Merged revisions 63977 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r63977 | thomas.heller | 2008-06-06 10:33:46 +0200 (Fri, 06 Jun 2008) | 31 lines

  Issue #1798: Add ctypes calling convention that allows safe access of errno.

  ctypes maintains thread-local storage that has space for two error
  numbers: private copies of the system 'errno' value and, on Windows,
  the system error code accessed by the GetLastError() and
  SetLastError() api functions.

  Foreign functions created with CDLL(..., use_errno=True), when called,
  swap the system 'errno' value with the private copy just before the
  actual function call, and swapped again immediately afterwards.  The
  'use_errno' parameter defaults to False, in this case 'ctypes_errno'
  is not touched.

  On Windows, foreign functions created with CDLL(...,
  use_last_error=True) or WinDLL(..., use_last_error=True) swap the
  system LastError value with the ctypes private copy.

  The values are also swapped immeditately before and after ctypes
  callback functions are called, if the callbacks are constructed using
  the new optional use_errno parameter set to True: CFUNCTYPE(...,
  use_errno=TRUE) or WINFUNCTYPE(..., use_errno=True).

  New ctypes functions are provided to access the ctypes private copies
  from Python:

  - ctypes.set_errno(value) and ctypes.set_last_error(value) store
    'value' in the private copy and returns the previous value.

  - ctypes.get_errno() and ctypes.get_last_error() returns the current
    ctypes private copies value.
........

Lib/ctypes/__init__.py

@@ -30,7 +30,9 @@ if _os.name == "posix" and _sys.platform == "darwin":
         DEFAULT_MODE = RTLD_GLOBAL
 
 from _ctypes import FUNCFLAG_CDECL as _FUNCFLAG_CDECL, \
-     FUNCFLAG_PYTHONAPI as _FUNCFLAG_PYTHONAPI
+     FUNCFLAG_PYTHONAPI as _FUNCFLAG_PYTHONAPI, \
+     FUNCFLAG_USE_ERRNO as _FUNCFLAG_USE_ERRNO, \
+     FUNCFLAG_USE_LASTERROR as _FUNCFLAG_USE_LASTERROR
 
 """
 WINOLEAPI -> HRESULT
@@ -70,8 +72,9 @@ def c_buffer(init, size=None):
     return create_string_buffer(init, size)
 
 _c_functype_cache = {}
-def CFUNCTYPE(restype, *argtypes):
+def CFUNCTYPE(restype, *argtypes, **kw):
-    """CFUNCTYPE(restype, *argtypes) -> function prototype.
+    """CFUNCTYPE(restype, *argtypes,
+                 use_errno=False, use_last_error=False) -> function prototype.
 
     restype: the result type
     argtypes: a sequence specifying the argument types
@@ -85,14 +88,21 @@ def CFUNCTYPE(restype, *argtypes):
     prototype((ordinal number, dll object)[, paramflags]) -> foreign function exported by ordinal
     prototype((function name, dll object)[, paramflags]) -> foreign function exported by name
     """
+    flags = _FUNCFLAG_CDECL
+    if kw.pop("use_errno", False):
+        flags |= _FUNCFLAG_USE_ERRNO
+    if kw.pop("use_last_error", False):
+        flags |= _FUNCFLAG_USE_LASTERROR
+    if kw:
+        raise ValueError("unexpected keyword argument(s) %s" % kw.keys())
     try:
-        return _c_functype_cache[(restype, argtypes)]
+        return _c_functype_cache[(restype, argtypes, flags)]
     except KeyError:
         class CFunctionType(_CFuncPtr):
             _argtypes_ = argtypes
             _restype_ = restype
-            _flags_ = _FUNCFLAG_CDECL
+            _flags_ = flags
-        _c_functype_cache[(restype, argtypes)] = CFunctionType
+        _c_functype_cache[(restype, argtypes, flags)] = CFunctionType
         return CFunctionType
 
 if _os.name in ("nt", "ce"):
@@ -103,16 +113,23 @@ if _os.name in ("nt", "ce"):
         _FUNCFLAG_STDCALL = _FUNCFLAG_CDECL
 
     _win_functype_cache = {}
-    def WINFUNCTYPE(restype, *argtypes):
+    def WINFUNCTYPE(restype, *argtypes, **kw):
         # docstring set later (very similar to CFUNCTYPE.__doc__)
+        flags = _FUNCFLAG_STDCALL
+        if kw.pop("use_errno", False):
+            flags |= _FUNCFLAG_USE_ERRNO
+        if kw.pop("use_last_error", False):
+            flags |= _FUNCFLAG_USE_LASTERROR
+        if kw:
+            raise ValueError("unexpected keyword argument(s) %s" % kw.keys())
         try:
-            return _win_functype_cache[(restype, argtypes)]
+            return _win_functype_cache[(restype, argtypes, flags)]
         except KeyError:
             class WinFunctionType(_CFuncPtr):
                 _argtypes_ = argtypes
                 _restype_ = restype
-                _flags_ = _FUNCFLAG_STDCALL
+                _flags_ = flags
-            _win_functype_cache[(restype, argtypes)] = WinFunctionType
+            _win_functype_cache[(restype, argtypes, flags)] = WinFunctionType
             return WinFunctionType
     if WINFUNCTYPE.__doc__:
         WINFUNCTYPE.__doc__ = CFUNCTYPE.__doc__.replace("CFUNCTYPE", "WINFUNCTYPE")
@@ -121,6 +138,7 @@ elif _os.name == "posix":
     from _ctypes import dlopen as _dlopen
 
 from _ctypes import sizeof, byref, addressof, alignment, resize
+from _ctypes import get_errno, set_errno
 from _ctypes import _SimpleCData
 
 def _check_size(typ, typecode=None):
@@ -310,12 +328,24 @@ class CDLL(object):
     Calling the functions releases the Python GIL during the call and
     reacquires it afterwards.
     """
-    class _FuncPtr(_CFuncPtr):
+    _func_flags_ = _FUNCFLAG_CDECL
-        _flags_ = _FUNCFLAG_CDECL
+    _func_restype_ = c_int
-        _restype_ = c_int # default, can be overridden in instances
 
-    def __init__(self, name, mode=DEFAULT_MODE, handle=None):
+    def __init__(self, name, mode=DEFAULT_MODE, handle=None,
+                 use_errno=False,
+                 use_last_error=False):
         self._name = name
+        flags = self._func_flags_
+        if use_errno:
+            flags |= _FUNCFLAG_USE_ERRNO
+        if use_last_error:
+            flags |= _FUNCFLAG_USE_LASTERROR
+
+        class _FuncPtr(_CFuncPtr):
+            _flags_ = flags
+            _restype_ = self._func_restype_
+        self._FuncPtr = _FuncPtr
+
         if handle is None:
             self._handle = _dlopen(self._name, mode)
         else:
@@ -345,9 +375,7 @@ class PyDLL(CDLL):
     access Python API functions.  The GIL is not released, and
     Python exceptions are handled correctly.
     """
-    class _FuncPtr(_CFuncPtr):
+    _func_flags_ = _FUNCFLAG_CDECL | _FUNCFLAG_PYTHONAPI
-        _flags_ = _FUNCFLAG_CDECL | _FUNCFLAG_PYTHONAPI
-        _restype_ = c_int # default, can be overridden in instances
 
 if _os.name in ("nt", "ce"):
 
@@ -355,9 +383,7 @@ if _os.name in ("nt", "ce"):
         """This class represents a dll exporting functions using the
         Windows stdcall calling convention.
         """
-        class _FuncPtr(_CFuncPtr):
+        _func_flags_ = _FUNCFLAG_STDCALL
-            _flags_ = _FUNCFLAG_STDCALL
-            _restype_ = c_int # default, can be overridden in instances
 
     # XXX Hm, what about HRESULT as normal parameter?
     # Mustn't it derive from c_long then?
@@ -381,9 +407,8 @@ if _os.name in ("nt", "ce"):
         HRESULT error values are automatically raised as WindowsError
         exceptions.
         """
-        class _FuncPtr(_CFuncPtr):
+        _func_flags_ = _FUNCFLAG_STDCALL
-            _flags_ = _FUNCFLAG_STDCALL
+        _func_restype_ = HRESULT
-            _restype_ = HRESULT
 
 class LibraryLoader(object):
     def __init__(self, dlltype):
@@ -421,6 +446,7 @@ if _os.name in ("nt", "ce"):
         GetLastError = windll.kernel32.GetLastError
     else:
         GetLastError = windll.coredll.GetLastError
+    from _ctypes import get_last_error, set_last_error
 
     def WinError(code=None, descr=None):
         if code is None:

Lib/ctypes/test/test_errno.py

@@ -0,0 +1,76 @@
+import unittest, os, errno
+from ctypes import *
+from ctypes.util import find_library
+import threading
+
+class Test(unittest.TestCase):
+    def test_open(self):
+        libc_name = find_library("c")
+        if libc_name is not None:
+            libc = CDLL(libc_name, use_errno=True)
+            if os.name == "nt":
+                libc_open = libc._open
+            else:
+                libc_open = libc.open
+
+            libc_open.argtypes = c_char_p, c_int
+
+            self.failUnlessEqual(libc_open("", 0), -1)
+            self.failUnlessEqual(get_errno(), errno.ENOENT)
+
+            self.failUnlessEqual(set_errno(32), errno.ENOENT)
+            self.failUnlessEqual(get_errno(), 32)
+
+
+            def _worker():
+                set_errno(0)
+
+                libc = CDLL(libc_name, use_errno=False)
+                if os.name == "nt":
+                    libc_open = libc._open
+                else:
+                    libc_open = libc.open
+                libc_open.argtypes = c_char_p, c_int
+                self.failUnlessEqual(libc_open("", 0), -1)
+                self.failUnlessEqual(get_errno(), 0)
+
+            t = threading.Thread(target=_worker)
+            t.start()
+            t.join()
+
+            self.failUnlessEqual(get_errno(), 32)
+            set_errno(0)
+
+    if os.name == "nt":
+
+        def test_GetLastError(self):
+            dll = WinDLL("kernel32", use_last_error=True)
+            GetModuleHandle = dll.GetModuleHandleA
+            GetModuleHandle.argtypes = [c_wchar_p]
+
+            self.failUnlessEqual(0, GetModuleHandle("foo"))
+            self.failUnlessEqual(get_last_error(), 126)
+
+            self.failUnlessEqual(set_last_error(32), 126)
+            self.failUnlessEqual(get_last_error(), 32)
+
+            def _worker():
+                set_last_error(0)
+
+                dll = WinDLL("kernel32", use_last_error=False)
+                GetModuleHandle = dll.GetModuleHandleW
+                GetModuleHandle.argtypes = [c_wchar_p]
+                GetModuleHandle("bar")
+
+                self.failUnlessEqual(get_last_error(), 0)
+
+            t = threading.Thread(target=_worker)
+            t.start()
+            t.join()
+
+            self.failUnlessEqual(get_last_error(), 32)
+
+            set_last_error(0)
+
+if __name__ == "__main__":
+    unittest.main()

Modules/_ctypes/_ctypes.c

@@ -3340,7 +3340,7 @@ CFuncPtr_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 	thunk = AllocFunctionCallback(callable,
 				      dict->argtypes,
 				      dict->restype,
-				      dict->flags & FUNCFLAG_CDECL);
+				      dict->flags);
 	if (!thunk)
 		return NULL;
 
@@ -5333,6 +5333,8 @@ init_ctypes(void)
 	PyModule_AddObject(m, "FUNCFLAG_STDCALL", PyLong_FromLong(FUNCFLAG_STDCALL));
 #endif
 	PyModule_AddObject(m, "FUNCFLAG_CDECL", PyLong_FromLong(FUNCFLAG_CDECL));
+	PyModule_AddObject(m, "FUNCFLAG_USE_ERRNO", PyLong_FromLong(FUNCFLAG_USE_ERRNO));
+	PyModule_AddObject(m, "FUNCFLAG_USE_LASTERROR", PyLong_FromLong(FUNCFLAG_USE_LASTERROR));
 	PyModule_AddObject(m, "FUNCFLAG_PYTHONAPI", PyLong_FromLong(FUNCFLAG_PYTHONAPI));
 	PyModule_AddStringConstant(m, "__version__", "1.1.0");
 

Modules/_ctypes/callbacks.c

@@ -185,12 +185,15 @@ static void _CallPythonObject(void *mem,
 			      SETFUNC setfunc,
 			      PyObject *callable,
 			      PyObject *converters,
+			      int flags,
 			      void **pArgs)
 {
 	Py_ssize_t i;
 	PyObject *result;
 	PyObject *arglist = NULL;
 	Py_ssize_t nArgs;
+	PyObject *error_object = NULL;
+	int *space;
 #ifdef WITH_THREAD
 	PyGILState_STATE state = PyGILState_Ensure();
 #endif
@@ -267,8 +270,41 @@ static void _CallPythonObject(void *mem,
 #define CHECK(what, x) \
 if (x == NULL) _AddTraceback(what, "_ctypes/callbacks.c", __LINE__ - 1), PyErr_Print()
 
+	if (flags & (FUNCFLAG_USE_ERRNO | FUNCFLAG_USE_LASTERROR)) {
+		error_object = get_error_object(&space);
+		if (error_object == NULL)
+			goto Done;
+		if (flags & FUNCFLAG_USE_ERRNO) {
+			int temp = space[0];
+			space[0] = errno;
+			errno = temp;
+		}
+#ifdef MS_WIN32
+		if (flags & FUNCFLAG_USE_LASTERROR) {
+			int temp = space[1];
+			space[1] = GetLastError();
+			SetLastError(temp);
+		}
+#endif
+	}
+
 	result = PyObject_CallObject(callable, arglist);
 	CHECK("'calling callback function'", result);
+
+#ifdef MS_WIN32
+	if (flags & FUNCFLAG_USE_LASTERROR) {
+		int temp = space[1];
+		space[1] = GetLastError();
+		SetLastError(temp);
+	}
+#endif
+	if (flags & FUNCFLAG_USE_ERRNO) {
+		int temp = space[0];
+		space[0] = errno;
+		errno = temp;
+	}
+	Py_XDECREF(error_object);
+
 	if ((restype != &ffi_type_void) && result) {
 		PyObject *keep;
 		assert(setfunc);
@@ -319,6 +355,7 @@ static void closure_fcn(ffi_cif *cif,
 			  p->setfunc,
 			  p->callable,
 			  p->converters,
+			  p->flags,
 			  args);
 }
 
@@ -348,7 +385,7 @@ static CThunkObject* CThunkObject_new(Py_ssize_t nArgs)
 CThunkObject *AllocFunctionCallback(PyObject *callable,
 				    PyObject *converters,
 				    PyObject *restype,
-				    int is_cdecl)
+				    int flags)
 {
 	int result;
 	CThunkObject *p;
@@ -368,6 +405,7 @@ CThunkObject *AllocFunctionCallback(PyObject *callable,
 		goto error;
 	}
 
+	p->flags = flags;
 	for (i = 0; i < nArgs; ++i) {
 		PyObject *cnv = PySequence_GetItem(converters, i);
 		if (cnv == NULL)
@@ -395,7 +433,7 @@ CThunkObject *AllocFunctionCallback(PyObject *callable,
 
 	cc = FFI_DEFAULT_ABI;
 #if defined(MS_WIN32) && !defined(_WIN32_WCE) && !defined(MS_WIN64)
-	if (is_cdecl == 0)
+	if ((flags & FUNCFLAG_CDECL) == 0)
 		cc = FFI_STDCALL;
 #endif
 	result = ffi_prep_cif(&p->cif, cc,

Modules/_ctypes/callproc.c

@@ -78,7 +78,129 @@
 #define DONT_USE_SEH
 #endif
 
+/*
+  ctypes maintains thread-local storage that has space for two error numbers:
+  private copies of the system 'errno' value and, on Windows, the system error code
+  accessed by the GetLastError() and SetLastError() api functions.
+  
+  Foreign functions created with CDLL(..., use_errno=True), when called, swap
+  the system 'errno' value with the private copy just before the actual
+  function call, and swapped again immediately afterwards.  The 'use_errno'
+  parameter defaults to False, in this case 'ctypes_errno' is not touched.
+
+  On Windows, foreign functions created with CDLL(..., use_last_error=True) or
+  WinDLL(..., use_last_error=True) swap the system LastError value with the
+  ctypes private copy.
+
+  The values are also swapped immeditately before and after ctypes callback
+  functions are called, if the callbacks are constructed using the new
+  optional use_errno parameter set to True: CFUNCTYPE(..., use_errno=TRUE) or
+  WINFUNCTYPE(..., use_errno=True).
+
+  New ctypes functions are provided to access the ctypes private copies from
+  Python:
+
+  - ctypes.set_errno(value) and ctypes.set_last_error(value) store 'value' in
+    the private copy and returns the previous value.
+
+  - ctypes.get_errno() and ctypes.get_last_error() returns the current ctypes
+    private copies value.
+*/
+
+/*
+  This function creates and returns a thread-local Python object that has
+  space to store two integer error numbers; once created the Python object is
+  kept alive in the thread state dictionary as long as the thread itself.
+*/
+PyObject *
+get_error_object(int **pspace)
+{
+	PyObject *dict = PyThreadState_GetDict();
+	PyObject *errobj;
+	if (dict == 0) {
+		PyErr_SetString(PyExc_RuntimeError,
+				"cannot get thread state");
+		return NULL;
+	}
+	errobj = PyDict_GetItemString(dict, "ctypes.error_object");
+	if (errobj)
+		Py_INCREF(errobj);
+	else {
+		void *space = PyMem_Malloc(sizeof(int) * 2);
+		if (space == NULL)
+			return NULL;
+		memset(space, 0, sizeof(int) * 2);
+		errobj = PyCObject_FromVoidPtr(space, PyMem_Free);
+		if (errobj == NULL)
+			return NULL;
+		if (-1 == PyDict_SetItemString(dict, "ctypes.error_object",
+					       errobj)) {
+			Py_DECREF(errobj);
+			return NULL;
+		}
+	}
+	*pspace = (int *)PyCObject_AsVoidPtr(errobj);
+	return errobj;
+}
+
+static PyObject *
+get_error_internal(PyObject *self, PyObject *args, int index)
+{
+	int *space;
+	PyObject *errobj = get_error_object(&space);
+	PyObject *result;
+
+	if (errobj == NULL)
+		return NULL;
+	result = PyLong_FromLong(space[index]);
+	Py_DECREF(errobj);
+	return result;
+}
+
+static PyObject *
+set_error_internal(PyObject *self, PyObject *args, int index)
+{
+	int new_errno, old_errno;
+	PyObject *errobj;
+	int *space;
+
+	if (!PyArg_ParseTuple(args, "i", &new_errno))
+		return NULL;
+	errobj = get_error_object(&space);
+	if (errobj == NULL)
+		return NULL;
+	old_errno = space[index];
+	space[index] = new_errno;
+	Py_DECREF(errobj);
+	return PyLong_FromLong(old_errno);
+}
+
+static PyObject *
+get_errno(PyObject *self, PyObject *args)
+{
+	return get_error_internal(self, args, 0);
+}
+
+static PyObject *
+set_errno(PyObject *self, PyObject *args)
+{
+	return set_error_internal(self, args, 0);
+}
+
 #ifdef MS_WIN32
+
+static PyObject *
+get_last_error(PyObject *self, PyObject *args)
+{
+	return get_error_internal(self, args, 1);
+}
+
+static PyObject *
+set_last_error(PyObject *self, PyObject *args)
+{
+	return set_error_internal(self, args, 1);
+}
+
 PyObject *ComError;
 
 static TCHAR *FormatError(DWORD code)
@@ -614,6 +736,8 @@ static int _call_function_pointer(int flags,
 #ifdef WITH_THREAD
 	PyThreadState *_save = NULL; /* For Py_BLOCK_THREADS and Py_UNBLOCK_THREADS */
 #endif
+	PyObject *error_object = NULL;
+	int *space;
 	ffi_cif cif;
 	int cc;
 #ifdef MS_WIN32
@@ -645,11 +769,26 @@ static int _call_function_pointer(int flags,
 		return -1;
 	}
 
+	if (flags & (FUNCFLAG_USE_ERRNO | FUNCFLAG_USE_LASTERROR)) {
+		error_object = get_error_object(&space);
+		if (error_object == NULL)
+			return -1;
+	}
 #ifdef WITH_THREAD
 	if ((flags & FUNCFLAG_PYTHONAPI) == 0)
 		Py_UNBLOCK_THREADS
 #endif
+	if (flags & FUNCFLAG_USE_ERRNO) {
+		int temp = space[0];
+		space[0] = errno;
+		errno = temp;
+	}
 #ifdef MS_WIN32
+	if (flags & FUNCFLAG_USE_LASTERROR) {
+		int temp = space[1];
+		space[1] = GetLastError();
+		SetLastError(temp);
+	}
 #ifndef DONT_USE_SEH
 	__try {
 #endif
@@ -664,7 +803,18 @@ static int _call_function_pointer(int flags,
 		;
 	}
 #endif
+	if (flags & FUNCFLAG_USE_LASTERROR) {
+		int temp = space[1];
+		space[1] = GetLastError();
+		SetLastError(temp);
+	}
 #endif
+	if (flags & FUNCFLAG_USE_ERRNO) {
+		int temp = space[0];
+		space[0] = errno;
+		errno = temp;
+	}
+	Py_XDECREF(error_object);
 #ifdef WITH_THREAD
 	if ((flags & FUNCFLAG_PYTHONAPI) == 0)
 		Py_BLOCK_THREADS
@@ -1658,6 +1808,8 @@ buffer_info(PyObject *self, PyObject *arg)
 }
 
 PyMethodDef module_methods[] = {
+	{"get_errno", get_errno, METH_NOARGS},
+	{"set_errno", set_errno, METH_VARARGS},
 	{"POINTER", POINTER, METH_O },
 	{"pointer", pointer, METH_O },
 	{"_unpickle", unpickle, METH_VARARGS },
@@ -1667,6 +1819,8 @@ PyMethodDef module_methods[] = {
 	{"set_conversion_mode", set_conversion_mode, METH_VARARGS, set_conversion_mode_doc},
 #endif
 #ifdef MS_WIN32
+	{"get_last_error", get_last_error, METH_NOARGS},
+	{"set_last_error", set_last_error, METH_VARARGS},
 	{"CopyComPointer", copy_com_pointer, METH_VARARGS, copy_com_pointer_doc},
 	{"FormatError", format_error, METH_VARARGS, format_error_doc},
 	{"LoadLibrary", load_library, METH_VARARGS, load_library_doc},

Modules/_ctypes/ctypes.h

@@ -56,6 +56,7 @@ typedef struct {
 	PyObject_VAR_HEAD
 	ffi_closure *pcl; /* the C callable */
 	ffi_cif cif;
+	int flags;
 	PyObject *converters;
 	PyObject *callable;
 	PyObject *restype;
@@ -154,7 +155,7 @@ extern PyMethodDef module_methods[];
 extern CThunkObject *AllocFunctionCallback(PyObject *callable,
 					   PyObject *converters,
 					   PyObject *restype,
-					   int stdcall);
+					   int flags);
 /* a table entry describing a predefined ctypes type */
 struct fielddesc {
 	char code;
@@ -280,6 +281,8 @@ PyObject *_CallProc(PPROC pProc,
 #define FUNCFLAG_CDECL   0x1
 #define FUNCFLAG_HRESULT 0x2
 #define FUNCFLAG_PYTHONAPI 0x4
+#define FUNCFLAG_USE_ERRNO 0x8
+#define FUNCFLAG_USE_LASTERROR 0x10
 
 #define TYPEFLAG_ISPOINTER 0x100
 #define TYPEFLAG_HASPOINTER 0x200
@@ -356,6 +359,7 @@ extern char *alloc_format_string(const char *prefix, const char *suffix);
 extern int IsSimpleSubType(PyObject *obj);
 
 extern PyObject *_pointer_type_cache;
+PyObject *get_error_object(int **pspace);
 
 #ifdef MS_WIN32
 extern PyObject *ComError;