qemu-char: Add qemu_chr_fe_claim / _release helper functions

Add qemu_chr_fe_claim / _release helper functions for properly dealing with
avail_connections.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Message-id: 1364412581-3672-2-git-send-email-hdegoede@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/include/char/char.h b/include/char/char.h
index 32c9999113..9d1ea46117 100644
--- a/include/char/char.h
+++ b/include/char/char.h
@@ -203,6 +203,35 @@ int qemu_chr_fe_ioctl(CharDriverState *s, int cmd, void *arg);
 int qemu_chr_fe_get_msgfd(CharDriverState *s);
 
 /**
+ * @qemu_chr_fe_claim:
+ *
+ * Claim a backend before using it, should be called before calling
+ * qemu_chr_add_handlers(). 
+ *
+ * Returns: -1 if the backend is already in use by another frontend, 0 on
+ *          success.
+ */
+int qemu_chr_fe_claim(CharDriverState *s);
+
+/**
+ * @qemu_chr_fe_claim_no_fail:
+ *
+ * Like qemu_chr_fe_claim, but will exit qemu with an error when the
+ * backend is already in use.
+ */
+void qemu_chr_fe_claim_no_fail(CharDriverState *s);
+
+/**
+ * @qemu_chr_fe_claim:
+ *
+ * Release a backend for use by another frontend.
+ *
+ * Returns: -1 if the backend is already in use by another frontend, 0 on
+ *          success.
+ */
+void qemu_chr_fe_release(CharDriverState *s);
+
+/**
  * @qemu_chr_be_can_write:
  *
  * Determine how much data the front end can currently accept.  This function