Repaired the COM Registration Fixing Tool so it is more effective on …

…64bit Windows (nvaccess#9039).

Problems:
- The registerServer function called the 32-bit version of regsvr32.exe, even in 64-bit contexts.
- The applyRegistryPatch function called the 32-bit version of regedit, even in 64-bit contexts.
Remediation:
- Replaced applyRegistryPatch function with two new functions: apply32bitRegistryPatch and apply64bitRegistryPatch.
- Replaced registerServer function with register32bitServer and register64bitServer, to make clear what they do.
- The new functions don't check 32/64 bitness; they leave that to the caller and log errors on failure.
- Updated to more descriptive error logging.
- Adjusted the Windows 7 code to use server registration with proper bitness for each DLL.
Path remediations:
- Moved the OLEACC_REG_FILE_PATH constant to the top of the file with the rest.
- Added sysnative path to the list of path constants at the top of the file.
- Now use Sysnative in the path for intentional 64bit calls, per discussions linked from nvaccess#9039.
- Now use System32 in the path for 32-bit calls on either 32-bit or 64-bit systems.
- For convenience, and because it's required in System32, renamed regedit.exe to regedt32.exe in the subprocess calls.
- Removed now unused sysWow64 path constant.
Misc:
- Added docstring note about 32 and 64 bit functions needing attention if NVDA goes 64-bit in the future.
- Updated copyright.

source/COMRegistrationFixes/__init__.py

@@ -1,5 +1,5 @@
 # A part of NonVisual Desktop Access (NVDA)
-# Copyright (C) 2018-2020 NV Access Limited
+# Copyright (C) 2018-2021 NV Access Limited
 # This file is covered by the GNU General Public License.
 # See the file COPYING for more details.
 
@@ -11,71 +11,110 @@
 import globalVars
 from logHandler import log
 
+OLEACC_REG_FILE_PATH = os.path.join(globalVars.appDir, "COMRegistrationFixes", "oleaccProxy.reg")
 # Particular  64 bit / 32 bit system paths
-systemRoot=os.path.expandvars('%SYSTEMROOT%')
-system32=os.path.join(systemRoot,'system32')
-sysWow64=os.path.join(systemRoot,'syswow64')
-systemDrive=os.path.expandvars('%SYSTEMDRIVE%\\')
-programFiles=os.path.join(systemDrive,'program files')
-programFilesX86=os.path.join(systemDrive,'program files (x86)')
+systemRoot = os.path.expandvars("%SYSTEMROOT%")
+system32 = os.path.join(systemRoot, "System32")
+sysnative = os.path.join(systemRoot, "Sysnative")  # Virtual folder for reaching 64-bit exes from 32-bit apps
+systemDrive = os.path.expandvars("%SYSTEMDRIVE%\\")
+programFiles = os.path.join(systemDrive, "program files")
+programFilesX86 = os.path.join(systemDrive, "program files (x86)")
+
 
-def registerServer(fileName,wow64=False):
+def register32bitServer(fileName: str) -> None:
+	"""Registers the COM proxy dll with the given file name, using the 32-bit version of regsvr32.
+	Note: this function is valid while NVDA remains a 32-bit app. Re-evaluate if we move to 64-bit.
+	@param fileName: the path to the dll
+	@type fileName: str
 	"""
-	Registers the COM proxy dll with the given file name
-	Using regsvr32.
+	# Points to the 32-bit version, on Windows 32-bit or 64-bit.
+	regsvr32 = os.path.join(system32, "regsvr32.exe")
+	try:
+		subprocess.check_call([regsvr32, "/s", fileName])
+	except subprocess.CalledProcessError as e:
+		log.error(f"Error registering {fileName} in a 32-bit context: {e}")
+	else:
+		log.debug(f"Registered {fileName} in a 32-bit context.")
+
+
+def register64bitServer(fileName: str) -> None:
+	"""Registers the COM proxy dll with the given file name, using the 64-bit version of regsvr64.
+	Note: this function is valid while NVDA remains a 32-bit app. Re-evaluate if we move to 64-bit.
 	@param fileName: the path to the dll
 	@type fileName: str
-	@param wow64: If true then the 32 bit (wow64) version of regsvr32 will be used.
-	@type wow64: bool
 	"""
-	regsvr32=os.path.join(sysWow64 if wow64 else system32,'regsvr32.exe')
+	# SysWOW64 provides a virtual directory to allow 32-bit programs to reach 64-bit executables.
+	regsvr32 = os.path.join(sysnative, "regsvr32.exe")
 	try:
-		subprocess.check_call([regsvr32,'/s',fileName])
+		subprocess.check_call([regsvr32, "/s", fileName])
 	except subprocess.CalledProcessError as e:
-		log.error("Error registering %s, %s"%(fileName,e))
+		log.error(f"Error registering {fileName} in a 64-bit context: {e}")
 	else:
-		log.debug("Registered %s"%fileName)
+		log.debug(f"Registered {fileName} in a 64-bit context.")
+
 
-def applyRegistryPatch(fileName,wow64=False):
+def apply32bitRegistryPatch(fileName: str) -> None:
+	"""Applies the registry patch with the given file name, using 32-bit regedit.
+	Note: this function is valid while NVDA remains a 32-bit app. Re-evaluate if we move to 64-bit.
+	@param fileName: the path to the .reg file
+	@type fileName: str
 	"""
-	Applies the registry patch with the given file name
-	using regedit.
+	if not os.path.isfile(fileName):
+		raise FileNotFoundError(f"Cannot apply 32-bit registry patch: {fileName} not found.")
+	# On 32-bit systems, regedt32 is in System32. On 64-bit systems, SysWOW64 will redirect to 32-bit version.
+	regedit = os.path.join(systemRoot, "System32", "regedt32.exe")
+	try:
+		subprocess.check_call([regedit, "/s", fileName])
+	except subprocess.CalledProcessError as e:
+		log.error(f"Error applying 32-bit registry patch from {fileName} with {regedit}: {e}")
+	else:
+		log.debug(f"Applied 32-bit registry patch from {fileName}")
+
+
+def apply64bitRegistryPatch(fileName: str) -> None:
+	"""Applies the registry patch with the given file name, using 64-bit regedit.
+	Note: this function is valid while NVDA remains a 32-bit app. Re-evaluate if we move to 64-bit.
 	@param fileName: the path to the .reg file
 	@type fileName: str
 	"""
 	if not os.path.isfile(fileName):
-		raise FileNotFoundError(f"Cannot apply registry patch, {fileName} not found.")
-	regedit=os.path.join(sysWow64 if wow64 else systemRoot,'regedit.exe')
+		raise FileNotFoundError(f"Cannot apply 64-bit registry patch: {fileName} not found.")
+	# On 64-bit systems, SysWOW64 provides 32-bit apps with a virtual directory to reach 64-bit executables.
+	# For hard coded historical compatibility, regedt32.exe is still the name of the 64-bit app.
+	regedit = os.path.join(sysnative, "regedt32.exe")
 	try:
-		subprocess.check_call([regedit,'/s',fileName])
+		subprocess.check_call([regedit, "/s", fileName])
 	except subprocess.CalledProcessError as e:
-		log.error("Error applying registry patch: %s with %s, %s"%(fileName,regedit,e))
+		log.error(f"Error applying 64-bit registry patch from {fileName} with {regedit}: {e}")
 	else:
-		log.debug("Applied registry patch: %s with %s"%(fileName,regedit))
+		log.debug(f"Applied 64-bit registry patch from {fileName}")
 
 
-OLEACC_REG_FILE_PATH = os.path.join(globalVars.appDir, "COMRegistrationFixes", "oleaccProxy.reg")
 def fixCOMRegistrations():
+	"""Registers most common COM proxies, in case they have accidentally been unregistered or overwritten by
+	3rd party software installs/uninstalls.
 	"""
-	Registers most common COM proxies, in case they had accidentally been unregistered or overwritten by 3rd party software installs/uninstalls.
-	"""
-	is64bit=os.environ.get("PROCESSOR_ARCHITEW6432","").endswith('64')
+	is64bit = os.environ.get("PROCESSOR_ARCHITEW6432", "").endswith("64")
 	winVer = winVersion.getWinVer()
 	OSMajorMinor = (winVer.major, winVer.minor)
-	log.debug("Fixing COM registration for Windows %s.%s, %s"%(OSMajorMinor[0],OSMajorMinor[1],"64 bit" if is64bit else "32 bit"))  
+	log.debug(
+		f"Fixing COM registration for Windows {OSMajorMinor[0]}.{OSMajorMinor[1]}, "
+		"{} bit.".format("64" if is64bit else "32")
+	)
 	# Commands taken from NVDA issue #2807 comment https://github.com/nvaccess/nvda/issues/2807#issuecomment-320149243
+	# And also the discussions in #9039 https://github.com/nvaccess/nvda/issues/9039
 	# OLEACC (MSAA) proxies
-	applyRegistryPatch(OLEACC_REG_FILE_PATH)
+	apply32bitRegistryPatch(OLEACC_REG_FILE_PATH)
 	if is64bit:
-		applyRegistryPatch(OLEACC_REG_FILE_PATH, wow64=True)
+		apply64bitRegistryPatch(OLEACC_REG_FILE_PATH)
 	# IDispatch and other common OLE interfaces
-	registerServer(os.path.join(system32,'oleaut32.dll'))
-	registerServer(os.path.join(system32,'actxprxy.dll'))
+	register32bitServer(os.path.join(system32, "oleaut32.dll"))
+	register32bitServer(os.path.join(system32, "actxprxy.dll"))
 	if is64bit:
-		registerServer(os.path.join(sysWow64,'oleaut32.dll'),wow64=True)
-		registerServer(os.path.join(sysWow64,'actxprxy.dll'),wow64=True)
+		register64bitServer(os.path.join(sysnative, "oleaut32.dll"))
+		register64bitServer(os.path.join(sysnative, "actxprxy.dll"))
 	# IServiceProvider on windows 7 can become unregistered 
-	if OSMajorMinor==(6,1): # Windows 7
-		registerServer(os.path.join(programFiles,'Internet Explorer','ieproxy.dll'))
+	if OSMajorMinor == (6, 1):  # Windows 7
+		register32bitServer(os.path.join(programFilesX86, "Internet Explorer", "ieproxy.dll"))
 		if is64bit:
-			registerServer(os.path.join(programFilesX86,'Internet Explorer','ieproxy.dll'),wow64=True)
+			register64bitServer(os.path.join(programFiles, "Internet Explorer", "ieproxy.dll"))