Implement deletion of SysV IPC message queues

As usual also the readme and the man page are updated.

README.md

@@ -58,10 +58,16 @@ queue. Following optional arguments are supported:
 - `-o,` `--timeout <timeout>`: As for example in "5h 23min 42ms"
 
 ### SysV IPC message queues
-The SysV IPC backend supports one command: `create`.
+The SysV IPC backend supports two commands: `create` and `unlink`.
 
 #### Create a message queue
 Use the `create` command to create a new SysV IPC message
 queue. Following optional arguments are supported:
 - `-m`, `--mode`: Permissions (octal) to create the queue
   with. Default: 0644.
+
+#### Delete a message queue
+Use the `unlink` command to delete a message queue. This can either be
+done by providing a `key` or an `id` of the queue:
+- `-i`, `--id <id>`: Id of the queue
+- `-k`, `--key <key>`: Key of the queue

mqrs.1

@@ -192,7 +192,7 @@ Set a different priority than default, priority >= 0 [default: 0]
 Timeout as for example in "5h 23min 42ms"
 .RE
 .SS unlink [FLAGS] \fI<QUEUE>\fP
-Deletes an existing POSIX message queue.
+Delete an existing POSIX message queue.
 .TP 8
 .SS ARGS
 .RS
@@ -211,8 +211,10 @@ Prints help information
 Produce verbose output
 .RE
 .SH SYSV IPC MESSAGE QUEUE SUBCOMMANDS
-The SysV IPC backend supports one command:
+The SysV IPC backend supports two commands:
 .B create\
+and
+.B unlink\
 .
 .SS create [FLAGS] [OPTIONS] \fI<KEY>\fP
 Create a new SysV IPC message queue.
@@ -239,6 +241,35 @@ Produce verbose output
 .B \-m, \-\-mode \fI<mode>\fP
 Permissions (octal) to create the queue with (default: 0644)
 .RE
+.SS unlink [FLAGS] [OPTIONS]
+Delete an existing SysV IPC message queue. It is mandatory to pass
+exactly one OPTION.
+.TP 8
+.SS ARGS
+.RS
+.TP 8
+.B \fI<KEY>\fP
+Key of the new queue
+.RE
+.TP 8
+.SS FLAGS
+.RS
+.TP 8
+.B \-h, \-\-help
+Prints help information
+.TP 8
+.B \-v, \-\-verbose
+Produce verbose output
+.TP 8
+.SS OPTIONS
+.RS
+.TP 8
+.B \-i, \-\-id \fI<id>\fP
+Id of the queue
+.TP 8
+.B \-k, \-\-key \fI<key>\fP
+Key of the queue
+.RE
 .SH SEE ALSO
 mq_overview(7)
 .SH BUGS

src/main.rs

@@ -25,6 +25,7 @@ enum PosixCommand {
 #[derive(Clap, Debug)]
 enum SysvCommand {
     Create(sysv::Create),
+    Unlink(sysv::Unlink),
 }
 
 #[derive(Clap, Debug)]
@@ -68,6 +69,7 @@ fn main() -> Result<()> {
         },
         Backend::Sysv(s) => match s {
             SysvCommand::Create(c) => c.run()?,
+            SysvCommand::Unlink(u) => u.run()?,
         },
     }
 

src/sysv.rs

@@ -1,3 +1,5 @@
 mod create;
+mod unlink;
 
 pub use create::Create;
+pub use unlink::Unlink;

src/sysv/unlink.rs

@@ -0,0 +1,35 @@
+use anyhow::Result;
+use clap::Clap;
+use log::info;
+
+/// Delete a message queue
+#[derive(Clap, Debug)]
+pub struct Unlink {
+    /// Id of the queue
+    #[clap(
+        long,
+        short,
+        required_unless_present_any = &["key"],
+        conflicts_with = "key"
+    )]
+    pub id: Option<i32>,
+    /// Key of the queue
+    #[clap(long, short, required_unless_present_any = &["id"], conflicts_with = "id")]
+    pub key: Option<i32>,
+}
+
+impl Unlink {
+    pub fn run(&self) -> Result<()> {
+        if let Some(id) = self.id {
+            sysvmq::unlink_id(id)?;
+
+            info!("Removed message queue with id: {}", id);
+        } else if let Some(key) = self.key {
+            sysvmq::unlink_key(key)?;
+
+            info!("Removed message queue key: {}", key);
+        }
+
+        Ok(())
+    }
+}

sysvmq/src/lib.rs

@@ -1,9 +1,9 @@
 use libc::{
-    msgget, IPC_CREAT, IPC_EXCL, IPC_INFO, IPC_NOWAIT, IPC_PRIVATE, IPC_RMID, IPC_SET, IPC_STAT,
+    msgctl, msgget, msqid_ds, IPC_CREAT, IPC_EXCL, IPC_INFO, IPC_NOWAIT, IPC_PRIVATE, IPC_RMID,
-    MSG_COPY, MSG_EXCEPT, MSG_INFO, MSG_NOERROR, MSG_STAT,
+    IPC_SET, IPC_STAT, MSG_COPY, MSG_EXCEPT, MSG_INFO, MSG_NOERROR, MSG_STAT,
 };
 use nix::errno::{errno, Errno};
-use std::{marker::PhantomData, num::ParseIntError};
+use std::{marker::PhantomData, num::ParseIntError, ptr};
 use thiserror::Error;
 
 #[derive(Debug, Error)]
@@ -54,6 +54,27 @@ pub enum ControlCommands {
     MsgInfo = MSG_INFO,
 }
 
+pub fn unlink_id(id: i32) -> Result<(), SysvMqError> {
+    let res = unsafe {
+        msgctl(
+            id,
+            ControlCommands::Remove as i32,
+            ptr::null::<msqid_ds>() as *mut msqid_ds,
+        )
+    };
+
+    match res {
+        -1 => Err(SysvMqError::ErrnoError(Errno::from_i32(errno()).desc())),
+        _ => Ok(()),
+    }
+}
+
+pub fn unlink_key(key: i32) -> Result<(), SysvMqError> {
+    let id = unsafe { msgget(key, 0) };
+
+    unlink_id(id)
+}
+
 pub struct SysvMq<T> {
     pub id: i32,
     pub key: i32,