unix: Implement PEP 475 to retry syscalls failing with EINTR.

https://www.python.org/dev/peps/pep-0475/

This implements something similar to PEP 475 on the unix port, and for the
VfsPosix class.

There are a few differences from the CPython implementation:
- Since we call mp_handle_pending() between any ENITR's, additional
  functions could be called if MICROPY_ENABLE_SCHEDULER is enabled, not
  just signal handlers.
- CPython only handles signal on the main thread, so other threads will
  raise InterruptedError instead of retrying.  On MicroPython,
  mp_handle_pending() will currently raise exceptions on any thread.

A new macro MP_HAL_RETRY_SYSCALL is introduced to reduce duplicated code
and ensure that all instances behave the same.  This will also allow other
ports that use POSIX-like system calls (and use, eg, VfsPosix) to provide
their own implementation if needed.

1 files changed, 5 insertions, 12 deletions

diff --git a/extmod/vfs_posix.c b/extmod/vfs_posix.c
index 55a3e71d1..f14f56e81 100644
--- a/extmod/vfs_posix.c
+++ b/extmod/vfs_posix.c
@@ -26,6 +26,7 @@
 
 #include "py/runtime.h"
 #include "py/mperrno.h"
+#include "py/mphal.h"
 #include "py/mpthread.h"
 #include "extmod/vfs.h"
 #include "extmod/vfs_posix.h"
@@ -290,12 +291,8 @@ STATIC mp_obj_t vfs_posix_stat(mp_obj_t self_in, mp_obj_t path_in) {
     mp_obj_vfs_posix_t *self = MP_OBJ_TO_PTR(self_in);
     struct stat sb;
     const char *path = vfs_posix_get_path_str(self, path_in);
-    MP_THREAD_GIL_EXIT();
-    int ret = stat(path, &sb);
-    MP_THREAD_GIL_ENTER();
-    if (ret != 0) {
-        mp_raise_OSError(errno);
-    }
+    int ret;
+    MP_HAL_RETRY_SYSCALL(ret, stat(path, &sb), mp_raise_OSError(err));
     mp_obj_tuple_t *t = MP_OBJ_TO_PTR(mp_obj_new_tuple(10, NULL));
     t->items[0] = MP_OBJ_NEW_SMALL_INT(sb.st_mode);
     t->items[1] = MP_OBJ_NEW_SMALL_INT(sb.st_ino);
@@ -335,12 +332,8 @@ STATIC mp_obj_t vfs_posix_statvfs(mp_obj_t self_in, mp_obj_t path_in) {
     mp_obj_vfs_posix_t *self = MP_OBJ_TO_PTR(self_in);
     STRUCT_STATVFS sb;
     const char *path = vfs_posix_get_path_str(self, path_in);
-    MP_THREAD_GIL_EXIT();
-    int ret = STATVFS(path, &sb);
-    MP_THREAD_GIL_ENTER();
-    if (ret != 0) {
-        mp_raise_OSError(errno);
-    }
+    int ret;
+    MP_HAL_RETRY_SYSCALL(ret, STATVFS(path, &sb), mp_raise_OSError(err));
     mp_obj_tuple_t *t = MP_OBJ_TO_PTR(mp_obj_new_tuple(10, NULL));
     t->items[0] = MP_OBJ_NEW_SMALL_INT(sb.f_bsize);
     t->items[1] = MP_OBJ_NEW_SMALL_INT(sb.f_frsize);