From 4675d798bfdef3ad916d1eef6d5a4d0529ccfda7 Mon Sep 17 00:00:00 2001
From: Tim Golden <mail@timgolden.me.uk>
Date: Sun, 27 Apr 2014 18:00:10 +0100
Subject: =?UTF-8?q?Issue=20#18314=20os.unlink=20will=20now=20remove=20junc?=
 =?UTF-8?q?tion=20points=20on=20Windows.=20Patch=20by=20Kim=20Gr=C3=A4sman?=
 =?UTF-8?q?.?=
MIME-Version: 1.0
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---
 Modules/_winapi.c | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)

(limited to 'Modules/_winapi.c')

diff --git a/Modules/_winapi.c b/Modules/_winapi.c
index b755178427..80c1e929d9 100644
--- a/Modules/_winapi.c
+++ b/Modules/_winapi.c
@@ -40,6 +40,7 @@
 #define WINDOWS_LEAN_AND_MEAN
 #include "windows.h"
 #include <crtdbg.h>
+#include "winreparse.h"
 
 #if defined(MS_WIN32) && !defined(MS_WIN64)
 #define HANDLE_TO_PYNUM(handle) \
@@ -400,6 +401,112 @@ winapi_CreateFile(PyObject *self, PyObject *args)
     return Py_BuildValue(F_HANDLE, handle);
 }
 
+static PyObject *
+winapi_CreateJunction(PyObject *self, PyObject *args)
+{
+    /* Input arguments */
+    LPWSTR src_path = NULL;
+    LPWSTR dst_path = NULL;
+
+    /* Privilege adjustment */
+    HANDLE token = NULL;
+    TOKEN_PRIVILEGES tp;
+
+    /* Reparse data buffer */
+    const USHORT prefix_len = 4;
+    USHORT print_len = 0;
+    USHORT rdb_size = 0;
+    PREPARSE_DATA_BUFFER rdb = NULL;
+
+    /* Junction point creation */
+    HANDLE junction = NULL;
+    DWORD ret = 0;
+
+    if (!PyArg_ParseTuple(args, "uu",
+                          &src_path, &dst_path))
+        return NULL;
+
+    if (memcmp(src_path, L"\\??\\", prefix_len * sizeof(WCHAR)) == 0)
+        return PyErr_SetFromWindowsErr(ERROR_INVALID_PARAMETER);
+
+    /* Adjust privileges to allow rewriting directory entry as a
+       junction point. */
+    if (!OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES, &token))
+        goto cleanup;
+
+    if (!LookupPrivilegeValue(NULL, SE_RESTORE_NAME, &tp.Privileges[0].Luid))
+        goto cleanup;
+
+    tp.PrivilegeCount = 1;
+    tp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
+    if (!AdjustTokenPrivileges(token, FALSE, &tp, sizeof(TOKEN_PRIVILEGES),
+                               NULL, NULL))
+        goto cleanup;
+
+    if (GetFileAttributesW(src_path) == INVALID_FILE_ATTRIBUTES)
+        goto cleanup;
+
+    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;
+
+    rdb_size = 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 = (PREPARSE_DATA_BUFFER)PyMem_RawMalloc(rdb_size, 1);
+
+    rdb->ReparseTag = IO_REPARSE_TAG_MOUNT_POINT;
+    rdb->ReparseDataLength = rdb_size - 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);
+
+    lstrcpyW(rdb->MountPointReparseBuffer.PathBuffer, L"\\??\\");
+    if (GetFullPathNameW(src_path, print_len + 1,
+                         rdb->MountPointReparseBuffer.PathBuffer + prefix_len,
+                         NULL) == 0)
+        goto cleanup;
+
+    lstrcpyW(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();
+
+    CloseHandle(token);
+    CloseHandle(junction);
+    free(rdb);
+
+    if (ret != 0)
+        return PyErr_SetFromWindowsErr(ret);
+
+    Py_RETURN_NONE;
+}
+
 static PyObject *
 winapi_CreateNamedPipe(PyObject *self, PyObject *args)
 {
@@ -1225,6 +1332,8 @@ static PyMethodDef winapi_functions[] = {
      METH_VARARGS | METH_KEYWORDS, ""},
     {"CreateFile", winapi_CreateFile, METH_VARARGS,
      ""},
+    {"CreateJunction", winapi_CreateJunction, METH_VARARGS,
+     ""},
     {"CreateNamedPipe", winapi_CreateNamedPipe, METH_VARARGS,
      ""},
     {"CreatePipe", winapi_CreatePipe, METH_VARARGS,
-- 
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