Implement creation of SysV IPC message queues

This adds the `sysvmq` package which handles SysV IPC message queues.
For consistency the parameter for `permissions` is renamed to `mode`
also for POSIX message queues.

src/sysv/create.rs

@@ -0,0 +1,31 @@
+use anyhow::Result;
+use clap::Clap;
+use log::info;
+use sysvmq::SysvMq;
+
+/// Create a SysV message queue
+#[derive(Clap, Debug)]
+pub struct Create {
+    /// Permissions (octal) to create the queue with (default: 0644)
+    #[clap(short, long)]
+    mode: Option<String>,
+    /// Key of the new queue
+    #[clap(value_name = "KEY")]
+    key: i32,
+}
+
+impl Create {
+    pub fn run(&self) -> Result<()> {
+        let mut mq = SysvMq::<String>::new();
+
+        if let Some(m) = &self.mode {
+            mq.mode(i32::from_str_radix(&m, 8)?);
+        }
+
+        mq.create(self.key)?;
+
+        info!("SysV message queue created, key: {}, id: {}", mq.key, mq.id);
+
+        Ok(())
+    }
+}