feat(usbmsc): Add is_writable function to the USBMSC class. (#9569)

* (feat)usbmsc: Add is_writable function

Add is_writable function to the USBMSC class.
Allows USBMSC to be mounted in read-only mode.

* Update USBMSC.ino

Changes to USB Mass Storage (MSC) example code in Arduino USB library

* Added MSC.isWritable(true) line to set the disk as writable

* ci(pre-commit): Apply automatic fixes

---------
Co-authored-by: Rodrigo Garcia <rodrigo.garcia@espressif.com>
Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

cores/esp32/USBMSC.cpp

@@ -33,6 +33,7 @@ extern "C" uint16_t tusb_msc_load_descriptor(uint8_t *dst, uint8_t *itf) {
 
 typedef struct {
   bool media_present;
+  bool is_writable;
   uint8_t vendor_id[8];
   uint8_t product_id[16];
   uint8_t product_rev[4];
@@ -179,11 +180,17 @@ int32_t tud_msc_scsi_cb(uint8_t lun, uint8_t const scsi_cmd[16], void *buffer, u
   return resplen;
 }
 
+bool tud_msc_is_writable_cb(uint8_t lun) {
+  log_v("[%u]: %u", lun, msc_luns[lun].is_writable);
+  return msc_luns[lun].is_writable;  // RAM disk is always ready
+}
+
 USBMSC::USBMSC() {
   if (MSC_ACTIVE_LUN < MSC_MAX_LUN) {
     _lun = MSC_ACTIVE_LUN;
     MSC_ACTIVE_LUN++;
     msc_luns[_lun].media_present = false;
+    msc_luns[_lun].is_writable = true;
     msc_luns[_lun].vendor_id[0] = 0;
     msc_luns[_lun].product_id[0] = 0;
     msc_luns[_lun].product_rev[0] = 0;
@@ -213,6 +220,7 @@ bool USBMSC::begin(uint32_t block_count, uint16_t block_size) {
 
 void USBMSC::end() {
   msc_luns[_lun].media_present = false;
+  msc_luns[_lun].is_writable = false;
   msc_luns[_lun].vendor_id[0] = 0;
   msc_luns[_lun].product_id[0] = 0;
   msc_luns[_lun].product_rev[0] = 0;
@@ -247,6 +255,10 @@ void USBMSC::onWrite(msc_write_cb cb) {
   msc_luns[_lun].write = cb;
 }
 
+void USBMSC::isWritable(bool is_writable) {
+  msc_luns[_lun].is_writable = is_writable;
+}
+
 void USBMSC::mediaPresent(bool media_present) {
   msc_luns[_lun].media_present = media_present;
 }

cores/esp32/USBMSC.h

@@ -44,6 +44,7 @@ public:
   void productID(const char *pid);        //max 16 chars
   void productRevision(const char *ver);  //max 4 chars
   void mediaPresent(bool media_present);
+  void isWritable(bool is_writable);
   void onStartStop(msc_start_stop_cb cb);
   void onRead(msc_read_cb cb);
   void onWrite(msc_write_cb cb);

cores/esp32/esp32-hal-tinyusb.c

@@ -390,6 +390,10 @@ __attribute__((weak)) int32_t tud_msc_write10_cb(uint8_t lun, uint32_t lba, uint
 __attribute__((weak)) int32_t tud_msc_scsi_cb(uint8_t lun, uint8_t const scsi_cmd[16], void *buffer, uint16_t bufsize) {
   return -1;
 }
+__attribute__((weak)) bool tud_msc_is_writable_cb(uint8_t lun) {
+  return false;
+}
+
 #endif
 
 /*

libraries/USB/examples/USBMSC/USBMSC.ino

@@ -152,7 +152,10 @@ void setup() {
   MSC.onStartStop(onStartStop);
   MSC.onRead(onRead);
   MSC.onWrite(onWrite);
+
   MSC.mediaPresent(true);
+  MSC.isWritable(true);  // true if writable, false if read-only
+
   MSC.begin(DISK_SECTOR_COUNT, DISK_SECTOR_SIZE);
   USB.begin();
 }