Show manuals with command line arguments

Add --manual, --conf-manual command line arguments that display manpages
through a pager. If no pager is found, this currently fails. It should
print the manuals to stdout instead.

The manuals are read from src/manuals and are generated with mandoc
whenever changes to the manpage sources meli.1 and meli.conf.5 are made.

.gitignore

@@ -6,3 +6,4 @@ target/
 **/*.rs.bk
 .gdb_history
 *.log
+src/manuals

Cargo.toml

@@ -3,6 +3,7 @@ name = "meli"
 version = "0.3.2"
 authors = ["Manos Pitsidianakis <el13635@mail.ntua.gr>"]
 edition = "2018"
+build = "build.rs"
 
 [[bin]]
 name = "meli"

build.rs

@@ -0,0 +1,52 @@
+/*
+ * meli - bin.rs
+ *
+ * Copyright 2019 Manos Pitsidianakis
+ *
+ * This file is part of meli.
+ *
+ * meli is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * meli 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with meli. If not, see <http://www.gnu.org/licenses/>.
+ */
+use std::fs::File;
+use std::io::prelude::*;
+use std::io::BufWriter;
+use std::path::PathBuf;
+use std::process::Command;
+
+fn main() -> Result<(), std::io::Error> {
+    if let Err(e) = std::fs::create_dir("src/manuals") {
+        if e.kind() != std::io::ErrorKind::AlreadyExists {
+            Err(e)?;
+        }
+    }
+    let meli_1_metadata = std::fs::metadata("meli.1")?;
+    if let Ok(metadata) = std::fs::metadata("src/manuals/meli.txt") {
+        if metadata.modified()? < meli_1_metadata.modified()? {
+            let output = Command::new("mandoc").args(&["meli.1"]).output()?;
+            let man_path = PathBuf::from("src/manuals/meli.txt");
+            let file = File::create(&man_path)?;
+            BufWriter::new(file).write_all(&output.stdout)?;
+        }
+    }
+    let meli_conf_5_metadata = std::fs::metadata("meli.conf.5")?;
+    if let Ok(metadata) = std::fs::metadata("src/manuals/meli_conf.txt") {
+        if metadata.modified()? < meli_conf_5_metadata.modified()? {
+            let output = Command::new("mandoc").args(&["meli.conf.5"]).output()?;
+            let man_path = PathBuf::from("src/manuals/meli_conf.txt");
+            let file = File::create(&man_path)?;
+            BufWriter::new(file).write_all(&output.stdout)?;
+        }
+    }
+    Ok(())
+}

meli.1

@@ -43,6 +43,10 @@ if given, or at
 .Pa $XDG_CONFIG_HOME/meli/config
 .It Fl -config Ar path
 Start meli with given configuration file.
+.It Fl -manual
+Show (this) manual for meli.
+.It Fl -conf-manual
+Show manual for meli configuration file.
 .El
 .Sh STARTING WITH meli
 When launched for the first time, meli will search for its configuration directory,
@@ -280,6 +284,8 @@ catchall for general errors
 Specifies the editor to use
 .It Ev MELI_CONFIG
 Override the configuration file
+.It Ev PAGER
+Pager to use for command line help output.
 .El
 .Sh FILES
 meli uses the following parts of the XDG standard:

src/bin.rs

@@ -81,6 +81,8 @@ struct CommandLineArguments {
     config: Option<String>,
     help: bool,
     version: bool,
+    manual: bool,
+    conf_manual: bool,
 }
 
 fn main() -> std::result::Result<(), std::io::Error> {
@@ -95,6 +97,8 @@ fn main() -> std::result::Result<(), std::io::Error> {
         config: None,
         help: false,
         version: false,
+        manual: false,
+        conf_manual: false,
     };
 
     for i in std::env::args().skip(1) {
@@ -119,6 +123,12 @@ fn main() -> std::result::Result<(), std::io::Error> {
             "--version" | "-v" => {
                 args.version = true;
             }
+            "--manual" => {
+                args.manual = true;
+            }
+            "--conf-manual" => {
+                args.conf_manual = true;
+            }
             e => match prev {
                 None => error_and_exit!("error: value without command {}", e),
                 Some(CreateConfig) if args.create_config.is_none() => {
@@ -144,6 +154,8 @@ fn main() -> std::result::Result<(), std::io::Error> {
         println!("\t--version, -v\t\tprint version and exit");
         println!("\t--create-config[ PATH]\tCreate a sample configuration file with available configuration options. If PATH is not specified, meli will try to create it in $XDG_CONFIG_HOME/meli/config");
         println!("\t--config PATH, -c PATH\tUse specified configuration file");
+        println!("\t--manual\t\tshow manual for meli");
+        println!("\t--conf-manual\t\tshow manual for meli configuration file");
         std::process::exit(0);
     }
 
@@ -152,6 +164,36 @@ fn main() -> std::result::Result<(), std::io::Error> {
         std::process::exit(0);
     }
 
+    if args.manual {
+        let man_contents = include_str!("manuals/meli.txt");
+        let pager = option_env!("PAGER").unwrap_or("less");
+        let (read_end, write_end) = nix::unistd::pipe()
+            .map_err(|e| std::io::Error::new(std::io::ErrorKind::Other, e.to_string()))?;
+        use std::os::unix::io::FromRawFd;
+        unsafe { std::fs::File::from_raw_fd(write_end) }.write_all(man_contents.as_bytes())?;
+        let mut handle = std::process::Command::new(pager)
+            .stdin(unsafe { std::process::Stdio::from_raw_fd(read_end) })
+            .stdout(std::process::Stdio::inherit())
+            .spawn()?;
+        handle.wait()?;
+        std::process::exit(0);
+    }
+
+    if args.conf_manual {
+        let man_contents = include_str!("manuals/meli_conf.txt");
+        let pager = option_env!("PAGER").unwrap_or("less");
+        let (read_end, write_end) = nix::unistd::pipe()
+            .map_err(|e| std::io::Error::new(std::io::ErrorKind::Other, e.to_string()))?;
+        use std::os::unix::io::FromRawFd;
+        unsafe { std::fs::File::from_raw_fd(write_end) }.write_all(man_contents.as_bytes())?;
+        let mut handle = std::process::Command::new(pager)
+            .stdin(unsafe { std::process::Stdio::from_raw_fd(read_end) })
+            .stdout(std::process::Stdio::inherit())
+            .spawn()?;
+        handle.wait()?;
+        std::process::exit(0);
+    }
+
     match prev {
         None => {}
         Some(CreateConfig) if args.create_config.is_none() => args.create_config = Some("".into()),