[Qemu-devel] [PATCH 1/3] chardev: Allow frontends to notify backends of guest open / close

[Hans de Goede <hdegoede@redhat.com>]

Some frontends know when the guest has opened the "channel" and is actively
listening to it, for example virtio-serial. This patch adds 2 new qemu-chardev
functions which can be used by frontends to signal guest open / close, and
allows interested backends to listen to this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 qemu-char.c |   17 +++++++++++++++++
 qemu-char.h |    4 ++++
 2 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index 31c9e79..7ec7196 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -476,6 +476,9 @@ static CharDriverState *qemu_chr_open_mux(CharDriverState *drv)
     chr->chr_write = mux_chr_write;
     chr->chr_update_read_handler = mux_chr_update_read_handler;
     chr->chr_accept_input = mux_chr_accept_input;
+    /* Frontend guest-open / -close notification is not support with muxes */
+    chr->chr_guest_open = NULL;
+    chr->chr_guest_close = NULL;
 
     /* Muxes are always open on creation */
     qemu_chr_generic_open(chr);
@@ -2575,6 +2578,20 @@ void qemu_chr_set_echo(struct CharDriverState *chr, bool echo)
     }
 }
 
+void qemu_chr_guest_open(struct CharDriverState *chr)
+{
+    if (chr->chr_guest_open) {
+        chr->chr_guest_open(chr);
+    }
+}
+
+void qemu_chr_guest_close(struct CharDriverState *chr)
+{
+    if (chr->chr_guest_close) {
+        chr->chr_guest_close(chr);
+    }
+}
+
 void qemu_chr_close(CharDriverState *chr)
 {
     QTAILQ_REMOVE(&chardevs, chr, next);
diff --git a/qemu-char.h b/qemu-char.h
index 56d9954..d2f5e5f 100644
--- a/qemu-char.h
+++ b/qemu-char.h
@@ -65,6 +65,8 @@ struct CharDriverState {
     void (*chr_close)(struct CharDriverState *chr);
     void (*chr_accept_input)(struct CharDriverState *chr);
     void (*chr_set_echo)(struct CharDriverState *chr, bool echo);
+    void (*chr_guest_open)(struct CharDriverState *chr);
+    void (*chr_guest_close)(struct CharDriverState *chr);
     void *opaque;
     QEMUBH *bh;
     char *label;
@@ -78,6 +80,8 @@ CharDriverState *qemu_chr_open_opts(QemuOpts *opts,
                                     void (*init)(struct CharDriverState *s));
 CharDriverState *qemu_chr_open(const char *label, const char *filename, void (*init)(struct CharDriverState *s));
 void qemu_chr_set_echo(struct CharDriverState *chr, bool echo);
+void qemu_chr_guest_open(struct CharDriverState *chr);
+void qemu_chr_guest_close(struct CharDriverState *chr);
 void qemu_chr_close(CharDriverState *chr);
 void qemu_chr_printf(CharDriverState *s, const char *fmt, ...)
     GCC_FMT_ATTR(2, 3);
-- 
1.7.3.2