Add launcher source and resources

1 files changed, 1377 insertions, 0 deletions

diff --git a/PC/launcher.c b/PC/launcher.c
new file mode 100644
index 0000000..22d2974
--- /dev/null
+++ b/PC/launcher.c
@@ -0,0 +1,1377 @@
+/*
+ * Copyright (C) 2011-2012 Vinay Sajip. All rights reserved.
+ *
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Based on the work of:
+ *
+ * Mark Hammond (original author of Python version)
+ * Curt Hagenlocher (job management)
+ */
+
+#include <windows.h>
+#include <shlobj.h>
+#include <stdio.h>
+#include <tchar.h>
+
+#define BUFSIZE 256
+#define MSGSIZE 1024
+
+/* Build options. */
+#define SKIP_PREFIX
+/* #define SEARCH_PATH */
+
+/* Just for now - static definition */
+
+static FILE * log_fp = NULL;
+
+static wchar_t *
+skip_whitespace(wchar_t * p)
+{
+    while (*p && isspace(*p))
+        ++p;
+    return p;
+}
+
+/*
+ * This function is here to minimise Visual Studio
+ * warnings about security implications of getenv, and to
+ * treat blank values as if they are absent.
+ */
+static wchar_t * get_env(wchar_t * key)
+{
+    wchar_t * result = _wgetenv(key);
+
+    if (result) {
+        result = skip_whitespace(result);
+        if (*result == L'\0')
+            result = NULL;
+    }
+    return result;
+}
+
+static void
+debug(wchar_t * format, ...)
+{
+    va_list va;
+
+    if (log_fp != NULL) {
+        va_start(va, format);
+        vfwprintf_s(log_fp, format, va);
+    }
+}
+
+static void
+winerror(int rc, wchar_t * message, int size)
+{
+    FormatMessageW(
+        FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+        NULL, rc, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+        message, size, NULL);
+}
+
+static void
+error(int rc, wchar_t * format, ... )
+{
+    va_list va;
+    wchar_t message[MSGSIZE];
+    wchar_t win_message[MSGSIZE];
+    int len;
+
+    va_start(va, format);
+    len = _vsnwprintf_s(message, MSGSIZE, _TRUNCATE, format, va);
+
+    if (rc == 0) {  /* a Windows error */
+        winerror(GetLastError(), win_message, MSGSIZE);
+        if (len >= 0) {
+            _snwprintf_s(&message[len], MSGSIZE - len, _TRUNCATE, L": %s",
+                         win_message);
+        }
+    }
+
+#if !defined(_WINDOWS)
+    fwprintf(stderr, L"%s\n", message);
+#else
+    MessageBox(NULL, message, TEXT("Python Launcher is sorry to say ..."), MB_OK); 
+#endif
+    ExitProcess(rc);
+}
+
+#if defined(_WINDOWS)
+
+#define PYTHON_EXECUTABLE L"pythonw.exe"
+
+#else
+
+#define PYTHON_EXECUTABLE L"python.exe"
+
+#endif
+
+#define RC_NO_STD_HANDLES   100
+#define RC_CREATE_PROCESS   101
+#define RC_BAD_VIRTUAL_PATH 102
+#define RC_NO_PYTHON        103
+
+#define MAX_VERSION_SIZE    4
+
+typedef struct {
+    wchar_t version[MAX_VERSION_SIZE]; /* m.n */
+    int bits;   /* 32 or 64 */
+    wchar_t executable[MAX_PATH];
+} INSTALLED_PYTHON;
+
+/*
+ * To avoid messing about with heap allocations, just assume we can allocate
+ * statically and never have to deal with more versions than this.
+ */
+#define MAX_INSTALLED_PYTHONS   100
+
+static INSTALLED_PYTHON installed_pythons[MAX_INSTALLED_PYTHONS];
+
+static size_t num_installed_pythons = 0;
+
+/* to hold SOFTWARE\Python\PythonCore\X.Y\InstallPath */
+#define IP_BASE_SIZE 40
+#define IP_SIZE (IP_BASE_SIZE + MAX_VERSION_SIZE)
+#define CORE_PATH L"SOFTWARE\\Python\\PythonCore"
+
+static wchar_t * location_checks[] = {
+    L"\\",
+    L"\\PCBuild\\",
+    L"\\PCBuild\\amd64\\",
+    NULL
+};
+
+static INSTALLED_PYTHON *
+find_existing_python(wchar_t * path)
+{
+    INSTALLED_PYTHON * result = NULL;
+    size_t i;
+    INSTALLED_PYTHON * ip;
+
+    for (i = 0, ip = installed_pythons; i < num_installed_pythons; i++, ip++) {
+        if (_wcsicmp(path, ip->executable) == 0) {
+            result = ip;
+            break;
+        }
+    }
+    return result;
+}
+
+static void
+locate_pythons_for_key(HKEY root, REGSAM flags)
+{
+    HKEY core_root, ip_key;
+    LSTATUS status = RegOpenKeyExW(root, CORE_PATH, 0, flags, &core_root);
+    wchar_t message[MSGSIZE];
+    DWORD i;
+    size_t n;
+    BOOL ok;
+    DWORD type, data_size, attrs;
+    INSTALLED_PYTHON * ip, * pip;
+    wchar_t ip_path[IP_SIZE];
+    wchar_t * check;
+    wchar_t ** checkp;
+    wchar_t *key_name = (root == HKEY_LOCAL_MACHINE) ? L"HKLM" : L"HKCU";
+
+    if (status != ERROR_SUCCESS)
+        debug(L"locate_pythons_for_key: unable to open PythonCore key in %s\n",
+              key_name);
+    else {
+        ip = &installed_pythons[num_installed_pythons];
+        for (i = 0; num_installed_pythons < MAX_INSTALLED_PYTHONS; i++) {
+            status = RegEnumKeyW(core_root, i, ip->version, MAX_VERSION_SIZE);
+            if (status != ERROR_SUCCESS) {
+                if (status != ERROR_NO_MORE_ITEMS) {
+                    /* unexpected error */
+                    winerror(status, message, MSGSIZE);
+                    debug(L"Can't enumerate registry key for version %s: %s\n",
+                          ip->version, message);
+                }
+                break;
+            }
+            else {
+                _snwprintf_s(ip_path, IP_SIZE, _TRUNCATE,
+                             L"%s\\%s\\InstallPath", CORE_PATH, ip->version);
+                status = RegOpenKeyExW(root, ip_path, 0, flags, &ip_key);
+                if (status != ERROR_SUCCESS) {
+                    winerror(status, message, MSGSIZE);
+                    // Note: 'message' already has a trailing \n
+                    debug(L"%s\\%s: %s", key_name, ip_path, message);
+                    continue;
+                }
+                data_size = sizeof(ip->executable) - 1;
+                status = RegQueryValueEx(ip_key, NULL, NULL, &type,
+                                         (LPBYTE) ip->executable, &data_size);
+                RegCloseKey(ip_key);
+                if (status != ERROR_SUCCESS) {
+                    winerror(status, message, MSGSIZE);
+                    debug(L"%s\\%s: %s\n", key_name, ip_path, message);
+                    continue;
+                }
+                if (type == REG_SZ) {
+                    data_size = data_size / sizeof(wchar_t) - 1;  /* for NUL */
+                    if (ip->executable[data_size - 1] == L'\\')
+                        --data_size; /* reg value ended in a backslash */
+                    /* ip->executable is data_size long */
+                    for (checkp = location_checks; *checkp; ++checkp) {
+                        check = *checkp;
+                        _snwprintf_s(&ip->executable[data_size],
+                                     MAX_PATH - data_size,
+                                     MAX_PATH - data_size,
+                                     L"%s%s", check, PYTHON_EXECUTABLE);
+                        attrs = GetFileAttributesW(ip->executable);
+                        if (attrs == INVALID_FILE_ATTRIBUTES) {
+                            winerror(GetLastError(), message, MSGSIZE);
+                            debug(L"locate_pythons_for_key: %s: %s",
+                                  ip->executable, message);
+                        }
+                        else if (attrs & FILE_ATTRIBUTE_DIRECTORY) {
+                            debug(L"locate_pythons_for_key: '%s' is a \
+directory\n",
+                                  ip->executable, attrs);
+                        }
+                        else if (find_existing_python(ip->executable)) {
+                            debug(L"locate_pythons_for_key: %s: already \
+found: %s\n", ip->executable);
+                        }
+                        else {
+                            /* check the executable type. */
+                            ok = GetBinaryTypeW(ip->executable, &attrs);
+                            if (!ok) {
+                                debug(L"Failure getting binary type: %s\n",
+                                      ip->executable);
+                            }
+                            else {
+                                if (attrs == SCS_64BIT_BINARY)
+                                    ip->bits = 64;
+                                else if (attrs == SCS_32BIT_BINARY)
+                                    ip->bits = 32;
+                                else
+                                    ip->bits = 0;
+                                if (ip->bits == 0) {
+                                    debug(L"locate_pythons_for_key: %s: \
+invalid binary type: %X\n",
+                                          ip->executable, attrs);
+                                }
+                                else {
+                                    if (wcschr(ip->executable, L' ') != NULL) {
+                                        /* has spaces, so quote */
+                                        n = wcslen(ip->executable);
+                                        memmove(&ip->executable[1],
+                                                ip->executable, n * sizeof(wchar_t));
+                                        ip->executable[0] = L'\"';
+                                        ip->executable[n + 1] = L'\"';
+                                        ip->executable[n + 2] = L'\0';
+                                    }
+                                    debug(L"locate_pythons_for_key: %s \
+is a %dbit executable\n",
+                                        ip->executable, ip->bits);
+                                    ++num_installed_pythons;
+                                    pip = ip++;
+                                    if (num_installed_pythons >=
+                                        MAX_INSTALLED_PYTHONS)
+                                        break;
+                                    /* Copy over the attributes for the next */
+                                    *ip = *pip;
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        RegCloseKey(core_root);
+    }
+}
+
+static int
+compare_pythons(const void * p1, const void * p2)
+{
+    INSTALLED_PYTHON * ip1 = (INSTALLED_PYTHON *) p1;
+    INSTALLED_PYTHON * ip2 = (INSTALLED_PYTHON *) p2;
+    /* note reverse sorting on version */
+    int result = wcscmp(ip2->version, ip1->version);
+
+    if (result == 0)
+        result = ip2->bits - ip1->bits; /* 64 before 32 */
+    return result;
+}
+
+static void
+locate_all_pythons()
+{
+#if defined(_M_X64)
+    // If we are a 64bit process, first hit the 32bit keys.
+    debug(L"locating Pythons in 32bit registry\n");
+    locate_pythons_for_key(HKEY_CURRENT_USER, KEY_READ | KEY_WOW64_32KEY);
+    locate_pythons_for_key(HKEY_LOCAL_MACHINE, KEY_READ | KEY_WOW64_32KEY);
+#else
+    // If we are a 32bit process on a 64bit Windows, first hit the 64bit keys.
+    BOOL f64 = FALSE;
+    if (IsWow64Process(GetCurrentProcess(), &f64) && f64) {
+        debug(L"locating Pythons in 64bit registry\n");
+        locate_pythons_for_key(HKEY_CURRENT_USER, KEY_READ | KEY_WOW64_64KEY);
+        locate_pythons_for_key(HKEY_LOCAL_MACHINE, KEY_READ | KEY_WOW64_64KEY);
+    }
+#endif    
+    // now hit the "native" key for this process bittedness.
+    debug(L"locating Pythons in native registry\n");
+    locate_pythons_for_key(HKEY_CURRENT_USER, KEY_READ);
+    locate_pythons_for_key(HKEY_LOCAL_MACHINE, KEY_READ);
+    qsort(installed_pythons, num_installed_pythons, sizeof(INSTALLED_PYTHON),
+          compare_pythons);
+}
+
+static INSTALLED_PYTHON *
+find_python_by_version(wchar_t const * wanted_ver)
+{
+    INSTALLED_PYTHON * result = NULL;
+    INSTALLED_PYTHON * ip = installed_pythons;
+    size_t i, n;
+    size_t wlen = wcslen(wanted_ver);
+    int bits = 0;
+
+    if (wcsstr(wanted_ver, L"-32"))
+        bits = 32;
+    for (i = 0; i < num_installed_pythons; i++, ip++) {
+        n = wcslen(ip->version);
+        if (n > wlen)
+            n = wlen;
+        if ((wcsncmp(ip->version, wanted_ver, n) == 0) &&
+            /* bits == 0 => don't care */
+            ((bits == 0) || (ip->bits == bits))) {
+            result = ip;
+            break;
+        }
+    }
+    return result;
+}
+
+
+static wchar_t appdata_ini_path[MAX_PATH];
+static wchar_t launcher_ini_path[MAX_PATH];
+
+/*
+ * Get a value either from the environment or a configuration file.
+ * The key passed in will either be "python", "python2" or "python3".
+ */
+static wchar_t *
+get_configured_value(wchar_t * key)
+{
+/*
+ * Note: this static value is used to return a configured value
+ * obtained either from the environment or configuration file.
+ * This should be OK since there wouldn't be any concurrent calls.
+ */
+    static wchar_t configured_value[MSGSIZE];
+    wchar_t * result = NULL;
+    wchar_t * found_in = L"environment";
+    DWORD size;
+
+    /* First, search the environment. */
+    _snwprintf_s(configured_value, MSGSIZE, _TRUNCATE, L"py_%s", key);
+    result = get_env(configured_value);
+    if (result == NULL && appdata_ini_path[0]) {
+        /* Not in environment: check local configuration. */
+        size = GetPrivateProfileStringW(L"defaults", key, NULL,
+                                        configured_value, MSGSIZE,
+                                        appdata_ini_path);
+        if (size > 0) {
+            result = configured_value;
+            found_in = appdata_ini_path;
+        }
+    }
+    if (result == NULL && launcher_ini_path[0]) {
+        /* Not in environment or local: check global configuration. */
+        size = GetPrivateProfileStringW(L"defaults", key, NULL,
+                                        configured_value, MSGSIZE,
+                                        launcher_ini_path);
+        if (size > 0) {
+            result = configured_value;
+            found_in = launcher_ini_path;
+        }
+    }
+    if (result) {
+        debug(L"found configured value '%s=%s' in %s\n",
+              key, result, found_in ? found_in : L"(unknown)");
+    } else {
+        debug(L"found no configured value for '%s'\n", key);
+    }
+    return result;
+}
+
+static INSTALLED_PYTHON *
+locate_python(wchar_t * wanted_ver)
+{
+    static wchar_t config_key [] = { L"pythonX" };
+    static wchar_t * last_char = &config_key[sizeof(config_key) /
+                                             sizeof(wchar_t) - 2];
+    INSTALLED_PYTHON * result = NULL;
+    size_t n = wcslen(wanted_ver);
+    wchar_t * configured_value;
+
+    if (num_installed_pythons == 0)
+        locate_all_pythons();
+
+    if (n == 1) {   /* just major version specified */
+        *last_char = *wanted_ver;
+        configured_value = get_configured_value(config_key);
+        if (configured_value != NULL)
+            wanted_ver = configured_value;
+    }
+    if (*wanted_ver) {
+        result = find_python_by_version(wanted_ver);
+        debug(L"search for Python version '%s' found ", wanted_ver);
+        if (result) {
+            debug(L"'%s'\n", result->executable);
+        } else {
+            debug(L"no interpreter\n");
+        }
+    }
+    else {
+        *last_char = L'\0'; /* look for an overall default */
+        configured_value = get_configured_value(config_key);
+        if (configured_value)
+            result = find_python_by_version(configured_value);
+        if (result == NULL)
+            result = find_python_by_version(L"2");
+        if (result == NULL)
+            result = find_python_by_version(L"3");
+        debug(L"search for default Python found ");
+        if (result) {
+            debug(L"version %s at '%s'\n",
+                  result->version, result->executable);
+        } else {
+            debug(L"no interpreter\n");
+        }
+    }
+    return result;
+}
+
+/*
+ * Process creation code
+ */
+
+static BOOL
+safe_duplicate_handle(HANDLE in, HANDLE * pout)
+{
+    BOOL ok;
+    HANDLE process = GetCurrentProcess();
+    DWORD rc;
+
+    *pout = NULL;
+    ok = DuplicateHandle(process, in, process, pout, 0, TRUE,
+                         DUPLICATE_SAME_ACCESS);
+    if (!ok) {
+        rc = GetLastError();
+        if (rc == ERROR_INVALID_HANDLE) {
+            debug(L"DuplicateHandle returned ERROR_INVALID_HANDLE\n");
+            ok = TRUE;
+        }
+        else {
+            debug(L"DuplicateHandle returned %d\n", rc);
+        }
+    }
+    return ok;
+}
+
+static BOOL WINAPI
+ctrl_c_handler(DWORD code)
+{
+    return TRUE;    /* We just ignore all control events. */
+}
+
+static void
+run_child(wchar_t * cmdline)
+{
+    HANDLE job;
+    JOBOBJECT_EXTENDED_LIMIT_INFORMATION info;
+    DWORD rc;
+    BOOL ok;
+    STARTUPINFOW si;
+    PROCESS_INFORMATION pi;
+
+    debug(L"run_child: about to run '%s'\n", cmdline);
+    job = CreateJobObject(NULL, NULL);
+    ok = QueryInformationJobObject(job, JobObjectExtendedLimitInformation,
+                                  &info, sizeof(info), &rc);
+    if (!ok || (rc != sizeof(info)) || !job)
+        error(RC_CREATE_PROCESS, L"Job information querying failed");
+    info.BasicLimitInformation.LimitFlags |= JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE |
+                                             JOB_OBJECT_LIMIT_SILENT_BREAKAWAY_OK;
+    ok = SetInformationJobObject(job, JobObjectExtendedLimitInformation, &info,
+                                 sizeof(info));
+    if (!ok)
+        error(RC_CREATE_PROCESS, L"Job information setting failed");
+    memset(&si, 0, sizeof(si));
+    si.cb = sizeof(si);
+    ok = safe_duplicate_handle(GetStdHandle(STD_INPUT_HANDLE), &si.hStdInput);
+    if (!ok)
+        error(RC_NO_STD_HANDLES, L"stdin duplication failed");
+    ok = safe_duplicate_handle(GetStdHandle(STD_OUTPUT_HANDLE), &si.hStdOutput);
+    if (!ok)
+        error(RC_NO_STD_HANDLES, L"stdout duplication failed");
+    ok = safe_duplicate_handle(GetStdHandle(STD_ERROR_HANDLE), &si.hStdError);
+    if (!ok)
+        error(RC_NO_STD_HANDLES, L"stderr duplication failed");
+
+    ok = SetConsoleCtrlHandler(ctrl_c_handler, TRUE);
+    if (!ok)
+        error(RC_CREATE_PROCESS, L"control handler setting failed");
+
+    si.dwFlags = STARTF_USESTDHANDLES;
+    ok = CreateProcessW(NULL, cmdline, NULL, NULL, TRUE,
+                        0, NULL, NULL, &si, &pi);
+    if (!ok)
+        error(RC_CREATE_PROCESS, L"Unable to create process using '%s'", cmdline);
+    AssignProcessToJobObject(job, pi.hProcess);
+    CloseHandle(pi.hThread);
+    WaitForSingleObject(pi.hProcess, INFINITE);
+    ok = GetExitCodeProcess(pi.hProcess, &rc);
+    if (!ok)
+        error(RC_CREATE_PROCESS, L"Failed to get exit code of process");
+    debug(L"child process exit code: %d\n", rc);
+    ExitProcess(rc);
+}
+
+static void
+invoke_child(wchar_t * executable, wchar_t * suffix, wchar_t * cmdline)
+{
+    wchar_t * child_command;
+    size_t child_command_size;
+    BOOL no_suffix = (suffix == NULL) || (*suffix == L'\0');
+    BOOL no_cmdline = (*cmdline == L'\0');
+
+    if (no_suffix && no_cmdline)
+        run_child(executable);
+    else {
+        if (no_suffix) {
+            /* add 2 for space separator + terminating NUL. */
+            child_command_size = wcslen(executable) + wcslen(cmdline) + 2;
+        }
+        else {
+            /* add 3 for 2 space separators + terminating NUL. */
+            child_command_size = wcslen(executable) + wcslen(suffix) +
+                                    wcslen(cmdline) + 3;
+        }
+        child_command = calloc(child_command_size, sizeof(wchar_t));
+        if (child_command == NULL)
+            error(RC_CREATE_PROCESS, L"unable to allocate %d bytes for child command.",
+                  child_command_size);
+        if (no_suffix)
+            _snwprintf_s(child_command, child_command_size,
+                         child_command_size - 1, L"%s %s",
+                         executable, cmdline);
+        else
+            _snwprintf_s(child_command, child_command_size,
+                         child_command_size - 1, L"%s %s %s",
+                         executable, suffix, cmdline);
+        run_child(child_command);
+        free(child_command);
+    }
+}
+
+static wchar_t * builtin_virtual_paths [] = {
+    L"/usr/bin/env python",
+    L"/usr/bin/python",
+    L"/usr/local/bin/python",
+    L"python",
+    NULL
+};
+
+/* For now, a static array of commands. */
+
+#define MAX_COMMANDS 100
+
+typedef struct {
+    wchar_t key[MAX_PATH];
+    wchar_t value[MSGSIZE];
+} COMMAND;
+
+static COMMAND commands[MAX_COMMANDS];
+static int num_commands = 0;
+
+#if defined(SKIP_PREFIX)
+
+static wchar_t * builtin_prefixes [] = {
+    /* These must be in an order that the longest matches should be found,
+     * i.e. if the prefix is "/usr/bin/env ", it should match that entry
+     * *before* matching "/usr/bin/".
+     */
+    L"/usr/bin/env ",
+    L"/usr/bin/",
+    L"/usr/local/bin/",
+    NULL
+};
+
+static wchar_t * skip_prefix(wchar_t * name)
+{
+    wchar_t ** pp = builtin_prefixes;
+    wchar_t * result = name;
+    wchar_t * p;
+    size_t n;
+
+    for (; p = *pp; pp++) {
+        n = wcslen(p);
+        if (_wcsnicmp(p, name, n) == 0) {
+            result += n;   /* skip the prefix */
+            if (p[n - 1] == L' ') /* No empty strings in table, so n > 1 */
+                result = skip_whitespace(result);
+            break;
+        }
+    }
+    return result;
+}
+
+#endif
+
+#if defined(SEARCH_PATH)
+
+static COMMAND path_command;
+
+static COMMAND * find_on_path(wchar_t * name)
+{
+    wchar_t * pathext;
+    size_t    varsize;
+    wchar_t * context = NULL;
+    wchar_t * extension;
+    COMMAND * result = NULL;
+    DWORD     len;
+    errno_t   rc;
+
+    wcscpy_s(path_command.key, MAX_PATH, name);
+    if (wcschr(name, L'.') != NULL) {
+        /* assume it has an extension. */
+        len = SearchPathW(NULL, name, NULL, MSGSIZE, path_command.value, NULL);
+        if (len) {
+            result = &path_command;
+        }
+    }
+    else {
+        /* No extension - search using registered extensions. */
+        rc = _wdupenv_s(&pathext, &varsize, L"PATHEXT");
+        if (rc == 0) {
+            extension = wcstok_s(pathext, L";", &context);
+            while (extension) {
+                len = SearchPathW(NULL, name, extension, MSGSIZE, path_command.value, NULL);
+                if (len) {
+                    result = &path_command;
+                    break;
+                }
+                extension = wcstok_s(NULL, L";", &context);
+            }
+            free(pathext);
+        }
+    }
+    return result;
+}
+
+#endif
+
+static COMMAND * find_command(wchar_t * name)
+{
+    COMMAND * result = NULL;
+    COMMAND * cp = commands;
+    int i;
+
+    for (i = 0; i < num_commands; i++, cp++) {
+        if (_wcsicmp(cp->key, name) == 0) {
+            result = cp;
+            break;
+        }
+    }
+#if defined(SEARCH_PATH)
+    if (result == NULL)
+        result = find_on_path(name);
+#endif
+    return result;
+}
+
+static void
+update_command(COMMAND * cp, wchar_t * name, wchar_t * cmdline)
+{
+    wcsncpy_s(cp->key, MAX_PATH, name, _TRUNCATE);
+    wcsncpy_s(cp->value, MSGSIZE, cmdline, _TRUNCATE);
+}
+
+static void
+add_command(wchar_t * name, wchar_t * cmdline)
+{
+    if (num_commands >= MAX_COMMANDS) {
+        debug(L"can't add %s = '%s': no room\n", name, cmdline);
+    }
+    else {
+        COMMAND * cp = &commands[num_commands++];
+
+        update_command(cp, name, cmdline);
+    }
+}
+
+static void
+read_config_file(wchar_t * config_path)
+{
+    wchar_t keynames[MSGSIZE];
+    wchar_t value[MSGSIZE];
+    DWORD read;
+    wchar_t * key;
+    COMMAND * cp;
+    wchar_t * cmdp;
+
+    read = GetPrivateProfileStringW(L"commands", NULL, NULL, keynames, MSGSIZE,
+                                    config_path);
+    if (read == MSGSIZE - 1) {
+        debug(L"read_commands: %s: not enough space for names\n", config_path);
+    }
+    key = keynames;
+    while (*key) {
+        read = GetPrivateProfileStringW(L"commands", key, NULL, value, MSGSIZE,
+                                       config_path);
+        if (read == MSGSIZE - 1) {
+            debug(L"read_commands: %s: not enough space for %s\n",
+                  config_path, key);
+        }
+        cmdp = skip_whitespace(value);
+        if (*cmdp) {
+            cp = find_command(key);
+            if (cp == NULL)
+                add_command(key, value);
+            else
+                update_command(cp, key, value);
+        }
+        key += wcslen(key) + 1;
+    }
+}
+
+static void read_commands()
+{
+    if (launcher_ini_path[0])
+        read_config_file(launcher_ini_path);
+    if (appdata_ini_path[0])
+        read_config_file(appdata_ini_path);
+}
+
+static BOOL
+parse_shebang(wchar_t * shebang_line, int nchars, wchar_t ** command,
+              wchar_t ** suffix)
+{
+    BOOL rc = FALSE;
+    wchar_t ** vpp;
+    size_t plen;
+    wchar_t * p;
+    wchar_t zapped;
+    wchar_t * endp = shebang_line + nchars - 1;
+    COMMAND * cp;
+    wchar_t * skipped;
+
+    *command = NULL;    /* failure return */
+    *suffix = NULL;
+
+    if ((*shebang_line++ == L'#') && (*shebang_line++ == L'!')) {
+        shebang_line = skip_whitespace(shebang_line);
+        if (*shebang_line) {
+            *command = shebang_line;
+            for (vpp = builtin_virtual_paths; *vpp; ++vpp) {
+                plen = wcslen(*vpp);
+                if (wcsncmp(shebang_line, *vpp, plen) == 0) {
+                    rc = TRUE;
+                    /* We can do this because all builtin commands contain
+                     * "python".
+                     */
+                    *command = wcsstr(shebang_line, L"python");
+                    break;
+                }
+            }
+            if (*vpp == NULL) {
+                /*
+                 * Not found in builtins - look in customised commands.
+                 *
+                 * We can't permanently modify the shebang line in case
+                 * it's not a customised command, but we can temporarily
+                 * stick a NUL after the command while searching for it,
+                 * then put back the char we zapped.
+                 */
+#if defined(SKIP_PREFIX)
+                skipped = skip_prefix(shebang_line);
+#else
+                skipped = shebang_line;
+#endif
+                p = wcspbrk(skipped, L" \t\r\n");
+                if (p != NULL) {
+                    zapped = *p;
+                    *p = L'\0';
+                }
+                cp = find_command(skipped);
+                if (p != NULL)
+                    *p = zapped;
+                if (cp != NULL) {
+                    *command = cp->value;
+                    if (p != NULL)
+                        *suffix = skip_whitespace(p);
+                }
+            }
+            /* remove trailing whitespace */
+            while ((endp > shebang_line) && isspace(*endp))
+                --endp;
+            if (endp > shebang_line)
+                endp[1] = L'\0';
+        }
+    }
+    return rc;
+}
+
+/* #define CP_UTF8             65001 defined in winnls.h */
+#define CP_UTF16LE          1200
+#define CP_UTF16BE          1201
+#define CP_UTF32LE          12000
+#define CP_UTF32BE          12001
+
+typedef struct {
+    int length;
+    char sequence[4];
+    UINT code_page;
+} BOM;
+
+/*
+ * Strictly, we don't need to handle UTF-16 anf UTF-32, since Python itself
+ * doesn't. Never mind, one day it might - there's no harm leaving it in.
+ */
+static BOM BOMs[] = {
+    { 3, { 0xEF, 0xBB, 0xBF }, CP_UTF8 },           /* UTF-8 - keep first */
+    { 2, { 0xFF, 0xFE }, CP_UTF16LE },              /* UTF-16LE */
+    { 2, { 0xFE, 0xFF }, CP_UTF16BE },              /* UTF-16BE */
+    { 4, { 0xFF, 0xFE, 0x00, 0x00 }, CP_UTF32LE },  /* UTF-32LE */
+    { 4, { 0x00, 0x00, 0xFE, 0xFF }, CP_UTF32BE },  /* UTF-32BE */
+    { 0 }                                           /* sentinel */
+};
+
+static BOM *
+find_BOM(char * buffer)
+{
+/*
+ * Look for a BOM in the input and return a pointer to the
+ * corresponding structure, or NULL if not found.
+ */
+    BOM * result = NULL;
+    BOM *bom;
+
+    for (bom = BOMs; bom->length; bom++) {
+        if (strncmp(bom->sequence, buffer, bom->length) == 0) {
+            result = bom;
+            break;
+        }
+    }
+    return result;
+}
+
+static char *
+find_terminator(char * buffer, int len, BOM *bom)
+{
+    char * result = NULL;
+    char * end = buffer + len;
+    char  * p;
+    char c;
+    int cp;
+
+    for (p = buffer; p < end; p++) {
+        c = *p;
+        if (c == '\r') {
+            result = p;
+            break;
+        }
+        if (c == '\n') {
+            result = p;
+            break;
+        }
+    }
+    if (result != NULL) {
+        cp = bom->code_page;
+
+        /* adjustments to include all bytes of the char */
+        /* no adjustment needed for UTF-8 or big endian */
+        if (cp == CP_UTF16LE)
+            ++result;
+        else if (cp == CP_UTF32LE)
+            result += 3;
+        ++result; /* point just past terminator */
+    }
+    return result;
+}
+
+static BOOL
+validate_version(wchar_t * p)
+{
+    BOOL result = TRUE;
+
+    if (!isdigit(*p))               /* expect major version */
+        result = FALSE;
+    else if (*++p) {                /* more to do */
+        if (*p != L'.')             /* major/minor separator */
+            result = FALSE;
+        else {
+            ++p;
+            if (!isdigit(*p))       /* expect minor version */
+                result = FALSE;
+            else {
+                ++p;
+                if (*p) {           /* more to do */
+                    if (*p != L'-')
+                        result = FALSE;
+                    else {
+                        ++p;
+                        if ((*p != '3') && (*++p != '2') && !*++p)
+                            result = FALSE;
+                    }
+                }
+            }
+        }
+    }
+    return result;
+}
+
+typedef struct {
+    unsigned short min;
+    unsigned short max;
+    wchar_t version[MAX_VERSION_SIZE];
+} PYC_MAGIC;
+
+static PYC_MAGIC magic_values[] = {
+    { 0xc687, 0xc687, L"2.0" },
+    { 0xeb2a, 0xeb2a, L"2.1" },
+    { 0xed2d, 0xed2d, L"2.2" },
+    { 0xf23b, 0xf245, L"2.3" },
+    { 0xf259, 0xf26d, L"2.4" },
+    { 0xf277, 0xf2b3, L"2.5" },
+    { 0xf2c7, 0xf2d1, L"2.6" },
+    { 0xf2db, 0xf303, L"2.7" },
+    { 0x0bb8, 0x0c3b, L"3.0" },
+    { 0x0c45, 0x0c4f, L"3.1" },
+    { 0x0c58, 0x0c6c, L"3.2" },
+    { 0x0c76, 0x0c76, L"3.3" },
+    { 0 }
+};
+
+static INSTALLED_PYTHON *
+find_by_magic(unsigned short magic)
+{
+    INSTALLED_PYTHON * result = NULL;
+    PYC_MAGIC * mp;
+
+    for (mp = magic_values; mp->min; mp++) {
+        if ((magic >= mp->min) && (magic <= mp->max)) {
+            result = locate_python(mp->version);
+            if (result != NULL)
+                break;
+        }
+    }
+    return result;
+}
+
+static void
+maybe_handle_shebang(wchar_t ** argv, wchar_t * cmdline)
+{
+/*
+ * Look for a shebang line in the first argument.  If found
+ * and we spawn a child process, this never returns.  If it
+ * does return then we process the args "normally".
+ *
+ * argv[0] might be a filename with a shebang.
+ */
+    FILE * fp;
+    errno_t rc = _wfopen_s(&fp, *argv, L"rb");
+    unsigned char buffer[BUFSIZE];
+    wchar_t shebang_line[BUFSIZE + 1];
+    size_t read;
+    char *p;
+    char * start;
+    char * shebang_alias = (char *) shebang_line;
+    BOM* bom;
+    int i, j, nchars = 0;
+    int header_len;
+    BOOL is_virt;
+    wchar_t * command;
+    wchar_t * suffix;
+    INSTALLED_PYTHON * ip;
+
+    if (rc == 0) {
+        read = fread(buffer, sizeof(char), BUFSIZE, fp);
+        debug(L"maybe_handle_shebang: read %d bytes\n", read);
+        fclose(fp);
+
+        if ((read >= 4) && (buffer[3] == '\n') && (buffer[2] == '\r')) {
+            ip = find_by_magic((buffer[1] << 8 | buffer[0]) & 0xFFFF);
+            if (ip != NULL) {
+                debug(L"script file is compiled against Python %s\n",
+                      ip->version);
+                invoke_child(ip->executable, NULL, cmdline);
+            }
+        }
+        /* Look for BOM */
+        bom = find_BOM(buffer);
+        if (bom == NULL) {
+            start = buffer;
+            debug(L"maybe_handle_shebang: BOM not found, using UTF-8\n");
+            bom = BOMs; /* points to UTF-8 entry - the default */
+        }
+        else {
+            debug(L"maybe_handle_shebang: BOM found, code page %d\n",
+                  bom->code_page);
+            start = &buffer[bom->length];
+        }
+        p = find_terminator(start, BUFSIZE, bom);
+        /*
+         * If no CR or LF was found in the heading,
+         * we assume it's not a shebang file.
+         */
+        if (p == NULL) {
+            debug(L"maybe_handle_shebang: No line terminator found\n");
+        }
+        else {
+            /*
+             * Found line terminator - parse the shebang.
+             *
+             * Strictly, we don't need to handle UTF-16 anf UTF-32,
+             * since Python itself doesn't.
+             * Never mind, one day it might.
+             */
+            header_len = (int) (p - start);
+            switch(bom->code_page) {
+            case CP_UTF8:
+                nchars = MultiByteToWideChar(bom->code_page,
+                                             0,
+                                             start, header_len, shebang_line,
+                                             BUFSIZE);
+                break;
+            case CP_UTF16BE:
+                if (header_len % 2 != 0) {
+                    debug(L"maybe_handle_shebang: UTF-16BE, but an odd number \
+of bytes: %d\n", header_len);
+                    /* nchars = 0; Not needed - initialised to 0. */
+                }
+                else {
+                    for (i = header_len; i > 0; i -= 2) {
+                        shebang_alias[i - 1] = start[i - 2];
+                        shebang_alias[i - 2] = start[i - 1];
+                    }
+                    nchars = header_len / sizeof(wchar_t);
+                }
+                break;
+            case CP_UTF16LE:
+                if ((header_len % 2) != 0) {
+                    debug(L"UTF-16LE, but an odd number of bytes: %d\n",
+                          header_len);
+                    /* nchars = 0; Not needed - initialised to 0. */
+                }
+                else {
+                    /* no actual conversion needed. */
+                    memcpy(shebang_line, start, header_len);
+                    nchars = header_len / sizeof(wchar_t);
+                }
+                break;
+            case CP_UTF32BE:
+                if (header_len % 4 != 0) {
+                    debug(L"UTF-32BE, but not divisible by 4: %d\n",
+                          header_len);
+                    /* nchars = 0; Not needed - initialised to 0. */
+                }
+                else {
+                    for (i = header_len, j = header_len / 2; i > 0; i -= 4,
+                                                                    j -= 2) {
+                        shebang_alias[j - 1] = start[i - 2];
+                        shebang_alias[j - 2] = start[i - 1];
+                    }
+                    nchars = header_len / sizeof(wchar_t);
+                }
+                break;
+            case CP_UTF32LE:
+                if (header_len % 4 != 0) {
+                    debug(L"UTF-32LE, but not divisible by 4: %d\n",
+                          header_len);
+                    /* nchars = 0; Not needed - initialised to 0. */
+                }
+                else {
+                    for (i = header_len, j = header_len / 2; i > 0; i -= 4,
+                                                                    j -= 2) {
+                        shebang_alias[j - 1] = start[i - 3];
+                        shebang_alias[j - 2] = start[i - 4];
+                    }
+                    nchars = header_len / sizeof(wchar_t);
+                }
+                break;
+            }
+            if (nchars > 0) {
+                shebang_line[--nchars] = L'\0';
+                is_virt = parse_shebang(shebang_line, nchars, &command,
+                                        &suffix);
+                if (command != NULL) {
+                    debug(L"parse_shebang: found command: %s\n", command);
+                    if (!is_virt) {
+                        invoke_child(command, suffix, cmdline);
+                    }
+                    else {
+                        suffix = wcschr(command, L' ');
+                        if (suffix != NULL) {
+                            *suffix++ = L'\0';
+                            suffix = skip_whitespace(suffix);
+                        }
+                        if (wcsncmp(command, L"python", 6))
+                            error(RC_BAD_VIRTUAL_PATH, L"Unknown virtual \
+path '%s'", command);
+                        command += 6;   /* skip past "python" */
+                        if (*command && !validate_version(command))
+                            error(RC_BAD_VIRTUAL_PATH, L"Invalid version \
+specification: '%s'.\nIn the first line of the script, 'python' needs to be \
+followed by a valid version specifier.\nPlease check the documentation.",
+                                  command);
+                        /* TODO could call validate_version(command) */
+                        ip = locate_python(command);
+                        if (ip == NULL) {
+                            error(RC_NO_PYTHON, L"Requested Python version \
+(%s) is not installed", command);
+                        }
+                        else {
+                            invoke_child(ip->executable, suffix, cmdline);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+static wchar_t *
+skip_me(wchar_t * cmdline)
+{
+    BOOL quoted;
+    wchar_t c;
+    wchar_t * result = cmdline;
+
+    quoted = cmdline[0] == L'\"';
+    if (!quoted)
+        c = L' ';
+    else {
+        c = L'\"';
+        ++result;
+    }
+    result = wcschr(result, c);
+    if (result == NULL) /* when, for example, just exe name on command line */
+        result = L"";
+    else {
+        ++result; /* skip past space or closing quote */
+        result = skip_whitespace(result);
+    }
+    return result;
+}
+
+static DWORD version_high = 0;
+static DWORD version_low = 0;
+
+static void
+get_version_info(wchar_t * version_text, size_t size)
+{
+    WORD maj, min, rel, bld;
+
+    if (!version_high && !version_low)
+        wcsncpy_s(version_text, size, L"0.1", _TRUNCATE);   /* fallback */
+    else {
+        maj = HIWORD(version_high);
+        min = LOWORD(version_high);
+        rel = HIWORD(version_low);
+        bld = LOWORD(version_low);
+        _snwprintf_s(version_text, size, _TRUNCATE, L"%d.%d.%d.%d", maj,
+                     min, rel, bld);
+    }
+}
+
+static int
+process(int argc, wchar_t ** argv)
+{
+    wchar_t * wp;
+    wchar_t * command;
+    wchar_t * p;
+    int rc = 0;
+    size_t plen;
+    INSTALLED_PYTHON * ip;
+    BOOL valid;
+    DWORD size, attrs;
+    HRESULT hr;
+    wchar_t message[MSGSIZE];
+    wchar_t version_text [MAX_PATH];
+    void * version_data;
+    VS_FIXEDFILEINFO * file_info;
+    UINT block_size;
+
+    wp = get_env(L"PYLAUNCH_DEBUG");
+    if ((wp != NULL) && (*wp != L'\0'))
+        log_fp = stderr;
+
+#if defined(_M_X64)
+    debug(L"launcher build: 64bit\n");
+#else
+    debug(L"launcher build: 32bit\n");
+#endif
+#if defined(_WINDOWS)
+    debug(L"launcher executable: Windows\n");
+#else
+    debug(L"launcher executable: Console\n");
+#endif
+    /* Get the local appdata folder (non-roaming) */
+    hr = SHGetFolderPathW(NULL, CSIDL_LOCAL_APPDATA,
+                          NULL, 0, appdata_ini_path);
+    if (hr != S_OK) {
+        debug(L"SHGetFolderPath failed: %X\n", hr);
+        appdata_ini_path[0] = L'\0';
+    }
+    else {
+        plen = wcslen(appdata_ini_path);
+        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 '%s' non-existent\n", appdata_ini_path);
+            appdata_ini_path[0] = L'\0';
+        } else {
+            debug(L"Using local configuration file '%s'\n", appdata_ini_path);
+        }
+    }
+    plen = GetModuleFileNameW(NULL, launcher_ini_path, MAX_PATH);
+    size = GetFileVersionInfoSizeW(launcher_ini_path, &size);
+    if (size == 0) {
+        winerror(GetLastError(), message, MSGSIZE);
+        debug(L"GetFileVersionInfoSize failed: %s\n", message);
+    }
+    else {
+        version_data = malloc(size);
+        if (version_data) {
+            valid = GetFileVersionInfoW(launcher_ini_path, 0, size,
+                                        version_data);
+            if (!valid)
+                debug(L"GetFileVersionInfo failed: %X\n", GetLastError());
+            else {
+                valid = VerQueryValueW(version_data, L"\\", &file_info,
+                                       &block_size);
+                if (!valid)
+                    debug(L"VerQueryValue failed: %X\n", GetLastError());
+                else {
+                    version_high = file_info->dwFileVersionMS;
+                    version_low = file_info->dwFileVersionLS;
+                }
+            }
+            free(version_data);
+        }
+    }
+    p = wcsrchr(launcher_ini_path, L'\\');
+    if (p == NULL) {
+        debug(L"GetModuleFileNameW returned value has no backslash: %s\n",
+              launcher_ini_path);
+        launcher_ini_path[0] = L'\0';
+    }
+    else {
+        wcsncpy_s(p, MAX_PATH - (p - launcher_ini_path), L"\\py.ini",
+                  _TRUNCATE);
+        attrs = GetFileAttributesW(launcher_ini_path);
+        if (attrs == INVALID_FILE_ATTRIBUTES) {
+            debug(L"File '%s' non-existent\n", launcher_ini_path);
+            launcher_ini_path[0] = L'\0';
+        } else {
+            debug(L"Using global configuration file '%s'\n", launcher_ini_path);
+        }
+    }
+
+    command = skip_me(GetCommandLineW());
+    debug(L"Called with command line: %s", command);
+    if (argc <= 1) {
+        valid = FALSE;
+        p = NULL;
+    }
+    else {
+        p = argv[1];
+        plen = wcslen(p);
+        if (p[0] != L'-') {
+            read_commands();
+            maybe_handle_shebang(&argv[1], command);
+        }
+        /* No file with shebang, or an unrecognised shebang.
+         * Is the first arg a special version qualifier?
+         */
+        valid = (*p == L'-') && validate_version(&p[1]);
+        if (valid) {
+            ip = locate_python(&p[1]);
+            if (ip == NULL)
+                error(RC_NO_PYTHON, L"Requested Python version (%s) not \
+installed", &p[1]);
+            command += wcslen(p);
+            command = skip_whitespace(command);
+        }
+    }
+    if (!valid) {
+        ip = locate_python(L"");
+        if (ip == NULL)
+            error(RC_NO_PYTHON, L"Can't find a default Python.");
+        if ((argc == 2) && (!_wcsicmp(p, L"-h") || !_wcsicmp(p, L"--help"))) {
+#if defined(_M_X64)
+            BOOL canDo64bit = TRUE;
+#else
+    // If we are a 32bit process on a 64bit Windows, first hit the 64bit keys.
+            BOOL canDo64bit = FALSE;
+            IsWow64Process(GetCurrentProcess(), &canDo64bit);
+#endif
+
+            get_version_info(version_text, MAX_PATH);
+            fwprintf(stdout, L"\
+Python Launcher for Windows Version %s\n\n", version_text);
+            fwprintf(stdout, L"\
+usage: %s [ launcher-arguments ] script [ script-arguments ]\n\n", argv[0]);
+            fputws(L"\
+Launcher arguments:\n\n\
+-2     : Launch the latest Python 2.x version\n\
+-3     : Launch the latest Python 3.x version\n\
+-X.Y   : Launch the specified Python version\n", stdout);
+            if (canDo64bit) {
+                fputws(L"\
+-X.Y-32: Launch the specified 32bit Python version", stdout);
+            }
+            fputws(L"\n\nThe following help text is from Python:\n\n", stdout);
+            fflush(stdout);
+        }
+    }
+    invoke_child(ip->executable, NULL, command);
+    return rc;
+}
+
+#if defined(_WINDOWS)
+
+int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
+                   LPWSTR lpstrCmd, int nShow)
+{
+    return process(__argc, __wargv);
+}
+
+#else
+
+int cdecl wmain(int argc, wchar_t ** argv)
+{
+    return process(argc, argv);
+}
+
+#endif
\ No newline at end of file