b64_rs/src/encode.rs

136 lines
3.5 KiB
Rust

pub use {
super::B64Alphabet,
std::{
fmt::{self, Write},
io::{self, ErrorKind, Read},
},
};
#[derive(Debug)]
pub enum Error {
Io(io::Error),
Fmt(fmt::Error),
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::Io(e) => write!(f, "{e}"),
Self::Fmt(e) => write!(f, "{e}"),
}
}
}
impl From<io::Error> for Error {
fn from(value: io::Error) -> Self {
Self::Io(value)
}
}
impl From<fmt::Error> for Error {
fn from(value: fmt::Error) -> Self {
Self::Fmt(value)
}
}
impl std::error::Error for Error {
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
match self {
Self::Fmt(e) => Some(e),
Self::Io(e) => Some(e),
}
}
}
pub struct Encoder<R: Read, W: Write> {
reader: R,
writer: W,
alphabet: B64Alphabet,
}
impl<R: Read, W: Write> Encoder<R, W> {
pub fn new(reader: R, writer: W, alphabet: Option<B64Alphabet>) -> Self {
Self {
reader,
writer,
alphabet: alphabet.unwrap_or_default(),
}
}
pub fn encode(&mut self) -> Result<(), Error> {
loop {
let mut ibuf = [0; 3];
let mut obuf = [self.alphabet.pad(); 4];
let mut n_bytes = 0;
let mut num: u64 = 0;
loop {
n_bytes += match self.reader.read(&mut ibuf) {
Ok(n) => n,
Err(e) if e.kind() == ErrorKind::Interrupted => continue,
Err(e) => return Err(e.into()),
};
break;
}
if n_bytes == 0 {
break;
}
for (idx, n) in ibuf.iter().enumerate() {
num <<= 8;
if idx < n_bytes {
num |= *n as u64;
}
}
let mut outlen = n_bytes * 8 / 6;
if n_bytes * 8 % 6 > 0 {
outlen += 1;
}
for idx in (0..4).rev() {
if outlen == 4 || idx < outlen {
let b = num & 0b111111;
obuf[idx] = self.alphabet.items[b as usize];
}
num >>= 6;
}
write!(
self.writer,
"{}{}{}{}",
char::try_from(obuf[0]).unwrap(),
char::try_from(obuf[1]).unwrap(),
char::try_from(obuf[2]).unwrap(),
char::try_from(obuf[3]).unwrap()
)?;
if outlen < 4 {
break;
}
}
Ok(())
}
}
impl<R: Read> Encoder<R, String> {
pub fn output(self) -> String {
self.writer
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn encode() {
let mut encoder = Encoder::new("Hello, World".as_bytes(), String::new(), None);
encoder.encode().unwrap();
assert_eq!(encoder.output(), "SGVsbG8sIFdvcmxk");
encoder = Encoder {
reader: "Hello, World!".as_bytes(),
writer: String::new(),
alphabet: B64Alphabet::default(),
};
encoder.encode().unwrap();
assert_eq!(encoder.output(), "SGVsbG8sIFdvcmxkIQ==");
encoder = Encoder::new("Hello, World!\n".as_bytes(), String::new(), None);
encoder.encode().unwrap();
assert_eq!(encoder.output(), "SGVsbG8sIFdvcmxkIQo=");
}
}