From edae40e22cb19a51dc1a02ba6806fc89f6c350fe Mon Sep 17 00:00:00 2001
From: Andrew Kozlik <andrew.kozlik@gmail.com>
Date: Sat, 23 Feb 2019 12:19:08 +0100
Subject: [PATCH] pin: do not allow the user to enter an empty PIN

An empty PIN is used to signify PIN removal and T1 does not allow entering an empty PIN neither via web-wallet nor via trezorctl.
---
 src/apps/common/request_pin.py | 13 +++++++++++++
 src/trezor/ui/button.py        |  3 +++
 2 files changed, 16 insertions(+)

diff --git a/src/apps/common/request_pin.py b/src/apps/common/request_pin.py
index 82eb3eb77b..c0d9f091c2 100644
--- a/src/apps/common/request_pin.py
+++ b/src/apps/common/request_pin.py
@@ -36,6 +36,17 @@ async def request_pin(
                 c.taint()
         c.render()
 
+        c = dialog.confirm
+        if matrix.pin:
+            if not c.is_enabled():
+                c.enable()
+                c.taint()
+        else:
+            if c.is_enabled():
+                c.disable()
+                c.taint()
+        c.render()
+
     if label is None:
         label = "Enter your PIN"
     sublabel = None
@@ -59,6 +70,8 @@ async def request_pin(
         else:
             result = await dialog
         if result == CONFIRMED:
+            if not matrix.pin:
+                continue
             return matrix.pin
         elif matrix.pin:  # reset
             matrix.change("")
diff --git a/src/trezor/ui/button.py b/src/trezor/ui/button.py
index 5d39410a77..75f5e427d2 100644
--- a/src/trezor/ui/button.py
+++ b/src/trezor/ui/button.py
@@ -36,6 +36,9 @@ class Button(Widget):
             self.state = BTN_DISABLED
             self.tainted = True
 
+    def is_enabled(self):
+        return self.state != BTN_DISABLED
+
     def render(self):
         if not self.tainted:
             return