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From 66945912c4bd1bc70f3221288a4e7acc5717b336 Mon Sep 17 00:00:00 2001
From: Amit Shah <amit.shah@redhat.com>
Date: Mon, 21 Mar 2011 21:41:42 +0100
Subject: [PATCH 04/13] char: Add framework for a 'write unblocked' callback

The char layer can let users know that the driver will block on further
input.  For users interested in not blocking, they can assign a function
pointer that will be called back when the driver becomes writable.  This
patch just adds the function pointers to the CharDriverState structure,
future patches will enable the nonblocking and callback functionality.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 qemu-char.c |    3 +++
 qemu-char.h |    4 ++++
 2 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index 1c33828..ec4eb68 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -214,11 +214,14 @@ void qemu_chr_add_handlers(CharDriverState *s,
     }
     s->chr_can_read = handlers->fd_can_read;
     s->chr_read = handlers->fd_read;
+    s->chr_write_unblocked = handlers->fd_write_unblocked;
     s->chr_event = handlers->fd_event;
     s->handler_opaque = opaque;
     if (s->chr_update_read_handler)
         s->chr_update_read_handler(s);
 
+    s->write_blocked = false;
+
     /* We're connecting to an already opened device, so let's make sure we
        also get the open event */
     if (s->opened) {
diff --git a/qemu-char.h b/qemu-char.h
index 9fe1b82..68e7b5b 100644
--- a/qemu-char.h
+++ b/qemu-char.h
@@ -62,6 +62,9 @@ struct CharDriverState {
     IOEventHandler *chr_event;
     IOCanReadHandler *chr_can_read;
     IOReadHandler *chr_read;
+    IOHandler *chr_write_unblocked;
+    void (*chr_enable_write_fd_handler)(struct CharDriverState *chr);
+    void (*chr_disable_write_fd_handler)(struct CharDriverState *chr);
     void *handler_opaque;
     void (*chr_send_event)(struct CharDriverState *chr, int event);
     void (*chr_close)(struct CharDriverState *chr);
@@ -75,6 +78,7 @@ struct CharDriverState {
     char *filename;
     int opened;
     int avail_connections;
+    bool write_blocked; /* Are we in a blocked state? */
     QTAILQ_ENTRY(CharDriverState) next;
 };
 
-- 
1.7.5.1