From 66f0afc91d22bb414d8247b795ce37743bd3f39d Mon Sep 17 00:00:00 2001
From: Yonatan Goldschmidt <yon.goldschmidt@gmail.com>
Date: Sun, 10 Feb 2019 00:36:08 +0200
Subject: [PATCH] unix/modmachine: Handle repeated /dev/mem open errors.

If opening of /dev/mem has failed an `OSError` is appropriately raised, but
the next time `mem8/16/32` is accessed the invalid file descriptor is used
and the program gets a SIGSEGV.
---
 ports/unix/modmachine.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/ports/unix/modmachine.c b/ports/unix/modmachine.c
index 48dddec0a..e2c44f94c 100644
--- a/ports/unix/modmachine.c
+++ b/ports/unix/modmachine.c
@@ -57,10 +57,11 @@ uintptr_t mod_machine_mem_get_addr(mp_obj_t addr_o, uint align) {
         static uintptr_t last_base = (uintptr_t)-1;
         static uintptr_t map_page;
         if (!fd) {
-            fd = open("/dev/mem", O_RDWR | O_SYNC);
-            if (fd == -1) {
+            int _fd = open("/dev/mem", O_RDWR | O_SYNC);
+            if (_fd == -1) {
                 mp_raise_OSError(errno);
             }
+            fd = _fd;
         }
 
         uintptr_t cur_base = addr & ~MICROPY_PAGE_MASK;