[orca] Fix for bgo#583199 - orca should not hang itself, or the desktop when brltty is killed

[William Walker <wwalker src gnome org>]

commit 0f602721bcb9bfdb65b12e6836869af163d47382
Author: Willie Walker <william walker sun com>
Date:   Thu Jul 9 15:30:17 2009 -0400

    Fix for bgo#583199 - orca should not hang itself, or the desktop when brltty is killed
    
    This fix allows BrlTTY to be killed, restarted, started before Orca, started
    after Orca, etc.  If the user has requested braille support and Orca has not
    yet connected to BrlTTY, Orca will try to connect to BrlTTY each time Orca has
    something to present in braille.  As a result, the default value for
    settings.enableBraille has been set to False to prevent speech-only users
    from incurring the overhead of this check.

 src/orca/braille.py  |  116 +++++++++++++++++++++++++++++++++----------------
 src/orca/settings.py |    2 +-
 2 files changed, 79 insertions(+), 39 deletions(-)
---
diff --git a/src/orca/braille.py b/src/orca/braille.py
index 11803e2..f9a8c82 100644
--- a/src/orca/braille.py
+++ b/src/orca/braille.py
@@ -45,6 +45,7 @@ except ImportError:
 try:
     import brlapi
     import gobject
+    gobject.threads_init()
 
     _brlAPI = None
     _brlAPIAvailable = True
@@ -71,13 +72,9 @@ from platform import tablesdir
 
 from orca_i18n import _                          # for gettext support
 
-# If True, this module has been initialized.
-#
-_initialized = False
-
 # The braille monitor
 #
-monitor = None
+_monitor = None
 
 # Common names for most used BrlTTY commands, to be shown in the GUI:
 # ATM, the ones used in default.py are:
@@ -178,7 +175,8 @@ if _brlAPIAvailable:
 #
 # [[[TODO: WDW - Only a height of 1 is support at this time.]]]
 #
-_displaySize = [32, 1]
+DEFAULT_DISPLAY_SIZE = 32
+_displaySize = [DEFAULT_DISPLAY_SIZE, 1]
 
 # The list of lines on the display.  This represents the entire amount of data
 # to be drawn on the display.  It will be clipped by the viewport if too large.
@@ -486,6 +484,8 @@ class Component(Region):
             try:
                 eventsynthesizer.clickObject(self.accessible, 1)
             except:
+                debug.println(debug.LEVEL_SEVERE,
+                              "Could not process routing key:")
                 debug.printException(debug.LEVEL_SEVERE)
         else:
             action.doAction(0)
@@ -1068,11 +1068,19 @@ def refresh(panToCursor=True, targetCursorCell=0, getLinkMask=True):
     global endIsShowing
     global beginningIsShowing
     global cursorCell
-    global monitor
+    global _monitor
 
     if len(_lines) == 0:
+        if not _brlAPIRunning:
+            init(_callback, settings.tty)
         if _brlAPIRunning:
-            _brlAPI.writeText("", 0)
+            try:
+                _brlAPI.writeText("", 0)
+            except:
+                debug.println(debug.LEVEL_WARNING,
+                              "BrlTTY seems to have disappeared:")
+                debug.printException(debug.LEVEL_WARNING)
+                shutdown()
         return
 
     # Now determine the location of the cursor.  First, we'll figure
@@ -1128,6 +1136,8 @@ def refresh(panToCursor=True, targetCursorCell=0, getLinkMask=True):
     log.info(logLine.encode("UTF-8"))
 
     substring = string[startPos:endPos]
+    if not _brlAPIRunning:
+        init(_callback, settings.tty)
     if _brlAPIRunning:
         writeStruct = brlapi.WriteStruct()
         writeStruct.regionBegin = 1
@@ -1158,20 +1168,29 @@ def refresh(panToCursor=True, targetCursorCell=0, getLinkMask=True):
         if attributeMask:
             writeStruct.attrOr = attributeMask[startPos:endPos]
 
-        _brlAPI.write(writeStruct)
+        if not _brlAPIRunning:
+            init(_callback, settings.tty)
+        if _brlAPIRunning:
+            try:
+                _brlAPI.write(writeStruct)
+            except:
+                debug.println(debug.LEVEL_WARNING,
+                              "BrlTTY seems to have disappeared:")
+                debug.printException(debug.LEVEL_WARNING)
+                shutdown()
 
     if settings.enableBrailleMonitor:
-        if not monitor:
-            monitor = brlmon.BrlMon(_displaySize[0])
-            monitor.show_all()
+        if not _monitor:
+            _monitor = brlmon.BrlMon(_displaySize[0])
+            _monitor.show_all()
         if attributeMask:
             subMask = attributeMask[startPos:endPos]
         else:
             subMask = None
-        monitor.writeText(cursorCell, substring, subMask)
-    elif monitor:
-        monitor.destroy()
-        monitor = None
+        _monitor.writeText(cursorCell, substring, subMask)
+    elif _monitor:
+        _monitor.destroy()
+        _monitor = None
 
     beginningIsShowing = startPos == 0
     endIsShowing = endPos >= len(string)
@@ -1343,6 +1362,7 @@ def _processBrailleEvent(event):
             #
             consumed = _callback(event)
         except:
+            debug.println(debug.LEVEL_WARNING, "Issue processing event:")
             debug.printException(debug.LEVEL_WARNING)
             consumed = False
 
@@ -1355,7 +1375,13 @@ def _brlAPIKeyReader(source, condition):
     """Method to read a key from the BrlAPI bindings.  This is a
     gobject IO watch handler.
     """
-    key = _brlAPI.readKey(False)
+    try:
+        key = _brlAPI.readKey(False)
+    except:
+        debug.println(debug.LEVEL_WARNING, "BrlTTY seems to have disappeared:")
+        debug.printException(debug.LEVEL_WARNING)
+        shutdown()
+        return
     if key:
         _processBrailleEvent(_brlAPI.expandKeyCode(key))
     return _brlAPIRunning
@@ -1368,6 +1394,8 @@ def setupKeyRanges(keys):
     -keys: a list of BrlAPI commands.
     """
     if not _brlAPIRunning:
+        init(_callback, settings.tty)
+    if not _brlAPIRunning:
         return
 
     # First, start by ignoring everything.
@@ -1391,25 +1419,26 @@ def init(callback=None, tty=7):
     Arguments:
     - callback: the method to call with a BrlTTY input event.
     - tty: the tty port to take ownership of (default = 7)
-    Returns True if the initialization procedure was run or False if this
-    module has already been initialized.
+    Returns False if BrlTTY cannot be accessed or braille has
+    not been enabled.
     """
 
-    global _initialized
+    global _brlAPI
+    global _brlAPIRunning
+    global _brlAPISourceId
     global _displaySize
     global _callback
+    global _monitor
+
+    if _brlAPIRunning:
+        return True
 
-    if _initialized:
+    if not settings.enableBraille:
         return False
 
     _callback = callback
 
     try:
-        global _brlAPI
-        global _brlAPIRunning
-        global _brlAPISourceId
-
-        gobject.threads_init()
         _brlAPI = brlapi.Connection()
 
         try:
@@ -1430,7 +1459,10 @@ def init(callback=None, tty=7):
                                                gobject.IO_IN,
                                                _brlAPIKeyReader)
     except:
-        debug.printException(debug.LEVEL_FINEST)
+        debug.println(debug.LEVEL_CONFIGURATION,
+                      "Could not initialize BrlTTY:")
+        debug.printException(debug.LEVEL_CONFIGURATION)
+        _brlAPIRunning = False
         return False
 
     # [[[TODO: WDW - For some reason, BrlTTY wants to say the height of the
@@ -1440,6 +1472,12 @@ def init(callback=None, tty=7):
     (x, y) = _brlAPI.displaySize
     _displaySize = [x, 1]
 
+    # The monitor will be created in refresh if needed.
+    #
+    if _monitor:
+        _monitor.destroy()
+        _monitor = None
+
     debug.println(debug.LEVEL_CONFIGURATION,
                   "braille display size = (%d, %d)" \
                   % (_displaySize[0], _displaySize[1]))
@@ -1447,29 +1485,31 @@ def init(callback=None, tty=7):
     clear()
     refresh(True)
 
-    _initialized = True
-
     return True
 
 def shutdown():
     """Shuts down the braille module.   Returns True if the shutdown procedure
-    was run or False if this module has not been initialized.
+    was run.
     """
 
-    global _initialized
-
-    if not _initialized:
-        return False
-
     global _brlAPIRunning
     global _brlAPISourceId
+    global _monitor
+    global _displaySize
 
     if _brlAPIRunning:
         _brlAPIRunning = False
         gobject.source_remove(_brlAPISourceId)
         _brlAPISourceId = 0
-        _brlAPI.leaveTtyMode()
-
-    _initialized = False
+        try:
+            _brlAPI.leaveTtyMode()
+        except:
+            pass
+        if _monitor:
+            _monitor.destroy()
+            _monitor = None
+        _displaySize = [DEFAULT_DISPLAY_SIZE, 1]
+    else:
+        return False
 
     return True
diff --git a/src/orca/settings.py b/src/orca/settings.py
index 8048d82..336d297 100644
--- a/src/orca/settings.py
+++ b/src/orca/settings.py
@@ -341,7 +341,7 @@ enableSpeechIndentation = False
 
 # If True, enable braille.
 #
-enableBraille           = True
+enableBraille           = False
 
 # If True, add the hierarchical context of an object to the braille
 # line.  People with very large braille displays may want to set this