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Reworked to eliminate all potential memory problems, including

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