io: add QIOChannelFile class

Add a QIOChannel subclass that is capable of operating on things
that are files, such as plain files, pipes, character/block
devices, but notably not sockets.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

io/channel-file.c

@@ -0,0 +1,225 @@
+/*
+ * QEMU I/O channels files driver
+ *
+ * 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 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 "io/channel-file.h"
+#include "io/channel-watch.h"
+#include "qemu/sockets.h"
+#include "trace.h"
+
+QIOChannelFile *
+qio_channel_file_new_fd(int fd)
+{
+    QIOChannelFile *ioc;
+
+    ioc = QIO_CHANNEL_FILE(object_new(TYPE_QIO_CHANNEL_FILE));
+
+    ioc->fd = fd;
+
+    trace_qio_channel_file_new_fd(ioc, fd);
+
+    return ioc;
+}
+
+
+QIOChannelFile *
+qio_channel_file_new_path(const char *path,
+                          int flags,
+                          mode_t mode,
+                          Error **errp)
+{
+    QIOChannelFile *ioc;
+
+    ioc = QIO_CHANNEL_FILE(object_new(TYPE_QIO_CHANNEL_FILE));
+
+    if (flags & O_WRONLY) {
+        ioc->fd = open(path, flags, mode);
+    } else {
+        ioc->fd = open(path, flags);
+    }
+    if (ioc->fd < 0) {
+        object_unref(OBJECT(ioc));
+        error_setg_errno(errp, errno,
+                         "Unable to open %s", path);
+        return NULL;
+    }
+
+    trace_qio_channel_file_new_path(ioc, path, flags, mode, ioc->fd);
+
+    return ioc;
+}
+
+
+static void qio_channel_file_init(Object *obj)
+{
+    QIOChannelFile *ioc = QIO_CHANNEL_FILE(obj);
+    ioc->fd = -1;
+}
+
+static void qio_channel_file_finalize(Object *obj)
+{
+    QIOChannelFile *ioc = QIO_CHANNEL_FILE(obj);
+    if (ioc->fd != -1) {
+        close(ioc->fd);
+        ioc->fd = -1;
+    }
+}
+
+
+static ssize_t qio_channel_file_readv(QIOChannel *ioc,
+                                      const struct iovec *iov,
+                                      size_t niov,
+                                      int **fds,
+                                      size_t *nfds,
+                                      Error **errp)
+{
+    QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
+    ssize_t ret;
+
+ retry:
+    ret = readv(fioc->fd, iov, niov);
+    if (ret < 0) {
+        if (errno == EAGAIN ||
+            errno == EWOULDBLOCK) {
+            return QIO_CHANNEL_ERR_BLOCK;
+        }
+        if (errno == EINTR) {
+            goto retry;
+        }
+
+        error_setg_errno(errp, errno,
+                         "Unable to read from file");
+        return -1;
+    }
+
+    return ret;
+}
+
+static ssize_t qio_channel_file_writev(QIOChannel *ioc,
+                                       const struct iovec *iov,
+                                       size_t niov,
+                                       int *fds,
+                                       size_t nfds,
+                                       Error **errp)
+{
+    QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
+    ssize_t ret;
+
+ retry:
+    ret = writev(fioc->fd, iov, niov);
+    if (ret <= 0) {
+        if (errno == EAGAIN ||
+            errno == EWOULDBLOCK) {
+            return QIO_CHANNEL_ERR_BLOCK;
+        }
+        if (errno == EINTR) {
+            goto retry;
+        }
+        error_setg_errno(errp, errno,
+                         "Unable to write to file");
+        return -1;
+    }
+    return ret;
+}
+
+static int qio_channel_file_set_blocking(QIOChannel *ioc,
+                                         bool enabled,
+                                         Error **errp)
+{
+    QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
+
+    if (enabled) {
+        qemu_set_block(fioc->fd);
+    } else {
+        qemu_set_nonblock(fioc->fd);
+    }
+    return 0;
+}
+
+
+static off_t qio_channel_file_seek(QIOChannel *ioc,
+                                   off_t offset,
+                                   int whence,
+                                   Error **errp)
+{
+    QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
+    off_t ret;
+
+    ret = lseek(fioc->fd, offset, whence);
+    if (ret == (off_t)-1) {
+        error_setg_errno(errp, errno,
+                         "Unable to seek to offset %lld whence %d in file",
+                         (long long int)offset, whence);
+        return -1;
+    }
+    return ret;
+}
+
+
+static int qio_channel_file_close(QIOChannel *ioc,
+                                  Error **errp)
+{
+    QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
+
+    if (close(fioc->fd) < 0) {
+        error_setg_errno(errp, errno,
+                         "Unable to close file");
+        return -1;
+    }
+    return 0;
+}
+
+
+static GSource *qio_channel_file_create_watch(QIOChannel *ioc,
+                                              GIOCondition condition)
+{
+    QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
+    return qio_channel_create_fd_watch(ioc,
+                                       fioc->fd,
+                                       condition);
+}
+
+static void qio_channel_file_class_init(ObjectClass *klass,
+                                        void *class_data G_GNUC_UNUSED)
+{
+    QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
+
+    ioc_klass->io_writev = qio_channel_file_writev;
+    ioc_klass->io_readv = qio_channel_file_readv;
+    ioc_klass->io_set_blocking = qio_channel_file_set_blocking;
+    ioc_klass->io_seek = qio_channel_file_seek;
+    ioc_klass->io_close = qio_channel_file_close;
+    ioc_klass->io_create_watch = qio_channel_file_create_watch;
+}
+
+static const TypeInfo qio_channel_file_info = {
+    .parent = TYPE_QIO_CHANNEL,
+    .name = TYPE_QIO_CHANNEL_FILE,
+    .instance_size = sizeof(QIOChannelFile),
+    .instance_init = qio_channel_file_init,
+    .instance_finalize = qio_channel_file_finalize,
+    .class_init = qio_channel_file_class_init,
+};
+
+static void qio_channel_file_register_types(void)
+{
+    type_register_static(&qio_channel_file_info);
+}
+
+type_init(qio_channel_file_register_types);