extmod/modselect: Handle growing the pollfds allocation correctly.

The poll_obj_t instances have their pollfd field point into this
allocation.  So if re-allocating results in a move, we need to update the
existing poll_obj_t's.

Update the test to cover this case.

Fixes issue #12887.

This work was funded through GitHub Sponsors.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This commit is contained in:
Jim Mussared 2023-11-06 16:36:15 +11:00 committed by Damien George
parent e9bcd49b3e
commit 8b24aa36ba
2 changed files with 48 additions and 3 deletions

View File

@ -41,6 +41,7 @@
#if MICROPY_PY_SELECT_POSIX_OPTIMISATIONS
#include <string.h>
#include <poll.h>
#if !((MP_STREAM_POLL_RD) == (POLLIN) && \
@ -142,14 +143,47 @@ STATIC void poll_obj_set_revents(poll_obj_t *poll_obj, mp_uint_t revents) {
}
}
// How much (in pollfds) to grow the allocation for poll_set->pollfds by.
#define POLL_SET_ALLOC_INCREMENT (4)
STATIC struct pollfd *poll_set_add_fd(poll_set_t *poll_set, int fd) {
struct pollfd *free_slot = NULL;
if (poll_set->used == poll_set->max_used) {
// No free slots below max_used, so expand max_used (and possibly allocate).
if (poll_set->max_used >= poll_set->alloc) {
poll_set->pollfds = m_renew(struct pollfd, poll_set->pollfds, poll_set->alloc, poll_set->alloc + 4);
poll_set->alloc += 4;
size_t new_alloc = poll_set->alloc + POLL_SET_ALLOC_INCREMENT;
// Try to grow in-place.
struct pollfd *new_fds = m_renew_maybe(struct pollfd, poll_set->pollfds, poll_set->alloc, new_alloc, false);
if (!new_fds) {
// Failed to grow in-place. Do a new allocation and copy over the pollfd values.
new_fds = m_new(struct pollfd, new_alloc);
memcpy(new_fds, poll_set->pollfds, sizeof(struct pollfd) * poll_set->alloc);
// Update existing poll_obj_t to update their pollfd field to
// point to the same offset inside the new allocation.
for (mp_uint_t i = 0; i < poll_set->map.alloc; ++i) {
if (!mp_map_slot_is_filled(&poll_set->map, i)) {
continue;
}
poll_obj_t *poll_obj = MP_OBJ_TO_PTR(poll_set->map.table[i].value);
if (!poll_obj) {
// This is the one we're currently adding,
// poll_set_add_obj doesn't assign elem->value until
// afterwards.
continue;
}
poll_obj->pollfd = new_fds + (poll_obj->pollfd - poll_set->pollfds);
}
// Delete the old allocation.
m_del(struct pollfd, poll_set->pollfds, poll_set->alloc);
}
poll_set->pollfds = new_fds;
poll_set->alloc = new_alloc;
}
free_slot = &poll_set->pollfds[poll_set->max_used++];
} else {

View File

@ -34,11 +34,22 @@ poller.register(1, select.POLLIN)
# Poll for input, should return an empty list.
print(poller.poll(0))
# Test registering a very large number of file descriptors.
# Test registering a very large number of file descriptors (will trigger
# EINVAL due to more than OPEN_MAX fds).
poller = select.poll()
for fd in range(6000):
poller.register(fd)
try:
poller.poll()
assert False
except OSError as er:
print(er.errno == errno.EINVAL)
# Register stdout/stderr, plus many extra ones to trigger the fd vector
# resizing. Then unregister the excess ones and verify poll still works.
poller = select.poll()
for fd in range(1, 1000):
poller.register(fd)
for i in range(3, 1000):
poller.unregister(i)
print(sorted(poller.poll()))