char: move CharBackend handling in char-fe unit

Move all the frontend struct and methods to a seperate unit. This avoids
accidentally mixing backend and frontend calls, and helps with readabilty.

Make qemu_chr_replay() a macro shared by both char and char-fe.

Export qemu_chr_write(), and use a macro for qemu_chr_write_all()

(nb: yes, CharBackend is for char frontend :)

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

9 files changed, 260 insertions, 244 deletions

diff --git a/include/chardev/char-fe.h b/include/chardev/char-fe.h
new file mode 100644
index 0000000000..bd82093218
--- /dev/null
+++ b/include/chardev/char-fe.h
@@ -0,0 +1,249 @@
+#ifndef QEMU_CHAR_FE_H
+#define QEMU_CHAR_FE_H
+
+#include "chardev/char.h"
+
+typedef void IOEventHandler(void *opaque, int event);
+
+/* 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;
+    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:
+ *
+ * Dissociate the CharBackend from the Chardev.
+ *
+ * Safe to call without associated Chardev.
+ */
+void qemu_chr_fe_deinit(CharBackend *b);
+
+/**
+ * @qemu_chr_fe_get_driver:
+ *
+ * Returns the driver associated with a CharBackend or NULL if no
+ * associated Chardev.
+ */
+Chardev *qemu_chr_fe_get_driver(CharBackend *be);
+
+/**
+ * @qemu_chr_fe_set_handlers:
+ * @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
+ * @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
+ *
+ * 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(CharBackend *b,
+                              IOCanReadHandler *fd_can_read,
+                              IOReadHandler *fd_read,
+                              IOEventHandler *fd_event,
+                              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 accpeted 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 assicated Chardev.
+ */
+int qemu_chr_fe_wait_connected(CharBackend *be, Error **errp);
+
+/**
+ * @qemu_chr_fe_set_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.
+ *
+ * @echo true to enable echo, false to disable echo
+ */
+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:
+ *
+ * Write to a character backend using a printf style interface.  This
+ * function is thread-safe. It does nothing without associated
+ * Chardev.
+ *
+ * @fmt see #printf
+ */
+void qemu_chr_fe_printf(CharBackend *be, const char *fmt, ...)
+    GCC_FMT_ATTR(2, 3);
+
+/**
+ * @qemu_chr_fe_add_watch:
+ *
+ * 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.
+ *
+ * @cond the condition to poll for
+ * @func the function to call when the condition happens
+ * @user_data the opaque pointer to pass to @func
+ *
+ * Returns: the source tag
+ */
+guint qemu_chr_fe_add_watch(CharBackend *be, GIOCondition cond,
+                            GIOFunc func, void *user_data);
+
+/**
+ * @qemu_chr_fe_write:
+ *
+ * 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.
+ *
+ * @buf the data
+ * @len the number of bytes to send
+ *
+ * Returns: the number of bytes consumed (0 if no assicated Chardev)
+ */
+int qemu_chr_fe_write(CharBackend *be, const uint8_t *buf, int len);
+
+/**
+ * @qemu_chr_fe_write_all:
+ *
+ * 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.
+ *
+ * @buf the data
+ * @len the number of bytes to send
+ *
+ * Returns: the number of bytes consumed (0 if no assicated Chardev)
+ */
+int qemu_chr_fe_write_all(CharBackend *be, const uint8_t *buf, int len);
+
+/**
+ * @qemu_chr_fe_read_all:
+ *
+ * Read data to a buffer from the back end.
+ *
+ * @buf the data buffer
+ * @len the number of bytes to read
+ *
+ * Returns: the number of bytes read (0 if no assicated Chardev)
+ */
+int qemu_chr_fe_read_all(CharBackend *be, uint8_t *buf, int len);
+
+/**
+ * @qemu_chr_fe_ioctl:
+ *
+ * Issue a device specific ioctl to a backend.  This function is thread-safe.
+ *
+ * @cmd see CHR_IOCTL_*
+ * @arg the data associated with @cmd
+ *
+ * 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 */
diff --git a/include/chardev/char-mux.h b/include/chardev/char-mux.h
index 45cdfc7e67..8928977897 100644
--- a/include/chardev/char-mux.h
+++ b/include/chardev/char-mux.h
@@ -25,6 +25,7 @@
 #define CHAR_MUX_H
 
 #include "chardev/char.h"
+#include "chardev/char-fe.h"
 
 extern bool muxes_realized;
 
diff --git a/include/chardev/char.h b/include/chardev/char.h
index 95273e10ae..8a9ade4931 100644
--- a/include/chardev/char.h
+++ b/include/chardev/char.h
@@ -16,6 +16,7 @@
 #define IAC 255
 
 /* character device */
+typedef struct CharBackend CharBackend;
 
 typedef enum {
     CHR_EVENT_BREAK, /* serial break char */
@@ -27,8 +28,6 @@ typedef enum {
 
 #define CHR_READ_BUF_LEN 4096
 
-typedef void IOEventHandler(void *opaque, int event);
-
 typedef enum {
     /* Whether the chardev peer is able to close and
      * reopen the data channel, thus requiring support
@@ -44,17 +43,7 @@ typedef enum {
     QEMU_CHAR_FEATURE_LAST,
 } ChardevFeature;
 
-/* This is the backend as seen by frontend, the actual backend is
- * Chardev */
-typedef struct CharBackend {
-    Chardev *chr;
-    IOEventHandler *chr_event;
-    IOCanReadHandler *chr_can_read;
-    IOReadHandler *chr_read;
-    void *opaque;
-    int tag;
-    int fe_open;
-} CharBackend;
+#define qemu_chr_replay(chr) qemu_chr_has_feature(chr, QEMU_CHAR_FEATURE_REPLAY)
 
 struct Chardev {
     Object parent_obj;
@@ -103,15 +92,6 @@ void qemu_chr_parse_common(QemuOpts *opts, ChardevCommon *backend);
  */
 Chardev *qemu_chr_new(const char *label, const char *filename);
 
-
-/**
- * @qemu_chr_fe_disconnect:
- *
- * Close a fd accpeted by character backend.
- * Without associated Chardev, do nothing.
- */
-void qemu_chr_fe_disconnect(CharBackend *be);
-
 /**
  * @qemu_chr_cleanup:
  *
@@ -120,14 +100,6 @@ void qemu_chr_fe_disconnect(CharBackend *be);
 void qemu_chr_cleanup(void);
 
 /**
- * @qemu_chr_fe_wait_connected:
- *
- * Wait for characted backend to be connected, return < 0 on error or
- * if no assicated Chardev.
- */
-int qemu_chr_fe_wait_connected(CharBackend *be, Error **errp);
-
-/**
  * @qemu_chr_new_noreplay:
  *
  * Create a new character backend from a URI.
@@ -142,150 +114,6 @@ int qemu_chr_fe_wait_connected(CharBackend *be, Error **errp);
 Chardev *qemu_chr_new_noreplay(const char *label, const char *filename);
 
 /**
- * @qemu_chr_fe_set_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.
- *
- * @echo true to enable echo, false to disable echo
- */
-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:
- *
- * Write to a character backend using a printf style interface.  This
- * function is thread-safe. It does nothing without associated
- * Chardev.
- *
- * @fmt see #printf
- */
-void qemu_chr_fe_printf(CharBackend *be, const char *fmt, ...)
-    GCC_FMT_ATTR(2, 3);
-
-/**
- * @qemu_chr_fe_add_watch:
- *
- * 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.
- *
- * @cond the condition to poll for
- * @func the function to call when the condition happens
- * @user_data the opaque pointer to pass to @func
- *
- * Returns: the source tag
- */
-guint qemu_chr_fe_add_watch(CharBackend *be, GIOCondition cond,
-                            GIOFunc func, void *user_data);
-
-/**
- * @qemu_chr_fe_write:
- *
- * 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.
- *
- * @buf the data
- * @len the number of bytes to send
- *
- * Returns: the number of bytes consumed (0 if no assicated Chardev)
- */
-int qemu_chr_fe_write(CharBackend *be, const uint8_t *buf, int len);
-
-/**
- * @qemu_chr_fe_write_all:
- *
- * 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.
- *
- * @buf the data
- * @len the number of bytes to send
- *
- * Returns: the number of bytes consumed (0 if no assicated Chardev)
- */
-int qemu_chr_fe_write_all(CharBackend *be, const uint8_t *buf, int len);
-
-/**
- * @qemu_chr_fe_read_all:
- *
- * Read data to a buffer from the back end.
- *
- * @buf the data buffer
- * @len the number of bytes to read
- *
- * Returns: the number of bytes read (0 if no assicated Chardev)
- */
-int qemu_chr_fe_read_all(CharBackend *be, uint8_t *buf, int len);
-
-/**
- * @qemu_chr_fe_ioctl:
- *
- * Issue a device specific ioctl to a backend.  This function is thread-safe.
- *
- * @cmd see CHR_IOCTL_*
- * @arg the data associated with @cmd
- *
- * 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);
-
-/**
  * @qemu_chr_be_can_write:
  *
  * Determine how much data the front end can currently accept.  This function
@@ -328,69 +156,6 @@ void qemu_chr_be_write_impl(Chardev *s, uint8_t *buf, int len);
  */
 void qemu_chr_be_event(Chardev *s, int event);
 
-/**
- * @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_get_driver:
- *
- * Returns the driver associated with a CharBackend or NULL if no
- * associated Chardev.
- */
-Chardev *qemu_chr_fe_get_driver(CharBackend *be);
-
-/**
- * @qemu_chr_fe_deinit:
- *
- * Dissociate the CharBackend from the Chardev.
- *
- * Safe to call without associated Chardev.
- */
-void qemu_chr_fe_deinit(CharBackend *b);
-
-/**
- * @qemu_chr_fe_set_handlers:
- * @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
- * @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
- *
- * 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(CharBackend *b,
-                              IOCanReadHandler *fd_can_read,
-                              IOReadHandler *fd_read,
-                              IOEventHandler *fd_event,
-                              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);
-
-void qemu_chr_fe_accept_input(CharBackend *be);
 int qemu_chr_add_client(Chardev *s, int fd);
 Chardev *qemu_chr_find(const char *name);
 
@@ -399,7 +164,8 @@ bool qemu_chr_has_feature(Chardev *chr,
 void qemu_chr_set_feature(Chardev *chr,
                           ChardevFeature feature);
 QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename);
-int qemu_chr_write_all(Chardev *s, const uint8_t *buf, int len);
+int qemu_chr_write(Chardev *s, const uint8_t *buf, int len, bool write_all);
+#define qemu_chr_write_all(s, buf, len) qemu_chr_write(s, buf, len, true)
 int qemu_chr_wait_connected(Chardev *chr, Error **errp);
 
 #define TYPE_CHARDEV "chardev"
diff --git a/include/hw/char/bcm2835_aux.h b/include/hw/char/bcm2835_aux.h
index 2a051c5646..cdbf7e3e37 100644
--- a/include/hw/char/bcm2835_aux.h
+++ b/include/hw/char/bcm2835_aux.h
@@ -9,7 +9,7 @@
 #define BCM2835_AUX_H
 
 #include "hw/sysbus.h"
-#include "chardev/char.h"
+#include "chardev/char-fe.h"
 
 #define TYPE_BCM2835_AUX "bcm2835-aux"
 #define BCM2835_AUX(obj) OBJECT_CHECK(BCM2835AuxState, (obj), TYPE_BCM2835_AUX)
diff --git a/include/hw/char/cadence_uart.h b/include/hw/char/cadence_uart.h
index eed7d8d358..118e3f10de 100644
--- a/include/hw/char/cadence_uart.h
+++ b/include/hw/char/cadence_uart.h
@@ -19,7 +19,7 @@
 #ifndef CADENCE_UART_H
 
 #include "hw/sysbus.h"
-#include "chardev/char.h"
+#include "chardev/char-fe.h"
 #include "qemu/timer.h"
 
 #define CADENCE_UART_RX_FIFO_SIZE           16
diff --git a/include/hw/char/digic-uart.h b/include/hw/char/digic-uart.h
index 370b48a6c5..de9a3e3551 100644
--- a/include/hw/char/digic-uart.h
+++ b/include/hw/char/digic-uart.h
@@ -19,7 +19,7 @@
 #define HW_CHAR_DIGIC_UART_H
 
 #include "hw/sysbus.h"
-#include "chardev/char.h"
+#include "chardev/char-fe.h"
 
 #define TYPE_DIGIC_UART "digic-uart"
 #define DIGIC_UART(obj) \
diff --git a/include/hw/char/imx_serial.h b/include/hw/char/imx_serial.h
index 05500f5346..baeec3183f 100644
--- a/include/hw/char/imx_serial.h
+++ b/include/hw/char/imx_serial.h
@@ -19,7 +19,7 @@
 #define IMX_SERIAL_H
 
 #include "hw/sysbus.h"
-#include "chardev/char.h"
+#include "chardev/char-fe.h"
 
 #define TYPE_IMX_SERIAL "imx.serial"
 #define IMX_SERIAL(obj) OBJECT_CHECK(IMXSerialState, (obj), TYPE_IMX_SERIAL)
diff --git a/include/hw/char/serial.h b/include/hw/char/serial.h
index 01dcd2a8d2..c4daf11a14 100644
--- a/include/hw/char/serial.h
+++ b/include/hw/char/serial.h
@@ -28,7 +28,7 @@
 
 #include "hw/hw.h"
 #include "sysemu/sysemu.h"
-#include "chardev/char.h"
+#include "chardev/char-fe.h"
 #include "exec/memory.h"
 #include "qemu/fifo8.h"
 #include "chardev/char.h"
diff --git a/include/hw/char/stm32f2xx_usart.h b/include/hw/char/stm32f2xx_usart.h
index 4259dbeb1e..9d03a7527c 100644
--- a/include/hw/char/stm32f2xx_usart.h
+++ b/include/hw/char/stm32f2xx_usart.h
@@ -26,7 +26,7 @@
 #define HW_STM32F2XX_USART_H
 
 #include "hw/sysbus.h"
-#include "chardev/char.h"
+#include "chardev/char-fe.h"
 #include "hw/hw.h"
 
 #define USART_SR   0x00