Implement info command for SysV IPC mqs

The `list` command was refactored a little bit as well and the man
page and readme were updated.

README.md

@@ -67,6 +67,12 @@ queue. Following optional arguments are supported:
 - `-m`, `--mode`: Permissions (octal) to create the queue
   with. Default: 0644.
 
+#### Print information about a message queue
+Use the `info` command to print further information about a message
+queue. Exactly of the following arguments is mandatory:
+- `-i`, `--id id`: Id of the queue
+- `-k`, `--key key`: Key of the queue
+
 #### List all message queues
 Use the `list` command to print a list of all message queues. No
 further arguments are supported.

mqrs.1

@@ -41,7 +41,7 @@ The POSIX backend supports six commands:
 and
 .B recv
 .
-.SS create [FLAGS] [OPTIONS] \fI<QUEUE>\fP
+.SS posix create [FLAGS] [OPTIONS] \fI<QUEUE>\fP
 Create a new POSIX message queue.
 .TP 8
 .SS ARGS
@@ -72,7 +72,7 @@ Message size in bytes
 .B \-m, \-\-mode \fI<mode>\fP
 Permissions (octal) to create the queue with
 .RE
-.SS help [SUBCOMMAND]
+.SS posix help [SUBCOMMAND]
 Prints this message or the help of the given subcommand.
 .TP 8
 .SS ARGS
@@ -81,7 +81,7 @@ Prints this message or the help of the given subcommand.
 .B \fI<SUBCOMMAND>\fP
 Show help for \fISUBCOMMAND\fP
 .RE
-.SS info [FLAGS] \fI<QUEUE>\fP
+.SS posix info [FLAGS] \fI<QUEUE>\fP
 Print further information about an existing message queue.
 .TP 8
 .SS ARGS
@@ -100,7 +100,7 @@ Prints help information
 .B \-v, \-\-verbose
 Produce verbose output
 .RE
-.SS list [FLAGS]
+.SS posix list [FLAGS]
 Print a list of all existing POSIX message queues.
 .TP 8
 .SS FLAGS
@@ -115,7 +115,7 @@ Produce verbose output
 .B \-a, \-\-all
 Print all available information
 .RE
-.SS recv [FLAGS] [OPTIONS] \fI<QUEUE>\fP
+.SS posix recv [FLAGS] [OPTIONS] \fI<QUEUE>\fP
 Receive and print one or more messages message from a message queue.
 .TP 8
 .SS ARGS
@@ -153,7 +153,7 @@ Deadline until messages are received (format: "%Y-%m-%d %H:%M:%S")
 .B \-o, \-\-timeout \fI<timeout>\fP
 Timeout as for example in "5h 23min 42ms"
 .RE
-.SS send [FLAGS] [OPTIONS] \fI<QUEUE>\fP \fI<MESSAGE>\fP
+.SS posix send [FLAGS] [OPTIONS] \fI<QUEUE>\fP \fI<MESSAGE>\fP
 Send a message to a message queue.
 .TP 8
 .SS ARGS
@@ -191,7 +191,7 @@ Set a different priority than default, priority >= 0 [default: 0]
 .B \-o, \-\-timeout \fI<timeout>\fP
 Timeout as for example in "5h 23min 42ms"
 .RE
-.SS unlink [FLAGS] \fI<QUEUE>\fP
+.SS posix unlink [FLAGS] \fI<QUEUE>\fP
 Delete an existing POSIX message queue.
 .TP 8
 .SS ARGS
@@ -211,12 +211,16 @@ Prints help information
 Produce verbose output
 .RE
 .SH SYSV IPC MESSAGE QUEUE SUBCOMMANDS
-The SysV IPC backend supports two commands:
+The SysV IPC backend supports four commands:
 .B create\
+,
+.B info\
+,
+.B list
 and
 .B unlink\
 .
-.SS create [FLAGS] [OPTIONS] \fI<KEY>\fP
+.SS sysv create [FLAGS] [OPTIONS] \fI<KEY>\fP
 Create a new SysV IPC message queue.
 .TP 8
 .SS ARGS
@@ -241,7 +245,39 @@ Produce verbose output
 .B \-m, \-\-mode \fI<mode>\fP
 Permissions (octal) to create the queue with (default: 0644)
 .RE
-.SS list [FLAGS]
+.SS sysv help [SUBCOMMAND]
+Prints this message or the help of the given subcommand.
+.TP 8
+.SS ARGS
+.RS
+.TP 8
+.B \fI<SUBCOMMAND>\fP
+Show help for \fISUBCOMMAND\fP
+.RE
+.SS sysv info [FLAGS] [OPTIONS]
+Print further information about an existing message queue. Exactly of
+the OPTION arguments is mandatory.
+.TP 8
+.SS FLAGS
+.RS
+.TP 8
+.B \-h, \-\-help
+Prints help information
+.TP 8
+.B \-v, \-\-verbose
+Produce verbose output
+.RE
+.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
+.SS sysv list [FLAGS]
 Print a list of all existing SysV IPC message queues.
 .TP 8
 .SS FLAGS
@@ -253,7 +289,7 @@ Prints help information
 .B \-v, \-\-verbose
 Produce verbose output
 .RE
-.SS unlink [FLAGS] [OPTIONS]
+.SS sysv unlink [FLAGS] [OPTIONS]
 Delete an existing SysV IPC message queue. It is mandatory to pass
 exactly one OPTION.
 .TP 8

src/main.rs

@@ -25,6 +25,7 @@ enum PosixCommand {
 #[derive(Clap, Debug)]
 enum SysvCommand {
     Create(sysv::Create),
+    Info(sysv::Info),
     List(sysv::List),
     Unlink(sysv::Unlink),
 }
@@ -70,6 +71,7 @@ fn main() -> Result<()> {
         },
         Backend::Sysv(s) => match s {
             SysvCommand::Create(c) => c.run()?,
+            SysvCommand::Info(i) => i.run()?,
             SysvCommand::List(l) => l.run()?,
             SysvCommand::Unlink(u) => u.run()?,
         },

src/sysv.rs

@@ -1,7 +1,9 @@
 mod create;
+mod info;
 mod list;
 mod unlink;
 
 pub use create::Create;
+pub use info::Info;
 pub use list::List;
 pub use unlink::Unlink;

src/sysv/info.rs

@@ -0,0 +1,53 @@
+use anyhow::Result;
+use clap::Clap;
+use std::{
+    fs::File,
+    io::{BufRead, BufReader},
+};
+
+/// Print information about an existing message queue
+#[derive(Clap, Debug)]
+pub struct Info {
+    /// Id of the queue
+    #[clap(short, long, required_unless_present_any = &["key"], conflicts_with = "key")]
+    id: Option<i32>,
+    /// Key of the queue
+    #[clap(short, long, required_unless_present_any = &["id"], conflicts_with = "id")]
+    key: Option<i32>,
+}
+
+fn print_line(line: &str) {
+    for field in line.split_whitespace().collect::<Vec<&str>>() {
+        print!("{0: <10}", field);
+    }
+
+    println!();
+}
+
+impl Info {
+    pub fn run(&self) -> Result<()> {
+        let mut lines = BufReader::new(File::open("/proc/sysvipc/msg")?).lines();
+
+        print_line(&lines.nth(0).unwrap_or(Ok(String::new()))?);
+
+        for line in lines {
+            let line = line?;
+
+            if let Some(id) = self.id {
+                if id == line.split_whitespace().collect::<Vec<&str>>()[1].parse::<i32>()? {
+                    print_line(&line);
+
+                    break;
+                }
+            } else if let Some(key) = self.key {
+                if key == line.split_whitespace().collect::<Vec<&str>>()[0].parse::<i32>()? {
+                    print_line(&line);
+
+                    break;
+                }
+            }
+        }
+
+        Ok(())
+    }
+}

src/sysv/list.rs

@@ -11,9 +11,7 @@ pub struct List {}
 
 impl List {
     pub fn run(&self) -> Result<()> {
-        let file = BufReader::new(File::open("/proc/sysvipc/msg")?);
-
-        for line in file.lines() {
+        for line in BufReader::new(File::open("/proc/sysvipc/msg")?).lines() {
             for field in line?.split_whitespace().collect::<Vec<&str>>() {
                 print!("{0: <10}", field);
             }

src/sysv/unlink.rs

@@ -7,14 +7,14 @@ use log::info;
 pub struct Unlink {
     /// Id of the queue
     #[clap(
-        long,
         short,
+        long,
         required_unless_present_any = &["key"],
         conflicts_with = "key"
     )]
     id: Option<i32>,
     /// Key of the queue
-    #[clap(long, short, required_unless_present_any = &["id"], conflicts_with = "id")]
+    #[clap(short, long, required_unless_present_any = &["id"], conflicts_with = "id")]
     key: Option<i32>,
 }