Add a base64 command line tool.

Author: khuey

Cargo.toml

@@ -19,6 +19,7 @@ harness = false
 # 0.3.3 requires rust 1.36.0 for stable copied()
 criterion = "=0.3.2"
 rand = "0.6.1"
+structopt = "0.3"
 
 [features]
 default = ["std"]

examples/base64.rs

@@ -0,0 +1,89 @@
+use std::fs::File;
+use std::io::{self, Read};
+use std::path::PathBuf;
+use std::process;
+use std::str::FromStr;
+
+use base64::{read, write};
+use structopt::StructOpt;
+
+#[derive(Debug, StructOpt)]
+enum CharacterSet {
+    Standard,
+    UrlSafe,
+}
+
+impl Default for CharacterSet {
+    fn default() -> Self {
+        CharacterSet::Standard
+    }
+}
+
+impl Into<base64::Config> for CharacterSet {
+    fn into(self) -> base64::Config {
+        match self {
+            CharacterSet::Standard => base64::STANDARD,
+            CharacterSet::UrlSafe => base64::URL_SAFE,
+        }
+    }
+}
+
+impl FromStr for CharacterSet {
+    type Err = String;
+    fn from_str(s: &str) -> Result<CharacterSet, String> {
+        match s {
+            "standard" => Ok(CharacterSet::Standard),
+            "urlsafe" => Ok(CharacterSet::UrlSafe),
+            _ => Err(format!("charset '{}' unrecognized", s)),
+        }
+    }
+}
+
+/// Base64 encode or decode FILE (or standard input), to standard output.
+#[derive(Debug, StructOpt)]
+struct Opt {
+    /// decode data
+    #[structopt(short = "d", long = "decode")]
+    decode: bool,
+    /// The character set to choose. Defaults to the standard base64 character set.
+    /// Supported character sets include "standard" and "urlsafe".
+    #[structopt(long = "charset")]
+    charset: Option<CharacterSet>,
+    /// The file to encode/decode.
+    #[structopt(parse(from_os_str))]
+    file: Option<PathBuf>,
+}
+
+fn main() {
+    let opt = Opt::from_args();
+    let stdin;
+    let mut input: Box<dyn Read> = match opt.file {
+        None => {
+            stdin = io::stdin();
+            Box::new(stdin.lock())
+        }
+        Some(ref f) if f.as_os_str() == "-" => {
+            stdin = io::stdin();
+            Box::new(stdin.lock())
+        }
+        Some(f) => Box::new(File::open(f).unwrap()),
+    };
+    let config = opt.charset.unwrap_or_default().into();
+    let stdout = io::stdout();
+    let mut stdout = stdout.lock();
+    let r = if opt.decode {
+        let mut decoder = read::DecoderReader::new(&mut input, config);
+        io::copy(&mut decoder, &mut stdout)
+    } else {
+        let mut encoder = write::EncoderWriter::new(&mut stdout, config);
+        io::copy(&mut input, &mut encoder)
+    };
+    if let Err(e) = r {
+        println!(
+            "Base64 {} failed with {}",
+            if opt.decode { "decode" } else { "encode" },
+            e
+        );
+        process::exit(1);
+    }
+}