io: add QIOChannelCommand class

Add a QIOChannel subclass that is capable of performing I/O
to/from a separate process, via a pair of pipes. The command
can be used for unidirectional or bi-directional I/O.

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

1 files changed, 91 insertions, 0 deletions

diff --git a/include/io/channel-command.h b/include/io/channel-command.h
new file mode 100644
index 0000000000..bd3c59946f
--- /dev/null
+++ b/include/io/channel-command.h
@@ -0,0 +1,91 @@
+/*
+ * QEMU I/O channels external command 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_COMMAND_H__
+#define QIO_CHANNEL_COMMAND_H__
+
+#include "io/channel.h"
+
+#define TYPE_QIO_CHANNEL_COMMAND "qio-channel-command"
+#define QIO_CHANNEL_COMMAND(obj)                                     \
+    OBJECT_CHECK(QIOChannelCommand, (obj), TYPE_QIO_CHANNEL_COMMAND)
+
+typedef struct QIOChannelCommand QIOChannelCommand;
+
+
+/**
+ * QIOChannelCommand:
+ *
+ * The QIOChannelCommand class provides a channel implementation
+ * that can transport data with an externally running command
+ * via its stdio streams.
+ */
+
+struct QIOChannelCommand {
+    QIOChannel parent;
+    int writefd;
+    int readfd;
+    pid_t pid;
+};
+
+
+/**
+ * qio_channel_command_new_pid:
+ * @writefd: the FD connected to the command's stdin
+ * @readfd: the FD connected to the command's stdout
+ * @pid: the PID of the running child command
+ * @errp: pointer to an uninitialized error object
+ *
+ * Create a channel for performing I/O with the
+ * previously spawned command identified by @pid.
+ * The two file descriptors provide the connection
+ * to command's stdio streams, either one or which
+ * may be -1 to indicate that stream is not open.
+ *
+ * The channel will take ownership of the process
+ * @pid and will kill it when closing the channel.
+ * Similarly it will take responsibility for
+ * closing the file descriptors @writefd and @readfd.
+ *
+ * Returns: the command channel object, or NULL on error
+ */
+QIOChannelCommand *
+qio_channel_command_new_pid(int writefd,
+                            int readfd,
+                            pid_t pid);
+
+/**
+ * qio_channel_command_new_spawn:
+ * @argv: the NULL terminated list of command arguments
+ * @flags: the I/O mode, one of O_RDONLY, O_WRONLY, O_RDWR
+ * @errp: pointer to an uninitialized error object
+ *
+ * Create a channel for performing I/O with the
+ * command to be spawned with arguments @argv.
+ *
+ * Returns: the command channel object, or NULL on error
+ */
+QIOChannelCommand *
+qio_channel_command_new_spawn(const char *const argv[],
+                              int flags,
+                              Error **errp);
+
+
+#endif /* QIO_CHANNEL_COMMAND_H__ */