Some polish and adjustment to make the interface and code closer to the

corresponding b64 crate

src/decode.rs

@@ -1,17 +1,7 @@
-use super::*;
-use std::io::{self, ErrorKind, Read, Write};
-
-#[derive(Debug)]
-pub enum DecoderError {
-    IO(io::Error),
-    IllegalChar,
-}
-
-impl From<io::Error> for DecoderError {
-    fn from(value: io::Error) -> Self {
-        Self::IO(value)
-    }
-}
+use {
+    crate::{error::Error, B32Alphabet},
+    std::io::{ErrorKind, Read, Write},
+};
 
 pub struct Decoder<R: Read, W: Write> {
     reader: R,
@@ -30,7 +20,22 @@ impl<R: Read, W: Write> Decoder<R, W> {
         }
     }
 
-    pub fn decode(mut self) -> Result<W, DecoderError> {
+
+    /// Decodes the bytes provided by `self.reader` and writes the resulting
+    /// bytes into `self.writer`.
+    /// # Important
+    /// Both reader and writer should be buffered for good performance, as the
+    /// process of decoding will perform a series of very short read and write
+    /// operations.
+    /// # Errors
+    /// - io failure will return `Error::Io`
+    /// - a character not in the alphabet, or encountering any character after
+    ///   the first occurance of the padding character, will return `Error::IllegalChar`
+    /// - if the reader comes up short of the final four byte block will return
+    ///   `Error::MissingPadding`
+    /// - `intError` should never be returned. If this error is recieved the code
+    ///   is somehow broken. Please file a bug.
+    pub fn decode(mut self) -> Result<W, Error> {
         let mut byte_reader = self.reader.bytes();
         'outer: loop {
             let mut in_buf = [0_u8; 8];
@@ -58,7 +63,7 @@ impl<R: Read, W: Write> Decoder<R, W> {
             for c in &in_buf {
                 num <<= 5;
                 if !matches!(self.alphabet.pad(), Some(ch) if ch == *c) {
-                    let idx = self.alphabet.idx(*c).ok_or(DecoderError::IllegalChar)?;
+                    let idx = self.alphabet.idx(*c).ok_or(Error::IllegalChar((*c).into()))?;
                     num |= idx as u64;
                 }
             }
@@ -83,6 +88,11 @@ impl<R: Read, W: Write> Decoder<R, W> {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::B32_RFC4648_ALPHABET;
+    use std::{
+        fs::File,
+        io::{BufReader, Read},
+    };
 
     static HELLO: &'static str = "Hello, World!";
     static ENCODED: &'static str = "JBSWY3DPFQQFO33SNRSCC===";
@@ -98,7 +108,25 @@ mod tests {
         let reader = ENCODED.as_bytes();
         let writer = Vec::<u8>::new();
         let decoder = Decoder::new(reader, writer, None, false);
-        let output = decoder.decode().unwrap();
-        assert_eq!(HELLO.as_bytes(), output);
+        assert_eq!(decoder.decode().unwrap(), HELLO.as_bytes());
+    }
+
+    #[test]
+    fn ignore_whitespace() {
+        let decoder = Decoder::new(" JBSWY3DP\tFQQFO33SNRSCC===".as_bytes(), vec![], None, true);
+        assert_eq!(decoder.decode().unwrap(), HELLO.as_bytes());
+    }
+
+    #[test]
+    fn decode_wrapped() {
+        let infile = File::open("src/testdata/lorem_b32.txt").unwrap();
+        let reader = BufReader::new(infile);
+        let mut outfile = vec![];
+        File::open("src/testdata/lorem.txt")
+            .unwrap()
+            .read_to_end(&mut outfile)
+            .unwrap();
+        let decoder = Decoder::new(reader, vec![], None, false);
+        assert_eq!(decoder.decode().unwrap(), outfile);
     }
 }

src/error.rs

@@ -2,7 +2,6 @@ use std::{error, fmt, io, num::TryFromIntError};
 
 #[derive(Debug)]
 pub enum Error {
-    Fmt(fmt::Error),
     Io(io::Error),
     IllegalChar(char),
     IntError(TryFromIntError),
@@ -12,7 +11,6 @@ pub enum Error {
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            Self::Fmt(e) => write!(f, "{e}"),
             Self::Io(e) => write!(f, "{e}"),
             Self::IllegalChar(c) => write!(f, "Illegal Character ({c})"),
             Self::MissingPadding => write!(f, "Missing Padding"),
@@ -21,12 +19,6 @@ impl fmt::Display for Error {
     }
 }
 
-impl From<fmt::Error> for Error {
-    fn from(value: fmt::Error) -> Self {
-        Self::Fmt(value)
-    }
-}
-
 impl From<io::Error> for Error {
     fn from(value: io::Error) -> Self {
         Self::Io(value)
@@ -48,7 +40,6 @@ impl From<TryFromIntError> for Error {
 impl 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),
             Self::IntError(e) => Some(e),
             _ => None,