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Repair widespread misuse of _PyString_Resize. Since it's clear people

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don't understand how this function works, also beefed up the docs.  The
most common usage error is of this form (often spread out across gotos):

	if (_PyString_Resize(&s, n) < 0) {
		Py_DECREF(s);
		s = NULL;
		goto outtahere;
	}

The error is that if _PyString_Resize runs out of memory, it automatically
decrefs the input string object s (which also deallocates it, since its
refcount must be 1 upon entry), and sets s to NULL.  So if the "if"
branch ever triggers, it's an error to call Py_DECREF(s):  s is already
NULL!  A correct way to write the above is the simpler (and intended)

	if (_PyString_Resize(&s, n) < 0)
		goto outtahere;

Bugfix candidate.
This commit is contained in:
Tim Peters 2002-04-27 18:44:32 +00:00
parent 602f740bc2
commit 5de9842b34
14 changed files with 54 additions and 90 deletions
Download patch file Download diff file Expand all files Collapse all files

34
Objects/unicodeobject.c
View file

@ -927,10 +927,7 @@ PyObject *PyUnicode_EncodeUTF7(const Py_UNICODE *s,
*out++ = '-';
}
if (_PyString_Resize(&v, out - start)) {
Py_DECREF(v);
return NULL;
}
_PyString_Resize(&v, out - start);
return v;
}
@ -1764,7 +1761,7 @@ PyObject *unicodeescape_string(const Py_UNICODE *s,
/* Resize the string if necessary */
if (offset + 12 > PyString_GET_SIZE(repr)) {
if (_PyString_Resize(&repr, PyString_GET_SIZE(repr) + 100))
goto onError;
return NULL;
p = PyString_AS_STRING(repr) + offset;
}
@ -1847,14 +1844,8 @@ PyObject *unicodeescape_string(const Py_UNICODE *s,
*p++ = PyString_AS_STRING(repr)[1];
*p = '\0';
if (_PyString_Resize(&repr, p - PyString_AS_STRING(repr)))
goto onError;
_PyString_Resize(&repr, p - PyString_AS_STRING(repr));
return repr;
onError:
Py_DECREF(repr);
return NULL;
}
PyObject *PyUnicode_EncodeUnicodeEscape(const Py_UNICODE *s,
@ -1985,14 +1976,8 @@ PyObject *PyUnicode_EncodeRawUnicodeEscape(const Py_UNICODE *s,
*p++ = (char) ch;
}
*p = '\0';
if (_PyString_Resize(&repr, p - q))
goto onError;
_PyString_Resize(&repr, p - q);
return repr;
onError:
Py_DECREF(repr);
return NULL;
}
PyObject *PyUnicode_AsRawUnicodeEscapeString(PyObject *unicode)
@ -2092,8 +2077,7 @@ PyObject *PyUnicode_EncodeLatin1(const Py_UNICODE *p,
}
/* Resize if error handling skipped some characters */
if (s - start < PyString_GET_SIZE(repr))
if (_PyString_Resize(&repr, s - start))
goto onError;
_PyString_Resize(&repr, s - start);
return repr;
onError:
@ -2240,8 +2224,7 @@ PyObject *PyUnicode_EncodeASCII(const Py_UNICODE *p,
}
/* Resize if error handling skipped some characters */
if (s - start < PyString_GET_SIZE(repr))
if (_PyString_Resize(&repr, s - start))
goto onError;
_PyString_Resize(&repr, s - start);
return repr;
onError:
@ -2588,12 +2571,11 @@ PyObject *PyUnicode_EncodeCharmap(const Py_UNICODE *p,
Py_DECREF(x);
}
if (s - PyString_AS_STRING(v) < PyString_GET_SIZE(v))
if (_PyString_Resize(&v, (int)(s - PyString_AS_STRING(v))))
goto onError;
_PyString_Resize(&v, (int)(s - PyString_AS_STRING(v)));
return v;
onError:
Py_DECREF(v);
Py_XDECREF(v);
return NULL;
}