ref: a70b93a356662355214f5405edda066786f6dd03
dir: /sys/src/cmd/python/Modules/selectmodule.c/
/* select - Module containing unix select(2) call.
Under Unix, the file descriptors are small integers.
Under Win32, select only exists for sockets, and sockets may
have any value except INVALID_SOCKET.
Under BeOS, we suffer the same dichotomy as Win32; sockets can be anything
>= 0.
*/
#include "Python.h"
#ifdef __APPLE__
/* Perform runtime testing for a broken poll on OSX to make it easier
* to use the same binary on multiple releases of the OS.
*/
#undef HAVE_BROKEN_POLL
#endif
/* Windows #defines FD_SETSIZE to 64 if FD_SETSIZE isn't already defined.
64 is too small (too many people have bumped into that limit).
Here we boost it.
Users who want even more than the boosted limit should #define
FD_SETSIZE higher before this; e.g., via compiler /D switch.
*/
#if defined(MS_WINDOWS) && !defined(FD_SETSIZE)
#define FD_SETSIZE 512
#endif
#if defined(HAVE_POLL_H)
#include <poll.h>
#elif defined(HAVE_SYS_POLL_H)
#include <sys/poll.h>
#endif
#ifdef __sgi
/* This is missing from unistd.h */
extern void bzero(void *, int);
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#if defined(PYOS_OS2) && !defined(PYCC_GCC)
#include <sys/time.h>
#include <utils.h>
#endif
#ifdef MS_WINDOWS
# include <winsock.h>
#else
# define SOCKET int
# ifdef __BEOS__
# include <net/socket.h>
# elif defined(__VMS)
# include <socket.h>
# endif
#endif
static PyObject *SelectError;
/* 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(pylist fd2obj[FD_SETSIZE + 1])
{
int i;
for (i = 0; i < FD_SETSIZE + 1 && 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
*/
static int
seq2set(PyObject *seq, fd_set *set, pylist fd2obj[FD_SETSIZE + 1])
{
int i;
int max = -1;
int index = 0;
int len = -1;
PyObject* fast_seq = NULL;
PyObject* o = NULL;
fd2obj[0].obj = (PyObject*)0; /* set list to zero size */
FD_ZERO(set);
fast_seq=PySequence_Fast(seq, "arguments 1-3 must be sequences");
if (!fast_seq)
return -1;
len = PySequence_Fast_GET_SIZE(fast_seq);
for (i = 0; i < len; i++) {
SOCKET v;
/* any intervening fileno() calls could decr this refcnt */
if (!(o = PySequence_Fast_GET_ITEM(fast_seq, i)))
return -1;
Py_INCREF(o);
v = PyObject_AsFileDescriptor( o );
if (v == -1) goto finally;
#if defined(_MSC_VER)
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()");
goto finally;
}
if (v > max)
max = v;
#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()");
goto finally;
}
fd2obj[index].obj = o;
fd2obj[index].fd = v;
fd2obj[index].sentinel = 0;
fd2obj[++index].sentinel = -1;
}
Py_DECREF(fast_seq);
return max+1;
finally:
Py_XDECREF(o);
Py_DECREF(fast_seq);
return -1;
}
/* returns NULL and sets the Python exception if an error occurred */
static PyObject *
set2list(fd_set *set, pylist fd2obj[FD_SETSIZE + 1])
{
int i, j, count=0;
PyObject *list, *o;
SOCKET fd;
for (j = 0; fd2obj[j].sentinel >= 0; j++) {
if (FD_ISSET(fd2obj[j].fd, set))
count++;
}
list = PyList_New(count);
if (!list)
return NULL;
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()");
goto finally;
}
#endif
o = fd2obj[j].obj;
fd2obj[j].obj = NULL;
/* transfer ownership */
if (PyList_SetItem(list, i, o) < 0)
goto finally;
i++;
}
}
return list;
finally:
Py_DECREF(list);
return NULL;
}
#undef SELECT_USES_HEAP
#if FD_SETSIZE > 1024
#define SELECT_USES_HEAP
#endif /* FD_SETSIZE > 1024 */
static PyObject *
select_select(PyObject *self, PyObject *args)
{
#ifdef SELECT_USES_HEAP
pylist *rfd2obj, *wfd2obj, *efd2obj;
#else /* !SELECT_USES_HEAP */
/* XXX: All this should probably be implemented as follows:
* - find the highest descriptor we're interested in
* - add one
* - that's the size
* See: Stevens, APitUE, $12.5.1
*/
pylist rfd2obj[FD_SETSIZE + 1];
pylist wfd2obj[FD_SETSIZE + 1];
pylist efd2obj[FD_SETSIZE + 1];
#endif /* SELECT_USES_HEAP */
PyObject *ifdlist, *ofdlist, *efdlist;
PyObject *ret = NULL;
PyObject *tout = Py_None;
fd_set ifdset, ofdset, efdset;
double timeout;
struct timeval tv, *tvp;
long seconds;
int imax, omax, emax, max;
int n;
/* convert arguments */
if (!PyArg_UnpackTuple(args, "select", 3, 4,
&ifdlist, &ofdlist, &efdlist, &tout))
return NULL;
if (tout == Py_None)
tvp = (struct timeval *)0;
else if (!PyNumber_Check(tout)) {
PyErr_SetString(PyExc_TypeError,
"timeout must be a float or None");
return NULL;
}
else {
timeout = PyFloat_AsDouble(tout);
if (timeout == -1 && PyErr_Occurred())
return NULL;
if (timeout > (double)LONG_MAX) {
PyErr_SetString(PyExc_OverflowError,
"timeout period too long");
return NULL;
}
seconds = (long)timeout;
timeout = timeout - (double)seconds;
tv.tv_sec = seconds;
tv.tv_usec = (long)(timeout*1000000.0);
tvp = &tv;
}
#ifdef SELECT_USES_HEAP
/* Allocate memory for the lists */
rfd2obj = PyMem_NEW(pylist, FD_SETSIZE + 1);
wfd2obj = PyMem_NEW(pylist, FD_SETSIZE + 1);
efd2obj = PyMem_NEW(pylist, FD_SETSIZE + 1);
if (rfd2obj == NULL || wfd2obj == NULL || efd2obj == NULL) {
if (rfd2obj) PyMem_DEL(rfd2obj);
if (wfd2obj) PyMem_DEL(wfd2obj);
if (efd2obj) PyMem_DEL(efd2obj);
return PyErr_NoMemory();
}
#endif /* SELECT_USES_HEAP */
/* Convert sequences to fd_sets, and get maximum fd number
* propagates the Python exception set in seq2set()
*/
rfd2obj[0].sentinel = -1;
wfd2obj[0].sentinel = -1;
efd2obj[0].sentinel = -1;
if ((imax=seq2set(ifdlist, &ifdset, rfd2obj)) < 0)
goto finally;
if ((omax=seq2set(ofdlist, &ofdset, wfd2obj)) < 0)
goto finally;
if ((emax=seq2set(efdlist, &efdset, efd2obj)) < 0)
goto finally;
max = imax;
if (omax > max) max = omax;
if (emax > max) max = emax;
Py_BEGIN_ALLOW_THREADS
n = select(max, &ifdset, &ofdset, &efdset, tvp);
Py_END_ALLOW_THREADS
#ifdef MS_WINDOWS
if (n == SOCKET_ERROR) {
PyErr_SetExcFromWindowsErr(SelectError, WSAGetLastError());
}
#else
if (n < 0) {
PyErr_SetFromErrno(SelectError);
}
#endif
else if (n == 0) {
/* optimization */
ifdlist = PyList_New(0);
if (ifdlist) {
ret = PyTuple_Pack(3, 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 = PyTuple_Pack(3, ifdlist, ofdlist, efdlist);
Py_DECREF(ifdlist);
Py_DECREF(ofdlist);
Py_DECREF(efdlist);
}
finally:
reap_obj(rfd2obj);
reap_obj(wfd2obj);
reap_obj(efd2obj);
#ifdef SELECT_USES_HEAP
PyMem_DEL(rfd2obj);
PyMem_DEL(wfd2obj);
PyMem_DEL(efd2obj);
#endif /* SELECT_USES_HEAP */
return ret;
}
#if defined(HAVE_POLL) && !defined(HAVE_BROKEN_POLL)
/*
* poll() support
*/
typedef struct {
PyObject_HEAD
PyObject *dict;
int ufd_uptodate;
int ufd_len;
struct pollfd *ufds;
} pollObject;
static PyTypeObject poll_Type;
/* Update the malloc'ed array of pollfds to match the dictionary
contained within a pollObject. Return 1 on success, 0 on an error.
*/
static int
update_ufd_array(pollObject *self)
{
Py_ssize_t i, pos;
PyObject *key, *value;
self->ufd_len = PyDict_Size(self->dict);
PyMem_Resize(self->ufds, struct pollfd, self->ufd_len);
if (self->ufds == NULL) {
PyErr_NoMemory();
return 0;
}
i = pos = 0;
while (PyDict_Next(self->dict, &pos, &key, &value)) {
self->ufds[i].fd = PyInt_AsLong(key);
self->ufds[i].events = (short)PyInt_AsLong(value);
i++;
}
self->ufd_uptodate = 1;
return 1;
}
PyDoc_STRVAR(poll_register_doc,
"register(fd [, eventmask] ) -> None\n\n\
Register a file descriptor with the polling object.\n\
fd -- either an integer, or an object with a fileno() method returning an\n\
int.\n\
events -- an optional bitmask describing the type of events to check for");
static PyObject *
poll_register(pollObject *self, PyObject *args)
{
PyObject *o, *key, *value;
int fd, events = POLLIN | POLLPRI | POLLOUT;
int err;
if (!PyArg_ParseTuple(args, "O|i:register", &o, &events)) {
return NULL;
}
fd = PyObject_AsFileDescriptor(o);
if (fd == -1) return NULL;
/* Add entry to the internal dictionary: the key is the
file descriptor, and the value is the event mask. */
key = PyInt_FromLong(fd);
if (key == NULL)
return NULL;
value = PyInt_FromLong(events);
if (value == NULL) {
Py_DECREF(key);
return NULL;
}
err = PyDict_SetItem(self->dict, key, value);
Py_DECREF(key);
Py_DECREF(value);
if (err < 0)
return NULL;
self->ufd_uptodate = 0;
Py_INCREF(Py_None);
return Py_None;
}
PyDoc_STRVAR(poll_unregister_doc,
"unregister(fd) -> None\n\n\
Remove a file descriptor being tracked by the polling object.");
static PyObject *
poll_unregister(pollObject *self, PyObject *o)
{
PyObject *key;
int fd;
fd = PyObject_AsFileDescriptor( o );
if (fd == -1)
return NULL;
/* Check whether the fd is already in the array */
key = PyInt_FromLong(fd);
if (key == NULL)
return NULL;
if (PyDict_DelItem(self->dict, key) == -1) {
Py_DECREF(key);
/* This will simply raise the KeyError set by PyDict_DelItem
if the file descriptor isn't registered. */
return NULL;
}
Py_DECREF(key);
self->ufd_uptodate = 0;
Py_INCREF(Py_None);
return Py_None;
}
PyDoc_STRVAR(poll_poll_doc,
"poll( [timeout] ) -> list of (fd, event) 2-tuples\n\n\
Polls the set of registered file descriptors, returning a list containing \n\
any descriptors that have events or errors to report.");
static PyObject *
poll_poll(pollObject *self, PyObject *args)
{
PyObject *result_list = NULL, *tout = NULL;
int timeout = 0, poll_result, i, j;
PyObject *value = NULL, *num = NULL;
if (!PyArg_UnpackTuple(args, "poll", 0, 1, &tout)) {
return NULL;
}
/* Check values for timeout */
if (tout == NULL || tout == Py_None)
timeout = -1;
else if (!PyNumber_Check(tout)) {
PyErr_SetString(PyExc_TypeError,
"timeout must be an integer or None");
return NULL;
}
else {
tout = PyNumber_Int(tout);
if (!tout)
return NULL;
timeout = PyInt_AsLong(tout);
Py_DECREF(tout);
if (timeout == -1 && PyErr_Occurred())
return NULL;
}
/* Ensure the ufd array is up to date */
if (!self->ufd_uptodate)
if (update_ufd_array(self) == 0)
return NULL;
/* call poll() */
Py_BEGIN_ALLOW_THREADS;
poll_result = poll(self->ufds, self->ufd_len, timeout);
Py_END_ALLOW_THREADS;
if (poll_result < 0) {
PyErr_SetFromErrno(SelectError);
return NULL;
}
/* build the result list */
result_list = PyList_New(poll_result);
if (!result_list)
return NULL;
else {
for (i = 0, j = 0; j < poll_result; j++) {
/* skip to the next fired descriptor */
while (!self->ufds[i].revents) {
i++;
}
/* if we hit a NULL return, set value to NULL
and break out of loop; code at end will
clean up result_list */
value = PyTuple_New(2);
if (value == NULL)
goto error;
num = PyInt_FromLong(self->ufds[i].fd);
if (num == NULL) {
Py_DECREF(value);
goto error;
}
PyTuple_SET_ITEM(value, 0, num);
/* The &0xffff is a workaround for AIX. 'revents'
is a 16-bit short, and IBM assigned POLLNVAL
to be 0x8000, so the conversion to int results
in a negative number. See SF bug #923315. */
num = PyInt_FromLong(self->ufds[i].revents & 0xffff);
if (num == NULL) {
Py_DECREF(value);
goto error;
}
PyTuple_SET_ITEM(value, 1, num);
if ((PyList_SetItem(result_list, j, value)) == -1) {
Py_DECREF(value);
goto error;
}
i++;
}
}
return result_list;
error:
Py_DECREF(result_list);
return NULL;
}
static PyMethodDef poll_methods[] = {
{"register", (PyCFunction)poll_register,
METH_VARARGS, poll_register_doc},
{"unregister", (PyCFunction)poll_unregister,
METH_O, poll_unregister_doc},
{"poll", (PyCFunction)poll_poll,
METH_VARARGS, poll_poll_doc},
{NULL, NULL} /* sentinel */
};
static pollObject *
newPollObject(void)
{
pollObject *self;
self = PyObject_New(pollObject, &poll_Type);
if (self == NULL)
return NULL;
/* ufd_uptodate is a Boolean, denoting whether the
array pointed to by ufds matches the contents of the dictionary. */
self->ufd_uptodate = 0;
self->ufds = NULL;
self->dict = PyDict_New();
if (self->dict == NULL) {
Py_DECREF(self);
return NULL;
}
return self;
}
static void
poll_dealloc(pollObject *self)
{
if (self->ufds != NULL)
PyMem_DEL(self->ufds);
Py_XDECREF(self->dict);
PyObject_Del(self);
}
static PyObject *
poll_getattr(pollObject *self, char *name)
{
return Py_FindMethod(poll_methods, (PyObject *)self, name);
}
static PyTypeObject poll_Type = {
/* The ob_type field must be initialized in the module init function
* to be portable to Windows without using C++. */
PyObject_HEAD_INIT(NULL)
0, /*ob_size*/
"select.poll", /*tp_name*/
sizeof(pollObject), /*tp_basicsize*/
0, /*tp_itemsize*/
/* methods */
(destructor)poll_dealloc, /*tp_dealloc*/
0, /*tp_print*/
(getattrfunc)poll_getattr, /*tp_getattr*/
0, /*tp_setattr*/
0, /*tp_compare*/
0, /*tp_repr*/
0, /*tp_as_number*/
0, /*tp_as_sequence*/
0, /*tp_as_mapping*/
0, /*tp_hash*/
};
PyDoc_STRVAR(poll_doc,
"Returns a polling object, which supports registering and\n\
unregistering file descriptors, and then polling them for I/O events.");
static PyObject *
select_poll(PyObject *self, PyObject *unused)
{
return (PyObject *)newPollObject();
}
#ifdef __APPLE__
/*
* On some systems poll() sets errno on invalid file descriptors. We test
* for this at runtime because this bug may be fixed or introduced between
* OS releases.
*/
static int select_have_broken_poll(void)
{
int poll_test;
int filedes[2];
struct pollfd poll_struct = { 0, POLLIN|POLLPRI|POLLOUT, 0 };
/* Create a file descriptor to make invalid */
if (pipe(filedes) < 0) {
return 1;
}
poll_struct.fd = filedes[0];
close(filedes[0]);
close(filedes[1]);
poll_test = poll(&poll_struct, 1, 0);
if (poll_test < 0) {
return 1;
} else if (poll_test == 0 && poll_struct.revents != POLLNVAL) {
return 1;
}
return 0;
}
#endif /* __APPLE__ */
#endif /* HAVE_POLL */
PyDoc_STRVAR(select_doc,
"select(rlist, wlist, xlist[, timeout]) -> (rlist, wlist, xlist)\n\
\n\
Wait until one or more file descriptors are ready for some kind of I/O.\n\
The first three arguments are sequences of file descriptors to be waited for:\n\
rlist -- wait until ready for reading\n\
wlist -- wait until ready for writing\n\
xlist -- wait for an ``exceptional condition''\n\
If only one kind of condition is required, pass [] for the other lists.\n\
A file descriptor is either a socket or file object, or a small integer\n\
gotten from a fileno() method call on one of those.\n\
\n\
The optional 4th argument specifies a timeout in seconds; it may be\n\
a floating point number to specify fractions of seconds. If it is absent\n\
or None, the call will never time out.\n\
\n\
The return value is a tuple of three lists corresponding to the first three\n\
arguments; each contains the subset of the corresponding file descriptors\n\
that are ready.\n\
\n\
*** IMPORTANT NOTICE ***\n\
On Windows and OpenVMS, only sockets are supported; on Unix, all file descriptors.");
static PyMethodDef select_methods[] = {
{"select", select_select, METH_VARARGS, select_doc},
#if defined(HAVE_POLL)
{"poll", select_poll, METH_NOARGS, poll_doc},
#endif /* HAVE_POLL */
{0, 0}, /* sentinel */
};
PyDoc_STRVAR(module_doc,
"This module supports asynchronous I/O on multiple file descriptors.\n\
\n\
*** IMPORTANT NOTICE ***\n\
On Windows and OpenVMS, only sockets are supported; on Unix, all file descriptors.");
PyMODINIT_FUNC
initselect(void)
{
PyObject *m;
m = Py_InitModule3("select", select_methods, module_doc);
if (m == NULL)
return;
SelectError = PyErr_NewException("select.error", NULL, NULL);
Py_INCREF(SelectError);
PyModule_AddObject(m, "error", SelectError);
#if defined(HAVE_POLL)
#ifdef __APPLE__
if (select_have_broken_poll()) {
if (PyObject_DelAttrString(m, "poll") == -1) {
PyErr_Clear();
}
} else {
#else
{
#endif
poll_Type.ob_type = &PyType_Type;
PyModule_AddIntConstant(m, "POLLIN", POLLIN);
PyModule_AddIntConstant(m, "POLLPRI", POLLPRI);
PyModule_AddIntConstant(m, "POLLOUT", POLLOUT);
PyModule_AddIntConstant(m, "POLLERR", POLLERR);
PyModule_AddIntConstant(m, "POLLHUP", POLLHUP);
PyModule_AddIntConstant(m, "POLLNVAL", POLLNVAL);
#ifdef POLLRDNORM
PyModule_AddIntConstant(m, "POLLRDNORM", POLLRDNORM);
#endif
#ifdef POLLRDBAND
PyModule_AddIntConstant(m, "POLLRDBAND", POLLRDBAND);
#endif
#ifdef POLLWRNORM
PyModule_AddIntConstant(m, "POLLWRNORM", POLLWRNORM);
#endif
#ifdef POLLWRBAND
PyModule_AddIntConstant(m, "POLLWRBAND", POLLWRBAND);
#endif
#ifdef POLLMSG
PyModule_AddIntConstant(m, "POLLMSG", POLLMSG);
#endif
}
#endif /* HAVE_POLL */
}