issue10802: fallback to pipe+fcntl when the pipe2 syscall fails with errno ENOSYS.
diff --git a/Modules/_posixsubprocess.c b/Modules/_posixsubprocess.c
index d2f8d45..a175d42 100644
--- a/Modules/_posixsubprocess.c
+++ b/Modules/_posixsubprocess.c
@@ -415,27 +415,39 @@
Py_BEGIN_ALLOW_THREADS
res = pipe2(fds, O_CLOEXEC);
Py_END_ALLOW_THREADS
-#else
- /* We hold the GIL which offers some protection from other code calling
- * fork() before the CLOEXEC flags have been set but we can't guarantee
- * anything without pipe2(). */
- long oldflags;
+ if (res != 0 && errno == ENOSYS)
+ {
+ if (PyErr_WarnEx(
+ PyExc_RuntimeWarning,
+ "pipe2 set errno ENOSYS; falling "
+ "back to non-atomic pipe+fcntl.", 1) != 0) {
+ return NULL;
+ }
+ {
+#endif
+ /* We hold the GIL which offers some protection from other code calling
+ * fork() before the CLOEXEC flags have been set but we can't guarantee
+ * anything without pipe2(). */
+ long oldflags;
- res = pipe(fds);
+ res = pipe(fds);
- if (res == 0) {
- oldflags = fcntl(fds[0], F_GETFD, 0);
- if (oldflags < 0) res = oldflags;
+ if (res == 0) {
+ oldflags = fcntl(fds[0], F_GETFD, 0);
+ if (oldflags < 0) res = oldflags;
+ }
+ if (res == 0)
+ res = fcntl(fds[0], F_SETFD, oldflags | FD_CLOEXEC);
+
+ if (res == 0) {
+ oldflags = fcntl(fds[1], F_GETFD, 0);
+ if (oldflags < 0) res = oldflags;
+ }
+ if (res == 0)
+ res = fcntl(fds[1], F_SETFD, oldflags | FD_CLOEXEC);
+#ifdef HAVE_PIPE2
+ }
}
- if (res == 0)
- res = fcntl(fds[0], F_SETFD, oldflags | FD_CLOEXEC);
-
- if (res == 0) {
- oldflags = fcntl(fds[1], F_GETFD, 0);
- if (oldflags < 0) res = oldflags;
- }
- if (res == 0)
- res = fcntl(fds[1], F_SETFD, oldflags | FD_CLOEXEC);
#endif
if (res != 0)
return PyErr_SetFromErrno(PyExc_OSError);