From: Marc-André Lureau <marcandre.lureau@redhat.com>

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 include/chardev/char.h | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/include/chardev/char.h b/include/chardev/char.h
index 589e7fe46d..2e4c16f82f 100644
--- a/include/chardev/char.h
+++ b/include/chardev/char.h
@@ -254,24 +254,57 @@ struct ChardevClass {
 
     bool internal; /* TODO: eventually use TYPE_USER_CREATABLE */
     bool supports_yank;
+
+    /* parse command line options and populate QAPI @backend */
     void (*parse)(QemuOpts *opts, ChardevBackend *backend, Error **errp);
 
+    /* called after construction, open/starts the backend */
     void (*open)(Chardev *chr, ChardevBackend *backend,
                  bool *be_opened, Error **errp);
 
+    /* write buf to the backend */
     int (*chr_write)(Chardev *s, const uint8_t *buf, int len);
+
+    /*
+     * Read from the backend (blocking). A typical front-end will instead rely
+     * on char_can_read/chr_read being called when polling/looping.
+     */
     int (*chr_sync_read)(Chardev *s, const uint8_t *buf, int len);
+
+    /* create a watch on the backend */
     GSource *(*chr_add_watch)(Chardev *s, GIOCondition cond);
+
+    /* update the backend internal sources */
     void (*chr_update_read_handler)(Chardev *s);
+
+    /* send an ioctl to the backend */
     int (*chr_ioctl)(Chardev *s, int cmd, void *arg);
+
+    /* get ancillary-received fds during last read */
     int (*get_msgfds)(Chardev *s, int* fds, int num);
+
+    /* set ancillary fds to be sent with next write */
     int (*set_msgfds)(Chardev *s, int *fds, int num);
+
+    /* accept the given fd */
     int (*chr_add_client)(Chardev *chr, int fd);
+
+    /* wait for a connection */
     int (*chr_wait_connected)(Chardev *chr, Error **errp);
+
+    /* disconnect a connection */
     void (*chr_disconnect)(Chardev *chr);
+
+    /* called by frontend when it can read */
     void (*chr_accept_input)(Chardev *chr);
+
+    /* set terminal echo */
     void (*chr_set_echo)(Chardev *chr, bool echo);
+
+    /* notify the backend of frontend open state */
     void (*chr_set_fe_open)(Chardev *chr, int fe_open);
+
+    /* handle various events */
     void (*chr_be_event)(Chardev *s, QEMUChrEvent event);
 };
 
-- 
2.32.0.264.g75ae10bc75

On Fri, Jul 23, 2021 at 02:28:25PM +0400, marcandre.lureau@redhat.com wrote:
> From: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  include/chardev/char.h | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/include/chardev/char.h b/include/chardev/char.h
> index 589e7fe46d..2e4c16f82f 100644
> --- a/include/chardev/char.h
> +++ b/include/chardev/char.h
> @@ -254,24 +254,57 @@ struct ChardevClass {
>  
>      bool internal; /* TODO: eventually use TYPE_USER_CREATABLE */
>      bool supports_yank;
> +
> +    /* parse command line options and populate QAPI @backend */
>      void (*parse)(QemuOpts *opts, ChardevBackend *backend, Error **errp);
>  
> +    /* called after construction, open/starts the backend */
>      void (*open)(Chardev *chr, ChardevBackend *backend,
>                   bool *be_opened, Error **errp);
>  
> +    /* write buf to the backend */
>      int (*chr_write)(Chardev *s, const uint8_t *buf, int len);
> +
> +    /*
> +     * Read from the backend (blocking). A typical front-end will instead rely
> +     * on char_can_read/chr_read being called when polling/looping.
> +     */

chr_can_read

>      int (*chr_sync_read)(Chardev *s, const uint8_t *buf, int len);
> +
> +    /* create a watch on the backend */
>      GSource *(*chr_add_watch)(Chardev *s, GIOCondition cond);
> +
> +    /* update the backend internal sources */
>      void (*chr_update_read_handler)(Chardev *s);
> +
> +    /* send an ioctl to the backend */
>      int (*chr_ioctl)(Chardev *s, int cmd, void *arg);
> +
> +    /* get ancillary-received fds during last read */
>      int (*get_msgfds)(Chardev *s, int* fds, int num);
> +
> +    /* set ancillary fds to be sent with next write */
>      int (*set_msgfds)(Chardev *s, int *fds, int num);
> +
> +    /* accept the given fd */
>      int (*chr_add_client)(Chardev *chr, int fd);
> +
> +    /* wait for a connection */
>      int (*chr_wait_connected)(Chardev *chr, Error **errp);
> +
> +    /* disconnect a connection */
>      void (*chr_disconnect)(Chardev *chr);
> +
> +    /* called by frontend when it can read */
>      void (*chr_accept_input)(Chardev *chr);
> +
> +    /* set terminal echo */
>      void (*chr_set_echo)(Chardev *chr, bool echo);
> +
> +    /* notify the backend of frontend open state */
>      void (*chr_set_fe_open)(Chardev *chr, int fe_open);
> +
> +    /* handle various events */
>      void (*chr_be_event)(Chardev *s, QEMUChrEvent event);
>  };

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

Regards,
Daniel
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