Staging
v0.5.1
https://github.com/python/cpython
Revision f4d644f36ffb6cb11b34bfcf533c14cfaebf709a authored by Gregory P. Smith on 30 January 2018, 05:27:39 UTC, committed by GitHub on 30 January 2018, 05:27:39 UTC
Do not allow receiving a SIGINT to cause the subprocess module to trigger an
immediate SIGKILL of the child process.  SIGINT is normally sent to all child
processes by the OS at the same time already as was the established normal
behavior in 2.7 and 3.2.  This behavior change was introduced during the fix to https://bugs.python.org/issue12494 and is generally surprising to command line
tool users who expect other tools launched in child processes to get their own
SIGINT and do their own cleanup.

In Python 3.3-3.6 subprocess.call and subprocess.run would immediately
SIGKILL the child process upon receiving a SIGINT (which raises a
KeyboardInterrupt).  We now give the child a small amount of time to
exit gracefully before resorting to a SIGKILL.

This is also the case for subprocess.Popen.__exit__ which would
previously block indefinitely waiting for the child to die.  This was
hidden from many users by virtue of subprocess.call and subprocess.run
sending the signal immediately.

Behavior change: subprocess.Popen.__exit__ will not block indefinitely
when the exiting exception is a KeyboardInterrupt.  This is done for
user friendliness as people expect their ^C to actually happen.  This
could cause occasional orphaned Popen objects when not using `call` or
`run` with a child process that hasn't exited.

Refactoring involved: The Popen.wait method deals with the
KeyboardInterrupt second chance, existing platform specific internals
have been renamed to _wait().
Also fixes comment typos.
1 parent 83e64c8
Raw File
Tip revision: f4d644f36ffb6cb11b34bfcf533c14cfaebf709a authored by Gregory P. Smith on 30 January 2018, 05:27:39 UTC
bpo-25942: make subprocess more graceful on ^C (GH-5026)
Tip revision: f4d644f
launcher.c
/*
 * Copyright (C) 2011-2013 Vinay Sajip.
 * Licensed to PSF under a contributor agreement.
 *
 * 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

/* Error codes */

#define RC_NO_STD_HANDLES   100
#define RC_CREATE_PROCESS   101
#define RC_BAD_VIRTUAL_PATH 102
#define RC_NO_PYTHON        103
#define RC_NO_MEMORY        104
/*
 * SCRIPT_WRAPPER is used to choose between two 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
 * with the appropriate Python interpreter.
 *
 * SCRIPT_WRAPPER should be undefined in the source, and defined in a VS project
 * which builds the setuptools-style launcher.
 */
#if defined(SCRIPT_WRAPPER)
#define RC_NO_SCRIPT        105
#endif

/* 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;
}

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": %ls",
                         win_message);
        }
    }

#if !defined(_WINDOWS)
    fwprintf(stderr, L"%ls\n", message);
#else
    MessageBox(NULL, message, TEXT("Python Launcher is sorry to say ..."),
               MB_OK);
#endif
    exit(rc);
}

/*
 * This function is here to simplify memory management
 * and to treat blank values as if they are absent.
 */
static wchar_t * get_env(wchar_t * key)
{
    /* This is not thread-safe, just like getenv */
    static wchar_t buf[BUFSIZE];
    DWORD result = GetEnvironmentVariableW(key, buf, BUFSIZE);

    if (result >= BUFSIZE) {
        /* Large environment variable. Accept some leakage */
        wchar_t *buf2 = (wchar_t*)malloc(sizeof(wchar_t) * (result+1));
        if (buf2 == NULL) {
            error(RC_NO_MEMORY, L"Could not allocate environment buffer");
        }
        GetEnvironmentVariableW(key, buf2, result);
        return buf2;
    }

    if (result == 0)
        /* Either some error, e.g. ERROR_ENVVAR_NOT_FOUND,
           or an empty environment variable. */
        return NULL;

    return buf;
}

#if defined(_WINDOWS)

#define PYTHON_EXECUTABLE L"pythonw.exe"

#else

#define PYTHON_EXECUTABLE L"python.exe"

#endif

#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
 * The version name can be longer than MAX_VERSION_SIZE, but will be
 * truncated to just X.Y for comparisons.
 */
#define IP_BASE_SIZE 40
#define IP_VERSION_SIZE 8
#define IP_SIZE (IP_BASE_SIZE + IP_VERSION_SIZE)
#define CORE_PATH L"SOFTWARE\\Python\\PythonCore"

static wchar_t * location_checks[] = {
    L"\\",
    L"\\PCbuild\\win32\\",
    L"\\PCbuild\\amd64\\",
    /* To support early 32bit versions of Python that stuck the build binaries
    * directly in PCbuild... */
    L"\\PCbuild\\",
    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_version[IP_VERSION_SIZE];
    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 %ls\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, IP_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 %ls: %ls\n",
                          ip_version, message);
                }
                break;
            }
            else {
                wcsncpy_s(ip->version, MAX_VERSION_SIZE, ip_version,
                          MAX_VERSION_SIZE-1);
                _snwprintf_s(ip_path, IP_SIZE, _TRUNCATE,
                             L"%ls\\%ls\\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"%ls\\%ls: %ls", key_name, ip_path, message);
                    continue;
                }
                data_size = sizeof(ip->executable) - 1;
                status = RegQueryValueExW(ip_key, NULL, NULL, &type,
                                          (LPBYTE)ip->executable, &data_size);
                RegCloseKey(ip_key);
                if (status != ERROR_SUCCESS) {
                    winerror(status, message, MSGSIZE);
                    debug(L"%ls\\%ls: %ls\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"%ls%ls", check, PYTHON_EXECUTABLE);
                        attrs = GetFileAttributesW(ip->executable);
                        if (attrs == INVALID_FILE_ATTRIBUTES) {
                            winerror(GetLastError(), message, MSGSIZE);
                            debug(L"locate_pythons_for_key: %ls: %ls",
                                  ip->executable, message);
                        }
                        else if (attrs & FILE_ATTRIBUTE_DIRECTORY) {
                            debug(L"locate_pythons_for_key: '%ls' is a \
directory\n",
                                  ip->executable, attrs);
                        }
                        else if (find_existing_python(ip->executable)) {
                            debug(L"locate_pythons_for_key: %ls: already \
found\n", ip->executable);
                        }
                        else {
                            /* check the executable type. */
                            ok = GetBinaryTypeW(ip->executable, &attrs);
                            if (!ok) {
                                debug(L"Failure getting binary type: %ls\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: %ls: \
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: %ls \
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;
        wlen -= wcslen(L"-32");
    }
    else if (wcsstr(wanted_ver, L"-64")) { /* Added option to select 64 bit explicitly */
        bits = 64;
        wlen -= wcslen(L"-64");
    }
    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 *
find_python_by_venv()
{
    static wchar_t venv_python[MAX_PATH];
    wchar_t *virtual_env = get_env(L"VIRTUAL_ENV");
    DWORD attrs;

    /* Check for VIRTUAL_ENV environment variable */
    if (virtual_env == NULL || virtual_env[0] == L'\0') {
        return NULL;
    }

    /* Check for a python executable in the venv */
    debug(L"Checking for Python executable in virtual env '%ls'\n", virtual_env);
    _snwprintf_s(venv_python, MAX_PATH, _TRUNCATE,
            L"%ls\\Scripts\\%ls", virtual_env, PYTHON_EXECUTABLE);
    attrs = GetFileAttributesW(venv_python);
    if (attrs == INVALID_FILE_ATTRIBUTES) {
        debug(L"Python executable %ls missing from virtual env\n", venv_python);
        return NULL;
    }

    return venv_python;
}

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_%ls", 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 '%ls=%ls' in %ls\n",
              key, result, found_in ? found_in : L"(unknown)");
    } else {
        debug(L"found no configured value for '%ls'\n", key);
    }
    return result;
}

static INSTALLED_PYTHON *
locate_python(wchar_t * wanted_ver, BOOL from_shebang)
{
    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 '%ls' found ", wanted_ver);
        if (result) {
            debug(L"'%ls'\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);
        /* Not found a value yet - try by major version.
         * If we're looking for an interpreter specified in a shebang line,
         * we want to try Python 2 first, then Python 3 (for Unix and backward
         * compatibility). If we're being called interactively, assume the user
         * wants the latest version available, so try Python 3 first, then
         * Python 2.
         */
        if (result == NULL)
            result = find_python_by_version(from_shebang ? L"2" : L"3");
        if (result == NULL)
            result = find_python_by_version(from_shebang ? L"3" : L"2");
        debug(L"search for default Python found ");
        if (result) {
            debug(L"version %ls at '%ls'\n",
                  result->version, result->executable);
        } else {
            debug(L"no interpreter\n");
        }
    }
    return result;
}

#if defined(SCRIPT_WRAPPER)
/*
 * Check for a script located alongside the executable
 */

#if defined(_WINDOWS)
#define SCRIPT_SUFFIX L"-script.pyw"
#else
#define SCRIPT_SUFFIX L"-script.py"
#endif

static wchar_t wrapped_script_path[MAX_PATH];

/* Locate the script being wrapped.
 *
 * This code should store the name of the wrapped script in
 * wrapped_script_path, or terminate the program with an error if there is no
 * valid wrapped script file.
 */
static void
locate_wrapped_script()
{
    wchar_t * p;
    size_t plen;
    DWORD attrs;

    plen = GetModuleFileNameW(NULL, wrapped_script_path, MAX_PATH);
    p = wcsrchr(wrapped_script_path, L'.');
    if (p == NULL) {
        debug(L"GetModuleFileNameW returned value has no extension: %ls\n",
              wrapped_script_path);
        error(RC_NO_SCRIPT, L"Wrapper name '%ls' is not valid.", wrapped_script_path);
    }

    wcsncpy_s(p, MAX_PATH - (p - wrapped_script_path) + 1, SCRIPT_SUFFIX, _TRUNCATE);
    attrs = GetFileAttributesW(wrapped_script_path);
    if (attrs == INVALID_FILE_ATTRIBUTES) {
        debug(L"File '%ls' non-existent\n", wrapped_script_path);
        error(RC_NO_SCRIPT, L"Script file '%ls' is not present.", wrapped_script_path);
    }

    debug(L"Using wrapped script file '%ls'\n", wrapped_script_path);
}
#endif

/*
 * 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;

#if defined(_WINDOWS)
    /*
    When explorer launches a Windows (GUI) application, it displays
    the "app starting" (the "pointer + hourglass") cursor for a number
    of seconds, or until the app does something UI-ish (eg, creating a
    window, or fetching a message).  As this launcher doesn't do this
    directly, that cursor remains even after the child process does these
    things.  We avoid that by doing a simple post+get message.
    See http://bugs.python.org/issue17290 and
    https://bitbucket.org/vinay.sajip/pylauncher/issue/20/busy-cursor-for-a-long-time-when-running
    */
    MSG msg;

    PostMessage(0, 0, 0, 0);
    GetMessage(&msg, 0, 0, 0);
#endif

    debug(L"run_child: about to run '%ls'\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 '%ls'", cmdline);
    AssignProcessToJobObject(job, pi.hProcess);
    CloseHandle(pi.hThread);
    WaitForSingleObjectEx(pi.hProcess, INFINITE, FALSE);
    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);
    exit(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"%ls %ls",
                         executable, cmdline);
        else
            _snwprintf_s(child_command, child_command_size,
                         child_command_size - 1, L"%ls %ls %ls",
                         executable, suffix, cmdline);
        run_child(child_command);
        free(child_command);
    }
}

typedef struct {
    wchar_t *shebang;
    BOOL search;
} SHEBANG;

static SHEBANG builtin_virtual_paths [] = {
    { L"/usr/bin/env python", TRUE },
    { L"/usr/bin/python", FALSE },
    { L"/usr/local/bin/python", FALSE },
    { L"python", FALSE },
    { NULL, FALSE },
};

/* 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 %ls = '%ls': 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: %ls: 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: %ls: not enough space for %ls\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 *search)
{
    BOOL rc = FALSE;
    SHEBANG * 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;
    *search = FALSE;

    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->shebang; ++vpp) {
                plen = wcslen(vpp->shebang);
                if (wcsncmp(shebang_line, vpp->shebang, plen) == 0) {
                    rc = TRUE;
                    *search = vpp->search;
                    /* We can do this because all builtin commands contain
                     * "python".
                     */
                    *command = wcsstr(shebang_line, L"python");
                    break;
                }
            }
            if (vpp->shebang == NULL) {
                /*
                 * Not found in builtins - look in customized commands.
                 *
                 * We can't permanently modify the shebang line in case
                 * it's not a customized 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 and 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 */
    /* Test UTF-32LE before UTF-16LE since UTF-16LE BOM is a prefix
     * of UTF-32LE BOM. */
    { 4, { 0xFF, 0xFE, 0x00, 0x00 }, CP_UTF32LE },  /* UTF-32LE */
    { 4, { 0x00, 0x00, 0xFE, 0xFF }, CP_UTF32BE },  /* UTF-32BE */
    { 2, { 0xFF, 0xFE }, CP_UTF16LE },              /* UTF-16LE */
    { 2, { 0xFE, 0xFF }, CP_UTF16BE },              /* UTF-16BE */
    { 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)
{
    /*
    Version information should start with one of 2 or 3,
    Optionally followed by a period and a minor version,
    Optionally followed by a minus and one of 32 or 64.
    Valid examples:
      2
      3
      2.7
      3.6
      2.7-32
      The intent is to add to the valid patterns:
      3.10
      3-32
      3.6-64
      3-64
    */
    BOOL result = (p != NULL); /* Default to False if null pointer. */

    result = result && iswdigit(*p);  /* Result = False if fist string element is not a digit. */

    while (result && iswdigit(*p))   /* Require a major version */
        ++p;  /* Skip all leading digit(s) */
    if (result && (*p == L'.'))     /* Allow . for major minor separator.*/
    {
        result = iswdigit(*++p);     /* Must be at least one digit */
        while (result && iswdigit(*++p)) ; /* Skip any more Digits */
    }
    if (result && (*p == L'-')) {   /* Allow - for Bits Separator */
        switch(*++p){
        case L'3':                            /* 3 is OK */
            result = (*++p == L'2') && !*++p; /* only if followed by 2 and ended.*/
            break;
        case L'6':                            /* 6 is OK */
            result = (*++p == L'4') && !*++p; /* only if followed by 4 and ended.*/
            break;
        default:
            result = FALSE;
            break;
        }
    }
    result = result && !*p; /* Must have reached EOS */
    return result;

}

typedef struct {
    unsigned short min;
    unsigned short max;
    wchar_t version[MAX_VERSION_SIZE];
} PYC_MAGIC;

static PYC_MAGIC magic_values[] = {
    { 50823, 50823, L"2.0" },
    { 60202, 60202, L"2.1" },
    { 60717, 60717, L"2.2" },
    { 62011, 62021, L"2.3" },
    { 62041, 62061, L"2.4" },
    { 62071, 62131, L"2.5" },
    { 62151, 62161, L"2.6" },
    { 62171, 62211, L"2.7" },
    { 3000, 3131, L"3.0" },
    { 3141, 3151, L"3.1" },
    { 3160, 3180, L"3.2" },
    { 3190, 3230, L"3.3" },
    { 3250, 3310, L"3.4" },
    { 3320, 3351, L"3.5" },
    { 3360, 3379, L"3.6" },
    { 3390, 3399, L"3.7" },
    { 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, FALSE);
            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");
    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;
    BOOL search;
    wchar_t * command;
    wchar_t * suffix;
    COMMAND *cmd = NULL;
    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((((unsigned char)buffer[1]) << 8 |
                                (unsigned char)buffer[0]) & 0xFFFF);
            if (ip != NULL) {
                debug(L"script file is compiled against Python %ls\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, &search);
                if (command != NULL) {
                    debug(L"parse_shebang: found command: %ls\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 '%ls'", command);
                        command += 6;   /* skip past "python" */
                        if (search && ((*command == L'\0') || isspace(*command))) {
                            /* Command is eligible for path search, and there
                             * is no version specification.
                             */
                            debug(L"searching PATH for python executable\n");
                            cmd = find_on_path(PYTHON_EXECUTABLE);
                            debug(L"Python on path: %ls\n", cmd ? cmd->value : L"<not found>");
                            if (cmd) {
                                debug(L"located python on PATH: %ls\n", cmd->value);
                                invoke_child(cmd->value, suffix, cmdline);
                                /* Exit here, as we have found the command */
                                return;
                            }
                            /* FALL THROUGH: No python found on PATH, so fall
                             * back to locating the correct installed python.
                             */
                        }
                        if (*command && !validate_version(command))
                            error(RC_BAD_VIRTUAL_PATH, L"Invalid version \
specification: '%ls'.\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, TRUE);
                        if (ip == NULL) {
                            error(RC_NO_PYTHON, L"Requested Python version \
(%ls) 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 void
show_help_text(wchar_t ** argv)
{
    wchar_t version_text [MAX_PATH];
#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 %ls\n\n", version_text);
    fwprintf(stdout, L"\
usage:\n\
%ls [launcher-args] [python-args] script [script-args]\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"\
     The above all default to 64 bit if a matching 64 bit python is present.\n\
-X.Y-32: Launch the specified 32bit Python version\n\
-X-32  : Launch the latest 32bit Python X version\n\
-X.Y-64: Launch the specified 64bit Python version\n\
-X-64  : Launch the latest 64bit Python X version", stdout);
    }
    fputws(L"\n-0  --list       : List the available pythons", stdout);
    fputws(L"\n-0p --list-paths : List with paths", stdout);
    fputws(L"\n\nThe following help text is from Python:\n\n", stdout);
    fflush(stdout);
}

static BOOL
show_python_list(wchar_t ** argv)
{
    /*
     * Display options -0
     */
    INSTALLED_PYTHON * result = NULL;
    INSTALLED_PYTHON * ip = installed_pythons; /* List of installed pythons */
    INSTALLED_PYTHON * defpy = locate_python(L"", FALSE);
    size_t i = 0;
    wchar_t *p = argv[1];
    wchar_t *fmt = L"\n -%ls-%d"; /* print VER-BITS */
    wchar_t *defind = L" *"; /* Default indicator */

    /*
    * Output informational messages to stderr to keep output
    * clean for use in pipes, etc.
    */
    fwprintf(stderr,
             L"Installed Pythons found by %s Launcher for Windows", argv[0]);
    if (!_wcsicmp(p, L"-0p") || !_wcsicmp(p, L"--list-paths")) /* Show path? */
        fmt = L"\n -%ls-%d\t%ls"; /* print VER-BITS path */

    if (num_installed_pythons == 0) /* We have somehow got here without searching for pythons */
        locate_all_pythons(); /* Find them, Populates installed_pythons */

    if (num_installed_pythons == 0) /* No pythons found */
        fwprintf(stderr, L"\nNo Installed Pythons Found!");
    else
    {
        for (i = 0; i < num_installed_pythons; i++, ip++) {
            fwprintf(stdout, fmt, ip->version, ip->bits, ip->executable);
            /* If there is a default indicate it */
            if ((defpy != NULL) && !_wcsicmp(ip->executable, defpy->executable))
                fwprintf(stderr, defind);
        }
    }

    if ((defpy == NULL) && (num_installed_pythons > 0))
        /* We have pythons but none is the default */
        fwprintf(stderr, L"\n\nCan't find a Default Python.\n\n");
    else
        fwprintf(stderr, L"\n\n"); /* End with a blank line */
    return(FALSE); /* If this has been called we cannot continue */
}

static int
process(int argc, wchar_t ** argv)
{
    wchar_t * wp;
    wchar_t * command;
    wchar_t * executable;
    wchar_t * p;
    int rc = 0;
    size_t plen;
    size_t slen;
    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(SCRIPT_WRAPPER)
    int newlen;
    wchar_t * newcommand;
    wchar_t * av[2];
#endif

    setvbuf(stderr, (char *)NULL, _IONBF, 0);
    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 '%ls' non-existent\n", appdata_ini_path);
            appdata_ini_path[0] = L'\0';
        } else {
            debug(L"Using local configuration file '%ls'\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: %ls\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"\\",
                                       (LPVOID *) &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: %ls\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 '%ls' non-existent\n", launcher_ini_path);
            launcher_ini_path[0] = L'\0';
        } else {
            debug(L"Using global configuration file '%ls'\n", launcher_ini_path);
        }
    }

    command = skip_me(GetCommandLineW());
    debug(L"Called with command line: %ls\n", command);

#if defined(SCRIPT_WRAPPER)
    /* The launcher is being used in "script wrapper" mode.
     * There should therefore be a Python script named <exename>-script.py in
     * the same directory as the launcher executable.
     * Put the script name into argv as the first (script name) argument.
     */

    /* Get the wrapped script name - if the script is not present, this will
     * terminate the program with an error.
     */
    locate_wrapped_script();

    /* Add the wrapped script to the start of command */
    newlen = wcslen(wrapped_script_path) + wcslen(command) + 2; /* ' ' + NUL */
    newcommand = malloc(sizeof(wchar_t) * newlen);
    if (!newcommand) {
        error(RC_NO_MEMORY, L"Could not allocate new command line");
    }
    else {
        wcscpy_s(newcommand, newlen, wrapped_script_path);
        wcscat_s(newcommand, newlen, L" ");
        wcscat_s(newcommand, newlen, command);
        debug(L"Running wrapped script with command line '%ls'\n", newcommand);
        read_commands();
        av[0] = wrapped_script_path;
        av[1] = NULL;
        maybe_handle_shebang(av, newcommand);
        /* Returns if no shebang line - pass to default processing */
        command = newcommand;
        valid = FALSE;
    }
#else
    if (argc <= 1) {
        valid = FALSE;
        p = NULL;
    }
    else {
        p = argv[1];
        plen = wcslen(p);
        if (argc == 2) {
            slen = wcslen(L"-0");
            if(!wcsncmp(p, L"-0", slen)) /* Starts with -0 */
                valid = show_python_list(argv); /* Check for -0 FIRST */
        }
        valid = valid && (*p == L'-') && validate_version(&p[1]);
        if (valid) {
            ip = locate_python(&p[1], FALSE);
            if (ip == NULL)
            {
                fwprintf(stdout, \
                         L"Python %ls not found!\n", &p[1]);
                valid = show_python_list(argv);
                error(RC_NO_PYTHON, L"Requested Python version (%ls) not \
installed, use -0 for available pythons", &p[1]);
            }
            executable = ip->executable;
            command += wcslen(p);
            command = skip_whitespace(command);
        }
        else {
            for (index = 1; index < argc; ++index) {
                if (*argv[index] != L'-')
                    break;
            }
            if (index < argc) {
                read_commands();
                maybe_handle_shebang(&argv[index], command);
            }
        }
    }
#endif

    if (!valid) {
        if ((argc == 2) && (!_wcsicmp(p, L"-h") || !_wcsicmp(p, L"--help")))
            show_help_text(argv);
        if ((argc == 2) && (!_wcsicmp(p, L"-0") || !_wcsicmp(p, L"-0p")))
            executable = NULL; /* Info call only */
        else
        {
            /* Look for an active virtualenv */
            executable = find_python_by_venv();

            /* If we didn't find one, look for the default Python */
            if (executable == NULL) {
                ip = locate_python(L"", FALSE);
                if (ip == NULL)
                    error(RC_NO_PYTHON, L"Can't find a default Python.");
                executable = ip->executable;
            }
        }
    }
    if (executable != NULL)
        invoke_child(executable, NULL, command);
    else
        rc = RC_NO_PYTHON;
    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
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