From 34689e206abddac87a5217d458534e24f2a05562 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Tue, 19 Jan 2016 14:13:29 +0100 Subject: [PATCH] qemu-char: Keep pty slave file descriptor open until the master is closed If a process opens the slave pts device, writes data to it, then immediately closes it, the data doesn't reliably get delivered to the emulated serial port. This seems to be because a read of the master pty device returns EIO on Linux if no process has the pts device open, even when data is waiting "in the pipe". A fix seems to be for QEMU to keep the pts file descriptor open until the pty is closed, as per the below patch. Signed-off-by: Ashley Jonathan Message-Id: Reviewed-by: Michael Tokarev Signed-off-by: Paolo Bonzini --- qemu-char.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/qemu-char.c b/qemu-char.c index 927c47e503..1fbccf02ac 100644 --- a/qemu-char.c +++ b/qemu-char.c @@ -1171,6 +1171,7 @@ typedef struct { int connected; guint timer_tag; guint open_tag; + int slave_fd; } PtyCharDriver; static void pty_chr_update_read_handler_locked(CharDriverState *chr); @@ -1347,6 +1348,7 @@ static void pty_chr_close(struct CharDriverState *chr) qemu_mutex_lock(&chr->chr_write_lock); pty_chr_state(chr, 0); + close(s->slave_fd); object_unref(OBJECT(s->ioc)); if (s->timer_tag) { g_source_remove(s->timer_tag); @@ -1374,7 +1376,6 @@ static CharDriverState *qemu_chr_open_pty(const char *id, return NULL; } - close(slave_fd); qemu_set_nonblock(master_fd); chr = qemu_chr_alloc(common, errp); @@ -1399,6 +1400,7 @@ static CharDriverState *qemu_chr_open_pty(const char *id, chr->explicit_be_open = true; s->ioc = QIO_CHANNEL(qio_channel_file_new_fd(master_fd)); + s->slave_fd = slave_fd; s->timer_tag = 0; return chr;