Stuff with no proper home (yet) */
PyAPI_FUNC(char *) PyOS_Readline(FILE *, FILE *, char *);
diff -up Python-2.7.5/Python/random.c.urandom Python-2.7.5/Python/random.c
--- Python-2.7.5/Python/random.c.urandom 2015-03-06 08:22:10.244699950 +0100
+++ Python-2.7.5/Python/random.c 2015-03-06 08:24:57.907317272 +0100
@@ -118,10 +118,16 @@ vms_urandom(unsigned char *buffer, Py_ss
#if !defined(MS_WINDOWS) && !defined(__VMS)
+static struct {
+ int fd;
+ dev_t st_dev;
+ ino_t st_ino;
+} urandom_cache = { -1 };
+
/* Read size bytes from /dev/urandom into buffer.
Call Py_FatalError() on error. */
static void
-dev_urandom_noraise(char *buffer, Py_ssize_t size)
+dev_urandom_noraise(unsigned char *buffer, Py_ssize_t size)
{
int fd;
Py_ssize_t n;
@@ -156,18 +162,56 @@ dev_urandom_python(char *buffer, Py_ssiz
{
int fd;
Py_ssize_t n;
+ struct stat st;
if (size <= 0)
return 0;
- Py_BEGIN_ALLOW_THREADS
- fd = open("/dev/urandom", O_RDONLY);
- Py_END_ALLOW_THREADS
- if (fd < 0)
- {
- PyErr_SetString(PyExc_NotImplementedError,
- "/dev/urandom (or equivalent) not found");
- return -1;
+ if (urandom_cache.fd >= 0) {
+ /* Does the fd point to the same thing as before? (issue #21207) */
+ if (fstat(urandom_cache.fd, &st)
+ || st.st_dev != urandom_cache.st_dev
+ || st.st_ino != urandom_cache.st_ino) {
+ /* Something changed: forget the cached fd (but don't close it,
+ since it probably points to something important for some
+ third-party code). */
+ urandom_cache.fd = -1;
+ }
+ }
+ if (urandom_cache.fd >= 0)
+ fd = urandom_cache.fd;
+ else {
+ Py_BEGIN_ALLOW_THREADS
+ fd = open("/dev/urandom", O_RDONLY);
+ Py_END_ALLOW_THREADS
+ if (fd < 0)
+ {
+ 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;
+ }
+ if (urandom_cache.fd >= 0) {
+ /* urandom_fd was initialized by another thread while we were
+ not holding the GIL, keep it. */
+ close(fd);
+ fd = urandom_cache.fd;
+ }
+ else {
+ if (fstat(fd, &st)) {
+ PyErr_SetFromErrno(PyExc_OSError);
+ close(fd);
+ return -1;
+ }
+ else {
+ urandom_cache.fd = fd;
+ urandom_cache.st_dev = st.st_dev;
+ urandom_cache.st_ino = st.st_ino;
+ }
+ }
}
Py_BEGIN_ALLOW_THREADS
@@ -191,12 +235,21 @@ dev_urandom_python(char *buffer, Py_ssiz
PyErr_Format(PyExc_RuntimeError,
"Failed to read %zi bytes from /dev/urandom",
size);
- close(fd);
return -1;
}
- close(fd);
return 0;
}
+
+static void
+dev_urandom_close(void)
+{
+ if (urandom_cache.fd >= 0) {
+ close(urandom_cache.fd);
+ urandom_cache.fd = -1;
+ }
+}
+
+
#endif /* !defined(MS_WINDOWS) && !defined(__VMS) */
/* Fill buffer with pseudo-random bytes generated by a linear congruent
@@ -300,8 +353,21 @@ _PyRandom_Init(void)
# ifdef __VMS
vms_urandom((unsigned char *)secret, secret_size, 0);
# else
- dev_urandom_noraise((char*)secret, secret_size);
+ dev_urandom_noraise((unsigned char*)secret, secret_size);
# endif
#endif
}
}
+
+void
+_PyRandom_Fini(void)
+{
+#ifdef MS_WINDOWS
+ if (hCryptProv) {
+ CryptReleaseContext(hCryptProv, 0);
+ hCryptProv = 0;
+ }
+#else
+ dev_urandom_close();
+#endif
+}