Prevent infinite display update recursion and fix VFS mounting

Fixes #1529

extmod/vfs_fat_file.c

@@ -186,12 +186,15 @@ STATIC mp_obj_t file_open(fs_user_mount_t *vfs, const mp_obj_type_t *type, mp_ar
                 break;
         }
     }
+    assert(vfs != NULL);
+    if ((vfs->flags & FSUSER_USB_WRITABLE) != 0 && (mode & FA_WRITE) != 0) {
+        mp_raise_OSError(MP_EROFS);
+    }
 
     pyb_file_obj_t *o = m_new_obj_with_finaliser(pyb_file_obj_t);
     o->base.type = type;
 
     const char *fname = mp_obj_str_get_str(args[0].u_obj);
-    assert(vfs != NULL);
     FRESULT res = f_open(&vfs->fatfs, &o->fp, fname, mode);
     if (res != FR_OK) {
         m_del_obj(pyb_file_obj_t, o);

main.c

@@ -127,6 +127,20 @@ void stop_mp(void) {
     #if CIRCUITPY_NETWORK
     network_module_deinit();
     #endif
+
+    #if MICROPY_VFS
+    mp_vfs_mount_t *vfs = MP_STATE_VM(vfs_mount_table);
+
+    // Unmount all heap allocated vfs mounts.
+    while (gc_nbytes(vfs) > 0) {
+        vfs = vfs->next;
+    }
+    MP_STATE_VM(vfs_mount_table) = vfs;
+    MP_STATE_VM(vfs_cur) = vfs;
+    #endif
+
+    // Run any finalizers before we stop using the heap.
+    gc_sweep_all();
 }
 
 #define STRING_LIST(...) {__VA_ARGS__, ""}

py/circuitpy_mpconfig.h

@@ -123,7 +123,6 @@
 #define MICROPY_FATFS_USE_LABEL       (1)
 #define MICROPY_FATFS_RPATH           (2)
 #define MICROPY_FATFS_MULTI_PARTITION (1)
-#define MICROPY_FATFS_NUM_PERSISTENT  (1)
 
 // Only enable this if you really need it. It allocates a byte cache of this size.
 // #define MICROPY_FATFS_MAX_SS           (4096)

py/runtime.c

@@ -131,31 +131,6 @@ void mp_init(void) {
            sizeof(MP_STATE_VM(fs_user_mount)) - MICROPY_FATFS_NUM_PERSISTENT);
     #endif
 
-    #if MICROPY_VFS
-    #if MICROPY_FATFS_NUM_PERSISTENT > 0
-    // We preserve the last MICROPY_FATFS_NUM_PERSISTENT mounts because newer
-    // mounts are put at the front of the list.
-    mp_vfs_mount_t *vfs = MP_STATE_VM(vfs_mount_table);
-    // Count how many mounts we have.
-    uint8_t count = 0;
-    while (vfs != NULL) {
-        vfs = vfs->next;
-        count++;
-    }
-    // Find the vfs MICROPY_FATFS_NUM_PERSISTENT mounts from the end.
-    vfs = MP_STATE_VM(vfs_mount_table);
-    for (uint8_t j = 0; j < count - MICROPY_FATFS_NUM_PERSISTENT; j++) {
-        vfs = vfs->next;
-    }
-    MP_STATE_VM(vfs_mount_table) = vfs;
-    MP_STATE_VM(vfs_cur) = vfs;
-    #else
-    // initialise the VFS sub-system
-    MP_STATE_VM(vfs_cur) = NULL;
-    MP_STATE_VM(vfs_mount_table) = NULL;
-    #endif
-    #endif
-
     #if MICROPY_PY_THREAD_GIL
     mp_thread_mutex_init(&MP_STATE_VM(gil_mutex));
     #endif

shared-module/displayio/__init__.c

@@ -6,6 +6,7 @@
 #include "shared-bindings/displayio/Display.h"
 #include "shared-bindings/displayio/Group.h"
 #include "shared-bindings/displayio/Palette.h"
+#include "supervisor/shared/autoreload.h"
 #include "supervisor/shared/display.h"
 #include "supervisor/memory.h"
 #include "supervisor/usb.h"
@@ -18,7 +19,13 @@ static inline void swap(uint16_t* a, uint16_t* b) {
     *b = temp;
 }
 
+bool refreshing_displays = false;
+
 void displayio_refresh_displays(void) {
+    if (refreshing_displays) {
+        return;
+    }
+    refreshing_displays = true;
     for (uint8_t i = 0; i < CIRCUITPY_DISPLAY_LIMIT; i++) {
         if (displays[i].display.base.type == NULL || displays[i].display.base.type == &mp_type_NoneType) {
             continue;
@@ -27,6 +34,7 @@ void displayio_refresh_displays(void) {
         displayio_display_update_backlight(display);
 
         if (!displayio_display_frame_queued(display)) {
+            refreshing_displays = false;
             return;
         }
         if (displayio_display_refresh_queued(display)) {
@@ -89,8 +97,9 @@ void displayio_refresh_displays(void) {
                     index += 1;
                     // The buffer is full, send it.
                     if (index >= buffer_size) {
-                        if (!displayio_display_send_pixels(display, buffer, buffer_size / 2)) {
+                        if (!displayio_display_send_pixels(display, buffer, buffer_size / 2) || reload_requested) {
                             displayio_display_finish_region_update(display);
+                            refreshing_displays = false;
                             return;
                         }
                         // TODO(tannewt): Make refresh displays faster so we don't starve other
@@ -103,12 +112,14 @@ void displayio_refresh_displays(void) {
             // Send the remaining data.
             if (index && !displayio_display_send_pixels(display, buffer, index * 2)) {
                 displayio_display_finish_region_update(display);
+                refreshing_displays = false;
                 return;
             }
             displayio_display_finish_region_update(display);
         }
         displayio_display_finish_refresh(display);
     }
+    refreshing_displays = false;
 }
 
 void common_hal_displayio_release_displays(void) {

supervisor/shared/filesystem.c

@@ -95,7 +95,7 @@ void filesystem_flush(void) {
 void filesystem_writable_by_python(bool writable) {
     fs_user_mount_t *vfs = &_internal_vfs;
 
-    if (writable) {
+    if (!writable) {
         vfs->flags |= FSUSER_USB_WRITABLE;
     } else {
         vfs->flags &= ~FSUSER_USB_WRITABLE;