Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 326 insertions, 0 deletions

diff --git a/include/chardev/char.h b/include/chardev/char.h
new file mode 100644
index 000000000..a319b5fdf
--- /dev/null
+++ b/include/chardev/char.h
@@ -0,0 +1,326 @@
+#ifndef QEMU_CHAR_H
+#define QEMU_CHAR_H
+
+#include "qapi/qapi-types-char.h"
+#include "qemu/bitmap.h"
+#include "qemu/thread.h"
+#include "qom/object.h"
+
+#define IAC_EOR 239
+#define IAC_SE 240
+#define IAC_NOP 241
+#define IAC_BREAK 243
+#define IAC_IP 244
+#define IAC_SB 250
+#define IAC 255
+
+/* character device */
+typedef struct CharBackend CharBackend;
+
+typedef enum {
+    CHR_EVENT_BREAK, /* serial break char */
+    CHR_EVENT_OPENED, /* new connection established */
+    CHR_EVENT_MUX_IN, /* mux-focus was set to this terminal */
+    CHR_EVENT_MUX_OUT, /* mux-focus will move on */
+    CHR_EVENT_CLOSED /* connection closed.  NOTE: currently this event
+                      * is only bound to the read port of the chardev.
+                      * Normally the read port and write port of a
+                      * chardev should be the same, but it can be
+                      * different, e.g., for fd chardevs, when the two
+                      * fds are different.  So when we received the
+                      * CLOSED event it's still possible that the out
+                      * port is still open.  TODO: we should only send
+                      * the CLOSED event when both ports are closed.
+                      */
+} QEMUChrEvent;
+
+#define CHR_READ_BUF_LEN 4096
+
+typedef enum {
+    /* Whether the chardev peer is able to close and
+     * reopen the data channel, thus requiring support
+     * for qemu_chr_wait_connected() to wait for a
+     * valid connection */
+    QEMU_CHAR_FEATURE_RECONNECTABLE,
+    /* Whether it is possible to send/recv file descriptors
+     * over the data channel */
+    QEMU_CHAR_FEATURE_FD_PASS,
+    /* Whether replay or record mode is enabled */
+    QEMU_CHAR_FEATURE_REPLAY,
+    /* Whether the gcontext can be changed after calling
+     * qemu_chr_be_update_read_handlers() */
+    QEMU_CHAR_FEATURE_GCONTEXT,
+
+    QEMU_CHAR_FEATURE_LAST,
+} ChardevFeature;
+
+#define qemu_chr_replay(chr) qemu_chr_has_feature(chr, QEMU_CHAR_FEATURE_REPLAY)
+
+struct Chardev {
+    Object parent_obj;
+
+    QemuMutex chr_write_lock;
+    CharBackend *be;
+    char *label;
+    char *filename;
+    int logfd;
+    int be_open;
+    /* used to coordinate the chardev-change special-case: */
+    bool handover_yank_instance;
+    GSource *gsource;
+    GMainContext *gcontext;
+    DECLARE_BITMAP(features, QEMU_CHAR_FEATURE_LAST);
+};
+
+/**
+ * qemu_chr_new_from_opts:
+ * @opts: see qemu-config.c for a list of valid options
+ * @context: the #GMainContext to be used at initialization time
+ *
+ * Create a new character backend from a QemuOpts list.
+ *
+ * Returns: on success: a new character backend
+ *          otherwise:  NULL; @errp specifies the error
+ *                            or left untouched in case of help option
+ */
+Chardev *qemu_chr_new_from_opts(QemuOpts *opts,
+                                GMainContext *context,
+                                Error **errp);
+
+/**
+ * qemu_chr_parse_common:
+ * @opts: the options that still need parsing
+ * @backend: a new backend
+ *
+ * Parse the common options available to all character backends.
+ */
+void qemu_chr_parse_common(QemuOpts *opts, ChardevCommon *backend);
+
+/**
+ * qemu_chr_parse_opts:
+ *
+ * Parse the options to the ChardevBackend struct.
+ *
+ * Returns: a new backend or NULL on error
+ */
+ChardevBackend *qemu_chr_parse_opts(QemuOpts *opts,
+                                    Error **errp);
+
+/**
+ * qemu_chr_new:
+ * @label: the name of the backend
+ * @filename: the URI
+ * @context: the #GMainContext to be used at initialization time
+ *
+ * Create a new character backend from a URI.
+ * Do not implicitly initialize a monitor if the chardev is muxed.
+ *
+ * Returns: a new character backend
+ */
+Chardev *qemu_chr_new(const char *label, const char *filename,
+                      GMainContext *context);
+
+/**
+ * qemu_chr_new_mux_mon:
+ * @label: the name of the backend
+ * @filename: the URI
+ * @context: the #GMainContext to be used at initialization time
+ *
+ * Create a new character backend from a URI.
+ * Implicitly initialize a monitor if the chardev is muxed.
+ *
+ * Returns: a new character backend
+ */
+Chardev *qemu_chr_new_mux_mon(const char *label, const char *filename,
+                              GMainContext *context);
+
+/**
+* qemu_chr_change:
+* @opts: the new backend options
+ *
+ * Change an existing character backend
+ */
+void qemu_chr_change(QemuOpts *opts, Error **errp);
+
+/**
+ * qemu_chr_cleanup:
+ *
+ * Delete all chardevs (when leaving qemu)
+ */
+void qemu_chr_cleanup(void);
+
+/**
+ * qemu_chr_new_noreplay:
+ * @label: the name of the backend
+ * @filename: the URI
+ * @permit_mux_mon: if chardev is muxed, initialize a monitor
+ * @context: the #GMainContext to be used at initialization time
+ *
+ * Create a new character backend from a URI.
+ * Character device communications are not written
+ * into the replay log.
+ *
+ * Returns: a new character backend
+ */
+Chardev *qemu_chr_new_noreplay(const char *label, const char *filename,
+                               bool permit_mux_mon, GMainContext *context);
+
+/**
+ * qemu_chr_be_can_write:
+ *
+ * Determine how much data the front end can currently accept.  This function
+ * returns the number of bytes the front end can accept.  If it returns 0, the
+ * front end cannot receive data at the moment.  The function must be polled
+ * to determine when data can be received.
+ *
+ * Returns: the number of bytes the front end can receive via @qemu_chr_be_write
+ */
+int qemu_chr_be_can_write(Chardev *s);
+
+/**
+ * qemu_chr_be_write:
+ * @buf: a buffer to receive data from the front end
+ * @len: the number of bytes to receive from the front end
+ *
+ * Write data from the back end to the front end.  Before issuing this call,
+ * the caller should call @qemu_chr_be_can_write to determine how much data
+ * the front end can currently accept.
+ */
+void qemu_chr_be_write(Chardev *s, uint8_t *buf, int len);
+
+/**
+ * qemu_chr_be_write_impl:
+ * @buf: a buffer to receive data from the front end
+ * @len: the number of bytes to receive from the front end
+ *
+ * Implementation of back end writing. Used by replay module.
+ */
+void qemu_chr_be_write_impl(Chardev *s, uint8_t *buf, int len);
+
+/**
+ * qemu_chr_be_update_read_handlers:
+ * @context: the gcontext that will be used to attach the watch sources
+ *
+ * Invoked when frontend read handlers are setup
+ */
+void qemu_chr_be_update_read_handlers(Chardev *s,
+                                      GMainContext *context);
+
+/**
+ * qemu_chr_be_event:
+ * @event: the event to send
+ *
+ * Send an event from the back end to the front end.
+ */
+void qemu_chr_be_event(Chardev *s, QEMUChrEvent event);
+
+int qemu_chr_add_client(Chardev *s, int fd);
+Chardev *qemu_chr_find(const char *name);
+
+bool qemu_chr_has_feature(Chardev *chr,
+                          ChardevFeature feature);
+void qemu_chr_set_feature(Chardev *chr,
+                          ChardevFeature feature);
+QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename,
+                                bool permit_mux_mon);
+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"
+OBJECT_DECLARE_TYPE(Chardev, ChardevClass, CHARDEV)
+
+#define TYPE_CHARDEV_NULL "chardev-null"
+#define TYPE_CHARDEV_MUX "chardev-mux"
+#define TYPE_CHARDEV_RINGBUF "chardev-ringbuf"
+#define TYPE_CHARDEV_PTY "chardev-pty"
+#define TYPE_CHARDEV_CONSOLE "chardev-console"
+#define TYPE_CHARDEV_STDIO "chardev-stdio"
+#define TYPE_CHARDEV_PIPE "chardev-pipe"
+#define TYPE_CHARDEV_MEMORY "chardev-memory"
+#define TYPE_CHARDEV_PARALLEL "chardev-parallel"
+#define TYPE_CHARDEV_FILE "chardev-file"
+#define TYPE_CHARDEV_SERIAL "chardev-serial"
+#define TYPE_CHARDEV_SOCKET "chardev-socket"
+#define TYPE_CHARDEV_UDP "chardev-udp"
+
+#define CHARDEV_IS_RINGBUF(chr) \
+    object_dynamic_cast(OBJECT(chr), TYPE_CHARDEV_RINGBUF)
+#define CHARDEV_IS_PTY(chr) \
+    object_dynamic_cast(OBJECT(chr), TYPE_CHARDEV_PTY)
+
+struct ChardevClass {
+    ObjectClass parent_class;
+
+    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 chr_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);
+};
+
+Chardev *qemu_chardev_new(const char *id, const char *typename,
+                          ChardevBackend *backend, GMainContext *context,
+                          Error **errp);
+
+extern int term_escape_char;
+
+GSource *qemu_chr_timeout_add_ms(Chardev *chr, guint ms,
+                                 GSourceFunc func, void *private);
+
+void suspend_mux_open(void);
+void resume_mux_open(void);
+
+/* console.c */
+void qemu_chr_parse_vc(QemuOpts *opts, ChardevBackend *backend, Error **errp);
+
+#endif