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poll: Change the lock to block only POLLIN events

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Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
(cherry picked from commit 30b5a2e33b)
This commit is contained in:
Jakub Jelen
2023-03-01 10:31:57 +01:00
parent 554fe06aeb
commit bb5bdac321
1 changed files with 22 additions and 6 deletions
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28
src/poll.c
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@@ -412,7 +412,8 @@ short ssh_poll_get_events(ssh_poll_handle p)
/**
* @brief Set the events of a poll object. The events will also be propagated
* to an associated poll context.
* to an associated poll context unless the fd is locked. In that case,
* only the POLLOUT can be set.
*
* @param p Pointer to an already allocated poll object.
* @param events Poll events.
@@ -420,8 +421,14 @@ short ssh_poll_get_events(ssh_poll_handle p)
void ssh_poll_set_events(ssh_poll_handle p, short events)
{
p->events = events;
if (p->ctx != NULL && !p->lock) {
p->ctx->pollfds[p->x.idx].events = events;
if (p->ctx != NULL) {
if (!p->lock) {
p->ctx->pollfds[p->x.idx].events = events;
} else if (!(p->ctx->pollfds[p->x.idx].events & POLLOUT)) {
/* if locked, allow only setting POLLOUT to prevent recursive
* callbacks */
p->ctx->pollfds[p->x.idx].events = events & POLLOUT;
}
}
}
@@ -691,6 +698,15 @@ int ssh_poll_ctx_dopoll(ssh_poll_ctx ctx, int timeout)
return SSH_ERROR;
}
/* Ignore any pollin events on locked sockets as that means we are called
* recursively and we only want process the POLLOUT events here to flush
* output buffer */
for (i = 0; i < ctx->polls_used; i++) {
/* The lock prevents invoking POLLIN events: drop them now */
if (ctx->pollptrs[i]->lock) {
ctx->pollfds[i].events &= ~POLLIN;
}
}
ssh_timestamp_init(&ts);
do {
int tm = ssh_timeout_update(&ts, timeout);
@@ -706,7 +722,7 @@ int ssh_poll_ctx_dopoll(ssh_poll_ctx ctx, int timeout)
used = ctx->polls_used;
for (i = 0; i < used && rc > 0; ) {
if (!ctx->pollfds[i].revents || ctx->pollptrs[i]->lock) {
if (ctx->pollfds[i].revents == 0) {
i++;
} else {
int ret;
@@ -716,7 +732,7 @@ int ssh_poll_ctx_dopoll(ssh_poll_ctx ctx, int timeout)
revents = ctx->pollfds[i].revents;
/* avoid having any event caught during callback */
ctx->pollfds[i].events = 0;
p->lock = 1;
p->lock++;
if (p->cb && (ret = p->cb(p, fd, revents, p->cb_data)) < 0) {
if (ret == -2) {
return -1;
@@ -727,7 +743,7 @@ int ssh_poll_ctx_dopoll(ssh_poll_ctx ctx, int timeout)
} else {
ctx->pollfds[i].revents = 0;
ctx->pollfds[i].events = p->events;
p->lock = 0;
p->lock--;
i++;
}