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Issue python#6012: Add cleanup support to O& argument parsing.
1 parent 2703fd9 commit c15bdef

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Lines changed: 120 additions & 11 deletions

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‎Doc/c-api/arg.rst‎

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -250,6 +250,14 @@ variable(s) whose address should be passed.
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the conversion has failed. When the conversion fails, the *converter* function
251251
should raise an exception and leave the content of *address* unmodified.
252252

253+
If the *converter* returns Py_CLEANUP_SUPPORTED, it may get called a second time
254+
if the argument parsing eventually fails, giving the converter a chance to release
255+
any memory that it had already allocated. In this second call, the *object* parameter
256+
will be NULL; *address* will have the same value as in the original call.
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258+
.. versionchanged:: 3.1
259+
Py_CLEANUP_SUPPORTED was added.
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``S`` (string) [PyStringObject \*]
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Like ``O`` but requires that the Python object is a string object. Raises
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:exc:`TypeError` if the object is not a string object. The C variable may also

‎Doc/c-api/unicode.rst‎

Lines changed: 20 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -379,11 +379,13 @@ Many of the following APIs take two arguments encoding and errors. These
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parameters encoding and errors have the same semantics as the ones of the
380380
builtin unicode() Unicode object constructor.
381381

382-
Setting encoding to *NULL* causes the default encoding to be used which is
383-
ASCII. The file system calls should use :cdata:`Py_FileSystemDefaultEncoding`
384-
as the encoding for file names. This variable should be treated as read-only: On
385-
some systems, it will be a pointer to a static string, on others, it will change
386-
at run-time (such as when the application invokes setlocale).
382+
Setting encoding to *NULL* causes the default encoding to be used
383+
which is ASCII. The file system calls should use
384+
:cfunc:`PyUnicode_FSConverter` for encoding file names. This uses the
385+
variable :cdata:`Py_FileSystemDefaultEncoding` internally. This
386+
variable should be treated as read-only: On some systems, it will be a
387+
pointer to a static string, on others, it will change at run-time
388+
(such as when the application invokes setlocale).
387389

388390
Error handling is set by errors which may also be set to *NULL* meaning to use
389391
the default handling defined for the codec. Default error handling for all
@@ -782,6 +784,19 @@ the user settings on the machine running the codec.
782784
object. Error handling is "strict". Return *NULL* if an exception was
783785
raised by the codec.
784786

787+
For decoding file names and other environment strings, :cdata:`Py_FileSystemEncoding`
788+
should be used as the encoding, and ``"surrogateescape"`` should be used as the error
789+
handler. For encoding file names during argument parsing, the ``O&`` converter should
790+
be used, passsing PyUnicode_FSConverter as the conversion function:
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792+
.. cfunction:: int PyUnicode_FSConverter(PyObject* obj, void* result)
793+
794+
Convert *obj* into *result*, using the file system encoding, and the ``surrogateescape``
795+
error handler. *result* must be a ``PyObject*``, yielding a bytes or bytearray object
796+
which must be released if it is no longer used.
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798+
.. versionadded:: 3.1
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785800
.. % --- Methods & Slots ----------------------------------------------------
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787802

‎Include/modsupport.h‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -43,6 +43,8 @@ PyAPI_FUNC(int) PyModule_AddStringConstant(PyObject *, const char *, const char
4343
#define PyModule_AddIntMacro(m, c) PyModule_AddIntConstant(m, #c, c)
4444
#define PyModule_AddStringMacro(m, c) PyModule_AddStringConstant(m, #c, c)
4545

46+
#define Py_CLEANUP_SUPPORTED 0x20000
47+
4648
#define PYTHON_API_VERSION 1013
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#define PYTHON_API_STRING "1013"
4850
/* The API version is maintained (independently from the Python version)

‎Lib/test/test_capi.py‎

Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -115,6 +115,10 @@ def test_pendingcalls_non_threaded(self):
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self.pendingcalls_submit(l, n)
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self.pendingcalls_wait(l, n)
117117

118+
# Bug #6012
119+
class Test6012(unittest.TestCase):
120+
def test(self):
121+
self.assertEqual(_testcapi.argparsing("Hello", "World"), 1)
118122

119123
def test_main():
120124
support.run_unittest(CAPITest)
@@ -159,7 +163,7 @@ def callback():
159163
t.start()
160164
t.join()
161165

162-
support.run_unittest(TestPendingCalls)
166+
support.run_unittest(TestPendingCalls, Test6012)
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164168

165169
if __name__ == "__main__":

‎Misc/NEWS‎

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Original file line numberDiff line numberDiff line change
@@ -12,6 +12,8 @@ What's New in Python 3.1 release candidate 1?
1212
Core and Builtins
1313
-----------------
1414

15+
- Issue #6012: Add cleanup support to O& argument parsing.
16+
1517
- Issue #6089: Fixed str.format with certain invalid field specifiers
1618
that would raise SystemError.
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‎Modules/_testcapimodule.c‎

Lines changed: 31 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1415,6 +1415,36 @@ raise_memoryerror(PyObject *self)
14151415
return NULL;
14161416
}
14171417

1418+
/* Issue 6012 */
1419+
static PyObject *str1, *str2;
1420+
static int
1421+
failing_converter(PyObject *obj, void *arg)
1422+
{
1423+
/* Clone str1, then let the conversion fail. */
1424+
assert(str1);
1425+
str2 = str1;
1426+
Py_INCREF(str2);
1427+
return 0;
1428+
}
1429+
static PyObject*
1430+
argparsing(PyObject *o, PyObject *args)
1431+
{
1432+
PyObject *res;
1433+
str1 = str2 = NULL;
1434+
if (!PyArg_ParseTuple(args, "O&O&",
1435+
PyUnicode_FSConverter, &str1,
1436+
failing_converter, &str2)) {
1437+
if (!str2)
1438+
/* argument converter not called? */
1439+
return NULL;
1440+
/* Should be 1 */
1441+
res = PyLong_FromLong(Py_REFCNT(str2));
1442+
Py_DECREF(str2);
1443+
PyErr_Clear();
1444+
return res;
1445+
}
1446+
Py_RETURN_NONE;
1447+
}
14181448

14191449
static PyMethodDef TestMethods[] = {
14201450
{"raise_exception", raise_exception, METH_VARARGS},
@@ -1433,7 +1463,6 @@ static PyMethodDef TestMethods[] = {
14331463
PyDoc_STR("This is a pretty normal docstring.")},
14341464
{"test_string_to_double", (PyCFunction)test_string_to_double, METH_NOARGS},
14351465
{"test_capsule", (PyCFunction)test_capsule, METH_NOARGS},
1436-
14371466
{"getargs_tuple", getargs_tuple, METH_VARARGS},
14381467
{"getargs_keywords", (PyCFunction)getargs_keywords,
14391468
METH_VARARGS|METH_KEYWORDS},
@@ -1468,6 +1497,7 @@ static PyMethodDef TestMethods[] = {
14681497
#endif
14691498
{"traceback_print", traceback_print, METH_VARARGS},
14701499
{"exception_print", exception_print, METH_VARARGS},
1500+
{"argparsing", argparsing, METH_VARARGS},
14711501
{NULL, NULL} /* sentinel */
14721502
};
14731503

‎Modules/posixmodule.c‎

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Original file line numberDiff line numberDiff line change
@@ -804,8 +804,6 @@ posix_2str(PyObject *args,
804804
if (!PyArg_ParseTuple(args, format,
805805
PyUnicode_FSConverter, &opath1,
806806
PyUnicode_FSConverter, &opath2)) {
807-
Py_XDECREF(opath1);
808-
Py_XDECREF(opath2);
809807
return NULL;
810808
}
811809
path1 = bytes2str(opath1, 1);

‎Objects/unicodeobject.c‎

Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1539,6 +1539,10 @@ PyUnicode_FSConverter(PyObject* arg, void* addr)
15391539
PyObject *output = NULL;
15401540
Py_ssize_t size;
15411541
void *data;
1542+
if (arg == NULL) {
1543+
Py_DECREF(*(PyObject**)addr);
1544+
return 1;
1545+
}
15421546
if (PyBytes_Check(arg) || PyByteArray_Check(arg)) {
15431547
output = arg;
15441548
Py_INCREF(output);
@@ -1573,7 +1577,7 @@ PyUnicode_FSConverter(PyObject* arg, void* addr)
15731577
return 0;
15741578
}
15751579
*(PyObject**)addr = output;
1576-
return 1;
1580+
return Py_CLEANUP_SUPPORTED;
15771581
}
15781582

15791583

‎Python/getargs.c‎

Lines changed: 47 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -141,6 +141,7 @@ _PyArg_VaParse_SizeT(PyObject *args, char *format, va_list va)
141141

142142
#define GETARGS_CAPSULE_NAME_CLEANUP_PTR "getargs.cleanup_ptr"
143143
#define GETARGS_CAPSULE_NAME_CLEANUP_BUFFER "getargs.cleanup_buffer"
144+
#define GETARGS_CAPSULE_NAME_CLEANUP_CONVERT "getargs.cleanup_convert"
144145

145146
static void
146147
cleanup_ptr(PyObject *self)
@@ -194,6 +195,46 @@ addcleanup(void *ptr, PyObject **freelist, PyCapsule_Destructor destr)
194195
return 0;
195196
}
196197

198+
static void
199+
cleanup_convert(PyObject *self)
200+
{
201+
typedef int (*destr_t)(PyObject *, void *);
202+
destr_t destr = (destr_t)PyCapsule_GetContext(self);
203+
void *ptr = PyCapsule_GetPointer(self,
204+
GETARGS_CAPSULE_NAME_CLEANUP_CONVERT);
205+
if (ptr && destr)
206+
destr(NULL, ptr);
207+
}
208+
209+
static int
210+
addcleanup_convert(void *ptr, PyObject **freelist, int (*destr)(PyObject*,void*))
211+
{
212+
PyObject *cobj;
213+
if (!*freelist) {
214+
*freelist = PyList_New(0);
215+
if (!*freelist) {
216+
destr(NULL, ptr);
217+
return -1;
218+
}
219+
}
220+
cobj = PyCapsule_New(ptr, GETARGS_CAPSULE_NAME_CLEANUP_CONVERT,
221+
cleanup_convert);
222+
if (!cobj) {
223+
destr(NULL, ptr);
224+
return -1;
225+
}
226+
if (PyCapsule_SetContext(cobj, destr) == -1) {
227+
/* This really should not happen. */
228+
Py_FatalError("capsule refused setting of context.");
229+
}
230+
if (PyList_Append(*freelist, cobj)) {
231+
Py_DECREF(cobj); /* This will also call destr. */
232+
return -1;
233+
}
234+
Py_DECREF(cobj);
235+
return 0;
236+
}
237+
197238
static int
198239
cleanreturn(int retval, PyObject *freelist)
199240
{
@@ -1253,10 +1294,15 @@ convertsimple(PyObject *arg, const char **p_format, va_list *p_va, int flags,
12531294
typedef int (*converter)(PyObject *, void *);
12541295
converter convert = va_arg(*p_va, converter);
12551296
void *addr = va_arg(*p_va, void *);
1297+
int res;
12561298
format++;
1257-
if (! (*convert)(arg, addr))
1299+
if (! (res = (*convert)(arg, addr)))
12581300
return converterr("(unspecified)",
12591301
arg, msgbuf, bufsize);
1302+
if (res == Py_CLEANUP_SUPPORTED &&
1303+
addcleanup_convert(addr, freelist, convert) == -1)
1304+
return converterr("(cleanup problem)",
1305+
arg, msgbuf, bufsize);
12601306
}
12611307
else {
12621308
p = va_arg(*p_va, PyObject **);

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