trezor: more user friendly when cannot connect

Tell the user and ask if they want to try again.  If they
say no, raise a silent exception.  Apply this more friendly
behaviour to the install wizard too (see issue #1668).

gui/qt/installwizard.py

@@ -1,4 +1,4 @@
-from sys import stdout
+import sys
 
 from PyQt4.QtGui import *
 from PyQt4.QtCore import *
@@ -14,8 +14,8 @@ from password_dialog import PasswordLayout, PW_NEW, PW_PASSPHRASE
 
 from electrum.wallet import Wallet
 from electrum.mnemonic import prepare_seed
-from electrum.util import SilentException
+from electrum.util import UserCancelled
-from electrum.wizard import (WizardBase, UserCancelled,
+from electrum.wizard import (WizardBase,
                              MSG_ENTER_PASSWORD, MSG_RESTORE_PASSPHRASE,
                              MSG_COSIGNER, MSG_ENTER_SEED_OR_MPK,
                              MSG_SHOW_MPK, MSG_VERIFY_SEED,
@@ -119,7 +119,7 @@ class InstallWizard(QDialog, MessageBoxMixin, WizardBase):
         self.refresh_gui()
 
     def on_error(self, exc_info):
-        if not isinstance(exc_info[1], SilentException):
+        if not isinstance(exc_info[1], UserCancelled):
             traceback.print_exception(*exc_info)
             self.show_error(str(exc_info[1]))
 
@@ -167,7 +167,7 @@ class InstallWizard(QDialog, MessageBoxMixin, WizardBase):
             self.print_error("wallet creation cancelled by user")
             self.accept()  # For when called from menu
         except BaseException as e:
-            self.show_error(str(e))
+            self.on_error(sys.exc_info())
             raise
         return wallet
 

gui/qt/main_window.py

@@ -40,7 +40,7 @@ from electrum.i18n import _
 from electrum.util import (block_explorer, block_explorer_info, format_time,
                            block_explorer_URL, format_satoshis, PrintError,
                            format_satoshis_plain, NotEnoughFunds, StoreDict,
-                           SilentException)
+                           UserCancelled)
 from electrum import Transaction, mnemonic
 from electrum import util, bitcoin, commands
 from electrum import SimpleConfig, COIN_CHOOSERS, paymentrequest
@@ -214,7 +214,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
         self.raise_()
 
     def on_error(self, exc_info):
-        if not isinstance(exc_info[1], SilentException):
+        if not isinstance(exc_info[1], UserCancelled):
             traceback.print_exception(*exc_info)
             self.show_error(str(exc_info[1]))
 

lib/plugins.py

@@ -26,7 +26,7 @@ import time
 
 from util import *
 from i18n import _
-from util import profiler, PrintError, DaemonThread
+from util import profiler, PrintError, DaemonThread, UserCancelled
 import wallet
 
 class Plugins(DaemonThread):
@@ -386,26 +386,20 @@ class DeviceMgr(PrintError):
         # The wallet has not been previously paired, so let the user
         # choose an unpaired device and compare its first address.
         info = self.select_device(wallet, plugin, devices)
-        if info:
-            client = self.client_lookup(info.device.id_)
-            if client and client.is_pairable():
-                # See comment above for same code
-                client.handler = wallet.handler
-                # This will trigger a PIN/passphrase entry request
-                client_first_address = client.first_address(derivation)
-                if client_first_address == first_address:
-                    self.pair_wallet(wallet, info.device.id_)
-                    return client
 
-        if info and client:
+        client = self.client_lookup(info.device.id_)
-            # The user input has wrong PIN or passphrase
+        if client and client.is_pairable():
-            raise DeviceUnpairableError(
+            # See comment above for same code
-                _('Unable to pair with your %s.') % plugin.device)
+            client.handler = wallet.handler
+            # This will trigger a PIN/passphrase entry request
+            client_first_address = client.first_address(derivation)
+            if client_first_address == first_address:
+                self.pair_wallet(wallet, info.device.id_)
+                return client
 
-        raise DeviceNotFoundError(
+        # The user input has wrong PIN or passphrase, or it is not pairable
-            _('Could not connect to your %s.  Verify the cable is '
+        raise DeviceUnpairableError(
-              'connected and that no other application is using it.')
+            _('Unable to pair with your %s.') % plugin.device)
-            % plugin.device)
 
     def unpaired_device_infos(self, handler, plugin, devices=None):
         '''Returns a list of DeviceInfo objects: one for each connected,
@@ -432,9 +426,17 @@ class DeviceMgr(PrintError):
     def select_device(self, wallet, plugin, devices=None):
         '''Ask the user to select a device to use if there is more than one,
         and return the DeviceInfo for the device.'''
-        infos = self.unpaired_device_infos(wallet.handler, plugin, devices)
+        while True:
-        if not infos:
+            infos = self.unpaired_device_infos(wallet.handler, plugin, devices)
-            return None
+            if infos:
+                break
+            msg = _('Could not connect to your %s.  Verify the cable is '
+                    'connected and that no other application is using it.\n\n'
+                    'Try to connect again?') % plugin.device
+            if not wallet.handler.yes_no_question(msg):
+                raise UserCancelled()
+            devices = None
+
         if len(infos) == 1:
             return infos[0]
         msg = _("Please select which %s device to use:") % plugin.device

lib/util.py

@@ -21,8 +21,10 @@ class InvalidPassword(Exception):
     def __str__(self):
         return _("Incorrect password")
 
-class SilentException(Exception):
+# Throw this exception to unwind the stack like when an error occurs.
-    '''An exception that should probably be suppressed from the user'''
+# However unlike other exceptions the user won't be informed.
+class UserCancelled(Exception):
+    '''An exception that is suppressed from the user'''
     pass
 
 class MyEncoder(json.JSONEncoder):

lib/wizard.py

@@ -36,9 +36,6 @@ MSG_RESTORE_PASSPHRASE = \
       "Note this is NOT a password.  Enter nothing if you did not use "
       "one or are unsure.")
 
-class UserCancelled(Exception):
-    pass
-
 class WizardBase(PrintError):
     '''Base class for gui-specific install wizards.'''
     user_actions = ('create', 'restore')

plugins/hw_wallet/qt.py

@@ -34,6 +34,7 @@ class QtHandlerBase(QObject, PrintError):
     logic for handling I/O.'''
 
     qcSig = pyqtSignal(object, object)
+    ynSig = pyqtSignal(object)
 
     def __init__(self, win, device):
         super(QtHandlerBase, self).__init__()
@@ -43,6 +44,7 @@ class QtHandlerBase(QObject, PrintError):
         win.connect(win, SIGNAL('passphrase_dialog'), self.passphrase_dialog)
         win.connect(win, SIGNAL('word_dialog'), self.word_dialog)
         self.qcSig.connect(self.win_query_choice)
+        self.ynSig.connect(self.win_yes_no_question)
         self.win = win
         self.device = device
         self.dialog = None
@@ -60,6 +62,12 @@ class QtHandlerBase(QObject, PrintError):
         self.done.wait()
         return self.choice
 
+    def yes_no_question(self, msg):
+        self.done.clear()
+        self.ynSig.emit(msg)
+        self.done.wait()
+        return self.ok
+
     def show_message(self, msg, on_cancel=None):
         self.win.emit(SIGNAL('message_dialog'), msg, on_cancel)
 
@@ -126,3 +134,7 @@ class QtHandlerBase(QObject, PrintError):
     def win_query_choice(self, msg, labels):
         self.choice = self.win.query_choice(msg, labels)
         self.done.set()
+
+    def win_yes_no_question(self, msg):
+        self.ok = self.top_level_window().question(msg)
+        self.done.set()

plugins/trezor/clientbase.py

@@ -1,7 +1,7 @@
 from sys import stderr
 
 from electrum.i18n import _
-from electrum.util import PrintError, SilentException
+from electrum.util import PrintError, UserCancelled
 
 
 class GuiMixin(object):
@@ -27,7 +27,7 @@ class GuiMixin(object):
         # gets old very quickly, so we suppress those.
         if msg.code in (self.types.Failure_PinCancelled,
                         self.types.Failure_ActionCancelled):
-            raise SilentException()
+            raise UserCancelled()
         raise RuntimeError(msg.message)
 
     def callback_ButtonRequest(self, msg):

plugins/trezor/plugin.py

@@ -220,8 +220,6 @@ class TrezorCompatiblePlugin(HW_PluginBase):
         process.  Then create the wallet accounts.'''
         devmgr = self.device_manager()
         device_info = devmgr.select_device(wallet, self)
-        if not device_info:
-            raise RuntimeError(_("No devices found"))
         devmgr.pair_wallet(wallet, device_info.device.id_)
         if device_info.initialized:
             task = partial(wallet.create_hd_account, None)

plugins/trezor/qt_generic.py

@@ -11,9 +11,8 @@ from ..hw_wallet.qt import QtHandlerBase
 
 from electrum.i18n import _
 from electrum.plugins import hook, DeviceMgr
-from electrum.util import PrintError
+from electrum.util import PrintError, UserCancelled
 from electrum.wallet import Wallet, BIP44_Wallet
-from electrum.wizard import UserCancelled
 
 PASSPHRASE_HELP_SHORT =_(
     "Passphrases allow you to access new wallets, each "
@@ -317,10 +316,7 @@ def qt_plugin_class(base_plugin_class):
         device_id = self.device_manager().wallet_id(window.wallet)
         if not device_id:
             info = self.device_manager().select_device(window.wallet, self)
-            if info:
+            device_id = info.device.id_
-                device_id = info.device.id_
-            else:
-                window.wallet.handler.show_error(_("No devices found"))
         return device_id
 
     def query_choice(self, window, msg, choices):