GenForwarders.py

import glob
import os
import subprocess
import sys

if len(sys.argv) != 3:
	print("Usage: GenForwarders.py <vs_folder> <vc_version_to_generate>")
	print("Last version generated 14.21.27702")
	exit()

VSFolder = sys.argv[1]
VCVersion = sys.argv[2]

archs = ["x86", "x64", "arm64"]

importLibMapping = {
	"concrt140" : "concrt.lib",
	"concrt140d" : "concrtd.lib",
	"msvcp140_1" : "msvcprt.lib",
	"msvcp140_1d" : "msvcprt.lib",
	"msvcp140_2" : "msvcprt.lib",
	"msvcp140_2d" : "msvcprt.lib",
	"msvcp140" : "msvcprt.lib",
	"msvcp140d" : "msvcprtd.lib",
	"vcamp140" : "vcamp.lib",
	"vcamp140d" : "vcampd.lib",
	"vccorlib140" : "vccorlib.lib",
	"vccorlib140d" : "vccorlibd.lib",
	"vcomp140" : "vcomp.lib",
	"vcomp140d" : "vcompd.lib",
	"vcruntime140" : "vcruntime.lib",
	"vcruntime140d" : "vcruntimed.lib",
	"vcruntime140_1" : "vcruntime.lib",
	"vcruntime140_1d" : "vcruntimed.lib",
};

def GetModules(arch):
	modules = []

	releaseFolder = os.path.join(VSFolder, r"VC\Redist\MSVC", VCVersion, arch)
	releaseModules = glob.glob(os.path.join(releaseFolder, r"**\*.dll"), recursive=True)

	modules += [[module, True] for module in releaseModules]

	debugFolder = os.path.join(VSFolder, r"VC\Redist\MSVC", VCVersion, r"debug_nonredist", arch)
	debugModules = glob.glob(os.path.join(debugFolder, r"**\*.dll"), recursive=True)

	modules += [[module, False] for module in debugModules]

	return modules

def GetImportLibFolder(arch):
	return os.path.join(VSFolder, r"VC\Tools\MSVC", VCVersion, "lib", arch)

def GetDumpbin():
	return os.path.join(VSFolder, r"VC\Tools\MSVC", VCVersion, r"bin\Hostx86\x86\dumpbin.exe")

def GenerateSymbolMapping(importLibPath):
	symbolTable = {}
	output = subprocess.Popen([GetDumpbin(), "/headers", importLibPath], stdout=subprocess.PIPE)
	for line in iter(output.stdout.readline,b''):
		strippedLine = line.strip().decode("windows-1251") 

		# ignore all lines other than for symbol entry
		if "Symbol name" not in strippedLine:
			continue

		# skip a few lines to get to the nameType and name field
		output.stdout.readline() # type
		nameType = output.stdout.readline().strip().decode("windows-1251")
		output.stdout.readline() # hint
		name = output.stdout.readline().strip().decode("windows-1251")
		
		# symbol line is in format of Symbol name : <symbol> [(extra info)]
		symbol = strippedLine.split(":")[1].strip().split(" ")[0].strip()
		name = name.split(":")[1].strip()
		nameType = nameType.split(":")[1].strip()
		
		if name in symbolTable:
			raise ValueError

		if nameType == "no prefix":
			symbolTable[name] = symbol
		elif nameType == "name":
			symbolTable[name] = name
		elif nameType == "undecorate":
			symbolTable[name] = "_" + name
		else:
			raise ValueError(nameType)

	return symbolTable

# Generate the same folder structure as the repo
# i.e. 140_debug\vcrt_fwd_x64_debug\concrt140d_app
def GetOutputFolder(arch, isRelease, module):
	folderSuffix = "release" if isRelease else "debug"
	return str.format(r"140_{0}\vcrt_fwd_{1}_{0}\{2}_app", folderSuffix, arch, module)

# main logic to go through each module and generate forwarders
errors = []
for arch in archs:
	for item in GetModules(arch):
		modulePath = item[0]
		module = os.path.splitext(os.path.basename(modulePath))[0]

		symbolMapping = GenerateSymbolMapping(os.path.join(GetImportLibFolder(arch), importLibMapping[module]))
		outputFolder = GetOutputFolder(arch, item[1], module)
		if not os.path.exists(outputFolder):
			os.makedirs(outputFolder)
		outputFile = open(os.path.join(outputFolder, module + "_app.cpp"), "w")
		
		output = subprocess.Popen([GetDumpbin(), "/exports", modulePath], stdout=subprocess.PIPE)
		headerParsed = False
		for line in iter(output.stdout.readline,b''):
			strippedLine = line.strip().decode("windows-1251") 
			if not headerParsed:
				if ("ordinal" in strippedLine and "hint" in strippedLine):
					# Skip line after header
					output.stdout.readline()
					headerParsed = True
				continue
			
			if strippedLine == "Summary":
				break
				
			if strippedLine == "":
				continue
			
			function = list(filter(None, strippedLine.split(" ")))[3]
			if function not in symbolMapping:
				# handle edge case for _EH_PROLOG as for some reason it is not in the symbol table and is only in X86.
				if function == "_EH_prolog":
					outputFile.write(str.format("""#pragma comment(linker, "/export:{0}={1}.{2}")\n""", "__EH_prolog", module, function))
				else:
					errors += [[module, function]]
			else:
				outputFile.write(str.format("""#pragma comment(linker, "/export:{0}={1}.{2}")\n""", symbolMapping[function], module, function))
				
		outputFile.close()

print(errors)