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>

include/io/channel-file.h

@@ -0,0 +1,93 @@
+/*
+ * 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/>.
+ *
+ */
+
+#ifndef QIO_CHANNEL_FILE_H__
+#define QIO_CHANNEL_FILE_H__
+
+#include "io/channel.h"
+
+#define TYPE_QIO_CHANNEL_FILE "qio-channel-file"
+#define QIO_CHANNEL_FILE(obj)                                     \
+    OBJECT_CHECK(QIOChannelFile, (obj), TYPE_QIO_CHANNEL_FILE)
+
+typedef struct QIOChannelFile QIOChannelFile;
+
+/**
+ * QIOChannelFile:
+ *
+ * The QIOChannelFile object provides a channel implementation
+ * that is able to perform I/O on block devices, character
+ * devices, FIFOs, pipes and plain files. While it is technically
+ * able to work on sockets too on the UNIX platform, this is not
+ * portable to Windows and lacks some extra sockets specific
+ * functionality. So the QIOChannelSocket object is recommended
+ * for that use case.
+ *
+ */
+
+struct QIOChannelFile {
+    QIOChannel parent;
+    int fd;
+};
+
+
+/**
+ * qio_channel_file_new_fd:
+ * @fd: the file descriptor
+ *
+ * Create a new IO channel object for a file represented
+ * by the @fd parameter. @fd can be associated with a
+ * block device, character device, fifo, pipe, or a
+ * regular file. For sockets, the QIOChannelSocket class
+ * should be used instead, as this provides greater
+ * functionality and cross platform portability.
+ *
+ * The channel will own the passed in file descriptor
+ * and will take responsibility for closing it, so the
+ * caller must not close it. If appropriate the caller
+ * should dup() its FD before opening the channel.
+ *
+ * Returns: the new channel object
+ */
+QIOChannelFile *
+qio_channel_file_new_fd(int fd);
+
+/**
+ * qio_channel_file_new_path:
+ * @fd: the file descriptor
+ * @flags: the open flags (O_RDONLY|O_WRONLY|O_RDWR, etc)
+ * @mode: the file creation mode if O_WRONLY is set in @flags
+ * @errp: pointer to initialized error object
+ *
+ * Create a new IO channel object for a file represented
+ * by the @path parameter. @path can point to any
+ * type of file on which sequential I/O can be
+ * performed, whether it be a plain file, character
+ * device or block device.
+ *
+ * Returns: the new channel object
+ */
+QIOChannelFile *
+qio_channel_file_new_path(const char *path,
+                          int flags,
+                          mode_t mode,
+                          Error **errp);
+
+#endif /* QIO_CHANNEL_FILE_H__ */

io/Makefile.objs

@@ -1,4 +1,5 @@
 io-obj-y = channel.o
+io-obj-y += channel-file.o
 io-obj-y += channel-socket.o
 io-obj-y += channel-watch.o
 io-obj-y += task.o

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);

tests/.gitignore

@@ -24,6 +24,8 @@ test-cutils
 test-hbitmap
 test-int128
 test-iov
+test-io-channel-file
+test-io-channel-file.txt
 test-io-channel-socket
 test-io-task
 test-mul64

tests/Makefile

@@ -86,6 +86,7 @@ check-unit-$(CONFIG_LINUX) += tests/test-qga$(EXESUF)
 check-unit-y += tests/test-timed-average$(EXESUF)
 check-unit-y += tests/test-io-task$(EXESUF)
 check-unit-y += tests/test-io-channel-socket$(EXESUF)
+check-unit-y += tests/test-io-channel-file$(EXESUF)
 
 check-block-$(CONFIG_POSIX) += tests/qemu-iotests-quick.sh
 
@@ -475,6 +476,8 @@ tests/test-crypto-tlssession$(EXESUF): tests/test-crypto-tlssession.o \
 tests/test-io-task$(EXESUF): tests/test-io-task.o $(test-io-obj-y)
 tests/test-io-channel-socket$(EXESUF): tests/test-io-channel-socket.o \
         tests/io-channel-helpers.o $(test-io-obj-y)
+tests/test-io-channel-file$(EXESUF): tests/test-io-channel-file.o \
+        tests/io-channel-helpers.o $(test-io-obj-y)
 
 libqos-obj-y = tests/libqos/pci.o tests/libqos/fw_cfg.o tests/libqos/malloc.o
 libqos-obj-y += tests/libqos/i2c.o tests/libqos/libqos.o

tests/test-io-channel-file.c

@@ -0,0 +1,100 @@
+/*
+ * QEMU I/O channel file test
+ *
+ * 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-helpers.h"
+
+
+static void test_io_channel_file(void)
+{
+    QIOChannel *src, *dst;
+    QIOChannelTest *test;
+
+#define TEST_FILE "tests/test-io-channel-file.txt"
+    unlink(TEST_FILE);
+    src = QIO_CHANNEL(qio_channel_file_new_path(
+                          TEST_FILE,
+                          O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0600,
+                          &error_abort));
+    dst = QIO_CHANNEL(qio_channel_file_new_path(
+                          TEST_FILE,
+                          O_RDONLY | O_BINARY, 0,
+                          &error_abort));
+
+    test = qio_channel_test_new();
+    qio_channel_test_run_writer(test, src);
+    qio_channel_test_run_reader(test, dst);
+    qio_channel_test_validate(test);
+
+    unlink(TEST_FILE);
+    object_unref(OBJECT(src));
+    object_unref(OBJECT(dst));
+}
+
+
+#ifndef _WIN32
+static void test_io_channel_pipe(bool async)
+{
+    QIOChannel *src, *dst;
+    QIOChannelTest *test;
+    int fd[2];
+
+    if (pipe(fd) < 0) {
+        perror("pipe");
+        abort();
+    }
+
+    src = QIO_CHANNEL(qio_channel_file_new_fd(fd[1]));
+    dst = QIO_CHANNEL(qio_channel_file_new_fd(fd[0]));
+
+    test = qio_channel_test_new();
+    qio_channel_test_run_threads(test, async, src, dst);
+    qio_channel_test_validate(test);
+
+    object_unref(OBJECT(src));
+    object_unref(OBJECT(dst));
+}
+
+
+static void test_io_channel_pipe_async(void)
+{
+    test_io_channel_pipe(true);
+}
+
+static void test_io_channel_pipe_sync(void)
+{
+    test_io_channel_pipe(false);
+}
+#endif /* ! _WIN32 */
+
+
+int main(int argc, char **argv)
+{
+    module_call_init(MODULE_INIT_QOM);
+
+    g_test_init(&argc, &argv, NULL);
+
+    g_test_add_func("/io/channel/file", test_io_channel_file);
+#ifndef _WIN32
+    g_test_add_func("/io/channel/pipe/sync", test_io_channel_pipe_sync);
+    g_test_add_func("/io/channel/pipe/async", test_io_channel_pipe_async);
+#endif
+    return g_test_run();
+}

trace-events

@@ -1836,3 +1836,7 @@ qio_channel_socket_dgram_complete(void *ioc, int fd) "Socket dgram complete ioc=
 qio_channel_socket_accept(void *ioc) "Socket accept start ioc=%p"
 qio_channel_socket_accept_fail(void *ioc) "Socket accept fail ioc=%p"
 qio_channel_socket_accept_complete(void *ioc, void *cioc, int fd) "Socket accept complete ioc=%p cioc=%p fd=%d"
+
+# io/channel-file.c
+qio_channel_file_new_fd(void *ioc, int fd) "File new fd ioc=%p fd=%d"
+qio_channel_file_new_path(void *ioc, const char *path, int flags, int mode, int fd) "File new fd ioc=%p path=%s flags=%d mode=%d fd=%d"