core/sdcard: add ensure_filesystem option (fixes #868)

It is possible to call `ensure_sdcard` in a way that requires only SD
card be inserted, but not necessarily formatted.

This is useful for SD-protect and possibly other use-cases where the SD
card is read-only, and "not formatted" is identical to "not containing
the right files".

core/src/apps/common/sdcard.py

@@ -70,11 +70,25 @@ async def sd_problem_dialog(ctx: wire.GenericContext) -> bool:
     return await confirm(ctx, text, confirm="Retry", cancel="Abort")
 
 
-async def ensure_sdcard(ctx: wire.GenericContext) -> None:
+async def ensure_sdcard(
+    ctx: wire.GenericContext, ensure_filesystem: bool = True
+) -> None:
+    """Ensure a SD card is ready for use.
+
+    This function runs the UI flow needed to ask the user to insert a SD card if there
+    isn't one.
+
+    If `ensure_filesystem` is True (the default), it also tries to mount the SD card
+    filesystem, and allows the user to format the card if a filesystem cannot be
+    mounted.
+    """
     while not sdcard.is_present():
         if not await insert_card_dialog(ctx):
             raise SdCardUnavailable("SD card required.")
 
+    if not ensure_filesystem:
+        return
+
     while True:
         try:
             with sdcard.get_filesystem(mounted=False) as fs:
@@ -105,7 +119,7 @@ async def request_sd_salt(
         return None
 
     while True:
-        await ensure_sdcard(ctx)
+        await ensure_sdcard(ctx, ensure_filesystem=False)
         try:
             return storage.sd_salt.load_sd_salt()
         except storage.sd_salt.WrongSdCard:
@@ -117,4 +131,4 @@ async def request_sd_salt(
             # In either case, there is no good way to recover. If the user clicks Retry,
             # we will try again.
             if not await sd_problem_dialog(ctx):
-                raise
+                raise SdCardUnavailable("Error accessing SD card.")

tests/device_tests/test_sdcard.py

@@ -43,3 +43,70 @@ def test_sd_no_format(client):
         device.sd_protect(client, Op.ENABLE)
 
     assert e.value.failure.code == messages.FailureType.ProcessError
+
+
+@pytest.mark.sd_card
+@pytest.mark.setup_client(pin="1234")
+def test_sd_protect_unlock(client):
+    def input_flow_enable_sd_protect():
+        yield  # do you really want to enable SD protection
+        assert "SD card protection" in client.debug.wait_layout().text
+        client.debug.press_yes()
+
+        yield  # enter current PIN
+        assert "PinDialog" == client.debug.wait_layout().text
+        client.debug.input("1234")
+
+        yield  # you have successfully enabled SD protection
+        assert "Success" in client.debug.wait_layout().text
+        client.debug.press_yes()
+
+    with client:
+        client.set_input_flow(input_flow_enable_sd_protect)
+        device.sd_protect(client, Op.ENABLE)
+
+    def input_flow_change_pin():
+        yield  # do you really want to change PIN?
+        assert "Change PIN" in client.debug.wait_layout().text
+        client.debug.press_yes()
+
+        yield  # enter current PIN
+        assert "PinDialog" == client.debug.wait_layout().text
+        client.debug.input("1234")
+
+        yield  # enter new PIN
+        assert "PinDialog" == client.debug.wait_layout().text
+        client.debug.input("1234")
+
+        yield  # enter new PIN again
+        assert "PinDialog" == client.debug.wait_layout().text
+        client.debug.input("1234")
+
+        yield  # Pin change successful
+        assert "Success" in client.debug.wait_layout().text
+        client.debug.press_yes()
+
+    with client:
+        client.set_input_flow(input_flow_change_pin)
+        device.change_pin(client)
+
+    client.debug.erase_sd_card(format=False)
+
+    def input_flow_change_pin_format():
+        yield  # do you really want to change PIN?
+        assert "Change PIN" in client.debug.wait_layout().text
+        client.debug.press_yes()
+
+        yield  # SD card problem
+        assert "SD card problem" in client.debug.wait_layout().text
+        client.debug.press_yes()  # retry
+
+        yield  # still SD card problem
+        assert "SD card problem" in client.debug.wait_layout().text
+        client.debug.press_no()  # do not retry
+
+    with client, pytest.raises(TrezorFailure) as e:
+        client.set_input_flow(input_flow_change_pin_format)
+        device.change_pin(client)
+
+    assert e.value.failure.code == messages.FailureType.ProcessError

tests/ui_tests/fixtures.json

@@ -388,6 +388,7 @@
 "test_reset_backup.py::test_skip_backup_msg[2-backup_flow_slip39_advanced]": "df213fe327a775563fd8c442ed1ed2dfe5053d56d50307059292d5a5fe091b4c",
 "test_sdcard.py::test_sd_format": "e0da54c8a26386bff4eb310e9c7ebaa56a02fed3870f976d1dd3b230750a28fe",
 "test_sdcard.py::test_sd_no_format": "f47e897caee95cf98c1b4506732825f853c4b8afcdc2713e38e3b4055973c9ac",
+"test_sdcard.py::test_sd_protect_unlock": "0b6cb625b59256552505575bce75fb0895b935d574f2a07ac4a5246d608252af",
 "test_u2f_counter.py::test_u2f_counter": "7d96a4d262b9d8a2c1158ac1e5f0f7b2c3ed5f2ba9d6235a014320313f9488fe",
 "test_zerosig.py-test_one_zero_signature": "401aeaf7b2f565e2064a3c1a57a8ee3afe1e9bf251fba0874390685e7e0f178f",
 "test_zerosig.py-test_two_zero_signature": "7a01a057fb5dd3e6e38e7986875c5d07f0700bd80b519660e0b42973a9afd664"