diff --git a/direct/src/showutil/FreezeTool.py b/direct/src/showutil/FreezeTool.py
index 9484c72b9c..d9f63d260b 100644
--- a/direct/src/showutil/FreezeTool.py
+++ b/direct/src/showutil/FreezeTool.py
@@ -652,7 +652,7 @@ class Freezer:
             return 'ModuleDef(%s)' % (', '.join(args))
 
     def __init__(self, previous = None, debugLevel = 0,
-                 platform = None):
+                 platform = None, path=None):
         # Normally, we are freezing for our own platform.  Change this
         # if untrue.
         self.platform = platform or PandaSystem.getPlatform()
@@ -663,6 +663,10 @@ class Freezer:
         # default object will be created when it is needed.
         self.cenv = None
 
+        # This is the search path to use for Python modules.  Leave it
+        # to the default value of None to use sys.path.
+        self.path = path
+
         # The filename extension to append to the source file before
         # compiling.
         self.sourceExtension = '.c'
@@ -999,7 +1003,7 @@ class Freezer:
             else:
                 includes.append(mdef)
 
-        self.mf = PandaModuleFinder(excludes = list(excludeDict.keys()), suffixes=self.moduleSuffixes)
+        self.mf = PandaModuleFinder(excludes=list(excludeDict.keys()), suffixes=self.moduleSuffixes, path=self.path)
 
         # Attempt to import the explicit modules into the modulefinder.
 
@@ -1672,6 +1676,7 @@ class Freezer:
             f.write(struct.pack('<I', modsoffset))
             f.write(struct.pack('<I', len(moduleList)))
         os.chmod(target, 0o755)
+        return target
 
     def makeModuleDef(self, mangledName, code):
         result = ''
diff --git a/direct/src/showutil/dist.py b/direct/src/showutil/dist.py
index 18f6d19781..344ad7655b 100644
--- a/direct/src/showutil/dist.py
+++ b/direct/src/showutil/dist.py
@@ -6,12 +6,15 @@ import pip
 import sys
 import subprocess
 import zipfile
+import struct
+import io
 
 import distutils.core
 import distutils.dir_util
 import distutils.file_util
 
-from direct.showutil import FreezeTool
+from . import FreezeTool
+from . import pefile
 import panda3d.core as p3d
 
 
@@ -19,27 +22,6 @@ if 'basestring' not in globals():
     basestring = str
 
 
-# TODO replace with Packager
-def find_packages(whlfile):
-    if whlfile is None:
-        dtool_fn = p3d.Filename(p3d.ExecutionEnvironment.get_dtool_name())
-        libdir = os.path.dirname(dtool_fn.to_os_specific())
-        filelist = [os.path.join(libdir, i) for i in os.listdir(libdir)]
-    else:
-        filelist = whlfile.namelist()
-
-    return [
-         i for i in filelist
-         if '.so.' in i or
-         #TODO: find a better way to exclude deploy_libs from this.
-         (i.endswith('.so') and not i.startswith('deploy_libs/')) or
-         i.endswith('.dll') or
-         i.endswith('.dylib') or
-         'libpandagl' in i or
-         'libpython' in i
-    ]
-
-
 class build_apps(distutils.core.Command):
     user_options = [] # TODO
 
@@ -57,6 +39,18 @@ class build_apps(distutils.core.Command):
         self.build_scripts= {
             '.egg': ('.bam', 'egg2bam -o {1} {0}'),
         }
+        self.exclude_dependencies = []
+
+        # We keep track of the zip files we've opened.
+        self._zip_files = {}
+
+    def _get_zip_file(self, path):
+        if path in self._zip_files:
+            return self._zip_files[path]
+
+        zip = zipfile.ZipFile(path)
+        self._zip_files[path] = zip
+        return zip
 
     def finalize_options(self):
         # TODO
@@ -69,252 +63,476 @@ class build_apps(distutils.core.Command):
         else:
             platforms = self.deploy_platforms
             use_wheels = True
-        print("Building platforms: {}".format(','.join(platforms)))
-
-        saved_path = sys.path[:]
+        print("Building platforms: {0}".format(','.join(platforms)))
 
         for platform in platforms:
-            builddir = os.path.join(self.build_base, platform)
+            self.build_runtimes(platform, use_wheels)
 
-            if os.path.exists(builddir):
-                distutils.dir_util.remove_tree(builddir)
-            distutils.dir_util.mkpath(builddir)
+    def download_wheels(self, platform):
+        """ Downloads panda3d wheels for the given platform using pip.
+        These are special wheels that are expected to contain a deploy_libs
+        directory containing the Python runtime libraries, which will be added
+        to sys.path."""
 
-            if use_wheels:
-                whldir = os.path.join(self.build_base, '__whl_cache__')
-                abi_tag = pip.pep425tags.get_abi_tag()
+        whldir = os.path.join(self.build_base, '__whl_cache__')
+        abi_tag = pip.pep425tags.get_abi_tag()
 
-                if 'u' in abi_tag and not platform.startswith('manylinux'):
-                    abi_tag = abi_tag.replace('u', '')
+        if 'u' in abi_tag and not platform.startswith('manylinux'):
+            abi_tag = abi_tag.replace('u', '')
 
-                pip_args = [
-                    'download',
-                    '-d', whldir,
-                    '-r', self.requirements_path,
-                    '--only-binary', ':all:',
-                    '--platform', platform,
-                    '--abi', abi_tag
-                ]
+        pip_args = [
+            'download',
+            '-d', whldir,
+            '-r', self.requirements_path,
+            '--only-binary', ':all:',
+            '--platform', platform,
+            '--abi', abi_tag
+        ]
 
-                for index in self.pypi_extra_indexes:
-                    pip_args += ['--extra-index-url', index]
+        for index in self.pypi_extra_indexes:
+            pip_args += ['--extra-index-url', index]
 
-                pip.main(args=pip_args)
+        pip.main(args=pip_args)
 
-                wheelpaths = [os.path.join(whldir,i) for i in os.listdir(whldir) if platform in i]
+        wheelpaths = [os.path.join(whldir,i) for i in os.listdir(whldir) if platform in i]
+        return wheelpaths
 
-                p3dwhl = None
-                for whl in wheelpaths:
-                    if 'panda3d-' in whl:
-                        p3dwhlfn = whl
-                        p3dwhl = zipfile.ZipFile(p3dwhlfn)
-                        break
-                else:
-                    raise RuntimeError("Missing panda3d wheel")
+    def build_runtimes(self, platform, use_wheels):
+        """ Builds the distributions for the given platform. """
 
-                whlfiles = {whl: zipfile.ZipFile(whl) for whl in wheelpaths}
+        builddir = os.path.join(self.build_base, platform)
 
-                # Add whl files to the path so they are picked up by modulefinder
-                sys.path = saved_path[:]
-                for whl in wheelpaths:
-                    sys.path.insert(0, whl)
+        if os.path.exists(builddir):
+            distutils.dir_util.remove_tree(builddir)
+        distutils.dir_util.mkpath(builddir)
 
-                # Add deploy_libs from panda3d whl to the path
-                sys.path.insert(0, os.path.join(p3dwhlfn, 'deploy_libs'))
+        path = sys.path[:]
+        p3dwhl = None
 
+        if use_wheels:
+            wheelpaths = self.download_wheels(platform)
 
-            # Create runtimes
-            freezer_extras = set()
-            freezer_modules = set()
-            def create_runtime(appname, mainscript, use_console):
-                freezer = FreezeTool.Freezer(platform=platform)
-                freezer.addModule('__main__', filename=mainscript)
-                for incmod in self.include_modules.get(appname, []) + self.include_modules.get('*', []):
-                    freezer.addModule(incmod)
-                for exmod in self.exclude_modules.get(appname, []) + self.exclude_modules.get('*', []):
-                    freezer.excludeModule(exmod)
-                freezer.done(addStartupModules=True)
-
-                stub_name = 'deploy-stub'
-                if platform.startswith('win'):
-                    if not use_console:
-                        stub_name = 'deploy-stubw'
-                    stub_name += '.exe'
-
-                if use_wheels:
-                    stub_file = p3dwhl.open('panda3d_tools/{}'.format(stub_name))
-                else:
-                    dtool_path = p3d.Filename(p3d.ExecutionEnvironment.get_dtool_name()).to_os_specific()
-                    stub_path = os.path.join(os.path.dirname(dtool_path), '..', 'bin', stub_name)
-                    stub_file = open(stub_path, 'rb')
-
-                freezer.generateRuntimeFromStub(os.path.join(builddir, appname), stub_file)
-                stub_file.close()
-
-                freezer_extras.update(freezer.extras)
-                freezer_modules.update(freezer.getAllModuleNames())
-
-            for appname, scriptname in self.gui_apps.items():
-                create_runtime(appname, scriptname, False)
-
-            for appname, scriptname in self.console_apps.items():
-                create_runtime(appname, scriptname, True)
-
-            # Copy extension modules
-            whl_modules = []
-            whl_modules_ext = ''
-            if use_wheels:
-                # Get the module libs
-                whl_modules = [
-                    i.replace('deploy_libs/', '') for i in p3dwhl.namelist() if i.startswith('deploy_libs/')
-                ]
-
-                # Pull off extension
-                if whl_modules:
-                    whl_modules_ext = '.'.join(whl_modules[0].split('.')[1:])
-                whl_modules = [i.split('.')[0] for i in whl_modules]
-
-            # Make sure to copy any builtins that have shared objects in the deploy libs
-            for mod in freezer_modules:
-                if mod in whl_modules:
-                    freezer_extras.add((mod, None))
-
-            # Copy any shared objects we need
-            for module, source_path in freezer_extras:
-                if source_path is not None:
-                    # Rename panda3d/core.pyd to panda3d.core.pyd
-                    basename = os.path.basename(source_path)
-                    if '.' in module:
-                        basename = module.rsplit('.', 1)[0] + '.' + basename
-
-                    # Remove python version string
-                    if sys.version_info >= (3, 0):
-                        parts = basename.split('.')
-                        parts = parts[:-2] + parts[-1:]
-                        basename = '.'.join(parts)
-                else:
-                    # Builtin module, but might not be builtin in wheel libs, so double check
-                    if module in whl_modules:
-                        source_path = '{}/deploy_libs/{}.{}'.format(p3dwhlfn, module, whl_modules_ext)
-                        basename = os.path.basename(source_path)
-                    else:
-                        continue
-
-
-                target_path = os.path.join(builddir, basename)
-                if '.whl/' in source_path:
-                    # This was found in a wheel, extract it
-                    whl, wf = source_path.split('.whl/')
-                    whl += '.whl'
-                    whlfile = whlfiles[whl]
-                    print("copying {} -> {}".format(os.path.join(whl, wf), target_path))
-                    with open(target_path, 'wb') as f:
-                        f.write(whlfile.read(wf))
-                else:
-                    # Regular file, copy it
-                    distutils.file_util.copy_file(source_path, target_path)
-
-            # Find Panda3D libs
-            libs = find_packages(p3dwhl if use_wheels else None)
-
-            # Copy Panda3D files
-            etcdir = os.path.join(builddir, 'etc')
-            if not use_wheels:
-                # Libs
-                for lib in libs:
-                    target_path = os.path.join(builddir, os.path.basename(lib))
-                    if not os.path.islink(source_path):
-                        distutils.file_util.copy_file(lib, target_path)
-
-                # etc
-                dtool_fn = p3d.Filename(p3d.ExecutionEnvironment.get_dtool_name())
-                libdir = os.path.dirname(dtool_fn.to_os_specific())
-                src = os.path.join(libdir, '..', 'etc')
-                distutils.dir_util.copy_tree(src, etcdir)
+            for whl in wheelpaths:
+                if 'panda3d-' in whl:
+                    p3dwhlfn = whl
+                    p3dwhl = self._get_zip_file(p3dwhlfn)
+                    break
             else:
-                distutils.dir_util.mkpath(etcdir)
+                raise RuntimeError("Missing panda3d wheel")
 
-                # Combine prc files with libs and copy the whole list
-                panda_files = libs + [i for i in p3dwhl.namelist() if i.endswith('.prc')]
-                for pf in panda_files:
-                    dstdir = etcdir if pf.endswith('.prc') else builddir
-                    target_path = os.path.join(dstdir, os.path.basename(pf))
-                    print("copying {} -> {}".format(os.path.join(p3dwhlfn, pf), target_path))
-                    with open(target_path, 'wb') as f:
-                        f.write(p3dwhl.read(pf))
+            #whlfiles = {whl: self._get_zip_file(whl) for whl in wheelpaths}
 
-            # Copy Game Files
-            ignore_copy_list = [
-                '__pycache__',
-                '*.pyc',
-                '*.py',
+            # Add whl files to the path so they are picked up by modulefinder
+            for whl in wheelpaths:
+                path.insert(0, whl)
+
+            # Add deploy_libs from panda3d whl to the path
+            path.insert(0, os.path.join(p3dwhlfn, 'deploy_libs'))
+
+        # Create runtimes
+        freezer_extras = set()
+        freezer_modules = set()
+        def create_runtime(appname, mainscript, use_console):
+            freezer = FreezeTool.Freezer(platform=platform, path=path)
+            freezer.addModule('__main__', filename=mainscript)
+            for incmod in self.include_modules.get(appname, []) + self.include_modules.get('*', []):
+                freezer.addModule(incmod)
+            for exmod in self.exclude_modules.get(appname, []) + self.exclude_modules.get('*', []):
+                freezer.excludeModule(exmod)
+            freezer.done(addStartupModules=True)
+
+            stub_name = 'deploy-stub'
+            if platform.startswith('win'):
+                if not use_console:
+                    stub_name = 'deploy-stubw'
+                stub_name += '.exe'
+
+            if use_wheels:
+                stub_file = p3dwhl.open('panda3d_tools/{0}'.format(stub_name))
+            else:
+                dtool_path = p3d.Filename(p3d.ExecutionEnvironment.get_dtool_name()).to_os_specific()
+                stub_path = os.path.join(os.path.dirname(dtool_path), '..', 'bin', stub_name)
+                stub_file = open(stub_path, 'rb')
+
+            freezer.generateRuntimeFromStub(os.path.join(builddir, appname), stub_file)
+            stub_file.close()
+
+            freezer_extras.update(freezer.extras)
+            freezer_modules.update(freezer.getAllModuleNames())
+
+        for appname, scriptname in self.gui_apps.items():
+            create_runtime(appname, scriptname, False)
+
+        for appname, scriptname in self.console_apps.items():
+            create_runtime(appname, scriptname, True)
+
+        # Copy extension modules
+        whl_modules = []
+        whl_modules_ext = ''
+        if use_wheels:
+            # Get the module libs
+            whl_modules = [
+                i.replace('deploy_libs/', '') for i in p3dwhl.namelist() if i.startswith('deploy_libs/')
             ]
-            ignore_copy_list += self.exclude_paths
-            ignore_copy_list = [p3d.GlobPattern(i) for i in ignore_copy_list]
 
-            def check_pattern(src):
-                for pattern in ignore_copy_list:
-                    # Normalize file paths across platforms
-                    path = p3d.Filename.from_os_specific(src).get_fullpath() 
-                    #print("check ignore:", pattern, src, pattern.matches(path))
-                    if pattern.matches(path):
-                        return True
-                return False
+            # Pull off extension
+            if whl_modules:
+                whl_modules_ext = '.'.join(whl_modules[0].split('.')[1:])
+            whl_modules = [i.split('.')[0] for i in whl_modules]
 
-            def dir_has_files(directory):
-                files = [
-                    i for i in os.listdir(directory)
-                    if not check_pattern(os.path.join(directory, i))
-                ]
-                return bool(files)
+        # Make sure to copy any builtins that have shared objects in the deploy libs
+        for mod in freezer_modules:
+            if mod in whl_modules:
+                freezer_extras.add((mod, None))
 
-            def copy_file(src, dst):
-                src = os.path.normpath(src)
-                dst = os.path.normpath(dst)
+        #FIXME: this is a temporary hack to pick up libpandagl.
+        for lib in p3dwhl.namelist():
+            if lib.startswith('panda3d/libpandagl.'):
+                source_path = os.path.join(p3dwhlfn, lib)
+                target_path = os.path.join(builddir, os.path.basename(lib))
+                search_path = [os.path.dirname(source_path)]
+                self.copy_with_dependencies(source_path, target_path, search_path)
 
-                if check_pattern(src):
-                    print("skipping file", src)
+        # Copy any shared objects we need
+        for module, source_path in freezer_extras:
+            if source_path is not None:
+                # Rename panda3d/core.pyd to panda3d.core.pyd
+                basename = os.path.basename(source_path)
+                if '.' in module:
+                    basename = module.rsplit('.', 1)[0] + '.' + basename
+
+                # Remove python version string
+                if sys.version_info >= (3, 0):
+                    parts = basename.split('.')
+                    parts = parts[:-2] + parts[-1:]
+                    basename = '.'.join(parts)
+            else:
+                # Builtin module, but might not be builtin in wheel libs, so double check
+                if module in whl_modules:
+                    source_path = '{0}/deploy_libs/{1}.{2}'.format(p3dwhlfn, module, whl_modules_ext)
+                    basename = os.path.basename(source_path)
+                else:
+                    continue
+
+            # If this is a dynamic library, search for dependencies.
+            search_path = [os.path.dirname(source_path)]
+            if use_wheels:
+                search_path.append(os.path.join(p3dwhlfn, 'deploy_libs'))
+
+            target_path = os.path.join(builddir, basename)
+            self.copy_with_dependencies(source_path, target_path, search_path)
+
+        # Copy Panda3D files
+        etcdir = os.path.join(builddir, 'etc')
+        if not use_wheels:
+            # etc
+            dtool_fn = p3d.Filename(p3d.ExecutionEnvironment.get_dtool_name())
+            libdir = os.path.dirname(dtool_fn.to_os_specific())
+            src = os.path.join(libdir, '..', 'etc')
+            distutils.dir_util.copy_tree(src, etcdir)
+        else:
+            distutils.dir_util.mkpath(etcdir)
+
+            # Combine prc files with libs and copy the whole list
+            panda_files = [i for i in p3dwhl.namelist() if i.endswith('.prc')]
+            for pf in panda_files:
+                dstdir = etcdir if pf.endswith('.prc') else builddir
+                target_path = os.path.join(dstdir, os.path.basename(pf))
+                source_path = os.path.join(p3dwhlfn, pf)
+
+                # If this is a dynamic library, search for dependencies.
+                search_path = [os.path.dirname(source_path)]
+                if use_wheels:
+                    search_path.append(os.path.join(p3dwhlfn, 'deploy_libs'))
+
+                self.copy_with_dependencies(source_path, target_path, search_path)
+
+        # Copy Game Files
+        ignore_copy_list = [
+            '__pycache__',
+            '*.pyc',
+            '*.py',
+        ]
+        ignore_copy_list += self.exclude_paths
+        ignore_copy_list = [p3d.GlobPattern(i) for i in ignore_copy_list]
+
+        def check_pattern(src):
+            for pattern in ignore_copy_list:
+                # Normalize file paths across platforms
+                path = p3d.Filename.from_os_specific(src).get_fullpath()
+                #print("check ignore:", pattern, src, pattern.matches(path))
+                if pattern.matches(path):
+                    return True
+            return False
+
+        def dir_has_files(directory):
+            files = [
+                i for i in os.listdir(directory)
+                if not check_pattern(os.path.join(directory, i))
+            ]
+            return bool(files)
+
+        def copy_file(src, dst):
+            src = os.path.normpath(src)
+            dst = os.path.normpath(dst)
+
+            if check_pattern(src):
+                print("skipping file", src)
+                return
+
+            dst_dir = os.path.dirname(dst)
+            if not os.path.exists(dst_dir):
+                distutils.dir_util.mkpath(dst_dir)
+
+            ext = os.path.splitext(src)[1]
+            if not ext:
+                ext = os.path.basename(src)
+            dst_root = os.path.splitext(dst)[0]
+
+            if ext in self.build_scripts:
+                dst_ext, script = self.build_scripts[ext]
+                dst = dst_root + dst_ext
+                script = script.format(src, dst)
+                print("using script:", script)
+                subprocess.call(script.split())
+            else:
+                #print("Copy file", src, dst)
+                distutils.file_util.copy_file(src, dst)
+
+        def copy_dir(src, dst):
+            for item in os.listdir(src):
+                s = os.path.join(src, item)
+                d = os.path.join(dst, item)
+                if os.path.isfile(s):
+                    copy_file(s, d)
+                elif dir_has_files(s):
+                    copy_dir(s, d)
+
+        for path in self.copy_paths:
+            if isinstance(path, basestring):
+                src = dst = path
+            else:
+                src, dst = path
+            dst = os.path.join(builddir, dst)
+
+            if os.path.isfile(src):
+                copy_file(src, dst)
+            else:
+                copy_dir(src, dst)
+
+    def add_dependency(self, name, target_dir, search_path, referenced_by):
+        """ Searches for the given DLL on the search path.  If it exists,
+        copies it to the target_dir. """
+
+        if os.path.exists(os.path.join(target_dir, name)):
+            # We've already added it earlier.
+            return
+
+        if name in self.exclude_dependencies:
+            return
+
+        for dir in search_path:
+            source_path = os.path.join(dir, name)
+
+            if os.path.isfile(source_path):
+                target_path = os.path.join(target_dir, name)
+                self.copy_with_dependencies(source_path, target_path, search_path)
+                return
+
+            elif '.whl/' in source_path:
+                # Check whether the file exists inside the wheel.
+                whl, wf = source_path.split('.whl/')
+                whl += '.whl'
+                whlfile = self._get_zip_file(whl)
+
+                # Look case-insensitively.
+                namelist = whlfile.namelist()
+                namelist_lower = [file.lower() for file in namelist]
+
+                if wf.lower() in namelist_lower:
+                    # We have a match.  Change it to the correct case.
+                    wf = namelist[namelist_lower.index(wf.lower())]
+                    source_path = '/'.join((whl, wf))
+                    target_path = os.path.join(target_dir, os.path.basename(wf))
+                    self.copy_with_dependencies(source_path, target_path, search_path)
                     return
 
-                dst_dir = os.path.dirname(dst)
-                if not os.path.exists(dst_dir):
-                    distutils.dir_util.mkpath(dst_dir)
+        # If we didn't find it, look again, but case-insensitively.
+        name_lower = name.lower()
 
-                ext = os.path.splitext(src)[1]
-                if not ext:
-                    ext = os.path.basename(src)
-                dst_root = os.path.splitext(dst)[0]
+        for dir in search_path:
+            if os.path.isdir(dir):
+                files = os.listdir(dir)
+                files_lower = [file.lower() for file in files]
 
-                if ext in self.build_scripts:
-                    dst_ext, script = self.build_scripts[ext]
-                    dst = dst_root + dst_ext
-                    script = script.format(src, dst)
-                    print("using script:", script)
-                    subprocess.call(script.split())
-                else:
-                    #print("Copy file", src, dst)
-                    distutils.file_util.copy_file(src, dst)
+                if name_lower in files_lower:
+                    name = files[files_lower.index(name_lower)]
+                    source_path = os.path.join(dir, name)
+                    target_path = os.path.join(target_dir, name)
+                    self.copy_with_dependencies(source_path, target_path, search_path)
 
-            def copy_dir(src, dst):
-                for item in os.listdir(src):
-                    s = os.path.join(src, item)
-                    d = os.path.join(dst, item)
-                    if os.path.isfile(s):
-                        copy_file(s, d)
-                    elif dir_has_files(s):
-                        copy_dir(s, d)
+        # Warn if we can't find it, but only once.
+        self.warn("could not find dependency {0} (referenced by {1})".format(name, referenced_by))
+        self.exclude_dependencies.append(name)
 
-            for path in self.copy_paths:
-                if isinstance(path, basestring):
-                    src = dst = path
-                else:
-                    src, dst = path
-                dst = os.path.join(builddir, dst)
+    def copy_with_dependencies(self, source_path, target_path, search_path):
+        """ Copies source_path to target_path.  It also scans source_path for
+        any dependencies, which are located along the given search_path and
+        copied to the same directory as target_path.
 
-                if os.path.isfile(src):
-                    copy_file(src, dst)
-                else:
-                    copy_dir(src, dst)
+        source_path may be located inside a .whl file. """
+
+        print("copying {0} -> {1}".format(os.path.relpath(source_path, self.build_base), os.path.relpath(target_path, self.build_base)))
+
+        # Copy the file, and open it for analysis.
+        if '.whl/' in source_path:
+            # This was found in a wheel, extract it
+            whl, wf = source_path.split('.whl/')
+            whl += '.whl'
+            whlfile = self._get_zip_file(whl)
+            data = whlfile.read(wf)
+            with open(target_path, 'wb') as f:
+                f.write(data)
+            # Wrap the data in a BytesIO, since we need to be able to seek in
+            # the file; the stream returned by whlfile.open won't let us seek.
+            fp = io.BytesIO(data)
+        else:
+            # Regular file, copy it
+            distutils.file_util.copy_file(source_path, target_path)
+            fp = open(target_path, 'rb')
+
+        # What kind of magic does the file contain?
+        deps = []
+        magic = fp.read(4)
+        if magic.startswith(b'MZ'):
+            # It's a Windows DLL or EXE file.
+            pe = pefile.PEFile()
+            pe.read(fp)
+            deps = pe.imports
+
+        elif magic == b'\x7FELF':
+            # Elf magic.  Used on (among others) Linux and FreeBSD.
+            deps = self._read_dependencies_elf(fp)
+
+        elif magic in (b'\xFE\xED\xFA\xCE', b'\xCE\xFA\xED\xFE',
+                       b'\xFE\xED\xFA\xCF', b'\xCF\xFA\xED\xFE'):
+            # A Mach-O file, as used on macOS.
+            deps = self._read_dependencies_macho(fp)
+
+        elif magic in (b'\xCA\xFE\xBA\xBE', b'\xBE\xBA\xFE\bCA'):
+            # A fat file, containing multiple Mach-O binaries.  In the future,
+            # we may want to extract the one containing the architecture we
+            # are building for.
+            deps = self._read_dependencies_fat(fp)
+
+        # If we discovered any dependencies, recursively add those.
+        if deps:
+            target_dir = os.path.dirname(target_path)
+            base = os.path.basename(target_path)
+            for dep in deps:
+                self.add_dependency(dep, target_dir, search_path, base)
+
+    def _read_dependencies_elf(self, elf):
+        """ Having read the first 4 bytes of the ELF file, fetches the
+        dependent libraries and returns those as a list. """
+
+        ident = elf.read(12)
+
+        # Make sure we read in the correct endianness and integer size
+        byte_order = "<>"[ord(ident[1:2]) - 1]
+        elf_class = ord(ident[0:1]) - 1 # 0 = 32-bits, 1 = 64-bits
+        header_struct = byte_order + ("HHIIIIIHHHHHH", "HHIQQQIHHHHHH")[elf_class]
+        section_struct = byte_order + ("4xI8xIII8xI", "4xI16xQQI12xQ")[elf_class]
+        dynamic_struct = byte_order + ("iI", "qQ")[elf_class]
+
+        type, machine, version, entry, phoff, shoff, flags, ehsize, phentsize, phnum, shentsize, shnum, shstrndx \
+          = struct.unpack(header_struct, elf.read(struct.calcsize(header_struct)))
+        dynamic_sections = []
+        string_tables = {}
+
+        # Seek to the section header table and find the .dynamic section.
+        elf.seek(shoff)
+        for i in range(shnum):
+            type, offset, size, link, entsize = struct.unpack_from(section_struct, elf.read(shentsize))
+            if type == 6 and link != 0: # DYNAMIC type, links to string table
+                dynamic_sections.append((offset, size, link, entsize))
+                string_tables[link] = None
+
+        # Read the relevant string tables.
+        for idx in string_tables.keys():
+            elf.seek(shoff + idx * shentsize)
+            type, offset, size, link, entsize = struct.unpack_from(section_struct, elf.read(shentsize))
+            if type != 3: continue
+            elf.seek(offset)
+            string_tables[idx] = elf.read(size)
+
+        # Loop through the dynamic sections and rewrite it if it has an rpath/runpath.
+        needed = []
+        rpath = []
+        for offset, size, link, entsize in dynamic_sections:
+            elf.seek(offset)
+            data = elf.read(entsize)
+            tag, val = struct.unpack_from(dynamic_struct, data)
+
+            # Read tags until we find a NULL tag.
+            while tag != 0:
+                if tag == 1: # A NEEDED entry.  Read it from the string table.
+                    string = string_tables[link][val : string_tables[link].find(b'\0', val)]
+                    needed.append(string.decode('utf-8'))
+
+                elif tag == 15 or tag == 29:
+                    # An RPATH or RUNPATH entry.
+                    string = string_tables[link][val : string_tables[link].find(b'\0', val)]
+                    rpath += string.split(b':')
+
+                data = elf.read(entsize)
+                tag, val = struct.unpack_from(dynamic_struct, data)
+        elf.close()
+
+        #TODO: should we respect the RPATH?  Clear it?  Warn about it?
+        return needed
+
+    def _read_dependencies_macho(self, fp):
+        """ Having read the first 4 bytes of the Mach-O file, fetches the
+        dependent libraries and returns those as a list. """
+
+        cputype, cpusubtype, filetype, ncmds, sizeofcmds, flags = \
+            struct.unpack('<IIIIII', fp.read(24))
+
+        is_64 = (cputype & 0x1000000) != 0
+        if is_64:
+            fp.read(4)
+
+        # After the header, we get a series of linker commands.  We just
+        # iterate through them and gather up the LC_LOAD_DYLIB commands.
+        load_dylibs = []
+        for i in range(ncmds):
+            cmd, cmdsize = struct.unpack('<II', fp.read(8))
+            cmd_data = fp.read(cmdsize - 8)
+            cmd &= ~0x80000000
+
+            if cmd == 0x0c: # LC_LOAD_DYLIB
+                dylib = cmd_data[16:].decode('ascii').split('\x00', 1)[0]
+                if dylib.startswith('@loader_path/'):
+                    dylib = dylib.replace('@loader_path/', '')
+                load_dylibs.append(dylib)
+
+        return load_dylibs
+
+    def _read_dependencies_fat(self, fp):
+        num_fat = struct.unpack('>I', fp.read(4))[0]
+        if num_fat == 0:
+            return []
+
+        # After the header we get a table of executables in this fat file,
+        # each one with a corresponding offset into the file.
+        # We are just interested in the first one for now.
+        cputype, cpusubtype, offset, size, align = \
+            struct.unpack('>IIIII', fp.read(20))
+
+        # Add 4, since it expects we've already read the magic.
+        fp.seek(offset + 4)
+        return self._read_dependencies_macho(fp)
 
 
 class bdist_apps(distutils.core.Command):
diff --git a/direct/src/showutil/pefile.py b/direct/src/showutil/pefile.py
new file mode 100755
index 0000000000..20af71c4b7
--- /dev/null
+++ b/direct/src/showutil/pefile.py
@@ -0,0 +1,863 @@
+""" Tools for manipulating Portable Executable files.
+
+This can be used, for example, to extract a list of dependencies from an .exe
+or .dll file, or to add version information and an icon resource to it. """
+
+__all__ = ["PEFile"]
+
+from struct import Struct, unpack, pack, pack_into
+from collections import namedtuple
+from array import array
+import time
+from io import BytesIO
+import sys
+
+if sys.version_info >= (3, 0):
+    unicode = str
+    unichr = chr
+
+# Define some internally used structures.
+RVASize = namedtuple('RVASize', ('addr', 'size'))
+impdirtab = namedtuple('impdirtab', ('lookup', 'timdat', 'forward', 'name', 'impaddr'))
+
+
+def _unpack_zstring(mem, offs=0):
+    "Read a zero-terminated string from memory."
+    c = mem[offs]
+    str = ""
+    while c:
+        str += chr(c)
+        offs += 1
+        c = mem[offs]
+    return str
+
+def _unpack_wstring(mem, offs=0):
+    "Read a UCS-2 string from memory."
+    name_len, = unpack('<H', mem[offs:offs+2])
+    name = ""
+    for i in range(name_len):
+        offs += 2
+        name += unichr(*unpack('<H', mem[offs:offs+2]))
+    return name
+
+def _padded(n, boundary):
+    align = n % boundary
+    if align:
+        n += boundary - align
+    return n
+
+
+class Section(object):
+    _header = Struct('<8sIIIIIIHHI')
+
+    modified = True
+
+    def read_header(self, fp):
+        name, vsize, vaddr, size, scnptr, relptr, lnnoptr, nreloc, nlnno, flags = \
+            self._header.unpack(fp.read(40))
+
+        self.name = name.rstrip(b'\x00')
+        self.vaddr = vaddr # Base virtual address to map to.
+        self.vsize = vsize
+        self.offset = scnptr # Offset of the section in the file.
+        self.size = size
+        self.flags = flags
+
+        self.modified = False
+
+    def write_header(self, fp):
+        fp.write(self._header.pack(self.name, self.vsize, self.vaddr,
+                                   self.size, self.offset, 0, 0, 0, 0,
+                                   self.flags))
+
+    def __repr__(self):
+        return "<section '%s' memory %x-%x>" % (self.name, self.vaddr, self.vaddr + self.vsize)
+
+    def __gt__(self, other):
+        return self.vaddr > other.vaddr
+
+    def __lt__(self, other):
+        return self.vaddr < other.vaddr
+
+
+class DataResource(object):
+    """ A resource entry in the resource table. """
+
+    # Resource types.
+    cursor = 1
+    bitmap = 2
+    icon = 3
+    menu = 4
+    dialog = 5
+    string = 6
+    font_directory = 7
+    font = 8
+    accelerator = 9
+    rcdata = 10
+    message_table = 11
+    cursor_group = 12
+    icon_group = 14
+    version = 16
+    dlg_include = 17
+    plug_play = 19
+    vxd = 20
+    animated_cursor = 21
+    animated_icon = 22
+    html = 23
+    manifest = 24
+
+    def __init__(self):
+        self._ident = ()
+        self.data = None
+        self.code_page = 0
+
+    def get_data(self):
+        if self.code_page:
+            return self.data.encode('cp%d' % self.code_page)
+        else:
+            return self.data
+
+
+class IconGroupResource(object):
+    code_page = 0
+    type = 14
+    _entry = Struct('<BBBxHHIH')
+    Icon = namedtuple('Icon', ('width', 'height', 'planes', 'bpp', 'size', 'id'))
+
+    def __init__(self):
+        self.icons = []
+
+    def add_icon(self, *args, **kwargs):
+        self.icons.append(self.Icon(*args, **kwargs))
+
+    def get_data(self):
+        data = bytearray(pack('<HHH', 0, 1, len(self.icons)))
+
+        for width, height, planes, bpp, size, id in self.icons:
+            colors = 1 << (planes * bpp)
+            if colors >= 256:
+                colors = 0
+            if width >= 256:
+                width = 0
+            if height >= 256:
+                height = 0
+            data += self._entry.pack(width, height, colors, planes, bpp, size, id)
+        return data
+
+    def unpack_from(self, data, offs=0):
+        type, count = unpack('<HH', data[offs+2:offs+6])
+        offs += 6
+        for i in range(count):
+            width, height, colors, planes, bpp, size, id = \
+                self._entry.unpack(data[offs:offs+14])
+            if width == 0:
+                width = 256
+            if height == 0:
+                height = 256
+            self.icons.append(self.Icon(width, height, planes, bpp, size, id))
+            offs += 14
+
+
+class VersionInfoResource(object):
+    code_page = 0
+    type = 16
+
+    def __init__(self):
+        self.string_info = {}
+        self.var_info = {}
+        self.signature = 0xFEEF04BD
+        self.struct_version = 0x10000
+        self.file_version = (0, 0, 0, 0)
+        self.product_version = (0, 0, 0, 0)
+        self.file_flags_mask = 0x3f
+        self.file_flags = 0
+        self.file_os = 0x40004 # Windows NT
+        self.file_type = 1 # Application
+        self.file_subtype = 0
+        self.file_date = (0, 0)
+
+    def get_data(self):
+        # The first part of the header is pretty much fixed - we'll go
+        # back later to write the struct size.
+        data = bytearray(b'\x00\x004\x00\x00\x00V\x00S\x00_\x00V\x00E\x00R\x00S\x00I\x00O\x00N\x00_\x00I\x00N\x00F\x00O\x00\x00\x00\x00\x00')
+        data += pack('<13I', self.signature, self.struct_version,
+                             self.file_version[1] | (self.file_version[0] << 16),
+                             self.file_version[3] | (self.file_version[2] << 16),
+                             self.product_version[1] | (self.product_version[0] << 16),
+                             self.product_version[3] | (self.product_version[2] << 16),
+                             self.file_flags_mask, self.file_flags,
+                             self.file_os, self.file_type, self.file_subtype,
+                             self.file_date[0], self.file_date[1])
+
+        self._pack_info(data, 'StringFileInfo', self.string_info)
+        self._pack_info(data, 'VarFileInfo', self.var_info)
+        data[0:2] = pack('<H', len(data))
+        return data
+
+    def _pack_info(self, data, key, value):
+        offset = len(data)
+
+        if isinstance(value, dict):
+            type = 1
+            value_length = 0
+        elif isinstance(value, bytes) or isinstance(value, unicode):
+            type = 1
+            value_length = len(value) * 2 + 2
+        else:
+            type = 0
+            value_length = len(value)
+
+        data += pack('<HHH', 0, value_length, type)
+
+        for c in key:
+            data += pack('<H', ord(c))
+        data += b'\x00\x00'
+        if len(data) & 2:
+            data += b'\x00\x00'
+        assert len(data) & 3 == 0
+
+        if isinstance(value, dict):
+            for key2, value2 in sorted(value.items(), key=lambda x:x[0]):
+                self._pack_info(data, key2, value2)
+        elif isinstance(value, bytes) or isinstance(value, unicode):
+            for c in value:
+                data += pack('<H', ord(c))
+            data += b'\x00\x00'
+        else:
+            data += value
+            if len(data) & 1:
+                data += b'\x00'
+
+        if len(data) & 2:
+            data += b'\x00\x00'
+        assert len(data) & 3 == 0
+
+        data[offset:offset+2] = pack('<H', len(data) - offset)
+
+    def unpack_from(self, data):
+        length, value_length = unpack('<HH', data[0:4])
+        offset = 40 + value_length + (value_length & 1)
+        dwords = array('I')
+        dwords.fromstring(bytes(data[40:offset]))
+        if len(dwords) > 0:
+            self.signature = dwords[0]
+        if len(dwords) > 1:
+            self.struct_version = dwords[1]
+        if len(dwords) > 3:
+            self.file_version = \
+               (int(dwords[2] >> 16), int(dwords[2] & 0xffff),
+                int(dwords[3] >> 16), int(dwords[3] & 0xffff))
+        if len(dwords) > 5:
+            self.product_version = \
+               (int(dwords[4] >> 16), int(dwords[4] & 0xffff),
+                int(dwords[5] >> 16), int(dwords[5] & 0xffff))
+        if len(dwords) > 7:
+            self.file_flags_mask = dwords[6]
+            self.file_flags = dwords[7]
+        if len(dwords) > 8:
+            self.file_os = dwords[8]
+        if len(dwords) > 9:
+            self.file_type = dwords[9]
+        if len(dwords) > 10:
+            self.file_subtype = dwords[10]
+        if len(dwords) > 12:
+            self.file_date = (dwords[11], dwords[12])
+
+        while offset < length:
+            offset += self._unpack_info(self, data, offset)
+
+    def __getitem__(self, key):
+        if key == 'StringFileInfo':
+            return self.string_info
+        elif key == 'VarFileInfo':
+            return self.var_info
+        else:
+            raise KeyError("%s does not exist" % (key))
+
+    def __contains__(self, key):
+        return key in ('StringFileInfo', 'VarFileInfo')
+
+    def _unpack_info(self, dict, data, offset):
+        length, value_length, type = unpack('<HHH', data[offset:offset+6])
+        assert length > 0
+        end = offset + length
+        offset += 6
+        key = ""
+        c, = unpack('<H', data[offset:offset+2])
+        offset += 2
+        while c:
+            key += unichr(c)
+            c, = unpack('<H', data[offset:offset+2])
+            offset += 2
+
+        # Padding bytes to align value to 32-bit boundary.
+        offset = _padded(offset, 4)
+
+        if value_length > 0:
+            # It contains a value.
+            if type:
+                # It's a wchar array value.
+                value = u""
+                c, = unpack('<H', data[offset:offset+2])
+                offset += 2
+                while c:
+                    value += unichr(c)
+                    c, = unpack('<H', data[offset:offset+2])
+                    offset += 2
+            else:
+                # A binary value.
+                value = bytes(data[offset:offset+value_length])
+                offset += value_length
+            dict[key] = value
+        else:
+            # It contains sub-entries.
+            if key not in dict:
+                dict[key] = {}
+            subdict = dict[key]
+            while offset < end:
+                offset += self._unpack_info(subdict, data, offset)
+
+        # Padding bytes to pad value to 32-bit boundary.
+        return _padded(length, 4)
+
+
+class ResourceTable(object):
+    """ A table in the resource directory. """
+
+    _header = Struct('<IIHHHH')
+
+    def __init__(self, ident=()):
+        self.flags = 0
+        self.timdat = 0
+        self.version = (0, 0)
+        self._name_leaves = []
+        self._id_leaves = []
+        self._ident = ident
+        self._strings_size = 0 # Amount of space occupied by table keys.
+        self._descs_size = 0
+
+    def __getitem__(self, key):
+        if isinstance(key, int):
+            leaves = self._id_leaves
+        else:
+            leaves = self._name_leaves
+
+        i = 0
+        while i < len(leaves):
+            idname, leaf = leaves[i]
+            if idname >= key:
+                if key == idname:
+                    return leaf
+                break
+            i += 1
+        if not isinstance(key, int):
+            self._strings_size += _padded(len(key) * 2 + 2, 4)
+        leaf = ResourceTable(ident=self._ident + (key,))
+        leaves.insert(i, (key, leaf))
+        return leaf
+
+    def __setitem__(self, key, value):
+        """ Adds the given item to the table.  Maintains sort order. """
+        if isinstance(key, int):
+            leaves = self._id_leaves
+        else:
+            leaves = self._name_leaves
+
+        if not isinstance(value, ResourceTable):
+            self._descs_size += 16
+
+        value._ident = self._ident + (key,)
+        i = 0
+        while i < len(leaves):
+            idname, leaf = leaves[i]
+            if idname >= key:
+                if key == idname:
+                    if not isinstance(leaves[i][1], ResourceTable):
+                        self._descs_size -= 16
+                    leaves[i] = (key, value)
+                    return
+                break
+            i += 1
+        if not isinstance(key, int):
+            self._strings_size += _padded(len(key) * 2 + 2, 4)
+        leaves.insert(i, (key, value))
+
+    def __len__(self):
+        return len(self._name_leaves) + len(self._id_leaves)
+
+    def __iter__(self):
+        keys = []
+        for name, leaf in self._name_leaves:
+            keys.append(name)
+        for id, leaf in self._id_leaves:
+            keys.append(id)
+        return iter(keys)
+
+    def items(self):
+        return self._name_leaves + self._id_leaves
+
+    def count_resources(self):
+        """Counts all of the resources."""
+        count = 0
+        for key, leaf in self._name_leaves + self._id_leaves:
+            if isinstance(leaf, ResourceTable):
+                count += leaf.count_resources()
+            else:
+                count += 1
+        return count
+
+    def get_nested_tables(self):
+        """Returns all tables in this table and subtables."""
+        # First we yield child tables, then nested tables.  This is the
+        # order in which pack_into assumes the tables will be written.
+        for key, leaf in self._name_leaves + self._id_leaves:
+            if isinstance(leaf, ResourceTable):
+                yield leaf
+
+        for key, leaf in self._name_leaves + self._id_leaves:
+            if isinstance(leaf, ResourceTable):
+                for table in leaf.get_nested_tables():
+                    yield table
+
+    def pack_header(self, data, offs):
+        self._header.pack_into(data, offs, self.flags, self.timdat,
+                               self.version[0], self.version[1],
+                               len(self._name_leaves), len(self._id_leaves))
+
+    def unpack_from(self, mem, addr=0, offs=0):
+        start = addr + offs
+        self.flags, self.timdat, majver, minver, nnames, nids = \
+            self._header.unpack(mem[start:start+16])
+        self.version = (majver, minver)
+        start += 16
+
+        # Subtables/entries specified by string name.
+        self._name_leaves = []
+        for i in range(nnames):
+            name_p, data = unpack('<II', mem[start:start+8])
+            if name_p & 0x80000000:
+                name = _unpack_wstring(mem, addr + (name_p & 0x7fffffff))
+            else:
+                # Not sure what to do with this; I don't have a file with this.
+                name = str(name_p)
+
+            if data & 0x80000000:
+                entry = ResourceTable(self._ident + (name,))
+                entry.unpack_from(mem, addr, data & 0x7fffffff)
+            else:
+                entry = self._unpack_data_entry(mem, addr + data, ident=self._ident+(name,))
+                self._descs_size += 16
+            self._name_leaves.append((name, entry))
+            self._strings_size += _padded(len(name) * 2 + 2, 4)
+            start += 8
+
+        # Subtables/entries specified by integer ID.
+        self._id_leaves = []
+        for i in range(nids):
+            id, data = unpack('<II', mem[start:start+8])
+            if data & 0x80000000:
+                entry = ResourceTable(self._ident + (id,))
+                entry.unpack_from(mem, addr, data & 0x7fffffff)
+            else:
+                entry = self._unpack_data_entry(mem, addr + data, ident=self._ident+(id,))
+                self._descs_size += 16
+            self._id_leaves.append((id, entry))
+            start += 8
+
+    def _unpack_data_entry(self, mem, addr, ident):
+        rva, size, code_page = unpack('<III', mem[addr:addr+12])
+        type, name, lang = ident
+        #print("%s/%s/%s: %s [%s]" % (type, name, lang, size, code_page))
+
+        data = mem[rva:rva+size]
+
+        if type == VersionInfoResource.type:
+            entry = VersionInfoResource()
+            entry.unpack_from(data)
+        elif type == IconGroupResource.type:
+            entry = IconGroupResource()
+            entry.unpack_from(data)
+        else:
+            if code_page != 0:
+                # Decode the data using the provided code page.
+                data = data.decode("cp%d" % code_page)
+
+            entry = DataResource()
+            entry.data = data
+            entry.code_page = code_page
+
+
+class PEFile(object):
+
+    imports = ()
+
+    def open(self, fn, mode='r'):
+        if 'b' not in mode:
+            mode += 'b'
+        self.fp = open(fn, mode)
+        self.read(self.fp)
+
+    def close(self):
+        self.fp.close()
+
+    def read(self, fp):
+        """ Reads a PE file from the given file object, which must be opened
+        in binary mode. """
+
+        # Read position of header.
+        fp.seek(0x3c)
+        offset, = unpack('<I', fp.read(4))
+
+        fp.seek(offset)
+        if fp.read(4) != b'PE\0\0':
+            raise ValueError("Invalid PE file.")
+
+        # Read the COFF header.
+        self.machine, nscns, timdat, symptr, nsyms, opthdr, flags = \
+            unpack('<HHIIIHH', fp.read(20))
+
+        if nscns == 0:
+            raise ValueError("No sections found.")
+
+        if not opthdr:
+            raise ValueError("No opthdr found.")
+
+        # Read part of the opthdr.
+        magic, self.code_size, self.initialized_size, self.uninitialized_size = \
+            unpack('<HxxIII', fp.read(16))
+
+        # Read alignments.
+        fp.seek(16, 1)
+        self.section_alignment, self.file_alignment = unpack('<II', fp.read(8))
+
+        # Read header/image sizes.
+        fp.seek(16, 1)
+        self.image_size, self.header_size = unpack('<II', fp.read(8))
+
+        if magic == 0x010b: # 32-bit.
+            fp.seek(28, 1)
+        elif magic == 0x20B: # 64-bit.
+            fp.seek(44, 1)
+        else:
+            raise ValueError("unknown type 0x%x" % (magic))
+
+        self.rva_offset = fp.tell()
+        numrvas, = unpack('<I', fp.read(4))
+
+        self.exp_rva = RVASize(0, 0)
+        self.imp_rva = RVASize(0, 0)
+        self.res_rva = RVASize(0, 0)
+
+        # Locate the relevant tables in memory.
+        if numrvas >= 1:
+            self.exp_rva = RVASize(*unpack('<II', fp.read(8)))
+        if numrvas >= 2:
+            self.imp_rva = RVASize(*unpack('<II', fp.read(8)))
+        if numrvas >= 3:
+            self.res_rva = RVASize(*unpack('<II', fp.read(8)))
+
+        # Skip the rest of the tables.
+        if numrvas >= 4:
+            fp.seek((numrvas - 3) * 8, 1)
+
+        # Loop through the sections to find the ones containing our tables.
+        self.sections = []
+        for i in range(nscns):
+            section = Section()
+            section.read_header(fp)
+            self.sections.append(section)
+
+        self.sections.sort()
+
+        # Read the sections into some kind of virtual memory.
+        self.vmem = bytearray(self.sections[-1].vaddr + self.sections[-1].size)
+
+        for section in self.sections:
+            fp.seek(section.offset)
+            fp.readinto(memoryview(self.vmem)[section.vaddr:section.vaddr+section.size])
+
+        # Read the import table.
+        start = self.imp_rva.addr
+        dir = impdirtab(*unpack('<IIIII', self.vmem[start:start+20]))
+
+        imports = []
+        while dir.name and dir.lookup:
+            name = _unpack_zstring(self.vmem, dir.name)
+            imports.append(name)
+
+            start += 20
+            dir = impdirtab(*unpack('<IIIII', self.vmem[start:start+20]))
+
+        # Make it a tuple to indicate we don't support modifying it for now.
+        self.imports = tuple(imports)
+
+        # Read the resource tables from the .rsrc section.
+        self.resources = ResourceTable()
+        if self.res_rva.addr and self.res_rva.size:
+            self.resources.unpack_from(self.vmem, self.res_rva.addr)
+
+    def add_icon(self, icon, ordinal=2):
+        """ Adds an icon resource from the given Icon object.  Requires
+        calling add_resource_section() afterwards. """
+
+        group = IconGroupResource()
+        self.resources[group.type][ordinal][1033] = group
+
+        images = sorted(icon.images.items(), key=lambda x:-x[0])
+        id = 1
+
+        # Write 8-bpp image headers for sizes under 256x256.
+        for size, image in images:
+            if size >= 256:
+                continue
+
+            xorsize = size
+            if xorsize % 4 != 0:
+                xorsize += 4 - (xorsize % 4)
+            andsize = (size + 7) >> 3
+            if andsize % 4 != 0:
+                andsize += 4 - (andsize % 4)
+            datasize = 40 + 256 * 4 + (xorsize + andsize) * size
+            group.add_icon(size, size, 1, 8, datasize, id)
+
+            buf = BytesIO()
+            icon._write_bitmap(buf, image, size, 8)
+
+            res = DataResource()
+            res.data = buf.getvalue()
+            self.resources[3][id][1033] = res
+            id += 1
+
+        # And now the 24/32 bpp versions.
+        for size, image in images:
+            if size > 256:
+                continue
+
+            # Calculate the size so we can write the offset within the file.
+            if image.hasAlpha():
+                bpp = 32
+                xorsize = size * 4
+            else:
+                bpp = 24
+                xorsize = size * 3 + (-(size * 3) & 3)
+            andsize = (size + 7) >> 3
+            if andsize % 4 != 0:
+                andsize += 4 - (andsize % 4)
+            datasize = 40 + (xorsize + andsize) * size
+
+            buf = BytesIO()
+            icon._write_bitmap(buf, image, size, bpp)
+
+            res = DataResource()
+            res.data = buf.getvalue()
+            self.resources[3][id][1033] = res
+            group.add_icon(size, size, 1, bpp, datasize, id)
+            id += 1
+
+    def add_section(self, name, flags, data):
+        """ Adds a new section with the given name, flags and data.  The
+        virtual address space is automatically resized to fit the new data.
+
+        Returns the newly created Section object. """
+
+        if isinstance(name, unicode):
+            name = name.encode('ascii')
+
+        section = Section()
+        section.name = name
+        section.flags = flags
+
+        # Put it at the end of all the other sections.
+        section.offset = 0
+        for s in self.sections:
+            section.offset = max(section.offset, s.offset + s.size)
+
+        # Align the offset.
+        section.offset = _padded(section.offset, self.file_alignment)
+
+        # Find a place to put it in the virtual address space.
+        section.vaddr = len(self.vmem)
+        align = section.vaddr % self.section_alignment
+        if align:
+            pad = self.section_alignment - align
+            self.vmem += bytearray(pad)
+            section.vaddr += pad
+
+        section.vsize = len(data)
+        section.size = _padded(section.vsize, self.file_alignment)
+        self.vmem += data
+        self.sections.append(section)
+
+        # Update the size tallies from the opthdr.
+        self.image_size += _padded(section.vsize, self.section_alignment)
+        if flags & 0x20:
+            self.code_size += section.size
+        if flags & 0x40:
+            self.initialized_size += section.size
+        if flags & 0x80:
+            self.uninitialized_size += section.size
+
+        return section
+
+    def add_version_info(self, file_ver, product_ver, data, lang=1033, codepage=1200):
+        """ Adds a version info resource to the file. """
+
+        if "FileVersion" not in data:
+            data["FileVersion"] = '.'.join(file_ver)
+        if "ProductVersion" not in data:
+            data["ProductVersion"] = '.'.join(product_ver)
+
+        assert len(file_ver) == 4
+        assert len(product_ver) == 4
+
+        res = VersionInfoResource()
+        res.file_version = file_ver
+        res.product_version = product_ver
+        res.string_info = {
+            "%04x%04x" % (lang, codepage): data
+        }
+        res.var_info = {
+            "Translation": bytearray(pack("<HH", lang, codepage))
+        }
+
+        self.resources[16][1][lang] = res
+
+    def add_resource_section(self):
+        """ Adds a resource section to the file containing the resources that
+        were previously added via add_icon et al.  Assumes the file does not
+        contain a resource section yet. """
+
+        # Calculate how much space to reserve.
+        tables = [self.resources] + list(self.resources.get_nested_tables())
+        table_size = 0
+        string_size = 0
+        desc_size = 16 * self.resources.count_resources()
+
+        for table in tables:
+            table._offset = table_size
+            table_size += 16 + 8 * len(table)
+            string_size += table._strings_size
+            desc_size += table._descs_size
+
+        # Now write the actual data.
+        tbl_offs = 0
+        str_offs = table_size
+        desc_offs = str_offs + string_size
+        data_offs = desc_offs + desc_size
+        data = bytearray(data_offs)
+        data_addr = _padded(len(self.vmem), self.section_alignment) + data_offs
+
+        for table in tables:
+            table.pack_header(data, tbl_offs)
+
+            tbl_offs += 16
+
+            for name, leaf in table._name_leaves:
+                if isinstance(leaf, ResourceTable):
+                    pack_into('<II', data, tbl_offs, str_offs | 0x80000000, leaf._offset | 0x80000000)
+                else:
+                    pack_into('<II', data, tbl_offs, str_offs | 0x80000000, desc_offs)
+                    resdata = leaf.get_data()
+                    pack_into('<IIII', data, desc_offs, data_addr, len(resdata), leaf.code_page, 0)
+                    data += resdata
+                    desc_offs += 16
+                    data_addr += len(resdata)
+                    align = len(resdata) & 3
+                    if align:
+                        data += bytearray(4 - align)
+                        data_addr += 4 - align
+                tbl_offs += 8
+
+                # Pack the name into the string table.
+                pack_into('<H', data, str_offs, len(name))
+                str_offs += 2
+                for c in name:
+                    pack_into('<H', data, str_offs, ord(c))
+                    str_offs += 2
+                str_offs = _padded(str_offs, 4)
+
+            for id, leaf in table._id_leaves:
+                if isinstance(leaf, ResourceTable):
+                    pack_into('<II', data, tbl_offs, id, leaf._offset | 0x80000000)
+                else:
+                    pack_into('<II', data, tbl_offs, id, desc_offs)
+                    resdata = leaf.get_data()
+                    pack_into('<IIII', data, desc_offs, data_addr, len(resdata), leaf.code_page, 0)
+                    data += resdata
+                    desc_offs += 16
+                    data_addr += len(resdata)
+                    align = len(resdata) & 3
+                    if align:
+                        data += bytearray(4 - align)
+                        data_addr += 4 - align
+                tbl_offs += 8
+
+        flags = 0x40000040 # readable, contains initialized data
+        section = self.add_section('.rsrc', flags, data)
+        self.res_rva = RVASize(section.vaddr, section.vsize)
+
+    def write_changes(self):
+        """ Assuming the file was opened in read-write mode, writes back the
+        changes made via this class to the .exe file. """
+
+        fp = self.fp
+        # Read position of header.
+        fp.seek(0x3c)
+        offset, = unpack('<I', fp.read(4))
+
+        fp.seek(offset)
+        if fp.read(4) != b'PE\0\0':
+            raise ValueError("Invalid PE file.")
+
+        # Sync read/write pointer.  Necessary before write.  Bug in Python?
+        fp.seek(fp.tell())
+
+        # Rewrite the first part of the COFF header.
+        timdat = int(time.time())
+        fp.write(pack('<HHI', self.machine, len(self.sections), timdat))
+
+        # Write calculated init and uninitialised sizes to the opthdr.
+        fp.seek(16, 1)
+        fp.write(pack('<III', self.code_size, self.initialized_size, self.uninitialized_size))
+
+        # Same for the image and header size.
+        fp.seek(40, 1)
+        fp.write(pack('<II', self.image_size, self.header_size))
+
+        # Write the modified RVA table.
+        fp.seek(self.rva_offset)
+        numrvas, = unpack('<I', fp.read(4))
+        assert numrvas >= 3
+
+        fp.seek(self.rva_offset + 4)
+        if numrvas >= 1:
+            fp.write(pack('<II', *self.exp_rva))
+        if numrvas >= 2:
+            fp.write(pack('<II', *self.imp_rva))
+        if numrvas >= 3:
+            fp.write(pack('<II', *self.res_rva))
+
+        # Skip the rest of the tables.
+        if numrvas >= 4:
+            fp.seek((numrvas - 3) * 8, 1)
+
+        # Write the modified section headers.
+        for section in self.sections:
+            section.write_header(fp)
+            assert fp.tell() <= self.header_size
+
+        # Write the section data of modified sections.
+        for section in self.sections:
+            if not section.modified:
+                continue
+
+            fp.seek(section.offset)
+            size = min(section.vsize, section.size)
+            fp.write(self.vmem[section.vaddr:section.vaddr+size])
+
+            pad = section.size - size
+            assert pad >= 0
+            if pad > 0:
+                fp.write(bytearray(pad))
+
+            section.modified = False