add persistance to trezor.config mock

src/.gitignore

@@ -0,0 +1 @@
+trezor.config

src/trezor/config.py

@@ -1,25 +1,50 @@
-# mock in-memory implementation
+import sys
 
-_mock = {}
+if sys.platform == 'trezor': # stmhal - use binary module (not working atm)
 
-def get(app, key, default=None):
-    return _mock.get((app << 8) | key, default)
+    from TrezorConfig import Config
 
-def set(app, key, value):
-    _mock[(app << 8) | key] = value
-    return True
+    _config = Config()
 
-# real implementation commented below
+    def get(app, key, default=None):
+        v = _config.get(app, key)
+        return v if v else default
 
-'''
-from TrezorConfig import Config
+    def set(app, key, value):
+        return _config.set(app, key, value)
 
-_config = Config()
+else: # emulator (mock implementation using binary file)
 
-def get(app, key, default=None):
-    v = _config.get(app, key)
-    return v if v else default
+    import ustruct
 
-def set(app, key, value):
-    return _config.set(app, key, value)
-'''
+    _mock = {}
+    _file = 'trezor.config'
+
+    def _load():
+        try:
+            with open(_file, 'rb') as f:
+                while True:
+                    d = f.read(4)
+                    if len(d) != 4:
+                        break
+                    k, l = ustruct.unpack('<HH', d)
+                    v = f.read(l)
+                    _mock[k] = v
+        except OSError:
+            pass
+
+    def _save():
+        with open(_file, 'wb') as f:
+            for k, v in _mock.items():
+                f.write(ustruct.pack('<HH', k, len(v)))
+                f.write(v)
+
+    _load()
+
+    def get(app, key, default=None):
+        return _mock.get((app << 8) | key, default)
+
+    def set(app, key, value):
+        _mock[(app << 8) | key] = value
+        _save()
+        return True