_winapi.c

/*
 * Support routines from the Windows API
 *
 * This module was originally created by merging PC/_subprocess.c with
 * Modules/_multiprocessing/win32_functions.c.
 *
 * Copyright (c) 2004 by Fredrik Lundh <fredrik@pythonware.com>
 * Copyright (c) 2004 by Secret Labs AB, http://www.pythonware.com
 * Copyright (c) 2004 by Peter Astrand <astrand@lysator.liu.se>
 *
 * By obtaining, using, and/or copying this software and/or its
 * associated documentation, you agree that you have read, understood,
 * and will comply with the following terms and conditions:
 *
 * Permission to use, copy, modify, and distribute this software and
 * its associated documentation for any purpose and without fee is
 * hereby granted, provided that the above copyright notice appears in
 * all copies, and that both that copyright notice and this permission
 * notice appear in supporting documentation, and that the name of the
 * authors not be used in advertising or publicity pertaining to
 * distribution of the software without specific, written prior
 * permission.
 *
 * THE AUTHORS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
 * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 */

/* Licensed to PSF under a Contributor Agreement. */
/* See https://www.python.org/2.4/license for licensing details. */

#include "Python.h"
#include "pycore_moduleobject.h"  // _PyModule_GetState()
#include "pycore_pylifecycle.h"   // _Py_IsInterpreterFinalizing()
#include "pycore_pystate.h"       // _PyInterpreterState_GET



#ifndef WINDOWS_LEAN_AND_MEAN
#define WINDOWS_LEAN_AND_MEAN
#endif
#include "windows.h"
#include <winioctl.h>
#include <crtdbg.h>
#include "winreparse.h"

#if defined(MS_WIN32) && !defined(MS_WIN64)
#define HANDLE_TO_PYNUM(handle) \
    PyLong_FromUnsignedLong((unsigned long) handle)
#define PYNUM_TO_HANDLE(obj) ((HANDLE)PyLong_AsUnsignedLong(obj))
#define F_POINTER "k"
#define T_POINTER Py_T_ULONG
#else
#define HANDLE_TO_PYNUM(handle) \
    PyLong_FromUnsignedLongLong((unsigned long long) handle)
#define PYNUM_TO_HANDLE(obj) ((HANDLE)PyLong_AsUnsignedLongLong(obj))
#define F_POINTER "K"
#define T_POINTER Py_T_ULONGLONG
#endif

#define F_HANDLE F_POINTER
#define F_DWORD "k"

#define T_HANDLE T_POINTER

// winbase.h limits the STARTF_* flags to the desktop API as of 10.0.19041.
#ifndef STARTF_USESHOWWINDOW
#define STARTF_USESHOWWINDOW 0x00000001
#endif
#ifndef STARTF_USESIZE
#define STARTF_USESIZE 0x00000002
#endif
#ifndef STARTF_USEPOSITION
#define STARTF_USEPOSITION 0x00000004
#endif
#ifndef STARTF_USECOUNTCHARS
#define STARTF_USECOUNTCHARS 0x00000008
#endif
#ifndef STARTF_USEFILLATTRIBUTE
#define STARTF_USEFILLATTRIBUTE 0x00000010
#endif
#ifndef STARTF_RUNFULLSCREEN
#define STARTF_RUNFULLSCREEN 0x00000020
#endif
#ifndef STARTF_FORCEONFEEDBACK
#define STARTF_FORCEONFEEDBACK 0x00000040
#endif
#ifndef STARTF_FORCEOFFFEEDBACK
#define STARTF_FORCEOFFFEEDBACK 0x00000080
#endif
#ifndef STARTF_USESTDHANDLES
#define STARTF_USESTDHANDLES 0x00000100
#endif
#ifndef STARTF_USEHOTKEY
#define STARTF_USEHOTKEY 0x00000200
#endif
#ifndef STARTF_TITLEISLINKNAME
#define STARTF_TITLEISLINKNAME 0x00000800
#endif
#ifndef STARTF_TITLEISAPPID
#define STARTF_TITLEISAPPID 0x00001000
#endif
#ifndef STARTF_PREVENTPINNING
#define STARTF_PREVENTPINNING 0x00002000
#endif
#ifndef STARTF_UNTRUSTEDSOURCE
#define STARTF_UNTRUSTEDSOURCE 0x00008000
#endif

typedef struct {
    PyTypeObject *overlapped_type;
} WinApiState;

static inline WinApiState*
winapi_get_state(PyObject *module)
{
    void *state = _PyModule_GetState(module);
    assert(state != NULL);
    return (WinApiState *)state;
}

/*
 * A Python object wrapping an OVERLAPPED structure and other useful data
 * for overlapped I/O
 */

typedef struct {
    PyObject_HEAD
    OVERLAPPED overlapped;
    /* For convenience, we store the file handle too */
    HANDLE handle;
    /* Whether there's I/O in flight */
    int pending;
    /* Whether I/O completed successfully */
    int completed;
    /* Buffer used for reading (optional) */
    PyObject *read_buffer;
    /* Buffer used for writing (optional) */
    Py_buffer write_buffer;
} OverlappedObject;

/*
Note: tp_clear (overlapped_clear) is not implemented because it
requires cancelling the IO operation if it's pending and the cancellation is
quite complex and can fail (see: overlapped_dealloc).
*/
static int
overlapped_traverse(OverlappedObject *self, visitproc visit, void *arg)
{
    Py_VISIT(self->read_buffer);
    Py_VISIT(self->write_buffer.obj);
    Py_VISIT(Py_TYPE(self));
    return 0;
}

static void
overlapped_dealloc(OverlappedObject *self)
{
    DWORD bytes;
    int err = GetLastError();

    PyObject_GC_UnTrack(self);
    if (self->pending) {
        if (CancelIoEx(self->handle, &self->overlapped) &&
            GetOverlappedResult(self->handle, &self->overlapped, &bytes, TRUE))
        {
            /* The operation is no longer pending -- nothing to do. */
        }
        else if (_Py_IsInterpreterFinalizing(_PyInterpreterState_GET()))
        {
            /* The operation is still pending -- give a warning.  This
               will probably only happen on Windows XP. */
            PyErr_SetString(PyExc_PythonFinalizationError,
                            "I/O operations still in flight while destroying "
                            "Overlapped object, the process may crash");
            PyErr_WriteUnraisable(NULL);
        }
        else
        {
            /* The operation is still pending, but the process is
               probably about to exit, so we need not worry too much
               about memory leaks.  Leaking self prevents a potential
               crash.  This can happen when a daemon thread is cleaned
               up at exit -- see #19565.  We only expect to get here
               on Windows XP. */
            CloseHandle(self->overlapped.hEvent);
            SetLastError(err);
            return;
        }
    }

    CloseHandle(self->overlapped.hEvent);
    SetLastError(err);
    if (self->write_buffer.obj)
        PyBuffer_Release(&self->write_buffer);
    Py_CLEAR(self->read_buffer);
    PyTypeObject *tp = Py_TYPE(self);
    tp->tp_free(self);
    Py_DECREF(tp);
}

/*[clinic input]
module _winapi
class _winapi.Overlapped "OverlappedObject *" "&OverlappedType"
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=c13d3f5fd1dabb84]*/

/*[python input]
def create_converter(type_, format_unit):
    name = type_ + '_converter'
    # registered upon creation by CConverter's metaclass
    type(name, (CConverter,), {'type': type_, 'format_unit': format_unit})

# format unit differs between platforms for these
create_converter('HANDLE', '" F_HANDLE "')
create_converter('HMODULE', '" F_HANDLE "')
create_converter('LPSECURITY_ATTRIBUTES', '" F_POINTER "')
create_converter('LPCVOID', '" F_POINTER "')

create_converter('BOOL', 'i') # F_BOOL used previously (always 'i')
create_converter('DWORD', 'k') # F_DWORD is always "k" (which is much shorter)
create_converter('UINT', 'I') # F_UINT used previously (always 'I')

class LPCWSTR_converter(Py_UNICODE_converter):
    type = 'LPCWSTR'

class HANDLE_return_converter(CReturnConverter):
    type = 'HANDLE'

    def render(self, function, data):
        self.declare(data)
        self.err_occurred_if("_return_value == INVALID_HANDLE_VALUE", data)
        data.return_conversion.append(
            'if (_return_value == NULL) {\n    Py_RETURN_NONE;\n}\n')
        data.return_conversion.append(
            'return_value = HANDLE_TO_PYNUM(_return_value);\n')

class DWORD_return_converter(CReturnConverter):
    type = 'DWORD'

    def render(self, function, data):
        self.declare(data)
        self.err_occurred_if("_return_value == PY_DWORD_MAX", data)
        data.return_conversion.append(
            'return_value = PyLong_FromUnsignedLong(_return_value);\n')

class LPVOID_return_converter(CReturnConverter):
    type = 'LPVOID'

    def render(self, function, data):
        self.declare(data)
        self.err_occurred_if("_return_value == NULL", data)
        data.return_conversion.append(
            'return_value = HANDLE_TO_PYNUM(_return_value);\n')
[python start generated code]*/
/*[python end generated code: output=da39a3ee5e6b4b0d input=da0a4db751936ee7]*/

#include "clinic/_winapi.c.h"

/*[clinic input]
_winapi.Overlapped.GetOverlappedResult

    wait: bool
    /
[clinic start generated code]*/

static PyObject *
_winapi_Overlapped_GetOverlappedResult_impl(OverlappedObject *self, int wait)
/*[clinic end generated code: output=bdd0c1ed6518cd03 input=194505ee8e0e3565]*/
{
    BOOL res;
    DWORD transferred = 0;
    DWORD err;

    Py_BEGIN_ALLOW_THREADS
    res = GetOverlappedResult(self->handle, &self->overlapped, &transferred,
                              wait != 0);
    Py_END_ALLOW_THREADS

    err = res ? ERROR_SUCCESS : GetLastError();
    switch (err) {
        case ERROR_SUCCESS:
        case ERROR_MORE_DATA:
        case ERROR_OPERATION_ABORTED:
            self->completed = 1;
            self->pending = 0;
            break;
        case ERROR_IO_INCOMPLETE:
            break;
        default:
            self->pending = 0;
            return PyErr_SetExcFromWindowsErr(PyExc_OSError, err);
    }
    if (self->completed && self->read_buffer != NULL) {
        assert(PyBytes_CheckExact(self->read_buffer));
        if (transferred != PyBytes_GET_SIZE(self->read_buffer) &&
            _PyBytes_Resize(&self->read_buffer, transferred))
            return NULL;
    }
    return Py_BuildValue("II", (unsigned) transferred, (unsigned) err);
}

/*[clinic input]
_winapi.Overlapped.getbuffer
[clinic start generated code]*/

static PyObject *
_winapi_Overlapped_getbuffer_impl(OverlappedObject *self)
/*[clinic end generated code: output=95a3eceefae0f748 input=347fcfd56b4ceabd]*/
{
    PyObject *res;
    if (!self->completed) {
        PyErr_SetString(PyExc_ValueError,
                        "can't get read buffer before GetOverlappedResult() "
                        "signals the operation completed");
        return NULL;
    }
    res = self->read_buffer ? self->read_buffer : Py_None;
    return Py_NewRef(res);
}

/*[clinic input]
_winapi.Overlapped.cancel
[clinic start generated code]*/

static PyObject *
_winapi_Overlapped_cancel_impl(OverlappedObject *self)
/*[clinic end generated code: output=fcb9ab5df4ebdae5 input=cbf3da142290039f]*/
{
    BOOL res = TRUE;

    if (self->pending) {
        Py_BEGIN_ALLOW_THREADS
        res = CancelIoEx(self->handle, &self->overlapped);
        Py_END_ALLOW_THREADS
    }

    /* CancelIoEx returns ERROR_NOT_FOUND if the I/O completed in-between */
    if (!res && GetLastError() != ERROR_NOT_FOUND)
        return PyErr_SetExcFromWindowsErr(PyExc_OSError, 0);
    self->pending = 0;
    Py_RETURN_NONE;
}

static PyMethodDef overlapped_methods[] = {
    _WINAPI_OVERLAPPED_GETOVERLAPPEDRESULT_METHODDEF
    _WINAPI_OVERLAPPED_GETBUFFER_METHODDEF
    _WINAPI_OVERLAPPED_CANCEL_METHODDEF
    {NULL}
};

static PyMemberDef overlapped_members[] = {
    {"event", T_HANDLE,
     offsetof(OverlappedObject, overlapped) + offsetof(OVERLAPPED, hEvent),
     Py_READONLY, "overlapped event handle"},
    {NULL}
};

static PyType_Slot winapi_overlapped_type_slots[] = {
    {Py_tp_traverse, overlapped_traverse},
    {Py_tp_dealloc, overlapped_dealloc},
    {Py_tp_doc, "OVERLAPPED structure wrapper"},
    {Py_tp_methods, overlapped_methods},
    {Py_tp_members, overlapped_members},
    {0,0}
};

static PyType_Spec winapi_overlapped_type_spec = {
    .name = "_winapi.Overlapped",
    .basicsize = sizeof(OverlappedObject),
    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION |
              Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_IMMUTABLETYPE),
    .slots = winapi_overlapped_type_slots,
};

static OverlappedObject *
new_overlapped(PyObject *module, HANDLE handle)
{
    WinApiState *st = winapi_get_state(module);
    OverlappedObject *self = PyObject_GC_New(OverlappedObject, st->overlapped_type);
    if (!self)
        return NULL;

    self->handle = handle;
    self->read_buffer = NULL;
    self->pending = 0;
    self->completed = 0;
    memset(&self->overlapped, 0, sizeof(OVERLAPPED));
    memset(&self->write_buffer, 0, sizeof(Py_buffer));
    /* Manual reset, initially non-signalled */
    self->overlapped.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

    PyObject_GC_Track(self);
    return self;
}

/* -------------------------------------------------------------------- */
/* windows API functions */

/*[clinic input]
_winapi.CloseHandle

    handle: HANDLE
    /

Close handle.
[clinic start generated code]*/

static PyObject *
_winapi_CloseHandle_impl(PyObject *module, HANDLE handle)
/*[clinic end generated code: output=7ad37345f07bd782 input=7f0e4ac36e0352b8]*/
{
    BOOL success;

    Py_BEGIN_ALLOW_THREADS
    success = CloseHandle(handle);
    Py_END_ALLOW_THREADS

    if (!success)
        return PyErr_SetFromWindowsErr(0);

    Py_RETURN_NONE;
}

/*[clinic input]
_winapi.ConnectNamedPipe

    handle: HANDLE
    overlapped as use_overlapped: bool = False
[clinic start generated code]*/

static PyObject *
_winapi_ConnectNamedPipe_impl(PyObject *module, HANDLE handle,
                              int use_overlapped)
/*[clinic end generated code: output=335a0e7086800671 input=a80e56e8bd370e31]*/
{
    BOOL success;
    OverlappedObject *overlapped = NULL;

    if (use_overlapped) {
        overlapped = new_overlapped(module, handle);
        if (!overlapped)
            return NULL;
    }

    Py_BEGIN_ALLOW_THREADS
    success = ConnectNamedPipe(handle,
                               overlapped ? &overlapped->overlapped : NULL);
    Py_END_ALLOW_THREADS

    if (overlapped) {
        int err = GetLastError();
        /* Overlapped ConnectNamedPipe never returns a success code */
        assert(success == 0);
        if (err == ERROR_IO_PENDING)
            overlapped->pending = 1;
        else if (err == ERROR_PIPE_CONNECTED)
            SetEvent(overlapped->overlapped.hEvent);
        else {
            Py_DECREF(overlapped);
            return PyErr_SetFromWindowsErr(err);
        }
        return (PyObject *) overlapped;
    }
    if (!success)
        return PyErr_SetFromWindowsErr(0);

    Py_RETURN_NONE;
}

/*[clinic input]
_winapi.CreateEventW -> HANDLE

    security_attributes: LPSECURITY_ATTRIBUTES
    manual_reset: BOOL
    initial_state: BOOL
    name: LPCWSTR(accept={str, NoneType})
[clinic start generated code]*/

static HANDLE
_winapi_CreateEventW_impl(PyObject *module,
                          LPSECURITY_ATTRIBUTES security_attributes,
                          BOOL manual_reset, BOOL initial_state,
                          LPCWSTR name)
/*[clinic end generated code: output=2d4c7d5852ecb298 input=4187cee28ac763f8]*/
{
    HANDLE handle;

    if (PySys_Audit("_winapi.CreateEventW", "bbu", manual_reset, initial_state, name) < 0) {
        return INVALID_HANDLE_VALUE;
    }

    Py_BEGIN_ALLOW_THREADS
    handle = CreateEventW(security_attributes, manual_reset, initial_state, name);
    Py_END_ALLOW_THREADS

    if (handle == INVALID_HANDLE_VALUE) {
        PyErr_SetFromWindowsErr(0);
    }

    return handle;
}

/*[clinic input]
_winapi.CreateFile -> HANDLE

    file_name: LPCWSTR
    desired_access: DWORD
    share_mode: DWORD
    security_attributes: LPSECURITY_ATTRIBUTES
    creation_disposition: DWORD
    flags_and_attributes: DWORD
    template_file: HANDLE
    /
[clinic start generated code]*/

static HANDLE
_winapi_CreateFile_impl(PyObject *module, LPCWSTR file_name,
                        DWORD desired_access, DWORD share_mode,
                        LPSECURITY_ATTRIBUTES security_attributes,
                        DWORD creation_disposition,
                        DWORD flags_and_attributes, HANDLE template_file)
/*[clinic end generated code: output=818c811e5e04d550 input=1fa870ed1c2e3d69]*/
{
    HANDLE handle;

    if (PySys_Audit("_winapi.CreateFile", "ukkkk",
                    file_name, desired_access, share_mode,
                    creation_disposition, flags_and_attributes) < 0) {
        return INVALID_HANDLE_VALUE;
    }

    Py_BEGIN_ALLOW_THREADS
    handle = CreateFileW(file_name, desired_access,
                         share_mode, security_attributes,
                         creation_disposition,
                         flags_and_attributes, template_file);
    Py_END_ALLOW_THREADS

    if (handle == INVALID_HANDLE_VALUE) {
        PyErr_SetFromWindowsErr(0);
    }

    return handle;
}

/*[clinic input]
_winapi.CreateFileMapping -> HANDLE

    file_handle: HANDLE
    security_attributes: LPSECURITY_ATTRIBUTES
    protect: DWORD
    max_size_high: DWORD
    max_size_low: DWORD
    name: LPCWSTR
    /
[clinic start generated code]*/

static HANDLE
_winapi_CreateFileMapping_impl(PyObject *module, HANDLE file_handle,
                               LPSECURITY_ATTRIBUTES security_attributes,
                               DWORD protect, DWORD max_size_high,
                               DWORD max_size_low, LPCWSTR name)
/*[clinic end generated code: output=6c0a4d5cf7f6fcc6 input=3dc5cf762a74dee8]*/
{
    HANDLE handle;

    Py_BEGIN_ALLOW_THREADS
    handle = CreateFileMappingW(file_handle, security_attributes,
                                protect, max_size_high, max_size_low,
                                name);
    Py_END_ALLOW_THREADS

    if (handle == NULL) {
        PyObject *temp = PyUnicode_FromWideChar(name, -1);
        PyErr_SetExcFromWindowsErrWithFilenameObject(PyExc_OSError, 0, temp);
        Py_XDECREF(temp);
        handle = INVALID_HANDLE_VALUE;
    }

    return handle;
}

/*[clinic input]
_winapi.CreateJunction

    src_path: LPCWSTR
    dst_path: LPCWSTR
    /
[clinic start generated code]*/

static PyObject *
_winapi_CreateJunction_impl(PyObject *module, LPCWSTR src_path,
                            LPCWSTR dst_path)
/*[clinic end generated code: output=44b3f5e9bbcc4271 input=963d29b44b9384a7]*/
{
    /* Privilege adjustment */
    HANDLE token = NULL;
    struct {
        TOKEN_PRIVILEGES base;
        /* overallocate by a few array elements */
        LUID_AND_ATTRIBUTES privs[4];
    } tp, previousTp;
    int previousTpSize = 0;

    /* Reparse data buffer */
    const USHORT prefix_len = 4;
    USHORT print_len = 0;
    USHORT rdb_size = 0;
    _Py_PREPARSE_DATA_BUFFER rdb = NULL;

    /* Junction point creation */
    HANDLE junction = NULL;
    DWORD ret = 0;

    if (src_path == NULL || dst_path == NULL)
        return PyErr_SetFromWindowsErr(ERROR_INVALID_PARAMETER);

    if (wcsncmp(src_path, L"\\??\\", prefix_len) == 0)
        return PyErr_SetFromWindowsErr(ERROR_INVALID_PARAMETER);

    if (PySys_Audit("_winapi.CreateJunction", "uu", src_path, dst_path) < 0) {
        return NULL;
    }

    /* Adjust privileges to allow rewriting directory entry as a
       junction point. */
    if (!OpenProcessToken(GetCurrentProcess(),
                          TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, &token)) {
        goto cleanup;
    }

    if (!LookupPrivilegeValue(NULL, SE_RESTORE_NAME, &tp.base.Privileges[0].Luid)) {
        goto cleanup;
    }

    tp.base.PrivilegeCount = 1;
    tp.base.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
    if (!AdjustTokenPrivileges(token, FALSE, &tp.base, sizeof(previousTp),
                               &previousTp.base, &previousTpSize)) {
        goto cleanup;
    }

    if (GetFileAttributesW(src_path) == INVALID_FILE_ATTRIBUTES)
        goto cleanup;

    /* Store the absolute link target path length in print_len. */
    print_len = (USHORT)GetFullPathNameW(src_path, 0, NULL, NULL);
    if (print_len == 0)
        goto cleanup;

    /* NUL terminator should not be part of print_len. */
    --print_len;

    /* REPARSE_DATA_BUFFER usage is heavily under-documented, especially for
       junction points. Here's what I've learned along the way:
       - A junction point has two components: a print name and a substitute
         name. They both describe the link target, but the substitute name is
         the physical target and the print name is shown in directory listings.
       - The print name must be a native name, prefixed with "\??\".
       - Both names are stored after each other in the same buffer (the
         PathBuffer) and both must be NUL-terminated.
       - There are four members defining their respective offset and length
         inside PathBuffer: SubstituteNameOffset, SubstituteNameLength,
         PrintNameOffset and PrintNameLength.
       - The total size we need to allocate for the REPARSE_DATA_BUFFER, thus,
         is the sum of:
         - the fixed header size (REPARSE_DATA_BUFFER_HEADER_SIZE)
         - the size of the MountPointReparseBuffer member without the PathBuffer
         - the size of the prefix ("\??\") in bytes
         - the size of the print name in bytes
         - the size of the substitute name in bytes
         - the size of two NUL terminators in bytes */
    rdb_size = _Py_REPARSE_DATA_BUFFER_HEADER_SIZE +
        sizeof(rdb->MountPointReparseBuffer) -
        sizeof(rdb->MountPointReparseBuffer.PathBuffer) +
        /* Two +1's for NUL terminators. */
        (prefix_len + print_len + 1 + print_len + 1) * sizeof(WCHAR);
    rdb = (_Py_PREPARSE_DATA_BUFFER)PyMem_RawCalloc(1, rdb_size);
    if (rdb == NULL)
        goto cleanup;

    rdb->ReparseTag = IO_REPARSE_TAG_MOUNT_POINT;
    rdb->ReparseDataLength = rdb_size - _Py_REPARSE_DATA_BUFFER_HEADER_SIZE;
    rdb->MountPointReparseBuffer.SubstituteNameOffset = 0;
    rdb->MountPointReparseBuffer.SubstituteNameLength =
        (prefix_len + print_len) * sizeof(WCHAR);
    rdb->MountPointReparseBuffer.PrintNameOffset =
        rdb->MountPointReparseBuffer.SubstituteNameLength + sizeof(WCHAR);
    rdb->MountPointReparseBuffer.PrintNameLength = print_len * sizeof(WCHAR);

    /* Store the full native path of link target at the substitute name
       offset (0). */
    wcscpy(rdb->MountPointReparseBuffer.PathBuffer, L"\\??\\");
    if (GetFullPathNameW(src_path, print_len + 1,
                         rdb->MountPointReparseBuffer.PathBuffer + prefix_len,
                         NULL) == 0)
        goto cleanup;

    /* Copy everything but the native prefix to the print name offset. */
    wcscpy(rdb->MountPointReparseBuffer.PathBuffer +
             prefix_len + print_len + 1,
             rdb->MountPointReparseBuffer.PathBuffer + prefix_len);

    /* Create a directory for the junction point. */
    if (!CreateDirectoryW(dst_path, NULL))
        goto cleanup;

    junction = CreateFileW(dst_path, GENERIC_READ | GENERIC_WRITE, 0, NULL,
        OPEN_EXISTING,
        FILE_FLAG_OPEN_REPARSE_POINT | FILE_FLAG_BACKUP_SEMANTICS, NULL);
    if (junction == INVALID_HANDLE_VALUE)
        goto cleanup;

    /* Make the directory entry a junction point. */
    if (!DeviceIoControl(junction, FSCTL_SET_REPARSE_POINT, rdb, rdb_size,
                         NULL, 0, &ret, NULL))
        goto cleanup;

cleanup:
    ret = GetLastError();

    if (previousTpSize) {
        AdjustTokenPrivileges(token, FALSE, &previousTp.base, previousTpSize,
                              NULL, NULL);
    }

    if (token != NULL)
        CloseHandle(token);
    if (junction != NULL)
        CloseHandle(junction);
    PyMem_RawFree(rdb);

    if (ret != 0)
        return PyErr_SetFromWindowsErr(ret);

    Py_RETURN_NONE;
}

/*[clinic input]
_winapi.CreateMutexW -> HANDLE

    security_attributes: LPSECURITY_ATTRIBUTES
    initial_owner: BOOL
    name: LPCWSTR(accept={str, NoneType})
[clinic start generated code]*/

static HANDLE
_winapi_CreateMutexW_impl(PyObject *module,
                          LPSECURITY_ATTRIBUTES security_attributes,
                          BOOL initial_owner, LPCWSTR name)
/*[clinic end generated code: output=31b9ee8fc37e49a5 input=7d54b921e723254a]*/
{
    HANDLE handle;

    if (PySys_Audit("_winapi.CreateMutexW", "bu", initial_owner, name) < 0) {
        return INVALID_HANDLE_VALUE;
    }

    Py_BEGIN_ALLOW_THREADS
    handle = CreateMutexW(security_attributes, initial_owner, name);
    Py_END_ALLOW_THREADS

    if (handle == INVALID_HANDLE_VALUE) {
        PyErr_SetFromWindowsErr(0);
    }

    return handle;
}

/*[clinic input]
_winapi.CreateNamedPipe -> HANDLE

    name: LPCWSTR
    open_mode: DWORD
    pipe_mode: DWORD
    max_instances: DWORD
    out_buffer_size: DWORD
    in_buffer_size: DWORD
    default_timeout: DWORD
    security_attributes: LPSECURITY_ATTRIBUTES
    /
[clinic start generated code]*/

static HANDLE
_winapi_CreateNamedPipe_impl(PyObject *module, LPCWSTR name, DWORD open_mode,
                             DWORD pipe_mode, DWORD max_instances,
                             DWORD out_buffer_size, DWORD in_buffer_size,
                             DWORD default_timeout,
                             LPSECURITY_ATTRIBUTES security_attributes)
/*[clinic end generated code: output=7d6fde93227680ba input=5bd4e4a55639ee02]*/
{
    HANDLE handle;

    if (PySys_Audit("_winapi.CreateNamedPipe", "ukk",
                    name, open_mode, pipe_mode) < 0) {
        return INVALID_HANDLE_VALUE;
    }

    Py_BEGIN_ALLOW_THREADS
    handle = CreateNamedPipeW(name, open_mode, pipe_mode,
                              max_instances, out_buffer_size,
                              in_buffer_size, default_timeout,
                              security_attributes);
    Py_END_ALLOW_THREADS

    if (handle == INVALID_HANDLE_VALUE)
        PyErr_SetFromWindowsErr(0);

    return handle;
}

/*[clinic input]
_winapi.CreatePipe

    pipe_attrs: object
        Ignored internally, can be None.
    size: DWORD
    /

Create an anonymous pipe.

Returns a 2-tuple of handles, to the read and write ends of the pipe.
[clinic start generated code]*/

static PyObject *
_winapi_CreatePipe_impl(PyObject *module, PyObject *pipe_attrs, DWORD size)
/*[clinic end generated code: output=1c4411d8699f0925 input=c4f2cfa56ef68d90]*/
{
    HANDLE read_pipe;
    HANDLE write_pipe;
    BOOL result;

    if (PySys_Audit("_winapi.CreatePipe", NULL) < 0) {
        return NULL;
    }

    Py_BEGIN_ALLOW_THREADS
    result = CreatePipe(&read_pipe, &write_pipe, NULL, size);
    Py_END_ALLOW_THREADS

    if (! result)
        return PyErr_SetFromWindowsErr(GetLastError());

    return Py_BuildValue(
        "NN", HANDLE_TO_PYNUM(read_pipe), HANDLE_TO_PYNUM(write_pipe));
}

/* helpers for createprocess */

static unsigned long
getulong(PyObject* obj, const char* name)
{
    PyObject* value;
    unsigned long ret;

    value = PyObject_GetAttrString(obj, name);
    if (! value) {
        PyErr_Clear(); /* FIXME: propagate error? */
        return 0;
    }
    ret = PyLong_AsUnsignedLong(value);
    Py_DECREF(value);
    return ret;
}

static HANDLE
gethandle(PyObject* obj, const char* name)
{
    PyObject* value;
    HANDLE ret;

    value = PyObject_GetAttrString(obj, name);
    if (! value) {
        PyErr_Clear(); /* FIXME: propagate error? */
        return NULL;
    }
    if (value == Py_None)
        ret = NULL;
    else
        ret = PYNUM_TO_HANDLE(value);
    Py_DECREF(value);
    return ret;
}

static PyObject *
sortenvironmentkey(PyObject *module, PyObject *item)
{
    return _winapi_LCMapStringEx_impl(NULL, LOCALE_NAME_INVARIANT,
                                      LCMAP_UPPERCASE, item);
}

static PyMethodDef sortenvironmentkey_def = {
    "sortenvironmentkey", _PyCFunction_CAST(sortenvironmentkey), METH_O, "",
};

static int
sort_environment_keys(PyObject *keys)
{
    PyObject *keyfunc = PyCFunction_New(&sortenvironmentkey_def, NULL);
    if (keyfunc == NULL) {
        return -1;
    }
    PyObject *kwnames = Py_BuildValue("(s)", "key");
    if (kwnames == NULL) {
        Py_DECREF(keyfunc);
        return -1;
    }
    PyObject *args[] = { keys, keyfunc };
    PyObject *ret = PyObject_VectorcallMethod(&_Py_ID(sort), args, 1, kwnames);
    Py_DECREF(keyfunc);
    Py_DECREF(kwnames);
    if (ret == NULL) {
        return -1;
    }
    Py_DECREF(ret);

    return 0;
}

static int
compare_string_ordinal(PyObject *str1, PyObject *str2, int *result)
{
    wchar_t *s1 = PyUnicode_AsWideCharString(str1, NULL);
    if (s1 == NULL) {
        return -1;
    }
    wchar_t *s2 = PyUnicode_AsWideCharString(str2, NULL);
    if (s2 == NULL) {
        PyMem_Free(s1);
        return -1;
    }
    *result = CompareStringOrdinal(s1, -1, s2, -1, TRUE);
    PyMem_Free(s1);
    PyMem_Free(s2);
    return 0;
}

static PyObject *
dedup_environment_keys(PyObject *keys)
{
    PyObject *result = PyList_New(0);
    if (result == NULL) {
        return NULL;
    }

    // Iterate over the pre-ordered keys, check whether the current key is equal
    // to the next key (ignoring case), if different, insert the current value
    // into the result list. If they are equal, do nothing because we always
    // want to keep the last inserted one.
    for (Py_ssize_t i = 0; i < PyList_GET_SIZE(keys); i++) {
        PyObject *key = PyList_GET_ITEM(keys, i);

        // The last key will always be kept.
        if (i + 1 == PyList_GET_SIZE(keys)) {
            if (PyList_Append(result, key) < 0) {
                Py_DECREF(result);
                return NULL;
            }
            continue;
        }

        PyObject *next_key = PyList_GET_ITEM(keys, i + 1);
        int compare_result;
        if (compare_string_ordinal(key, next_key, &compare_result) < 0) {
            Py_DECREF(result);
            return NULL;
        }
        if (compare_result == CSTR_EQUAL) {
            continue;
        }
        if (PyList_Append(result, key) < 0) {
            Py_DECREF(result);
            return NULL;
        }
    }

    return result;
}

static PyObject *
normalize_environment(PyObject *environment)
{
    PyObject *keys = PyMapping_Keys(environment);
    if (keys == NULL) {
        return NULL;
    }

    if (sort_environment_keys(keys) < 0) {
        Py_DECREF(keys);
        return NULL;
    }

    PyObject *normalized_keys = dedup_environment_keys(keys);
    Py_DECREF(keys);