migration: introduce a new QEMUFile impl based on QIOChannel

Introduce a new QEMUFile implementation that is based on
the QIOChannel objects. This impl is different from existing
impls in that there is no file descriptor that can be made
available, as some channels may be based on higher level
protocols such as TLS.

Although the QIOChannel based implementation can trivially
provide a bi-directional stream, initially we have separate
functions for opening input & output directions to fit with
the expectation of the current QEMUFile interface.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Message-Id: <1461751518-12128-9-git-send-email-berrange@redhat.com>
Signed-off-by: NAmit Shah <amit.shah@redhat.com>

include/migration/qemu-file.h

@@ -23,7 +23,9 @@
  */
 #ifndef QEMU_FILE_H
 #define QEMU_FILE_H 1
+#include "qemu-common.h"
 #include "exec/cpu-common.h"
+#include "io/channel.h"
 
 
 /* This function writes a chunk of data to a file at the given position.
@@ -135,6 +137,8 @@ QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops);
 QEMUFile *qemu_fopen(const char *filename, const char *mode);
 QEMUFile *qemu_fdopen(int fd, const char *mode);
 QEMUFile *qemu_fopen_socket(int fd, const char *mode);
+QEMUFile *qemu_fopen_channel_input(QIOChannel *ioc);
+QEMUFile *qemu_fopen_channel_output(QIOChannel *ioc);
 QEMUFile *qemu_popen_cmd(const char *command, const char *mode);
 QEMUFile *qemu_bufopen(const char *mode, QEMUSizedBuffer *input);
 void qemu_file_set_hooks(QEMUFile *f, const QEMUFileHooks *hooks);

migration/Makefile.objs

 common-obj-y += migration.o tcp.o
 common-obj-y += vmstate.o
 common-obj-y += qemu-file.o qemu-file-buf.o qemu-file-unix.o qemu-file-stdio.o
+common-obj-y += qemu-file-channel.o
 common-obj-y += xbzrle.o postcopy-ram.o
 common-obj-y += qjson.o
 

migration/qemu-file-channel.c

+/*
+ * QEMUFile backend for QIOChannel objects
+ *
+ * Copyright (c) 2015-2016 Red Hat, Inc
+ *
+ * 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 "migration/qemu-file.h"
+#include "io/channel-socket.h"
+#include "qemu/iov.h"
+
+
+static ssize_t channel_writev_buffer(void *opaque,
+                                     struct iovec *iov,
+                                     int iovcnt,
+                                     int64_t pos)
+{
+    QIOChannel *ioc = QIO_CHANNEL(opaque);
+    ssize_t done = 0;
+    struct iovec *local_iov = g_new(struct iovec, iovcnt);
+    struct iovec *local_iov_head = local_iov;
+    unsigned int nlocal_iov = iovcnt;
+
+    nlocal_iov = iov_copy(local_iov, nlocal_iov,
+                          iov, iovcnt,
+                          0, iov_size(iov, iovcnt));
+
+    while (nlocal_iov > 0) {
+        ssize_t len;
+        len = qio_channel_writev(ioc, local_iov, nlocal_iov, NULL);
+        if (len == QIO_CHANNEL_ERR_BLOCK) {
+            qio_channel_wait(ioc, G_IO_OUT);
+            continue;
+        }
+        if (len < 0) {
+            /* XXX handle Error objects */
+            done = -EIO;
+            goto cleanup;
+        }
+
+        iov_discard_front(&local_iov, &nlocal_iov, len);
+        done += len;
+    }
+
+ cleanup:
+    g_free(local_iov_head);
+    return done;
+}
+
+
+static ssize_t channel_get_buffer(void *opaque,
+                                  uint8_t *buf,
+                                  int64_t pos,
+                                  size_t size)
+{
+    QIOChannel *ioc = QIO_CHANNEL(opaque);
+    ssize_t ret;
+
+    do {
+        ret = qio_channel_read(ioc, (char *)buf, size, NULL);
+        if (ret < 0) {
+            if (ret == QIO_CHANNEL_ERR_BLOCK) {
+                qio_channel_yield(ioc, G_IO_IN);
+            } else {
+                /* XXX handle Error * object */
+                return -EIO;
+            }
+        }
+    } while (ret == QIO_CHANNEL_ERR_BLOCK);
+
+    return ret;
+}
+
+
+static int channel_close(void *opaque)
+{
+    QIOChannel *ioc = QIO_CHANNEL(opaque);
+    qio_channel_close(ioc, NULL);
+    object_unref(OBJECT(ioc));
+    return 0;
+}
+
+
+static int channel_shutdown(void *opaque,
+                            bool rd,
+                            bool wr)
+{
+    QIOChannel *ioc = QIO_CHANNEL(opaque);
+
+    if (qio_channel_has_feature(ioc,
+                                QIO_CHANNEL_FEATURE_SHUTDOWN)) {
+        QIOChannelShutdown mode;
+        if (rd && wr) {
+            mode = QIO_CHANNEL_SHUTDOWN_BOTH;
+        } else if (rd) {
+            mode = QIO_CHANNEL_SHUTDOWN_READ;
+        } else {
+            mode = QIO_CHANNEL_SHUTDOWN_WRITE;
+        }
+        if (qio_channel_shutdown(ioc, mode, NULL) < 0) {
+            /* XXX handler Error * object */
+            return -EIO;
+        }
+    }
+    return 0;
+}
+
+
+static int channel_set_blocking(void *opaque,
+                                bool enabled)
+{
+    QIOChannel *ioc = QIO_CHANNEL(opaque);
+
+    if (qio_channel_set_blocking(ioc, enabled, NULL) < 0) {
+        return -1;
+    }
+    return 0;
+}
+
+static QEMUFile *channel_get_input_return_path(void *opaque)
+{
+    QIOChannel *ioc = QIO_CHANNEL(opaque);
+
+    return qemu_fopen_channel_output(ioc);
+}
+
+static QEMUFile *channel_get_output_return_path(void *opaque)
+{
+    QIOChannel *ioc = QIO_CHANNEL(opaque);
+
+    return qemu_fopen_channel_input(ioc);
+}
+
+static const QEMUFileOps channel_input_ops = {
+    .get_buffer = channel_get_buffer,
+    .close = channel_close,
+    .shut_down = channel_shutdown,
+    .set_blocking = channel_set_blocking,
+    .get_return_path = channel_get_input_return_path,
+};
+
+
+static const QEMUFileOps channel_output_ops = {
+    .writev_buffer = channel_writev_buffer,
+    .close = channel_close,
+    .shut_down = channel_shutdown,
+    .set_blocking = channel_set_blocking,
+    .get_return_path = channel_get_output_return_path,
+};
+
+
+QEMUFile *qemu_fopen_channel_input(QIOChannel *ioc)
+{
+    object_ref(OBJECT(ioc));
+    return qemu_fopen_ops(ioc, &channel_input_ops);
+}
+
+QEMUFile *qemu_fopen_channel_output(QIOChannel *ioc)
+{
+    object_ref(OBJECT(ioc));
+    return qemu_fopen_ops(ioc, &channel_output_ops);
+}