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bpo-29849: fix memory leak in import_from #712

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Merged
merged 4 commits into from
Mar 21, 2017
Merged

bpo-29849: fix memory leak in import_from #712

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4b9cdb7
fix memory leak in import_from
zhangyangyu Mar 18, 2017
e5348a3
Merge branch 'master' into bpo-29849
zhangyangyu Mar 20, 2017
0dc322f
add NEWS
zhangyangyu Mar 20, 2017
44c9d72
fix comment and style
zhangyangyu Mar 21, 2017
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2 changes: 2 additions & 0 deletions Misc/NEWS
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,8 @@ What's New in Python 3.7.0 alpha 1?
Core and Builtins
-----------------

- bpo-29849: Fix a memory leak when an ImportError is raised during from import.

- bpo-28856: Fix an oversight that %b format for bytes should support objects
follow the buffer protocol.

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23 changes: 14 additions & 9 deletions Python/ceval.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5024,7 +5024,7 @@ import_from(PyObject *v, PyObject *name)
{
PyObject *x;
_Py_IDENTIFIER(__name__);
PyObject *fullmodname, *pkgname, *pkgpath, *pkgname_or_unknown;
PyObject *fullmodname, *pkgname, *pkgpath, *pkgname_or_unknown, *errmsg;

x = PyObject_GetAttr(v, name);
if (x != NULL || !PyErr_ExceptionMatches(PyExc_AttributeError))
Expand All @@ -5039,6 +5039,7 @@ import_from(PyObject *v, PyObject *name)
}
fullmodname = PyUnicode_FromFormat("%U.%U", pkgname, name);
if (fullmodname == NULL) {
Py_DECREF(pkgname);
return NULL;
}
x = PyDict_GetItem(PyImport_GetModuleDict(), fullmodname);
Expand All @@ -5063,17 +5064,21 @@ import_from(PyObject *v, PyObject *name)

if (pkgpath == NULL || !PyUnicode_Check(pkgpath)) {
PyErr_Clear();
PyErr_SetImportError(
PyUnicode_FromFormat("cannot import name %R from %R (unknown location)",
name, pkgname_or_unknown),
pkgname, NULL);
errmsg = PyUnicode_FromFormat(
"cannot import name %R from %R (unknown location)",
name, pkgname_or_unknown
);
/* doesn't check NULL for errmsg, PyErr_SetImportError will catch */
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I don't think the comment is necessary long-term.

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@zhangyangyu zhangyangyu Mar 20, 2017 •
edited
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This comment is to make others know the error check is left out deliberately. It is not an oversight.
Do you think it's a must to remove it?

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If you want to keep it then please change it to "/* NULL check for errmsg done by PyErr_SetImportError. */".

PyErr_SetImportError(errmsg, pkgname, NULL);
} else {
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While you're here you might as well fix the formatting for this.

PyErr_SetImportError(
PyUnicode_FromFormat("cannot import name %R from %R (%S)",
name, pkgname_or_unknown, pkgpath),
pkgname, pkgpath);
errmsg = PyUnicode_FromFormat(
"cannot import name %R from %R (%S)",
name, pkgname_or_unknown, pkgpath
);
PyErr_SetImportError(errmsg, pkgname, pkgpath);
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Need a similar comment here if you are going to leave it in.

}

Py_XDECREF(errmsg);
Py_XDECREF(pkgname_or_unknown);
Py_XDECREF(pkgpath);
return NULL;
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