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Reworked to eliminate all potential memory problems, including 

deletion of object from list argument during callout to fileno().
This commit is contained in:
Barry Warsaw 1996-12-12 22:16:21 +00:00
parent 32616fbee6
commit c1cb360683
1 changed files with 110 additions and 73 deletions
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183
Modules/selectmodule.c
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@ -57,11 +57,26 @@ extern void bzero();
static PyObject *SelectError;
typedef struct { /* list of Python objects and their file descriptor */
PyObject *obj;
/* list of Python objects and their file descriptor */
typedef struct {
PyObject *obj; /* owned reference */
SOCKET fd;
int sentinel; /* -1 == sentinel */
} pylist;
static void
reap_obj(fd2obj)
pylist fd2obj[FD_SETSIZE + 3];
{
int i;
for (i = 0; i < FD_SETSIZE + 3 && fd2obj[i].sentinel >= 0; i++) {
Py_XDECREF(fd2obj[i].obj);
fd2obj[i].obj = NULL;
}
fd2obj[0].sentinel = -1;
}
/* returns -1 and sets the Python exception if an error occurred, otherwise
returns a number >= 0
*/
@ -71,67 +86,76 @@ list2set(list, set, fd2obj)
fd_set *set;
pylist fd2obj[FD_SETSIZE + 3];
{
int i, len, index, max = -1;
PyObject *o, *fno;
PyObject *meth;
SOCKET v;
int i;
int max = -1;
int index = 0;
int len = PyList_Size(list);
PyObject* o = NULL;
index = 0;
fd2obj[0].obj = (PyObject*)0; /* set list to zero size */
FD_ZERO(set);
len = PyList_Size(list);
for (i=0; i<len; i++) {
for (i = 0; i < len; i++) {
PyObject *meth;
SOCKET v;
/* any intervening fileno() calls could decr this refcnt */
o = PyList_GetItem(list, i);
Py_INCREF(o);
if (PyInt_Check(o)) {
v = PyInt_AsLong(o);
}
else if ((meth = PyObject_GetAttrString(o, "fileno")) != NULL)
{
fno = PyEval_CallObject(meth, NULL);
PyObject *fno = PyEval_CallObject(meth, NULL);
Py_DECREF(meth);
if (fno == NULL)
return -1;
goto finally;
if (!PyInt_Check(fno)) {
PyErr_SetString(PyExc_TypeError,
PyErr_SetString(PyExc_TypeError,
"fileno method returned a non-integer");
Py_DECREF(fno);
return -1;
Py_DECREF(fno);
goto finally;
}
v = PyInt_AsLong(fno);
Py_DECREF(fno);
}
else {
PyErr_SetString(PyExc_TypeError,
"argument must be an int, or have a fileno() method."
);
return -1;
"argument must be an int, or have a fileno() method.");
goto finally;
}
#ifdef _MSC_VER
max = 0; /* not used for Win32 */
#else
max = 0; /* not used for Win32 */
#else /* !_MSC_VER */
if (v < 0 || v >= FD_SETSIZE) {
PyErr_SetString(
PyExc_ValueError,
"filedescriptor out of range in select()");
return -1;
PyErr_SetString(PyExc_ValueError,
"filedescriptor out of range in select()");
goto finally;
}
if (v > max)
max = v;
#endif
#endif /* _MSC_VER */
FD_SET(v, set);
/* add object and its file descriptor to the list */
if (index >= FD_SETSIZE) {
PyErr_SetString(
PyExc_ValueError,
"too many file descriptors in select()");
return -1;
PyErr_SetString(PyExc_ValueError,
"too many file descriptors in select()");
goto finally;
}
fd2obj[index].obj = o;
fd2obj[index].fd = v;
fd2obj[++index].obj = (PyObject *)0; /* sentinel */
fd2obj[index].sentinel = 0;
fd2obj[++index].sentinel = -1;
}
return max+1;
finally:
Py_XDECREF(o);
return -1;
}
/* returns NULL and sets the Python exception if an error occurred */
@ -140,40 +164,44 @@ set2list(set, fd2obj)
fd_set *set;
pylist fd2obj[FD_SETSIZE + 3];
{
int j, num=0;
int i, j, count=0;
PyObject *list, *o;
SOCKET fd;
for (j=0; fd2obj[j].obj; j++)
for (j = 0; fd2obj[j].sentinel >= 0; j++) {
if (FD_ISSET(fd2obj[j].fd, set))
num++;
list = PyList_New(num);
count++;
}
list = PyList_New(count);
if (!list)
return NULL;
num = 0;
for (j=0; fd2obj[j].obj; j++) {
i = 0;
for (j = 0; fd2obj[j].sentinel >= 0; j++) {
fd = fd2obj[j].fd;
if (FD_ISSET(fd, set)) {
#ifndef _MSC_VER
if (fd > FD_SETSIZE) {
PyErr_SetString(PyExc_SystemError,
"filedescriptor out of range returned in select()");
return NULL;
goto finally;
}
#endif
o = fd2obj[j].obj;
Py_INCREF(o);
if (PyList_SetItem(list, num, o) < 0) {
Py_DECREF(list);
return NULL;
}
num++;
fd2obj[j].obj = NULL;
/* transfer ownership */
if (PyList_SetItem(list, i, o) < 0)
goto finally;
i++;
}
}
return list;
finally:
Py_DECREF(list);
return NULL;
}
static PyObject *
select_select(self, args)
@ -184,7 +212,7 @@ select_select(self, args)
pylist wfd2obj[FD_SETSIZE + 3];
pylist efd2obj[FD_SETSIZE + 3];
PyObject *ifdlist, *ofdlist, *efdlist;
PyObject *ret;
PyObject *ret = NULL;
PyObject *tout = Py_None;
fd_set ifdset, ofdset, efdset;
double timeout;
@ -200,9 +228,11 @@ select_select(self, args)
if (tout == Py_None)
tvp = (struct timeval *)0;
else if (!PyArg_Parse(tout, "d;timeout must be float or None",
&timeout))
else if (!PyArg_Parse(tout, "d", &timeout)) {
PyErr_SetString(PyExc_TypeError,
"timeout must be a float or None");
return NULL;
}
else {
seconds = (int)timeout;
timeout = timeout - (double)seconds;
@ -224,12 +254,15 @@ select_select(self, args)
/* Convert lists to fd_sets, and get maximum fd number
* propagates the Python exception set in list2set()
*/
rfd2obj[0].sentinel = -1;
wfd2obj[0].sentinel = -1;
efd2obj[0].sentinel = -1;
if ((imax=list2set(ifdlist, &ifdset, rfd2obj)) < 0)
return NULL;
goto finally;
if ((omax=list2set(ofdlist, &ofdset, wfd2obj)) < 0)
return NULL;
goto finally;
if ((emax=list2set(efdlist, &efdset, efd2obj)) < 0)
return NULL;
goto finally;
max = imax;
if (omax > max) max = omax;
if (emax > max) max = emax;
@ -240,33 +273,37 @@ select_select(self, args)
if (n < 0) {
PyErr_SetFromErrno(SelectError);
return NULL;
}
if (n == 0) { /* Speedup hack */
else if (n == 0) {
/* optimization */
ifdlist = PyList_New(0);
if (!ifdlist)
return NULL;
ret = Py_BuildValue("OOO", ifdlist, ifdlist, ifdlist);
Py_XDECREF(ifdlist);
return ret;
if (ifdlist) {
ret = Py_BuildValue("OOO", ifdlist, ifdlist, ifdlist);
Py_DECREF(ifdlist);
}
}
else {
/* any of these three calls can raise an exception. it's more
convenient to test for this after all three calls... but
is that acceptable?
*/
ifdlist = set2list(&ifdset, rfd2obj);
ofdlist = set2list(&ofdset, wfd2obj);
efdlist = set2list(&efdset, efd2obj);
if (PyErr_Occurred())
ret = NULL;
else
ret = Py_BuildValue("OOO", ifdlist, ofdlist, efdlist);
/* any of these three calls can raise an exception. it's more
convenient to test for this after all three calls... but is that
acceptable?
*/
ifdlist = set2list(&ifdset, rfd2obj);
ofdlist = set2list(&ofdset, wfd2obj);
efdlist = set2list(&efdset, efd2obj);
if (PyErr_Occurred())
ret = NULL;
else
ret = Py_BuildValue("OOO", ifdlist, ofdlist, efdlist);
Py_DECREF(ifdlist);
Py_DECREF(ofdlist);
Py_DECREF(efdlist);
Py_DECREF(ifdlist);
Py_DECREF(ofdlist);
Py_DECREF(efdlist);
}
finally:
reap_obj(rfd2obj);
reap_obj(wfd2obj);
reap_obj(efd2obj);
return ret;
}