bpo-34977: Use venv redirector instead of original python.exe on Windows (GH-11029)

Doc/library/venv.rst

@@ -130,7 +130,6 @@ creation according to their needs, the :class:`EnvBuilder` class.
     .. versionadded:: 3.6
        Added the ``prompt`` parameter
 
-
     Creators of third-party virtual environment tools will be free to use the
     provided ``EnvBuilder`` class as a base class.
 
@@ -177,16 +176,15 @@ creation according to their needs, the :class:`EnvBuilder` class.
 
     .. method:: setup_python(context)
 
-        Creates a copy of the Python executable (and, under Windows, DLLs) in
+        Creates a copy of the Python executable in the environment on POSIX
-        the environment. On a POSIX system, if a specific executable
+        systems. If a specific executable ``python3.x`` was used, symlinks to
-        ``python3.x`` was used, symlinks to ``python`` and ``python3`` will be
+        ``python`` and ``python3`` will be created pointing to that executable,
-        created pointing to that executable, unless files with those names
+        unless files with those names already exist.
-        already exist.
 
     .. method:: setup_scripts(context)
 
         Installs activation scripts appropriate to the platform into the virtual
-        environment.
+        environment. On Windows, also installs the ``python[w].exe`` scripts.
 
     .. method:: post_setup(context)
 
@@ -194,6 +192,11 @@ creation according to their needs, the :class:`EnvBuilder` class.
         implementations to pre-install packages in the virtual environment or
         perform other post-creation steps.
 
+    .. versionchanged:: 3.7.2
+       Windows now uses redirector scripts for ``python[w].exe`` instead of
+       copying the actual binaries, and so :meth:`setup_python` does nothing
+       unless running from a build in the source tree.
+
     In addition, :class:`EnvBuilder` provides this utility method that can be
     called from :meth:`setup_scripts` or :meth:`post_setup` in subclasses to
     assist in installing custom scripts into the virtual environment.

Doc/whatsnew/3.7.rst

@@ -2512,3 +2512,13 @@ In 3.7.1 the :mod:`tokenize` module now implicitly emits a ``NEWLINE`` token
 when provided with input that does not have a trailing new line.  This behavior
 now matches what the C tokenizer does internally.
 (Contributed by Ammar Askar in :issue:`33899`.)
+
+Notable changes in Python 3.7.2
+===============================
+
+In 3.7.2, :mod:`venv` on Windows no longer copies the original binaries, but
+creates redirector scripts named ``python.exe`` and ``pythonw.exe`` instead.
+This resolves a long standing issue where all virtual environments would have
+to be upgraded or recreated with each Python update. However, note that this
+release will still require recreation of virtual environments in order to get
+the new scripts.

Lib/test/test_venv.py

@@ -243,6 +243,7 @@ class BasicTest(BaseTest):
             self.assertIn('include-system-site-packages = %s\n' % s, data)
 
     @unittest.skipUnless(can_symlink(), 'Needs symlinks')
+    @unittest.skipIf(os.name == 'nt', 'Symlinks are never used on Windows')
     def test_symlinking(self):
         """
         Test symlinking works as expected

Lib/venv/__init__.py

@@ -64,10 +64,11 @@ class EnvBuilder:
         self.system_site_packages = False
         self.create_configuration(context)
         self.setup_python(context)
+        if not self.upgrade:
+            self.setup_scripts(context)
         if self.with_pip:
             self._setup_pip(context)
         if not self.upgrade:
-            self.setup_scripts(context)
             self.post_setup(context)
         if true_system_site_packages:
             # We had set it to False before, now
@@ -158,14 +159,6 @@ class EnvBuilder:
             f.write('include-system-site-packages = %s\n' % incl)
             f.write('version = %d.%d.%d\n' % sys.version_info[:3])
 
-    if os.name == 'nt':
-        def include_binary(self, f):
-            if f.endswith(('.pyd', '.dll')):
-                result = True
-            else:
-                result = f.startswith('python') and f.endswith('.exe')
-            return result
-
     def symlink_or_copy(self, src, dst, relative_symlinks_ok=False):
         """
         Try symlinking a file, and if that fails, fall back to copying.
@@ -195,9 +188,9 @@ class EnvBuilder:
         binpath = context.bin_path
         path = context.env_exe
         copier = self.symlink_or_copy
-        copier(context.executable, path)
         dirname = context.python_dir
         if os.name != 'nt':
+            copier(context.executable, path)
             if not os.path.islink(path):
                 os.chmod(path, 0o755)
             for suffix in ('python', 'python3'):
@@ -209,26 +202,22 @@ class EnvBuilder:
                     if not os.path.islink(path):
                         os.chmod(path, 0o755)
         else:
-            # See bpo-34011. When using a proper install, we should only need to
+            # For normal cases, the venvlauncher will be copied from
-            # copy the top-level of DLLs.
+            # our scripts folder. For builds, we need to copy it
-            include = self.include_binary
+            # manually.
-            files = [f for f in os.listdir(dirname) if include(f)]
-            for f in files:
-                src = os.path.join(dirname, f)
-                dst = os.path.join(binpath, f)
-                if dst != context.env_exe:  # already done, above
-                    copier(src, dst)
-
-            # When creating from a build directory, we continue to copy all files.
             if sysconfig.is_python_build(True):
-                subdir = 'DLLs'
+                suffix = '.exe'
-                dirname = os.path.join(dirname, subdir)
+                if context.python_exe.lower().endswith('_d.exe'):
-                if os.path.isdir(dirname):
+                    suffix = '_d.exe'
-                    files = [f for f in os.listdir(dirname) if include(f)]
+
-                    for f in files:
+                src = os.path.join(dirname, "venvlauncher" + suffix)
-                        src = os.path.join(dirname, f)
+                dst = os.path.join(binpath, context.python_exe)
-                        dst = os.path.join(binpath, f)
+                copier(src, dst)
-                        copier(src, dst)
+
+                src = os.path.join(dirname, "venvwlauncher" + suffix)
+                dst = os.path.join(binpath, "pythonw" + suffix)
+                copier(src, dst)
+
                 # copy init.tcl over
                 for root, dirs, files in os.walk(context.python_dir):
                     if 'init.tcl' in files:
@@ -326,7 +315,7 @@ class EnvBuilder:
                 dstfile = os.path.join(dstdir, f)
                 with open(srcfile, 'rb') as f:
                     data = f.read()
-                if not srcfile.endswith('.exe'):
+                if not srcfile.endswith(('.exe', '.pdb')):
                     try:
                         data = data.decode('utf-8')
                         data = self.replace_variables(data, context)

Misc/NEWS.d/next/Windows/2018-12-07-10-00-38.bpo-34977.agQJbD.rst

@@ -0,0 +1,2 @@
+venv on Windows will now use a python.exe redirector rather than copying the
+actual binaries from the base environment.

PC/getpathp.c

@@ -536,10 +536,16 @@ static _PyInitError
 get_program_full_path(const _PyCoreConfig *core_config,
                       PyCalculatePath *calculate, _PyPathConfig *config)
 {
+    const wchar_t *pyvenv_launcher;
     wchar_t program_full_path[MAXPATHLEN+1];
     memset(program_full_path, 0, sizeof(program_full_path));
 
-    if (!GetModuleFileNameW(NULL, program_full_path, MAXPATHLEN)) {
+    /* The launcher may need to force the executable path to a
+     * different environment, so override it here. */
+    pyvenv_launcher = _wgetenv(L"__PYVENV_LAUNCHER__");
+    if (pyvenv_launcher && pyvenv_launcher[0]) {
+        wcscpy_s(program_full_path, MAXPATHLEN+1, pyvenv_launcher);
+    } else if (!GetModuleFileNameW(NULL, program_full_path, MAXPATHLEN)) {
         /* GetModuleFileName should never fail when passed NULL */
         return _Py_INIT_ERR("Cannot determine program path");
     }

PC/launcher.c

@@ -28,7 +28,7 @@
 #define RC_NO_PYTHON        103
 #define RC_NO_MEMORY        104
 /*
- * SCRIPT_WRAPPER is used to choose between two variants of an executable built
+ * SCRIPT_WRAPPER is used to choose one of the variants of an executable built
  * from this source file. If not defined, the PEP 397 Python launcher is built;
  * if defined, a script launcher of the type used by setuptools is built, which
  * looks for a script name related to the executable name and runs that script
@@ -40,6 +40,15 @@
 #if defined(SCRIPT_WRAPPER)
 #define RC_NO_SCRIPT        105
 #endif
+/*
+ * VENV_REDIRECT is used to choose the variant that looks for an adjacent or
+ * one-level-higher pyvenv.cfg, and uses its "home" property to locate and
+ * launch the original python.exe.
+ */
+#if defined(VENV_REDIRECT)
+#define RC_NO_VENV_CFG      106
+#define RC_BAD_VENV_CFG     107
+#endif
 
 /* Just for now - static definition */
 
@@ -97,7 +106,7 @@ error(int rc, wchar_t * format, ... )
 #if !defined(_WINDOWS)
     fwprintf(stderr, L"%ls\n", message);
 #else
-    MessageBox(NULL, message, TEXT("Python Launcher is sorry to say ..."),
+    MessageBoxW(NULL, message, L"Python Launcher is sorry to say ...",
                MB_OK);
 #endif
     exit(rc);
@@ -131,6 +140,17 @@ static wchar_t * get_env(wchar_t * key)
     return buf;
 }
 
+#if defined(_DEBUG)
+#if defined(_WINDOWS)
+
+#define PYTHON_EXECUTABLE L"pythonw_d.exe"
+
+#else
+
+#define PYTHON_EXECUTABLE L"python_d.exe"
+
+#endif
+#else
 #if defined(_WINDOWS)
 
 #define PYTHON_EXECUTABLE L"pythonw.exe"
@@ -139,6 +159,7 @@ static wchar_t * get_env(wchar_t * key)
 
 #define PYTHON_EXECUTABLE L"python.exe"
 
+#endif
 #endif
 
 #define MAX_VERSION_SIZE    4
@@ -1457,6 +1478,87 @@ show_python_list(wchar_t ** argv)
     return FALSE; /* If this has been called we cannot continue */
 }
 
+#if defined(VENV_REDIRECT)
+
+static int
+find_home_value(const char *buffer, const char **start, DWORD *length)
+{
+    for (const char *s = strstr(buffer, "home"); s; s = strstr(s + 1, "\nhome")) {
+        if (*s == '\n') {
+            ++s;
+        }
+        for (int i = 4; i > 0 && *s; --i, ++s);
+
+        while (*s && iswspace(*s)) {
+            ++s;
+        }
+        if (*s != L'=') {
+            continue;
+        }
+
+        do {
+            ++s;
+        } while (*s && iswspace(*s));
+
+        *start = s;
+        char *nl = strchr(s, '\n');
+        if (nl) {
+            *length = (DWORD)((ptrdiff_t)nl - (ptrdiff_t)s);
+        } else {
+            *length = (DWORD)strlen(s);
+        }
+        return 1;
+    }
+    return 0;
+}
+#endif
+
+static wchar_t *
+wcsdup_pad(const wchar_t *s, int padding, int *newlen)
+{
+    size_t len = wcslen(s);
+    len += 1 + padding;
+    wchar_t *r = (wchar_t *)malloc(len * sizeof(wchar_t));
+    if (!r) {
+        return NULL;
+    }
+    if (wcscpy_s(r, len, s)) {
+        free(r);
+        return NULL;
+    }
+    *newlen = len < MAXINT ? (int)len : MAXINT;
+    return r;
+}
+
+static wchar_t *
+get_process_name()
+{
+    DWORD bufferLen = MAX_PATH;
+    DWORD len = bufferLen;
+    wchar_t *r = NULL;
+
+    while (!r) {
+        r = (wchar_t *)malloc(bufferLen * sizeof(wchar_t));
+        if (!r) {
+            error(RC_NO_MEMORY, L"out of memory");
+            return NULL;
+        }
+        len = GetModuleFileNameW(NULL, r, bufferLen);
+        if (len == 0) {
+            free(r);
+            error(0, L"Failed to get module name");
+            return NULL;
+        } else if (len == bufferLen &&
+                   GetLastError() == ERROR_INSUFFICIENT_BUFFER) {
+            free(r);
+            r = NULL;
+            bufferLen *= 2;
+        }
+    }
+
+    return r;
+}
+
 static int
 process(int argc, wchar_t ** argv)
 {
@@ -1464,21 +1566,27 @@ process(int argc, wchar_t ** argv)
     wchar_t * command;
     wchar_t * executable;
     wchar_t * p;
+    wchar_t * argv0;
     int rc = 0;
-    size_t plen;
     INSTALLED_PYTHON * ip;
     BOOL valid;
     DWORD size, attrs;
-    HRESULT hr;
     wchar_t message[MSGSIZE];
     void * version_data;
     VS_FIXEDFILEINFO * file_info;
     UINT block_size;
-    int index;
+#if defined(VENV_REDIRECT)
-#if defined(SCRIPT_WRAPPER)
+    wchar_t * venv_cfg_path;
     int newlen;
+#elif defined(SCRIPT_WRAPPER)
     wchar_t * newcommand;
     wchar_t * av[2];
+    int newlen;
+    HRESULT hr;
+    int index;
+#else
+    HRESULT hr;
+    int index;
 #endif
 
     setvbuf(stderr, (char *)NULL, _IONBF, 0);
@@ -1496,6 +1604,7 @@ process(int argc, wchar_t ** argv)
 #else
     debug(L"launcher executable: Console\n");
 #endif
+#if !defined(VENV_REDIRECT)
     /* Get the local appdata folder (non-roaming) */
     hr = SHGetFolderPathW(NULL, CSIDL_LOCAL_APPDATA,
                           NULL, 0, appdata_ini_path);
@@ -1504,9 +1613,7 @@ process(int argc, wchar_t ** argv)
         appdata_ini_path[0] = L'\0';
     }
     else {
-        plen = wcslen(appdata_ini_path);
+        wcsncat_s(appdata_ini_path, MAX_PATH, L"\\py.ini", _TRUNCATE);
-        p = &appdata_ini_path[plen];
-        wcsncpy_s(p, MAX_PATH - plen, L"\\py.ini", _TRUNCATE);
         attrs = GetFileAttributesW(appdata_ini_path);
         if (attrs == INVALID_FILE_ATTRIBUTES) {
             debug(L"File '%ls' non-existent\n", appdata_ini_path);
@@ -1515,8 +1622,9 @@ process(int argc, wchar_t ** argv)
             debug(L"Using local configuration file '%ls'\n", appdata_ini_path);
         }
     }
-    plen = GetModuleFileNameW(NULL, launcher_ini_path, MAX_PATH);
+#endif
-    size = GetFileVersionInfoSizeW(launcher_ini_path, &size);
+    argv0 = get_process_name();
+    size = GetFileVersionInfoSizeW(argv0, &size);
     if (size == 0) {
         winerror(GetLastError(), message, MSGSIZE);
         debug(L"GetFileVersionInfoSize failed: %ls\n", message);
@@ -1524,7 +1632,7 @@ process(int argc, wchar_t ** argv)
     else {
         version_data = malloc(size);
         if (version_data) {
-            valid = GetFileVersionInfoW(launcher_ini_path, 0, size,
+            valid = GetFileVersionInfoW(argv0, 0, size,
                                         version_data);
             if (!valid)
                 debug(L"GetFileVersionInfo failed: %X\n", GetLastError());
@@ -1541,15 +1649,51 @@ process(int argc, wchar_t ** argv)
             free(version_data);
         }
     }
+
+#if defined(VENV_REDIRECT)
+    /* Allocate some extra space for new filenames */
+    venv_cfg_path = wcsdup_pad(argv0, 32, &newlen);
+    if (!venv_cfg_path) {
+        error(RC_NO_MEMORY, L"Failed to copy module name");
+    }
+    p = wcsrchr(venv_cfg_path, L'\\');
+
+    if (p == NULL) {
+        error(RC_NO_VENV_CFG, L"No pyvenv.cfg file");
+    }
+    p[0] = L'\0';
+    wcscat_s(venv_cfg_path, newlen, L"\\pyvenv.cfg");
+    attrs = GetFileAttributesW(venv_cfg_path);
+    if (attrs == INVALID_FILE_ATTRIBUTES) {
+        debug(L"File '%ls' non-existent\n", venv_cfg_path);
+        p[0] = '\0';
+        p = wcsrchr(venv_cfg_path, L'\\');
+        if (p != NULL) {
+            p[0] = '\0';
+            wcscat_s(venv_cfg_path, newlen, L"\\pyvenv.cfg");
+            attrs = GetFileAttributesW(venv_cfg_path);
+            if (attrs == INVALID_FILE_ATTRIBUTES) {
+                debug(L"File '%ls' non-existent\n", venv_cfg_path);
+                error(RC_NO_VENV_CFG, L"No pyvenv.cfg file");
+            }
+        }
+    }
+    debug(L"Using venv configuration file '%ls'\n", venv_cfg_path);
+#else
+    /* Allocate some extra space for new filenames */
+    if (wcscpy_s(launcher_ini_path, MAX_PATH, argv0)) {
+        error(RC_NO_MEMORY, L"Failed to copy module name");
+    }
     p = wcsrchr(launcher_ini_path, L'\\');
+
     if (p == NULL) {
         debug(L"GetModuleFileNameW returned value has no backslash: %ls\n",
               launcher_ini_path);
         launcher_ini_path[0] = L'\0';
     }
     else {
-        wcsncpy_s(p, MAX_PATH - (p - launcher_ini_path), L"\\py.ini",
+        p[0] = L'\0';
-                  _TRUNCATE);
+        wcscat_s(launcher_ini_path, MAX_PATH, L"\\py.ini");
         attrs = GetFileAttributesW(launcher_ini_path);
         if (attrs == INVALID_FILE_ATTRIBUTES) {
             debug(L"File '%ls' non-existent\n", launcher_ini_path);
@@ -1558,6 +1702,7 @@ process(int argc, wchar_t ** argv)
             debug(L"Using global configuration file '%ls'\n", launcher_ini_path);
         }
     }
+#endif
 
     command = skip_me(GetCommandLineW());
     debug(L"Called with command line: %ls\n", command);
@@ -1593,6 +1738,55 @@ process(int argc, wchar_t ** argv)
         command = newcommand;
         valid = FALSE;
     }
+#elif defined(VENV_REDIRECT)
+    {
+        FILE *f;
+        char buffer[4096]; /* 4KB should be enough for anybody */
+        char *start;
+        DWORD len, cch, cch_actual;
+        size_t cb;
+        if (_wfopen_s(&f, venv_cfg_path, L"r")) {
+            error(RC_BAD_VENV_CFG, L"Cannot read '%ls'", venv_cfg_path);
+        }
+        cb = fread_s(buffer, sizeof(buffer), sizeof(buffer[0]),
+                     sizeof(buffer) / sizeof(buffer[0]), f);
+        fclose(f);
+
+        if (!find_home_value(buffer, &start, &len)) {
+            error(RC_BAD_VENV_CFG, L"Cannot find home in '%ls'",
+                  venv_cfg_path);
+        }
+
+        cch = MultiByteToWideChar(CP_UTF8, 0, start, len, NULL, 0);
+        if (!cch) {
+            error(0, L"Cannot determine memory for home path");
+        }
+        cch += (DWORD)wcslen(PYTHON_EXECUTABLE) + 1 + 1; /* include sep and null */
+        executable = (wchar_t *)malloc(cch * sizeof(wchar_t));
+        if (executable == NULL) {
+            error(RC_NO_MEMORY, L"A memory allocation failed");
+        }
+        cch_actual = MultiByteToWideChar(CP_UTF8, 0, start, len, executable, cch);
+        if (!cch_actual) {
+            error(RC_BAD_VENV_CFG, L"Cannot decode home path in '%ls'",
+                  venv_cfg_path);
+        }
+        if (executable[cch_actual - 1] != L'\\') {
+            executable[cch_actual++] = L'\\';
+            executable[cch_actual] = L'\0';
+        }
+        if (wcscat_s(executable, cch, PYTHON_EXECUTABLE)) {
+            error(RC_BAD_VENV_CFG, L"Cannot create executable path from '%ls'",
+                  venv_cfg_path);
+        }
+        if (GetFileAttributesW(executable) == INVALID_FILE_ATTRIBUTES) {
+            error(RC_NO_PYTHON, L"No Python at '%ls'", executable);
+        }
+        if (!SetEnvironmentVariableW(L"__PYVENV_LAUNCHER__", argv0)) {
+            error(0, L"Failed to set launcher environment");
+        }
+        valid = 1;
+    }
 #else
     if (argc <= 1) {
         valid = FALSE;
@@ -1600,7 +1794,6 @@ process(int argc, wchar_t ** argv)
     }
     else {
         p = argv[1];
-        plen = wcslen(p);
         if ((argc == 2) && // list version args
             (!wcsncmp(p, L"-0", wcslen(L"-0")) ||
             !wcsncmp(p, L"--list", wcslen(L"--list"))))

PCbuild/pcbuild.proj

@@ -70,6 +70,8 @@
     <Projects2 Include="_freeze_importlib.vcxproj" />
     <!-- python[w].exe -->
     <Projects2 Include="python.vcxproj;pythonw.vcxproj" />
+    <!-- venv[w]launcher.exe -->
+    <Projects2 Include="venvlauncher.vcxproj;venvwlauncher.vcxproj" />
   </ItemGroup>
 
   <Target Name="Build">

PCbuild/venvlauncher.vcxproj

@@ -0,0 +1,85 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|Win32">
+      <Configuration>Debug</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|x64">
+      <Configuration>Debug</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="PGInstrument|Win32">
+      <Configuration>PGInstrument</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="PGInstrument|x64">
+      <Configuration>PGInstrument</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="PGUpdate|Win32">
+      <Configuration>PGUpdate</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="PGUpdate|x64">
+      <Configuration>PGUpdate</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|Win32">
+      <Configuration>Release</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|x64">
+      <Configuration>Release</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+  <PropertyGroup Label="Globals">
+    <ProjectGuid>{494BAC80-A60C-43A9-99E7-ACB691CE2C4D}</ProjectGuid>
+    <RootNamespace>venvlauncher</RootNamespace>
+    <TargetName>venvlauncher</TargetName>
+    <SupportPGO>false</SupportPGO>
+  </PropertyGroup>
+  <Import Project="python.props" />
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
+  <PropertyGroup Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <CharacterSet>MultiByte</CharacterSet>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+  <ImportGroup Label="ExtensionSettings">
+  </ImportGroup>
+  <PropertyGroup>
+    <MakeVersionInfoBeforeTarget>ClCompile</MakeVersionInfoBeforeTarget>
+  </PropertyGroup>
+  <ImportGroup Label="PropertySheets">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+    <Import Project="pyproject.props" />
+  </ImportGroup>
+  <PropertyGroup Label="UserMacros" />
+  <ItemDefinitionGroup>
+    <ClCompile>
+      <PreprocessorDefinitions>_CONSOLE;VENV_REDIRECT;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <RuntimeLibrary>MultiThreaded</RuntimeLibrary>
+    </ClCompile>
+    <ResourceCompile>
+      <PreprocessorDefinitions>PY_ICON;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+    </ResourceCompile>
+    <Link>
+      <AdditionalDependencies>version.lib;%(AdditionalDependencies)</AdditionalDependencies>
+      <SubSystem>Console</SubSystem>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemGroup>
+    <ClCompile Include="..\PC\launcher.c" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="..\PC\launcher.ico" />
+  </ItemGroup>
+  <ItemGroup>
+    <ResourceCompile Include="..\PC\pylauncher.rc" />
+  </ItemGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+  <ImportGroup Label="ExtensionTargets">
+  </ImportGroup>
+</Project>

PCbuild/venvwlauncher.vcxproj

@@ -0,0 +1,85 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|Win32">
+      <Configuration>Debug</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|x64">
+      <Configuration>Debug</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="PGInstrument|Win32">
+      <Configuration>PGInstrument</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="PGInstrument|x64">
+      <Configuration>PGInstrument</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="PGUpdate|Win32">
+      <Configuration>PGUpdate</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="PGUpdate|x64">
+      <Configuration>PGUpdate</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|Win32">
+      <Configuration>Release</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|x64">
+      <Configuration>Release</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+  <PropertyGroup Label="Globals">
+    <ProjectGuid>{FDB84CBB-2FB6-47C8-A2D6-091E0833239D}</ProjectGuid>
+    <RootNamespace>venvwlauncher</RootNamespace>
+    <TargetName>venvwlauncher</TargetName>
+    <SupportPGO>false</SupportPGO>
+  </PropertyGroup>
+  <Import Project="python.props" />
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
+  <PropertyGroup Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <CharacterSet>MultiByte</CharacterSet>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+  <ImportGroup Label="ExtensionSettings">
+  </ImportGroup>
+  <PropertyGroup>
+    <MakeVersionInfoBeforeTarget>ClCompile</MakeVersionInfoBeforeTarget>
+  </PropertyGroup>
+  <ImportGroup Label="PropertySheets">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+    <Import Project="pyproject.props" />
+  </ImportGroup>
+  <PropertyGroup Label="UserMacros" />
+  <ItemDefinitionGroup>
+    <ClCompile>
+      <PreprocessorDefinitions>_WINDOWS;VENV_REDIRECT;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <RuntimeLibrary>MultiThreaded</RuntimeLibrary>
+    </ClCompile>
+    <ResourceCompile>
+      <PreprocessorDefinitions>PYW_ICON;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+    </ResourceCompile>
+    <Link>
+      <AdditionalDependencies>version.lib;%(AdditionalDependencies)</AdditionalDependencies>
+      <SubSystem>Windows</SubSystem>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemGroup>
+    <ClCompile Include="..\PC\launcher.c" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="..\PC\launcher.ico" />
+  </ItemGroup>
+  <ItemGroup>
+    <ResourceCompile Include="..\PC\pylauncher.rc" />
+  </ItemGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+  <ImportGroup Label="ExtensionTargets">
+  </ImportGroup>
+</Project>

Tools/msi/lib/lib_files.wxs

@@ -2,6 +2,8 @@
 <Wix xmlns="http://schemas.microsoft.com/wix/2006/wi">
     <?define exts=pyexpat;select;unicodedata;winsound;_bz2;_elementtree;_socket;_ssl;_msi;_ctypes;_hashlib;_multiprocessing;_lzma;_decimal;_overlapped;_sqlite3;_asyncio;_queue;_contextvars ?>
     <Fragment>
+        <DirectoryRef Id="Lib_venv_scripts_nt" />
+
         <ComponentGroup Id="lib_extensions">
             <?foreach ext in $(var.exts)?>
         
@@ -20,10 +22,25 @@
             <Component Id="libssl.dll" Directory="DLLs" Guid="*">
                 <File Name="libssl$(var.ssltag).dll" KeyPath="yes" />
             </Component>
+            <Component Id="venvlauncher.exe" Directory="Lib_venv_scripts_nt" Guid="*">
+                <File Name="python.exe" Source="venvlauncher.exe" KeyPath="yes" />
+            </Component>
+            <Component Id="venvwlauncher.exe" Directory="Lib_venv_scripts_nt" Guid="*">
+                <File Name="pythonw.exe" Source="venvwlauncher.exe" KeyPath="yes" />
+            </Component>
         </ComponentGroup>
     </Fragment>
     
     <Fragment>
+        <!-- The auto-generated directory is not available when building symbols -->
+        <DirectoryRef Id="Lib">
+            <Directory Id="Lib_venv__pdbs" Name="venv">
+                <Directory Id="Lib_venv_scripts__pdbs" Name="scripts">
+                    <Directory Id="Lib_venv_scripts_nt__pdbs" Name="nt" />
+                </Directory>
+            </Directory>
+        </DirectoryRef>
+
         <ComponentGroup Id="lib_extensions_symbols">
             <?foreach ext in $(var.exts)?>
             
@@ -42,6 +59,12 @@
             <Component Id="libssl.pdb" Directory="DLLs" Guid="*">
                 <File Name="libssl$(var.ssltag).pdb" KeyPath="yes" />
             </Component>
+            <Component Id="venvlauncher.pdb" Directory="Lib_venv_scripts_nt__pdbs" Guid="*">
+                <File Name="python.pdb" Source="venvlauncher.pdb" KeyPath="yes" />
+            </Component>
+            <Component Id="venvwlauncher.pdb" Directory="Lib_venv_scripts_nt__pdbs" Guid="*">
+                <File Name="pythonw.pdb" Source="venvwlauncher.pdb" KeyPath="yes" />
+            </Component>
         </ComponentGroup>
     </Fragment>