sd: prompt user for formatting if format is not VFAT compatible

This commit inserts a check to validate whether the sdcard where the
backup will be put is VFAT compatible or not. VFAT compatilibity is
crucial for using the card and lack of it could result in errors in the
firmware. Therefore, when setting up the device, this commit validates
it and if it is not compatible, it asks user whether he/she is okay with
formatting or not. When the user confirms, SD card is formatted
accordingly and the fresh SD card is ready to be used by BitBox02.

Signed-off-by: asi345 <inanata15@gmail.com>

CHANGELOG.md

@@ -10,6 +10,7 @@ customers cannot upgrade their bootloader, its changes are recorded separately.
 - Update manufacturer HID descriptor to bitbox.swiss
 - Ethereum: remove deprecated Goerli network
 - SD card: solve backup bug when sd card is re-inserted
+- SD card: prompt user for formatting if sd is not VFAT compatible
 
 ### 9.21.0
 - Bitcoin: add support for sending to silent payment (BIP-352) addresses

src/rust/bitbox02-rust/src/hww/api/backup.rs

@@ -89,6 +89,17 @@ pub async fn create(
     })
     .await?;
 
+    let is_vfat_formatted = bitbox02::sd::sdcard_vfat_formatted();
+    if !is_vfat_formatted {
+        confirm::confirm(&confirm::Params {
+            title: "SD card\nformatting needed",
+            body: "This will erase all\ndata on the SD card.",
+            ..Default::default()
+        })
+        .await?;
+        bitbox02::sd::format()?;
+    }
+
     let is_initialized = bitbox02::memory::is_initialized();
 
     if is_initialized {

src/rust/bitbox02-sys/build.rs

@@ -117,6 +117,7 @@ const ALLOWLIST_FNS: &[&str] = &[
     "screen_saver_disable",
     "screen_saver_enable",
     "sd_card_inserted",
+    "sd_card_vfat_formatted",
     "sd_erase_file_in_subdir",
     "sd_format",
     "sd_free_list",

src/rust/bitbox02/src/sd.rs

@@ -30,6 +30,23 @@ pub fn sdcard_inserted() -> bool {
     data.sdcard_inserted.unwrap()
 }
 
+#[cfg(not(feature = "testing"))]
+pub fn sdcard_vfat_formatted() -> bool {
+    unsafe { bitbox02_sys::sd_card_vfat_formatted() }
+}
+
+#[cfg(feature = "testing")]
+pub fn sdcard_vfat_formatted() -> bool {
+    true
+}
+
+pub fn format() -> Result<(), ()> {
+    match unsafe { bitbox02_sys::sd_format() } {
+        true => Ok(()),
+        false => Err(()),
+    }
+}
+
 struct SdList(bitbox02_sys::sd_list_t);
 
 impl Drop for SdList {

src/sd.c

@@ -370,7 +370,14 @@ bool sd_erase_file_in_subdir(const char* fn, const char* subdir)
     return status;
 }
 
-#ifdef TESTING
+bool sd_card_vfat_formatted(void)
+{
+    memset(&fs, 0, sizeof(FATFS));
+    FRESULT res = f_mount(&fs, "", 1);
+    f_unmount("");
+    return res == FR_OK;
+}
+
 bool sd_format(void)
 {
     const MKFS_PARM params = {
@@ -384,4 +391,3 @@ bool sd_format(void)
     uint8_t work[FF_MAX_SS] = {0};
     return f_mkfs("SD", &params, work, sizeof(work)) == FR_OK;
 }
-#endif

src/sd.h

@@ -64,8 +64,7 @@ USE_RESULT bool sd_write_bin(
     uint16_t length,
     bool replace);
 
-#ifdef TESTING
+USE_RESULT bool sd_card_vfat_formatted(void);
 USE_RESULT bool sd_format(void);
-#endif
 
 #endif