From 0321cf25503e291eb4125411183e124f45793f64 Mon Sep 17 00:00:00 2001 From: Tim Golden Date: Mon, 5 May 2014 19:46:17 +0100 Subject: [PATCH] =?UTF-8?q?Issue18314=20Allow=20unlink=20to=20remove=20jun?= =?UTF-8?q?ctions.=20Includes=20support=20for=20creating=20junctions.=20Pa?= =?UTF-8?q?tch=20by=20Kim=20Gr=C3=A4sman?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- Lib/test/test_os.py | 36 +++++++++++ Modules/_winapi.c | 137 ++++++++++++++++++++++++++++++++++++++++++ Modules/posixmodule.c | 45 +++----------- Modules/winreparse.h | 53 ++++++++++++++++ 4 files changed, 235 insertions(+), 36 deletions(-) create mode 100644 Modules/winreparse.h diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py index e129beff547..7d5ee69c45e 100644 --- a/Lib/test/test_os.py +++ b/Lib/test/test_os.py @@ -39,6 +39,10 @@ try: import fcntl except ImportError: fcntl = None +try: + import _winapi +except ImportError: + _winapi = None from test.script_helper import assert_python_ok @@ -1773,6 +1777,37 @@ class Win32SymlinkTests(unittest.TestCase): shutil.rmtree(level1) +@unittest.skipUnless(sys.platform == "win32", "Win32 specific tests") +class Win32JunctionTests(unittest.TestCase): + junction = 'junctiontest' + junction_target = os.path.dirname(os.path.abspath(__file__)) + + def setUp(self): + assert os.path.exists(self.junction_target) + assert not os.path.exists(self.junction) + + def tearDown(self): + if os.path.exists(self.junction): + # os.rmdir delegates to Windows' RemoveDirectoryW, + # which removes junction points safely. + os.rmdir(self.junction) + + def test_create_junction(self): + _winapi.CreateJunction(self.junction_target, self.junction) + self.assertTrue(os.path.exists(self.junction)) + self.assertTrue(os.path.isdir(self.junction)) + + # Junctions are not recognized as links. + self.assertFalse(os.path.islink(self.junction)) + + def test_unlink_removes_junction(self): + _winapi.CreateJunction(self.junction_target, self.junction) + self.assertTrue(os.path.exists(self.junction)) + + os.unlink(self.junction) + self.assertFalse(os.path.exists(self.junction)) + + @support.skip_unless_symlink class NonLocalSymlinkTests(unittest.TestCase): @@ -2544,6 +2579,7 @@ def test_main(): RemoveDirsTests, CPUCountTests, FDInheritanceTests, + Win32JunctionTests, ) if __name__ == "__main__": diff --git a/Modules/_winapi.c b/Modules/_winapi.c index b7551784273..f118436f915 100644 --- a/Modules/_winapi.c +++ b/Modules/_winapi.c @@ -40,6 +40,7 @@ #define WINDOWS_LEAN_AND_MEAN #include "windows.h" #include +#include "winreparse.h" #if defined(MS_WIN32) && !defined(MS_WIN64) #define HANDLE_TO_PYNUM(handle) \ @@ -400,6 +401,140 @@ 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 (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) { @@ -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, diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c index 8cd5485cebc..916be81e431 100644 --- a/Modules/posixmodule.c +++ b/Modules/posixmodule.c @@ -27,6 +27,8 @@ #include "Python.h" #ifndef MS_WINDOWS #include "posixmodule.h" +#else +#include "winreparse.h" #endif #ifdef __cplusplus @@ -301,6 +303,9 @@ extern int lstat(const char *, struct stat *); #ifndef IO_REPARSE_TAG_SYMLINK #define IO_REPARSE_TAG_SYMLINK (0xA000000CL) #endif +#ifndef IO_REPARSE_TAG_MOUNT_POINT +#define IO_REPARSE_TAG_MOUNT_POINT (0xA0000003L) +#endif #include "osdefs.h" #include #include @@ -1109,41 +1114,6 @@ _PyVerify_fd_dup2(int fd1, int fd2) #endif #ifdef MS_WINDOWS -/* The following structure was copied from - http://msdn.microsoft.com/en-us/library/ms791514.aspx as the required - include doesn't seem to be present in the Windows SDK (at least as included - with Visual Studio Express). */ -typedef struct _REPARSE_DATA_BUFFER { - ULONG ReparseTag; - USHORT ReparseDataLength; - USHORT Reserved; - union { - struct { - USHORT SubstituteNameOffset; - USHORT SubstituteNameLength; - USHORT PrintNameOffset; - USHORT PrintNameLength; - ULONG Flags; - WCHAR PathBuffer[1]; - } SymbolicLinkReparseBuffer; - - struct { - USHORT SubstituteNameOffset; - USHORT SubstituteNameLength; - USHORT PrintNameOffset; - USHORT PrintNameLength; - WCHAR PathBuffer[1]; - } MountPointReparseBuffer; - - struct { - UCHAR DataBuffer[1]; - } GenericReparseBuffer; - }; -} REPARSE_DATA_BUFFER, *PREPARSE_DATA_BUFFER; - -#define REPARSE_DATA_BUFFER_HEADER_SIZE FIELD_OFFSET(REPARSE_DATA_BUFFER,\ - GenericReparseBuffer) -#define MAXIMUM_REPARSE_DATA_BUFFER_SIZE ( 16 * 1024 ) static int win32_get_reparse_tag(HANDLE reparse_point_handle, ULONG *reparse_tag) @@ -4492,7 +4462,10 @@ BOOL WINAPI Py_DeleteFileW(LPCWSTR lpFileName) find_data_handle = FindFirstFileW(lpFileName, &find_data); if(find_data_handle != INVALID_HANDLE_VALUE) { - is_link = find_data.dwReserved0 == IO_REPARSE_TAG_SYMLINK; + /* IO_REPARSE_TAG_SYMLINK if it is a symlink and + IO_REPARSE_TAG_MOUNT_POINT if it is a junction point. */ + is_link = find_data.dwReserved0 == IO_REPARSE_TAG_SYMLINK || + find_data.dwReserved0 == IO_REPARSE_TAG_MOUNT_POINT; FindClose(find_data_handle); } } diff --git a/Modules/winreparse.h b/Modules/winreparse.h new file mode 100644 index 00000000000..66f7775dd2e --- /dev/null +++ b/Modules/winreparse.h @@ -0,0 +1,53 @@ +#ifndef Py_WINREPARSE_H +#define Py_WINREPARSE_H + +#ifdef MS_WINDOWS +#include + +#ifdef __cplusplus +extern "C" { +#endif + +/* The following structure was copied from + http://msdn.microsoft.com/en-us/library/ff552012.aspx as the required + include doesn't seem to be present in the Windows SDK (at least as included + with Visual Studio Express). */ +typedef struct _REPARSE_DATA_BUFFER { + ULONG ReparseTag; + USHORT ReparseDataLength; + USHORT Reserved; + union { + struct { + USHORT SubstituteNameOffset; + USHORT SubstituteNameLength; + USHORT PrintNameOffset; + USHORT PrintNameLength; + ULONG Flags; + WCHAR PathBuffer[1]; + } SymbolicLinkReparseBuffer; + + struct { + USHORT SubstituteNameOffset; + USHORT SubstituteNameLength; + USHORT PrintNameOffset; + USHORT PrintNameLength; + WCHAR PathBuffer[1]; + } MountPointReparseBuffer; + + struct { + UCHAR DataBuffer[1]; + } GenericReparseBuffer; + }; +} REPARSE_DATA_BUFFER, *PREPARSE_DATA_BUFFER; + +#define REPARSE_DATA_BUFFER_HEADER_SIZE FIELD_OFFSET(REPARSE_DATA_BUFFER,\ + GenericReparseBuffer) +#define MAXIMUM_REPARSE_DATA_BUFFER_SIZE ( 16 * 1024 ) + +#ifdef __cplusplus +} +#endif + +#endif /* MS_WINDOWS */ + +#endif /* !Py_WINREPARSE_H */