view Python/structmember.c @ 56382:2e4d7a40c2dd 3.1

Merged revisions 75246 via svnmerge from svn+ssh://pythondev@svn.python.org/python/branches/py3k ................ r75246 | benjamin.peterson | 2009-10-04 15:32:25 -0500 (Sun, 04 Oct 2009) | 29 lines Merged revisions 74841 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r74841 | thomas.wouters | 2009-09-16 14:55:54 -0500 (Wed, 16 Sep 2009) | 23 lines Fix issue #1590864, multiple threads and fork() can cause deadlocks, by acquiring the import lock around fork() calls. This prevents other threads from having that lock while the fork happens, and is the recommended way of dealing with such issues. There are two other locks we care about, the GIL and the Thread Local Storage lock. The GIL is obviously held when calling Python functions like os.fork(), and the TLS lock is explicitly reallocated instead, while also deleting now-orphaned TLS data. This only fixes calls to os.fork(), not extension modules or embedding programs calling C's fork() directly. Solving that requires a new set of API functions, and possibly a rewrite of the Python/thread_*.c mess. Add a warning explaining the problem to the documentation in the mean time. This also changes behaviour a little on AIX. Before, AIX (but only AIX) was getting the import lock reallocated, seemingly to avoid this very same problem. This is not the right approach, because the import lock is a re-entrant one, and reallocating would do the wrong thing when forking while holding the import lock. Will backport to 2.6, minus the tiny AIX behaviour change. ........ ................
author Benjamin Peterson <benjamin@python.org>
date Sun, 04 Oct 2009 20:35:30 +0000
parents 85b67fb5672b
children 46f4b7b5b4dd
line wrap: on
line source


/* Map C struct members to Python object attributes */

#include "Python.h"

#include "structmember.h"

PyObject *
PyMember_GetOne(const char *addr, PyMemberDef *l)
{
	PyObject *v;

	addr += l->offset;
	switch (l->type) {
	case T_BOOL:
		v = PyBool_FromLong(*(char*)addr);
		break;
	case T_BYTE:
		v = PyLong_FromLong(*(char*)addr);
		break;
	case T_UBYTE:
		v = PyLong_FromUnsignedLong(*(unsigned char*)addr);
		break;
	case T_SHORT:
		v = PyLong_FromLong(*(short*)addr);
		break;
	case T_USHORT:
		v = PyLong_FromUnsignedLong(*(unsigned short*)addr);
		break;
	case T_INT:
		v = PyLong_FromLong(*(int*)addr);
		break;
	case T_UINT:
		v = PyLong_FromUnsignedLong(*(unsigned int*)addr);
		break;
	case T_LONG:
		v = PyLong_FromLong(*(long*)addr);
		break;
	case T_ULONG:
		v = PyLong_FromUnsignedLong(*(unsigned long*)addr);
		break;
	case T_PYSSIZET:
		v = PyLong_FromSsize_t(*(Py_ssize_t*)addr);
		break;
	case T_FLOAT:
		v = PyFloat_FromDouble((double)*(float*)addr);
		break;
	case T_DOUBLE:
		v = PyFloat_FromDouble(*(double*)addr);
		break;
	case T_STRING:
		if (*(char**)addr == NULL) {
			Py_INCREF(Py_None);
			v = Py_None;
		}
		else
			v = PyUnicode_FromString(*(char**)addr);
		break;
	case T_STRING_INPLACE:
		v = PyUnicode_FromString((char*)addr);
		break;
	case T_CHAR:
		v = PyUnicode_FromStringAndSize((char*)addr, 1);
		break;
	case T_OBJECT:
		v = *(PyObject **)addr;
		if (v == NULL)
			v = Py_None;
		Py_INCREF(v);
		break;
	case T_OBJECT_EX:
		v = *(PyObject **)addr;
		if (v == NULL)
			PyErr_SetString(PyExc_AttributeError, l->name);
		Py_XINCREF(v);
		break;
#ifdef HAVE_LONG_LONG
	case T_LONGLONG:
		v = PyLong_FromLongLong(*(PY_LONG_LONG *)addr);
		break;
	case T_ULONGLONG:
		v = PyLong_FromUnsignedLongLong(*(unsigned PY_LONG_LONG *)addr);
		break;
#endif /* HAVE_LONG_LONG */
        case T_NONE:
		v = Py_None;
		Py_INCREF(v);
		break;
	default:
		PyErr_SetString(PyExc_SystemError, "bad memberdescr type");
		v = NULL;
	}
	return v;
}

#define WARN(msg)						\
    do {							\
	if (PyErr_WarnEx(PyExc_RuntimeWarning, msg, 1) < 0)	\
		return -1;					\
    } while (0)

int
PyMember_SetOne(char *addr, PyMemberDef *l, PyObject *v)
{
	PyObject *oldv;

	if ((l->flags & READONLY) || l->type == T_STRING)
	{
		PyErr_SetString(PyExc_AttributeError, "readonly attribute");
		return -1;
	}
	if (v == NULL && l->type != T_OBJECT_EX && l->type != T_OBJECT) {
		PyErr_SetString(PyExc_TypeError,
				"can't delete numeric/char attribute");
		return -1;
	}
	addr += l->offset;
	switch (l->type) {
	case T_BOOL:{
		if (!PyBool_Check(v)) {
			PyErr_SetString(PyExc_TypeError,
					"attribute value type must be bool");
			return -1;
		}
		if (v == Py_True)
			*(char*)addr = (char) 1;
		else
			*(char*)addr = (char) 0;
		break;
		}
	case T_BYTE:{
		long long_val = PyLong_AsLong(v);
		if ((long_val == -1) && PyErr_Occurred())
			return -1;
		*(char*)addr = (char)long_val;
		/* XXX: For compatibility, only warn about truncations
		   for now. */
		if ((long_val > CHAR_MAX) || (long_val < CHAR_MIN))
			WARN("Truncation of value to char");
		break;
		}
	case T_UBYTE:{
		long long_val = PyLong_AsLong(v);
		if ((long_val == -1) && PyErr_Occurred())
			return -1;
		*(unsigned char*)addr = (unsigned char)long_val;
		if ((long_val > UCHAR_MAX) || (long_val < 0))
			WARN("Truncation of value to unsigned char");
		break;
		}
	case T_SHORT:{
		long long_val = PyLong_AsLong(v);
		if ((long_val == -1) && PyErr_Occurred())
			return -1;
		*(short*)addr = (short)long_val;
		if ((long_val > SHRT_MAX) || (long_val < SHRT_MIN))
			WARN("Truncation of value to short");
		break;
		}
	case T_USHORT:{
		long long_val = PyLong_AsLong(v);
		if ((long_val == -1) && PyErr_Occurred())
			return -1;
		*(unsigned short*)addr = (unsigned short)long_val;
		if ((long_val > USHRT_MAX) || (long_val < 0))
			WARN("Truncation of value to unsigned short");
		break;
		}
  	case T_INT:{
		long long_val = PyLong_AsLong(v);
		if ((long_val == -1) && PyErr_Occurred())
			return -1;
		*(int *)addr = (int)long_val;
		if ((long_val > INT_MAX) || (long_val < INT_MIN))
			WARN("Truncation of value to int");
		break;
		}
	case T_UINT:{
		unsigned long ulong_val = PyLong_AsUnsignedLong(v);
		if ((ulong_val == (unsigned int)-1) && PyErr_Occurred()) {
			/* XXX: For compatibility, accept negative int values
			   as well. */
			PyErr_Clear();
			ulong_val = PyLong_AsLong(v);
			if ((ulong_val == (unsigned int)-1) && PyErr_Occurred())
				return -1;
			*(unsigned int *)addr = (unsigned int)ulong_val;
			WARN("Writing negative value into unsigned field");
		} else
			*(unsigned int *)addr = (unsigned int)ulong_val;
		if (ulong_val > UINT_MAX)
			WARN("Truncation of value to unsigned int");
		break;
		}
	case T_LONG:{
		*(long*)addr = PyLong_AsLong(v);
		if ((*(long*)addr == -1) && PyErr_Occurred())
			return -1;
		break;
		}
	case T_ULONG:{
		*(unsigned long*)addr = PyLong_AsUnsignedLong(v);
		if ((*(unsigned long*)addr == (unsigned long)-1)
		    && PyErr_Occurred()) {
			/* XXX: For compatibility, accept negative int values
			   as well. */
			PyErr_Clear();
			*(unsigned long*)addr = PyLong_AsLong(v);
			if ((*(unsigned long*)addr == (unsigned int)-1)
			    && PyErr_Occurred())
				return -1;
			WARN("Writing negative value into unsigned field");
		}
		break;
		}
	case T_PYSSIZET:{
		*(Py_ssize_t*)addr = PyLong_AsSsize_t(v);
		if ((*(Py_ssize_t*)addr == (Py_ssize_t)-1)
		    && PyErr_Occurred())
				return -1;
		break;
		}
	case T_FLOAT:{
		double double_val = PyFloat_AsDouble(v);
		if ((double_val == -1) && PyErr_Occurred())
			return -1;
		*(float*)addr = (float)double_val;
		break;
		}
	case T_DOUBLE:
		*(double*)addr = PyFloat_AsDouble(v);
		if ((*(double*)addr == -1) && PyErr_Occurred())
			return -1;
		break;
	case T_OBJECT:
	case T_OBJECT_EX:
		Py_XINCREF(v);
		oldv = *(PyObject **)addr;
		*(PyObject **)addr = v;
		Py_XDECREF(oldv);
		break;
	case T_CHAR: {
		char *string;
		Py_ssize_t len;

		if (!PyUnicode_Check(v)) {
			PyErr_BadArgument();
			return -1;
		}
		string = _PyUnicode_AsStringAndSize(v, &len);
		if (len != 1) {
			PyErr_BadArgument();
			return -1;
		}
		*(char*)addr = string[0];
		break;
		}
#ifdef HAVE_LONG_LONG
	case T_LONGLONG:{
		PY_LONG_LONG value;
		*(PY_LONG_LONG*)addr = value = PyLong_AsLongLong(v);
		if ((value == -1) && PyErr_Occurred())
			return -1;
		break;
		}
	case T_ULONGLONG:{
		unsigned PY_LONG_LONG value;
		/* ??? PyLong_AsLongLong accepts an int, but PyLong_AsUnsignedLongLong
			doesn't ??? */
		if (PyLong_Check(v))
			*(unsigned PY_LONG_LONG*)addr = value = PyLong_AsUnsignedLongLong(v);
		else
			*(unsigned PY_LONG_LONG*)addr = value = PyLong_AsLong(v);
		if ((value == (unsigned PY_LONG_LONG)-1) && PyErr_Occurred())
			return -1;
		break;
		}
#endif /* HAVE_LONG_LONG */
	default:
		PyErr_Format(PyExc_SystemError,
			     "bad memberdescr type for %s", l->name);
		return -1;
	}
	return 0;
}