Mercurial > cpython-lru_cache-weakref
view Python/structmember.c @ 22621:830c829a7eb2 legacy-trunk
Fix an issue that was reported in but unrelated to the main problem of
SF bug 535905 (Evil Trashcan and GC interaction).
The SETLOCAL() macro should not DECREF the local variable in-place and
then store the new value; it should copy the old value to a temporary
value, then store the new value, and then DECREF the temporary value.
This is because it is possible that during the DECREF the frame is
accessed by other code (e.g. a __del__ method or gc.collect()) and the
variable would be pointing to already-freed memory.
BUGFIX CANDIDATE!
| author | Guido van Rossum <guido@python.org> |
|---|---|
| date | Thu, 28 Mar 2002 20:17:52 +0000 |
| parents | ef6f692c76e2 |
| children | 86fdf8fe7f17 |
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/* Map C struct members to Python object attributes */ #include "Python.h" #include "structmember.h" static PyObject * listmembers(struct memberlist *mlist) { int i, n; PyObject *v; for (n = 0; mlist[n].name != NULL; n++) ; v = PyList_New(n); if (v != NULL) { for (i = 0; i < n; i++) PyList_SetItem(v, i, PyString_FromString(mlist[i].name)); if (PyErr_Occurred()) { Py_DECREF(v); v = NULL; } else { PyList_Sort(v); } } return v; } PyObject * PyMember_Get(char *addr, struct memberlist *mlist, char *name) { struct memberlist *l; if (strcmp(name, "__members__") == 0) return listmembers(mlist); for (l = mlist; l->name != NULL; l++) { if (strcmp(l->name, name) == 0) { PyMemberDef copy; copy.name = l->name; copy.type = l->type; copy.offset = l->offset; copy.flags = l->flags; copy.doc = NULL; return PyMember_GetOne(addr, ©); } } PyErr_SetString(PyExc_AttributeError, name); return NULL; } PyObject * PyMember_GetOne(char *addr, PyMemberDef *l) { PyObject *v; if ((l->flags & READ_RESTRICTED) && PyEval_GetRestricted()) { PyErr_SetString(PyExc_RuntimeError, "restricted attribute"); return NULL; } addr += l->offset; switch (l->type) { case T_BYTE: v = PyInt_FromLong( (long) (((*(char*)addr & 0xff) ^ 0x80) - 0x80)); break; case T_UBYTE: v = PyInt_FromLong((long) *(char*)addr & 0xff); break; case T_SHORT: v = PyInt_FromLong((long) *(short*)addr); break; case T_USHORT: v = PyInt_FromLong((long) *(unsigned short*)addr); break; case T_INT: v = PyInt_FromLong((long) *(int*)addr); break; case T_UINT: v = PyInt_FromLong((long) *(unsigned int*)addr); break; case T_LONG: v = PyInt_FromLong(*(long*)addr); break; case T_ULONG: v = PyLong_FromDouble((double) *(unsigned long*)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 = PyString_FromString(*(char**)addr); break; case T_STRING_INPLACE: v = PyString_FromString((char*)addr); break; #ifdef macintosh case T_PSTRING: if (*(char**)addr == NULL) { Py_INCREF(Py_None); v = Py_None; } else v = PyString_FromStringAndSize( (*(char**)addr)+1, **(unsigned char**)addr); break; case T_PSTRING_INPLACE: v = PyString_FromStringAndSize( ((char*)addr)+1, *(unsigned char*)addr); break; #endif /* macintosh */ case T_CHAR: v = PyString_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; default: PyErr_SetString(PyExc_SystemError, "bad memberdescr type"); v = NULL; } return v; } int PyMember_Set(char *addr, struct memberlist *mlist, char *name, PyObject *v) { struct memberlist *l; for (l = mlist; l->name != NULL; l++) { if (strcmp(l->name, name) == 0) { PyMemberDef copy; copy.name = l->name; copy.type = l->type; copy.offset = l->offset; copy.flags = l->flags; copy.doc = NULL; return PyMember_SetOne(addr, ©, v); } } PyErr_SetString(PyExc_AttributeError, name); return -1; } int PyMember_SetOne(char *addr, PyMemberDef *l, PyObject *v) { PyObject *oldv; if ((l->flags & READONLY) || l->type == T_STRING #ifdef macintosh || l->type == T_PSTRING #endif ) { PyErr_SetString(PyExc_TypeError, "readonly attribute"); return -1; } if ((l->flags & WRITE_RESTRICTED) && PyEval_GetRestricted()) { PyErr_SetString(PyExc_RuntimeError, "restricted 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_BYTE: case T_UBYTE: if (!PyInt_Check(v)) { PyErr_BadArgument(); return -1; } *(char*)addr = (char) PyInt_AsLong(v); break; case T_SHORT: case T_USHORT: if (!PyInt_Check(v)) { PyErr_BadArgument(); return -1; } *(short*)addr = (short) PyInt_AsLong(v); break; case T_UINT: case T_INT: if (!PyInt_Check(v)) { PyErr_BadArgument(); return -1; } *(int*)addr = (int) PyInt_AsLong(v); break; case T_LONG: if (!PyInt_Check(v)) { PyErr_BadArgument(); return -1; } *(long*)addr = PyInt_AsLong(v); break; case T_ULONG: if (PyInt_Check(v)) *(long*)addr = PyInt_AsLong(v); else if (PyLong_Check(v)) *(long*)addr = PyLong_AsLong(v); else { PyErr_BadArgument(); return -1; } break; case T_FLOAT: if (PyInt_Check(v)) *(float*)addr = (float) PyInt_AsLong(v); else if (PyFloat_Check(v)) *(float*)addr = (float) PyFloat_AsDouble(v); else { PyErr_BadArgument(); return -1; } break; case T_DOUBLE: if (PyInt_Check(v)) *(double*)addr = (double) PyInt_AsLong(v); else if (PyFloat_Check(v)) *(double*)addr = PyFloat_AsDouble(v); else { PyErr_BadArgument(); 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: if (PyString_Check(v) && PyString_Size(v) == 1) { *(char*)addr = PyString_AsString(v)[0]; } else { PyErr_BadArgument(); return -1; } break; default: PyErr_Format(PyExc_SystemError, "bad memberdescr type for %s", l->name); return -1; } return 0; }
