diff options
Diffstat (limited to 'Modules/_winapi.c')
| -rw-r--r-- | Modules/_winapi.c | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/Modules/_winapi.c b/Modules/_winapi.c index b755178427..f118436f91 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) \ @@ -401,6 +402,140 @@ winapi_CreateFile(PyObject *self, PyObject *args) } 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 (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); + + /* 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; + + /* 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 = 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); + if (rdb == NULL) + goto cleanup; + + memset(rdb, 0, rdb_size); + 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); + + /* 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(); + + CloseHandle(token); + CloseHandle(junction); + PyMem_RawFree(rdb); + + if (ret != 0) + return PyErr_SetFromWindowsErr(ret); + + Py_RETURN_NONE; +} + +static PyObject * winapi_CreateNamedPipe(PyObject *self, PyObject *args) { LPCTSTR lpName; @@ -1225,6 +1360,8 @@ 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, |