WIP - extend trezorhal translations interface

core/embed/rust/build.rs

@@ -291,6 +291,9 @@ fn generate_trezorhal_bindings() {
         .allowlist_function("storage_set_counter")
         .allowlist_function("storage_next_counter")
         .allowlist_function("translations_read")
+        .allowlist_function("translations_write")
+        .allowlist_function("translations_erase")
+        .allowlist_function("translations_area_bytesize")
         // display
         .allowlist_function("display_clear")
         .allowlist_function("display_offset")

core/embed/rust/src/trezorhal/translations.rs

@@ -1,27 +1,29 @@
 use super::ffi;
 
-#[repr(C)]
-pub struct PointerData {
-    pub ptr: *const u8,
-    pub len: u32,
-}
-
-pub fn get_translations_blob() -> &'static [u8] {
+// SAFETY: Returned slice is valid and immutable until a call to `erase()` and/or `set_blob()`.
+// Caller is responsible for disposing of all references to the slice before touching
+// the flash contents.
+pub unsafe fn get_blob<'a>() -> &'a [u8] {
     let mut len: u32 = 0;
     let ptr = unsafe { ffi::translations_read(&mut len, 0) };
     if ptr.is_null() {
         fatal_error!("Translations read failed", "");
     }
+    // SAFETY: The pointer is always valid.
     unsafe { core::slice::from_raw_parts(ptr, len as usize) }
 }
 
-pub fn get_pointer_with_offset(offset: u16, len: u16) -> PointerData {
-    let ptr = unsafe { ffi::translations_read(&mut 0, offset.into()) };
-    if ptr.is_null() {
-        fatal_error!("Translations read failed", "");
-    }
-    PointerData {
-        ptr,
-        len: len.into(),
-    }
+// SAFETY: This call invalidates the reference to the blob returned by `get_blob()`.
+pub unsafe fn erase() {
+    unsafe { ffi::translations_erase() };
+}
+
+pub fn area_bytesize() -> usize {
+    // SAFETY: Safe, no side effects.
+    unsafe { ffi::translations_area_bytesize() as usize }
+}
+
+// SAFETY: This call may invalidate the reference to the blob returned by `get_blob()`.
+pub unsafe fn write(data: &[u8], offset: usize) {
+    unsafe { ffi::translations_write(data.as_ptr(), offset as u32, data.len() as u32) };
 }

core/embed/trezorhal/stm32f4/translations.c

@@ -5,9 +5,11 @@
 #include "flash.h"
 #include "model.h"
 
-void translations_write(uint8_t* data, uint32_t offset, uint32_t len) {
+void translations_write(const uint8_t* data, uint32_t offset, uint32_t len) {
+  // TODO maybe return errors from here?
   ensure(flash_unlock_write(), "translations_write unlock");
   for (int i = 0; i < len; i++) {
+    // TODO optimize by writing by (quad)words
     ensure(flash_area_write_byte(&TRANSLATIONS_AREA, offset + i, data[i]),
            "translations_write write");
   }

core/embed/trezorhal/translations.h

@@ -1,6 +1,6 @@
 #include <stdint.h>
 
-void translations_write(uint8_t* data, uint32_t offset, uint32_t len);
+void translations_write(const uint8_t* data, uint32_t offset, uint32_t len);
 
 const uint8_t* translations_read(uint32_t* len, uint32_t offset);