init commit

src/args.rs

@@ -0,0 +1,102 @@
+use clap::crate_description;
+use clap::{Arg, ArgMatches};
+use std::env;
+use std::fs::canonicalize;
+use std::net::SocketAddr;
+use std::path::{Path, PathBuf};
+
+use crate::BoxResult;
+
+const ABOUT: &str = concat!("\n", crate_description!()); // Add extra newline.
+
+fn app() -> clap::Command<'static> {
+    let arg_port = Arg::new("port")
+        .short('p')
+        .long("port")
+        .default_value("5000")
+        .help("Specify port to listen on")
+        .value_name("port");
+
+    let arg_address = Arg::new("address")
+        .short('b')
+        .long("bind")
+        .default_value("127.0.0.1")
+        .help("Specify bind address")
+        .value_name("address");
+
+    let arg_path = Arg::new("path")
+        .default_value(".")
+        .allow_invalid_utf8(true)
+        .help("Path to a directory for serving files");
+
+    clap::command!()
+        .about(ABOUT)
+        .arg(arg_address)
+        .arg(arg_port)
+        .arg(arg_path)
+}
+
+pub fn matches() -> ArgMatches {
+    app().get_matches()
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct Args {
+    pub address: String,
+    pub port: u16,
+    pub path: PathBuf,
+}
+
+impl Args {
+    /// Parse command-line arguments.
+    ///
+    /// If a parsing error ocurred, exit the process and print out informative
+    /// error message to user.
+    pub fn parse(matches: ArgMatches) -> BoxResult<Args> {
+        let address = matches.value_of("address").unwrap_or_default().to_owned();
+        let port = matches.value_of_t::<u16>("port")?;
+        let path = matches.value_of_os("path").unwrap_or_default();
+        let path = Args::parse_path(path)?;
+
+        Ok(Args {
+            address,
+            port,
+            path,
+        })
+    }
+
+    /// Parse path.
+    fn parse_path<P: AsRef<Path>>(path: P) -> BoxResult<PathBuf> {
+        let path = path.as_ref();
+        if !path.exists() {
+            bail!("error: path \"{}\" doesn't exist", path.display());
+        }
+
+        env::current_dir()
+            .and_then(|mut p| {
+                p.push(path); // If path is absolute, it replaces the current path.
+                canonicalize(p)
+            })
+            .or_else(|err| {
+                bail!(
+                    "error: failed to access path \"{}\": {}",
+                    path.display(),
+                    err,
+                )
+            })
+    }
+
+    /// Construct socket address from arguments.
+    pub fn address(&self) -> BoxResult<SocketAddr> {
+        format!("{}:{}", self.address, self.port)
+            .parse()
+            .or_else(|err| {
+                bail!(
+                    "error: invalid address {}:{} : {}",
+                    self.address,
+                    self.port,
+                    err,
+                )
+            })
+    }
+}