1 files changed, 292 insertions, 0 deletions
diff --git a/include/chardev/char-fe.h b/include/chardev/char-fe.h
new file mode 100644
index 000000000..867ef1b3b
--- /dev/null
+++ b/include/chardev/char-fe.h
@@ -0,0 +1,292 @@
+#ifndef QEMU_CHAR_FE_H
+#define QEMU_CHAR_FE_H
+
+#include "chardev/char.h"
+#include "qemu/main-loop.h"
+
+typedef void IOEventHandler(void *opaque, QEMUChrEvent event);
+typedef int BackendChangeHandler(void *opaque);
+
+/* This is the backend as seen by frontend, the actual backend is
+ * Chardev */
+struct CharBackend {
+    Chardev *chr;
+    IOEventHandler *chr_event;
+    IOCanReadHandler *chr_can_read;
+    IOReadHandler *chr_read;
+    BackendChangeHandler *chr_be_change;
+    void *opaque;
+    int tag;
+    int fe_open;
+};
+
+/**
+ * qemu_chr_fe_init:
+ *
+ * Initializes a front end for the given CharBackend and
+ * Chardev. Call qemu_chr_fe_deinit() to remove the association and
+ * release the driver.
+ *
+ * Returns: false on error.
+ */
+bool qemu_chr_fe_init(CharBackend *b, Chardev *s, Error **errp);
+
+/**
+ * qemu_chr_fe_deinit:
+ * @b: a CharBackend
+ * @del: if true, delete the chardev backend
+*
+ * Dissociate the CharBackend from the Chardev.
+ *
+ * Safe to call without associated Chardev.
+ */
+void qemu_chr_fe_deinit(CharBackend *b, bool del);
+
+/**
+ * qemu_chr_fe_get_driver:
+ *
+ * Returns: the driver associated with a CharBackend or NULL if no
+ * associated Chardev.
+ * Note: avoid this function as the driver should never be accessed directly,
+ *       especially by the frontends that support chardevice hotswap.
+ *       Consider qemu_chr_fe_backend_connected() to check for driver existence
+ */
+Chardev *qemu_chr_fe_get_driver(CharBackend *be);
+
+/**
+ * qemu_chr_fe_backend_connected:
+ *
+ * Returns: true if there is a chardevice associated with @be.
+ */
+bool qemu_chr_fe_backend_connected(CharBackend *be);
+
+/**
+ * qemu_chr_fe_backend_open:
+ *
+ * Returns: true if chardevice associated with @be is open.
+ */
+bool qemu_chr_fe_backend_open(CharBackend *be);
+
+/**
+ * qemu_chr_fe_set_handlers_full:
+ * @b: a CharBackend
+ * @fd_can_read: callback to get the amount of data the frontend may
+ *               receive
+ * @fd_read: callback to receive data from char
+ * @fd_event: event callback
+ * @be_change: backend change callback; passing NULL means hot backend change
+ *             is not supported and will not be attempted
+ * @opaque: an opaque pointer for the callbacks
+ * @context: a main loop context or NULL for the default
+ * @set_open: whether to call qemu_chr_fe_set_open() implicitely when
+ * any of the handler is non-NULL
+ * @sync_state: whether to issue event callback with updated state
+ *
+ * Set the front end char handlers. The front end takes the focus if
+ * any of the handler is non-NULL.
+ *
+ * Without associated Chardev, nothing is changed.
+ */
+void qemu_chr_fe_set_handlers_full(CharBackend *b,
+                                   IOCanReadHandler *fd_can_read,
+                                   IOReadHandler *fd_read,
+                                   IOEventHandler *fd_event,
+                                   BackendChangeHandler *be_change,
+                                   void *opaque,
+                                   GMainContext *context,
+                                   bool set_open,
+                                   bool sync_state);
+
+/**
+ * qemu_chr_fe_set_handlers:
+ *
+ * Version of qemu_chr_fe_set_handlers_full() with sync_state = true.
+ */
+void qemu_chr_fe_set_handlers(CharBackend *b,
+                              IOCanReadHandler *fd_can_read,
+                              IOReadHandler *fd_read,
+                              IOEventHandler *fd_event,
+                              BackendChangeHandler *be_change,
+                              void *opaque,
+                              GMainContext *context,
+                              bool set_open);
+
+/**
+ * qemu_chr_fe_take_focus:
+ *
+ * Take the focus (if the front end is muxed).
+ *
+ * Without associated Chardev, nothing is changed.
+ */
+void qemu_chr_fe_take_focus(CharBackend *b);
+
+/**
+ * qemu_chr_fe_accept_input:
+ *
+ * Notify that the frontend is ready to receive data
+ */
+void qemu_chr_fe_accept_input(CharBackend *be);
+
+/**
+ * qemu_chr_fe_disconnect:
+ *
+ * Close a fd accepted by character backend.
+ * Without associated Chardev, do nothing.
+ */
+void qemu_chr_fe_disconnect(CharBackend *be);
+
+/**
+ * qemu_chr_fe_wait_connected:
+ *
+ * Wait for characted backend to be connected, return < 0 on error or
+ * if no associated Chardev.
+ */
+int qemu_chr_fe_wait_connected(CharBackend *be, Error **errp);
+
+/**
+ * qemu_chr_fe_set_echo:
+ * @echo: true to enable echo, false to disable echo
+ *
+ * Ask the backend to override its normal echo setting.  This only really
+ * applies to the stdio backend and is used by the QMP server such that you
+ * can see what you type if you try to type QMP commands.
+ * Without associated Chardev, do nothing.
+ */
+void qemu_chr_fe_set_echo(CharBackend *be, bool echo);
+
+/**
+ * qemu_chr_fe_set_open:
+ *
+ * Set character frontend open status.  This is an indication that the
+ * front end is ready (or not) to begin doing I/O.
+ * Without associated Chardev, do nothing.
+ */
+void qemu_chr_fe_set_open(CharBackend *be, int fe_open);
+
+/**
+ * qemu_chr_fe_printf:
+ * @fmt: see #printf
+ *
+ * Write to a character backend using a printf style interface.  This
+ * function is thread-safe. It does nothing without associated
+ * Chardev.
+ */
+void qemu_chr_fe_printf(CharBackend *be, const char *fmt, ...)
+    GCC_FMT_ATTR(2, 3);
+
+
+typedef gboolean (*FEWatchFunc)(void *do_not_use, GIOCondition condition, void *data);
+
+/**
+ * qemu_chr_fe_add_watch:
+ * @cond: the condition to poll for
+ * @func: the function to call when the condition happens
+ * @user_data: the opaque pointer to pass to @func
+ *
+ * If the backend is connected, create and add a #GSource that fires
+ * when the given condition (typically G_IO_OUT|G_IO_HUP or G_IO_HUP)
+ * is active; return the #GSource's tag.  If it is disconnected,
+ * or without associated Chardev, return 0.
+ *
+ * Note that you are responsible to update the front-end sources if
+ * you are switching the main context with qemu_chr_fe_set_handlers().
+ *
+ * Warning: DO NOT use the first callback argument (it may be either
+ * a GIOChannel or a QIOChannel, depending on the underlying chardev)
+ *
+ * Returns: the source tag
+ */
+guint qemu_chr_fe_add_watch(CharBackend *be, GIOCondition cond,
+                            FEWatchFunc func, void *user_data);
+
+/**
+ * qemu_chr_fe_write:
+ * @buf: the data
+ * @len: the number of bytes to send
+ *
+ * Write data to a character backend from the front end.  This function
+ * will send data from the front end to the back end.  This function
+ * is thread-safe.
+ *
+ * Returns: the number of bytes consumed (0 if no associated Chardev)
+ */
+int qemu_chr_fe_write(CharBackend *be, const uint8_t *buf, int len);
+
+/**
+ * qemu_chr_fe_write_all:
+ * @buf: the data
+ * @len: the number of bytes to send
+ *
+ * Write data to a character backend from the front end.  This function will
+ * send data from the front end to the back end.  Unlike @qemu_chr_fe_write,
+ * this function will block if the back end cannot consume all of the data
+ * attempted to be written.  This function is thread-safe.
+ *
+ * Returns: the number of bytes consumed (0 if no associated Chardev)
+ */
+int qemu_chr_fe_write_all(CharBackend *be, const uint8_t *buf, int len);
+
+/**
+ * qemu_chr_fe_read_all:
+ * @buf: the data buffer
+ * @len: the number of bytes to read
+ *
+ * Read data to a buffer from the back end.
+ *
+ * Returns: the number of bytes read (0 if no associated Chardev)
+ */
+int qemu_chr_fe_read_all(CharBackend *be, uint8_t *buf, int len);
+
+/**
+ * qemu_chr_fe_ioctl:
+ * @cmd: see CHR_IOCTL_*
+ * @arg: the data associated with @cmd
+ *
+ * Issue a device specific ioctl to a backend.  This function is thread-safe.
+ *
+ * Returns: if @cmd is not supported by the backend or there is no
+ *          associated Chardev, -ENOTSUP, otherwise the return
+ *          value depends on the semantics of @cmd
+ */
+int qemu_chr_fe_ioctl(CharBackend *be, int cmd, void *arg);
+
+/**
+ * qemu_chr_fe_get_msgfd:
+ *
+ * For backends capable of fd passing, return the latest file descriptor passed
+ * by a client.
+ *
+ * Returns: -1 if fd passing isn't supported or there is no pending file
+ *          descriptor.  If a file descriptor is returned, subsequent calls to
+ *          this function will return -1 until a client sends a new file
+ *          descriptor.
+ */
+int qemu_chr_fe_get_msgfd(CharBackend *be);
+
+/**
+ * qemu_chr_fe_get_msgfds:
+ *
+ * For backends capable of fd passing, return the number of file received
+ * descriptors and fills the fds array up to num elements
+ *
+ * Returns: -1 if fd passing isn't supported or there are no pending file
+ *          descriptors.  If file descriptors are returned, subsequent calls to
+ *          this function will return -1 until a client sends a new set of file
+ *          descriptors.
+ */
+int qemu_chr_fe_get_msgfds(CharBackend *be, int *fds, int num);
+
+/**
+ * qemu_chr_fe_set_msgfds:
+ *
+ * For backends capable of fd passing, set an array of fds to be passed with
+ * the next send operation.
+ * A subsequent call to this function before calling a write function will
+ * result in overwriting the fd array with the new value without being send.
+ * Upon writing the message the fd array is freed.
+ *
+ * Returns: -1 if fd passing isn't supported or no associated Chardev.
+ */
+int qemu_chr_fe_set_msgfds(CharBackend *be, int *fds, int num);
+
+#endif /* QEMU_CHAR_FE_H */