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, 623 insertions, 0 deletions

diff --git a/io/channel.c b/io/channel.c
new file mode 100644
index 000000000..e8b019dc3
--- /dev/null
+++ b/io/channel.c
@@ -0,0 +1,623 @@
+/*
+ * QEMU I/O channels
+ *
+ * Copyright (c) 2015 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "io/channel.h"
+#include "qapi/error.h"
+#include "qemu/main-loop.h"
+#include "qemu/module.h"
+#include "qemu/iov.h"
+
+bool qio_channel_has_feature(QIOChannel *ioc,
+                             QIOChannelFeature feature)
+{
+    return ioc->features & (1 << feature);
+}
+
+
+void qio_channel_set_feature(QIOChannel *ioc,
+                             QIOChannelFeature feature)
+{
+    ioc->features |= (1 << feature);
+}
+
+
+void qio_channel_set_name(QIOChannel *ioc,
+                          const char *name)
+{
+    g_free(ioc->name);
+    ioc->name = g_strdup(name);
+}
+
+
+ssize_t qio_channel_readv_full(QIOChannel *ioc,
+                               const struct iovec *iov,
+                               size_t niov,
+                               int **fds,
+                               size_t *nfds,
+                               Error **errp)
+{
+    QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
+
+    if ((fds || nfds) &&
+        !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_FD_PASS)) {
+        error_setg_errno(errp, EINVAL,
+                         "Channel does not support file descriptor passing");
+        return -1;
+    }
+
+    return klass->io_readv(ioc, iov, niov, fds, nfds, errp);
+}
+
+
+ssize_t qio_channel_writev_full(QIOChannel *ioc,
+                                const struct iovec *iov,
+                                size_t niov,
+                                int *fds,
+                                size_t nfds,
+                                Error **errp)
+{
+    QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
+
+    if ((fds || nfds) &&
+        !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_FD_PASS)) {
+        error_setg_errno(errp, EINVAL,
+                         "Channel does not support file descriptor passing");
+        return -1;
+    }
+
+    return klass->io_writev(ioc, iov, niov, fds, nfds, errp);
+}
+
+
+int qio_channel_readv_all_eof(QIOChannel *ioc,
+                              const struct iovec *iov,
+                              size_t niov,
+                              Error **errp)
+{
+    return qio_channel_readv_full_all_eof(ioc, iov, niov, NULL, NULL, errp);
+}
+
+int qio_channel_readv_all(QIOChannel *ioc,
+                          const struct iovec *iov,
+                          size_t niov,
+                          Error **errp)
+{
+    return qio_channel_readv_full_all(ioc, iov, niov, NULL, NULL, errp);
+}
+
+int qio_channel_readv_full_all_eof(QIOChannel *ioc,
+                                   const struct iovec *iov,
+                                   size_t niov,
+                                   int **fds, size_t *nfds,
+                                   Error **errp)
+{
+    int ret = -1;
+    struct iovec *local_iov = g_new(struct iovec, niov);
+    struct iovec *local_iov_head = local_iov;
+    unsigned int nlocal_iov = niov;
+    int **local_fds = fds;
+    size_t *local_nfds = nfds;
+    bool partial = false;
+
+    if (nfds) {
+        *nfds = 0;
+    }
+
+    if (fds) {
+        *fds = NULL;
+    }
+
+    nlocal_iov = iov_copy(local_iov, nlocal_iov,
+                          iov, niov,
+                          0, iov_size(iov, niov));
+
+    while ((nlocal_iov > 0) || local_fds) {
+        ssize_t len;
+        len = qio_channel_readv_full(ioc, local_iov, nlocal_iov, local_fds,
+                                     local_nfds, errp);
+        if (len == QIO_CHANNEL_ERR_BLOCK) {
+            if (qemu_in_coroutine()) {
+                qio_channel_yield(ioc, G_IO_IN);
+            } else {
+                qio_channel_wait(ioc, G_IO_IN);
+            }
+            continue;
+        }
+
+        if (len == 0) {
+            if (local_nfds && *local_nfds) {
+                /*
+                 * Got some FDs, but no data yet. This isn't an EOF
+                 * scenario (yet), so carry on to try to read data
+                 * on next loop iteration
+                 */
+                goto next_iter;
+            } else if (!partial) {
+                /* No fds and no data - EOF before any data read */
+                ret = 0;
+                goto cleanup;
+            } else {
+                len = -1;
+                error_setg(errp,
+                           "Unexpected end-of-file before all data were read");
+                /* Fallthrough into len < 0 handling */
+            }
+        }
+
+        if (len < 0) {
+            /* Close any FDs we previously received */
+            if (nfds && fds) {
+                size_t i;
+                for (i = 0; i < (*nfds); i++) {
+                    close((*fds)[i]);
+                }
+                g_free(*fds);
+                *fds = NULL;
+                *nfds = 0;
+            }
+            goto cleanup;
+        }
+
+        if (nlocal_iov) {
+            iov_discard_front(&local_iov, &nlocal_iov, len);
+        }
+
+next_iter:
+        partial = true;
+        local_fds = NULL;
+        local_nfds = NULL;
+    }
+
+    ret = 1;
+
+ cleanup:
+    g_free(local_iov_head);
+    return ret;
+}
+
+int qio_channel_readv_full_all(QIOChannel *ioc,
+                               const struct iovec *iov,
+                               size_t niov,
+                               int **fds, size_t *nfds,
+                               Error **errp)
+{
+    int ret = qio_channel_readv_full_all_eof(ioc, iov, niov, fds, nfds, errp);
+
+    if (ret == 0) {
+        error_setg(errp, "Unexpected end-of-file before all data were read");
+        return -1;
+    }
+    if (ret == 1) {
+        return 0;
+    }
+
+    return ret;
+}
+
+int qio_channel_writev_all(QIOChannel *ioc,
+                           const struct iovec *iov,
+                           size_t niov,
+                           Error **errp)
+{
+    return qio_channel_writev_full_all(ioc, iov, niov, NULL, 0, errp);
+}
+
+int qio_channel_writev_full_all(QIOChannel *ioc,
+                                const struct iovec *iov,
+                                size_t niov,
+                                int *fds, size_t nfds,
+                                Error **errp)
+{
+    int ret = -1;
+    struct iovec *local_iov = g_new(struct iovec, niov);
+    struct iovec *local_iov_head = local_iov;
+    unsigned int nlocal_iov = niov;
+
+    nlocal_iov = iov_copy(local_iov, nlocal_iov,
+                          iov, niov,
+                          0, iov_size(iov, niov));
+
+    while (nlocal_iov > 0) {
+        ssize_t len;
+        len = qio_channel_writev_full(ioc, local_iov, nlocal_iov, fds, nfds,
+                                      errp);
+        if (len == QIO_CHANNEL_ERR_BLOCK) {
+            if (qemu_in_coroutine()) {
+                qio_channel_yield(ioc, G_IO_OUT);
+            } else {
+                qio_channel_wait(ioc, G_IO_OUT);
+            }
+            continue;
+        }
+        if (len < 0) {
+            goto cleanup;
+        }
+
+        iov_discard_front(&local_iov, &nlocal_iov, len);
+
+        fds = NULL;
+        nfds = 0;
+    }
+
+    ret = 0;
+ cleanup:
+    g_free(local_iov_head);
+    return ret;
+}
+
+ssize_t qio_channel_readv(QIOChannel *ioc,
+                          const struct iovec *iov,
+                          size_t niov,
+                          Error **errp)
+{
+    return qio_channel_readv_full(ioc, iov, niov, NULL, NULL, errp);
+}
+
+
+ssize_t qio_channel_writev(QIOChannel *ioc,
+                           const struct iovec *iov,
+                           size_t niov,
+                           Error **errp)
+{
+    return qio_channel_writev_full(ioc, iov, niov, NULL, 0, errp);
+}
+
+
+ssize_t qio_channel_read(QIOChannel *ioc,
+                         char *buf,
+                         size_t buflen,
+                         Error **errp)
+{
+    struct iovec iov = { .iov_base = buf, .iov_len = buflen };
+    return qio_channel_readv_full(ioc, &iov, 1, NULL, NULL, errp);
+}
+
+
+ssize_t qio_channel_write(QIOChannel *ioc,
+                          const char *buf,
+                          size_t buflen,
+                          Error **errp)
+{
+    struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
+    return qio_channel_writev_full(ioc, &iov, 1, NULL, 0, errp);
+}
+
+
+int qio_channel_read_all_eof(QIOChannel *ioc,
+                             char *buf,
+                             size_t buflen,
+                             Error **errp)
+{
+    struct iovec iov = { .iov_base = buf, .iov_len = buflen };
+    return qio_channel_readv_all_eof(ioc, &iov, 1, errp);
+}
+
+
+int qio_channel_read_all(QIOChannel *ioc,
+                         char *buf,
+                         size_t buflen,
+                         Error **errp)
+{
+    struct iovec iov = { .iov_base = buf, .iov_len = buflen };
+    return qio_channel_readv_all(ioc, &iov, 1, errp);
+}
+
+
+int qio_channel_write_all(QIOChannel *ioc,
+                          const char *buf,
+                          size_t buflen,
+                          Error **errp)
+{
+    struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
+    return qio_channel_writev_all(ioc, &iov, 1, errp);
+}
+
+
+int qio_channel_set_blocking(QIOChannel *ioc,
+                              bool enabled,
+                              Error **errp)
+{
+    QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
+    return klass->io_set_blocking(ioc, enabled, errp);
+}
+
+
+int qio_channel_close(QIOChannel *ioc,
+                      Error **errp)
+{
+    QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
+    return klass->io_close(ioc, errp);
+}
+
+
+GSource *qio_channel_create_watch(QIOChannel *ioc,
+                                  GIOCondition condition)
+{
+    QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
+    GSource *ret = klass->io_create_watch(ioc, condition);
+
+    if (ioc->name) {
+        g_source_set_name(ret, ioc->name);
+    }
+
+    return ret;
+}
+
+
+void qio_channel_set_aio_fd_handler(QIOChannel *ioc,
+                                    AioContext *ctx,
+                                    IOHandler *io_read,
+                                    IOHandler *io_write,
+                                    void *opaque)
+{
+    QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
+
+    klass->io_set_aio_fd_handler(ioc, ctx, io_read, io_write, opaque);
+}
+
+guint qio_channel_add_watch_full(QIOChannel *ioc,
+                                 GIOCondition condition,
+                                 QIOChannelFunc func,
+                                 gpointer user_data,
+                                 GDestroyNotify notify,
+                                 GMainContext *context)
+{
+    GSource *source;
+    guint id;
+
+    source = qio_channel_create_watch(ioc, condition);
+
+    g_source_set_callback(source, (GSourceFunc)func, user_data, notify);
+
+    id = g_source_attach(source, context);
+    g_source_unref(source);
+
+    return id;
+}
+
+guint qio_channel_add_watch(QIOChannel *ioc,
+                            GIOCondition condition,
+                            QIOChannelFunc func,
+                            gpointer user_data,
+                            GDestroyNotify notify)
+{
+    return qio_channel_add_watch_full(ioc, condition, func,
+                                      user_data, notify, NULL);
+}
+
+GSource *qio_channel_add_watch_source(QIOChannel *ioc,
+                                      GIOCondition condition,
+                                      QIOChannelFunc func,
+                                      gpointer user_data,
+                                      GDestroyNotify notify,
+                                      GMainContext *context)
+{
+    GSource *source;
+    guint id;
+
+    id = qio_channel_add_watch_full(ioc, condition, func,
+                                    user_data, notify, context);
+    source = g_main_context_find_source_by_id(context, id);
+    g_source_ref(source);
+    return source;
+}
+
+
+int qio_channel_shutdown(QIOChannel *ioc,
+                         QIOChannelShutdown how,
+                         Error **errp)
+{
+    QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
+
+    if (!klass->io_shutdown) {
+        error_setg(errp, "Data path shutdown not supported");
+        return -1;
+    }
+
+    return klass->io_shutdown(ioc, how, errp);
+}
+
+
+void qio_channel_set_delay(QIOChannel *ioc,
+                           bool enabled)
+{
+    QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
+
+    if (klass->io_set_delay) {
+        klass->io_set_delay(ioc, enabled);
+    }
+}
+
+
+void qio_channel_set_cork(QIOChannel *ioc,
+                          bool enabled)
+{
+    QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
+
+    if (klass->io_set_cork) {
+        klass->io_set_cork(ioc, enabled);
+    }
+}
+
+
+off_t qio_channel_io_seek(QIOChannel *ioc,
+                          off_t offset,
+                          int whence,
+                          Error **errp)
+{
+    QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
+
+    if (!klass->io_seek) {
+        error_setg(errp, "Channel does not support random access");
+        return -1;
+    }
+
+    return klass->io_seek(ioc, offset, whence, errp);
+}
+
+
+static void qio_channel_restart_read(void *opaque)
+{
+    QIOChannel *ioc = opaque;
+    Coroutine *co = ioc->read_coroutine;
+
+    /* Assert that aio_co_wake() reenters the coroutine directly */
+    assert(qemu_get_current_aio_context() ==
+           qemu_coroutine_get_aio_context(co));
+    aio_co_wake(co);
+}
+
+static void qio_channel_restart_write(void *opaque)
+{
+    QIOChannel *ioc = opaque;
+    Coroutine *co = ioc->write_coroutine;
+
+    /* Assert that aio_co_wake() reenters the coroutine directly */
+    assert(qemu_get_current_aio_context() ==
+           qemu_coroutine_get_aio_context(co));
+    aio_co_wake(co);
+}
+
+static void qio_channel_set_aio_fd_handlers(QIOChannel *ioc)
+{
+    IOHandler *rd_handler = NULL, *wr_handler = NULL;
+    AioContext *ctx;
+
+    if (ioc->read_coroutine) {
+        rd_handler = qio_channel_restart_read;
+    }
+    if (ioc->write_coroutine) {
+        wr_handler = qio_channel_restart_write;
+    }
+
+    ctx = ioc->ctx ? ioc->ctx : iohandler_get_aio_context();
+    qio_channel_set_aio_fd_handler(ioc, ctx, rd_handler, wr_handler, ioc);
+}
+
+void qio_channel_attach_aio_context(QIOChannel *ioc,
+                                    AioContext *ctx)
+{
+    assert(!ioc->read_coroutine);
+    assert(!ioc->write_coroutine);
+    ioc->ctx = ctx;
+}
+
+void qio_channel_detach_aio_context(QIOChannel *ioc)
+{
+    ioc->read_coroutine = NULL;
+    ioc->write_coroutine = NULL;
+    qio_channel_set_aio_fd_handlers(ioc);
+    ioc->ctx = NULL;
+}
+
+void coroutine_fn qio_channel_yield(QIOChannel *ioc,
+                                    GIOCondition condition)
+{
+    assert(qemu_in_coroutine());
+    if (condition == G_IO_IN) {
+        assert(!ioc->read_coroutine);
+        ioc->read_coroutine = qemu_coroutine_self();
+    } else if (condition == G_IO_OUT) {
+        assert(!ioc->write_coroutine);
+        ioc->write_coroutine = qemu_coroutine_self();
+    } else {
+        abort();
+    }
+    qio_channel_set_aio_fd_handlers(ioc);
+    qemu_coroutine_yield();
+
+    /* Allow interrupting the operation by reentering the coroutine other than
+     * through the aio_fd_handlers. */
+    if (condition == G_IO_IN && ioc->read_coroutine) {
+        ioc->read_coroutine = NULL;
+        qio_channel_set_aio_fd_handlers(ioc);
+    } else if (condition == G_IO_OUT && ioc->write_coroutine) {
+        ioc->write_coroutine = NULL;
+        qio_channel_set_aio_fd_handlers(ioc);
+    }
+}
+
+
+static gboolean qio_channel_wait_complete(QIOChannel *ioc,
+                                          GIOCondition condition,
+                                          gpointer opaque)
+{
+    GMainLoop *loop = opaque;
+
+    g_main_loop_quit(loop);
+    return FALSE;
+}
+
+
+void qio_channel_wait(QIOChannel *ioc,
+                      GIOCondition condition)
+{
+    GMainContext *ctxt = g_main_context_new();
+    GMainLoop *loop = g_main_loop_new(ctxt, TRUE);
+    GSource *source;
+
+    source = qio_channel_create_watch(ioc, condition);
+
+    g_source_set_callback(source,
+                          (GSourceFunc)qio_channel_wait_complete,
+                          loop,
+                          NULL);
+
+    g_source_attach(source, ctxt);
+
+    g_main_loop_run(loop);
+
+    g_source_unref(source);
+    g_main_loop_unref(loop);
+    g_main_context_unref(ctxt);
+}
+
+
+static void qio_channel_finalize(Object *obj)
+{
+    QIOChannel *ioc = QIO_CHANNEL(obj);
+
+    g_free(ioc->name);
+
+#ifdef _WIN32
+    if (ioc->event) {
+        CloseHandle(ioc->event);
+    }
+#endif
+}
+
+static const TypeInfo qio_channel_info = {
+    .parent = TYPE_OBJECT,
+    .name = TYPE_QIO_CHANNEL,
+    .instance_size = sizeof(QIOChannel),
+    .instance_finalize = qio_channel_finalize,
+    .abstract = true,
+    .class_size = sizeof(QIOChannelClass),
+};
+
+
+static void qio_channel_register_types(void)
+{
+    type_register_static(&qio_channel_info);
+}
+
+
+type_init(qio_channel_register_types);