diff options
Diffstat (limited to 'chardev')
| -rw-r--r-- | chardev/char-io.c | 56 | ||||
| -rw-r--r-- | chardev/char-socket.c | 22 |
2 files changed, 70 insertions, 8 deletions
diff --git a/chardev/char-io.c b/chardev/char-io.c index 4451128cba..dab77b112e 100644 --- a/chardev/char-io.c +++ b/chardev/char-io.c @@ -33,6 +33,7 @@ typedef struct IOWatchPoll { IOCanReadHandler *fd_can_read; GSourceFunc fd_read; void *opaque; + GMainContext *context; } IOWatchPoll; static IOWatchPoll *io_watch_poll_from_source(GSource *source) @@ -50,28 +51,59 @@ static gboolean io_watch_poll_prepare(GSource *source, return FALSE; } + /* + * We do not register the QIOChannel watch as a child GSource. + * The 'prepare' function on the parent GSource will be + * skipped if a child GSource's 'prepare' function indicates + * readiness. We need this prepare function be guaranteed + * to run on *every* iteration of the main loop, because + * it is critical to ensure we remove the QIOChannel watch + * if 'fd_can_read' indicates the frontend cannot receive + * more data. + */ if (now_active) { iwp->src = qio_channel_create_watch( iwp->ioc, G_IO_IN | G_IO_ERR | G_IO_HUP | G_IO_NVAL); g_source_set_callback(iwp->src, iwp->fd_read, iwp->opaque, NULL); - g_source_add_child_source(source, iwp->src); - g_source_unref(iwp->src); + g_source_attach(iwp->src, iwp->context); } else { - g_source_remove_child_source(source, iwp->src); + g_source_destroy(iwp->src); + g_source_unref(iwp->src); iwp->src = NULL; } return FALSE; } +static gboolean io_watch_poll_check(GSource *source) +{ + return FALSE; +} + static gboolean io_watch_poll_dispatch(GSource *source, GSourceFunc callback, gpointer user_data) { - return G_SOURCE_CONTINUE; + abort(); +} + +static void io_watch_poll_finalize(GSource *source) +{ + /* + * Due to a glib bug, removing the last reference to a source + * inside a finalize callback causes recursive locking (and a + * deadlock). This is not a problem inside other callbacks, + * including dispatch callbacks, so we call io_remove_watch_poll + * to remove this source. At this point, iwp->src must + * be NULL, or we would leak it. + */ + IOWatchPoll *iwp = io_watch_poll_from_source(source); + assert(iwp->src == NULL); } static GSourceFuncs io_watch_poll_funcs = { .prepare = io_watch_poll_prepare, + .check = io_watch_poll_check, .dispatch = io_watch_poll_dispatch, + .finalize = io_watch_poll_finalize, }; GSource *io_add_watch_poll(Chardev *chr, @@ -91,6 +123,7 @@ GSource *io_add_watch_poll(Chardev *chr, iwp->ioc = ioc; iwp->fd_read = (GSourceFunc) fd_read; iwp->src = NULL; + iwp->context = context; name = g_strdup_printf("chardev-iowatch-%s", chr->label); g_source_set_name((GSource *)iwp, name); @@ -101,10 +134,23 @@ GSource *io_add_watch_poll(Chardev *chr, return (GSource *)iwp; } +static void io_remove_watch_poll(GSource *source) +{ + IOWatchPoll *iwp; + + iwp = io_watch_poll_from_source(source); + if (iwp->src) { + g_source_destroy(iwp->src); + g_source_unref(iwp->src); + iwp->src = NULL; + } + g_source_destroy(&iwp->parent); +} + void remove_fd_in_watch(Chardev *chr) { if (chr->gsource) { - g_source_destroy(chr->gsource); + io_remove_watch_poll(chr->gsource); chr->gsource = NULL; } } diff --git a/chardev/char-socket.c b/chardev/char-socket.c index 8a0406cc1e..812d7aa38a 100644 --- a/chardev/char-socket.c +++ b/chardev/char-socket.c @@ -496,9 +496,9 @@ static gboolean tcp_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque) s->max_size <= 0) { return TRUE; } - len = tcp_chr_read_poll(opaque); - if (len > sizeof(buf)) { - len = sizeof(buf); + len = sizeof(buf); + if (len > s->max_size) { + len = s->max_size; } size = tcp_chr_recv(chr, (void *)buf, len); if (size == 0 || (size == -1 && errno != EAGAIN)) { @@ -601,6 +601,22 @@ static void update_ioc_handlers(SocketChardev *s) remove_hup_source(s); s->hup_source = qio_channel_create_watch(s->ioc, G_IO_HUP); + /* + * poll() is liable to return POLLHUP even when there is + * still incoming data available to read on the FD. If + * we have the hup_source at the same priority as the + * main io_add_watch_poll GSource, then we might end up + * processing the POLLHUP event first, closing the FD, + * and as a result silently discard data we should have + * read. + * + * By setting the hup_source to G_PRIORITY_DEFAULT + 1, + * we ensure that io_add_watch_poll GSource will always + * be dispatched first, thus guaranteeing we will be + * able to process all incoming data before closing the + * FD + */ + g_source_set_priority(s->hup_source, G_PRIORITY_DEFAULT + 1); g_source_set_callback(s->hup_source, (GSourceFunc)tcp_chr_hup, chr, NULL); g_source_attach(s->hup_source, chr->gcontext); |