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bpo-46606: os.getgroups() doesn't overallocate (GH-31569)

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Victor Stinner 2022-02-27 00:14:28 +01:00 • committed by GitHub
parent fc44b8136f
commit e02c47528b
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1 changed files with 25 additions and 32 deletions
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53
Modules/posixmodule.c
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@ -7623,30 +7623,20 @@ static PyObject *
os_getgroups_impl(PyObject *module)
/*[clinic end generated code: output=42b0c17758561b56 input=d3f109412e6a155c]*/
{
/* On MacOSX getgroups(2) can return more than MAX_GROUPS results
* This is a helper variable to store the intermediate result when
* that happens.
*
* See bpo-7900.
*/
gid_t *grouplist = NULL;
int n;
/* Issue #17557: As of OS X 10.8, getgroups(2) no longer raises EINVAL if
* there are more groups than can fit in grouplist. Therefore, on OS X
* always first call getgroups with length 0 to get the actual number
* of groups.
*/
n = getgroups(0, NULL);
// Call getgroups with length 0 to get the actual number of groups
int n = getgroups(0, NULL);
if (n < 0) {
return posix_error();
} else {
n++; // Avoid malloc(0)
grouplist = PyMem_New(gid_t, n+1);
}
if (n == 0) {
return PyList_New(0);
}
gid_t *grouplist = PyMem_New(gid_t, n);
if (grouplist == NULL) {
return PyErr_NoMemory();
}
}
n = getgroups(n, grouplist);
if (n == -1) {
@ -7655,22 +7645,25 @@ os_getgroups_impl(PyObject *module)
}
PyObject *result = PyList_New(n);
if (result != NULL) {
int i;
for (i = 0; i < n; ++i) {
PyObject *o = _PyLong_FromGid(grouplist[i]);
if (o == NULL) {
Py_DECREF(result);
result = NULL;
break;
}
PyList_SET_ITEM(result, i, o);
}
if (result == NULL) {
goto error;
}
for (int i = 0; i < n; ++i) {
PyObject *group = _PyLong_FromGid(grouplist[i]);
if (group == NULL) {
goto error;
}
PyList_SET_ITEM(result, i, group);
}
PyMem_Free(grouplist);
return result;
error:
PyMem_Free(grouplist);
Py_XDECREF(result);
return NULL;
}
#endif /* HAVE_GETGROUPS */