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, 265 insertions, 0 deletions

diff --git a/chardev/char-fd.c b/chardev/char-fd.c
new file mode 100644
index 000000000..93c56913b
--- /dev/null
+++ b/chardev/char-fd.c
@@ -0,0 +1,265 @@
+/*
+ * QEMU System Emulator
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "qemu/module.h"
+#include "qemu/sockets.h"
+#include "qapi/error.h"
+#include "chardev/char.h"
+#include "chardev/char-fe.h"
+#include "io/channel-file.h"
+
+#include "chardev/char-fd.h"
+#include "chardev/char-io.h"
+
+/* Called with chr_write_lock held.  */
+static int fd_chr_write(Chardev *chr, const uint8_t *buf, int len)
+{
+    FDChardev *s = FD_CHARDEV(chr);
+
+    if (!s->ioc_out) {
+        return -1;
+    }
+
+    return io_channel_send(s->ioc_out, buf, len);
+}
+
+static gboolean fd_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque)
+{
+    Chardev *chr = CHARDEV(opaque);
+    FDChardev *s = FD_CHARDEV(opaque);
+    int len;
+    uint8_t buf[CHR_READ_BUF_LEN];
+    ssize_t ret;
+
+    len = sizeof(buf);
+    if (len > s->max_size) {
+        len = s->max_size;
+    }
+    if (len == 0) {
+        return TRUE;
+    }
+
+    ret = qio_channel_read(
+        chan, (gchar *)buf, len, NULL);
+    if (ret == 0) {
+        remove_fd_in_watch(chr);
+        qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
+        return FALSE;
+    }
+    if (ret > 0) {
+        qemu_chr_be_write(chr, buf, ret);
+    }
+
+    return TRUE;
+}
+
+static int fd_chr_read_poll(void *opaque)
+{
+    Chardev *chr = CHARDEV(opaque);
+    FDChardev *s = FD_CHARDEV(opaque);
+
+    s->max_size = qemu_chr_be_can_write(chr);
+    return s->max_size;
+}
+
+typedef struct FDSource {
+    GSource parent;
+
+    GIOCondition cond;
+} FDSource;
+
+static gboolean
+fd_source_prepare(GSource *source,
+                  gint *timeout_)
+{
+    FDSource *src = (FDSource *)source;
+
+    return src->cond != 0;
+}
+
+static gboolean
+fd_source_check(GSource *source)
+{
+    FDSource *src = (FDSource *)source;
+
+    return src->cond != 0;
+}
+
+static gboolean
+fd_source_dispatch(GSource *source, GSourceFunc callback,
+                   gpointer user_data)
+{
+    FDSource *src = (FDSource *)source;
+    FEWatchFunc func = (FEWatchFunc)callback;
+    gboolean ret = G_SOURCE_CONTINUE;
+
+    if (src->cond) {
+        ret = func(NULL, src->cond, user_data);
+        src->cond = 0;
+    }
+
+    return ret;
+}
+
+static GSourceFuncs fd_source_funcs = {
+  fd_source_prepare,
+  fd_source_check,
+  fd_source_dispatch,
+  NULL, NULL, NULL
+};
+
+static GSource *fd_source_new(FDChardev *chr)
+{
+    return g_source_new(&fd_source_funcs, sizeof(FDSource));
+}
+
+static gboolean child_func(GIOChannel *source,
+                           GIOCondition condition,
+                           gpointer data)
+{
+    FDSource *parent = data;
+
+    parent->cond |= condition;
+
+    return G_SOURCE_CONTINUE;
+}
+
+static GSource *fd_chr_add_watch(Chardev *chr, GIOCondition cond)
+{
+    FDChardev *s = FD_CHARDEV(chr);
+    g_autoptr(GSource) source = fd_source_new(s);
+
+    if (s->ioc_out) {
+        g_autoptr(GSource) child = qio_channel_create_watch(s->ioc_out, cond & ~G_IO_IN);
+        g_source_set_callback(child, (GSourceFunc)child_func, source, NULL);
+        g_source_add_child_source(source, child);
+    }
+    if (s->ioc_in) {
+        g_autoptr(GSource) child = qio_channel_create_watch(s->ioc_in, cond & ~G_IO_OUT);
+        g_source_set_callback(child, (GSourceFunc)child_func, source, NULL);
+        g_source_add_child_source(source, child);
+    }
+
+    return g_steal_pointer(&source);
+}
+
+static void fd_chr_update_read_handler(Chardev *chr)
+{
+    FDChardev *s = FD_CHARDEV(chr);
+
+    remove_fd_in_watch(chr);
+    if (s->ioc_in) {
+        chr->gsource = io_add_watch_poll(chr, s->ioc_in,
+                                           fd_chr_read_poll,
+                                           fd_chr_read, chr,
+                                           chr->gcontext);
+    }
+}
+
+static void char_fd_finalize(Object *obj)
+{
+    Chardev *chr = CHARDEV(obj);
+    FDChardev *s = FD_CHARDEV(obj);
+
+    remove_fd_in_watch(chr);
+    if (s->ioc_in) {
+        object_unref(OBJECT(s->ioc_in));
+    }
+    if (s->ioc_out) {
+        object_unref(OBJECT(s->ioc_out));
+    }
+
+    qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
+}
+
+int qmp_chardev_open_file_source(char *src, int flags, Error **errp)
+{
+    int fd = -1;
+
+    TFR(fd = qemu_open_old(src, flags, 0666));
+    if (fd == -1) {
+        error_setg_file_open(errp, errno, src);
+    }
+    return fd;
+}
+
+/* open a character device to a unix fd */
+void qemu_chr_open_fd(Chardev *chr,
+                      int fd_in, int fd_out)
+{
+    FDChardev *s = FD_CHARDEV(chr);
+    g_autofree char *name = NULL;
+
+    if (fd_out >= 0) {
+        qemu_set_nonblock(fd_out);
+    }
+
+    if (fd_out == fd_in && fd_in >= 0) {
+        s->ioc_in = QIO_CHANNEL(qio_channel_file_new_fd(fd_in));
+        name = g_strdup_printf("chardev-file-%s", chr->label);
+        qio_channel_set_name(QIO_CHANNEL(s->ioc_in), name);
+        s->ioc_out = QIO_CHANNEL(object_ref(s->ioc_in));
+        return;
+    }
+
+    if (fd_in >= 0) {
+        s->ioc_in = QIO_CHANNEL(qio_channel_file_new_fd(fd_in));
+        name = g_strdup_printf("chardev-file-in-%s", chr->label);
+        qio_channel_set_name(QIO_CHANNEL(s->ioc_in), name);
+    }
+
+    if (fd_out >= 0) {
+        s->ioc_out = QIO_CHANNEL(qio_channel_file_new_fd(fd_out));
+        g_free(name);
+        name = g_strdup_printf("chardev-file-out-%s", chr->label);
+        qio_channel_set_name(QIO_CHANNEL(s->ioc_out), name);
+    }
+}
+
+static void char_fd_class_init(ObjectClass *oc, void *data)
+{
+    ChardevClass *cc = CHARDEV_CLASS(oc);
+
+    cc->chr_add_watch = fd_chr_add_watch;
+    cc->chr_write = fd_chr_write;
+    cc->chr_update_read_handler = fd_chr_update_read_handler;
+}
+
+static const TypeInfo char_fd_type_info = {
+    .name = TYPE_CHARDEV_FD,
+    .parent = TYPE_CHARDEV,
+    .instance_size = sizeof(FDChardev),
+    .instance_finalize = char_fd_finalize,
+    .class_init = char_fd_class_init,
+    .abstract = true,
+};
+
+static void register_types(void)
+{
+    type_register_static(&char_fd_type_info);
+}
+
+type_init(register_types);