Fixed unsafe bufread (still cringe)

src/main.rs

@@ -233,8 +233,6 @@ fn decoder(inputfile: &str) -> Result<(u32, u32, ColorType, ArrayVec<String, 124
     let infile = File::open(inputfile)?;
     let mut lines = UnsafeBufReader::new(infile).lines();
 
-    println!("{:?}", lines);
-
     // "CIF: <flags>"
     if !lines.next().transpose()?.ok_or(InvalidHeaderError)?.starts_with("CIF:") {
         return Err(InvalidHeaderError)

src/unsafe_std/bufread.rs

@@ -17,21 +17,6 @@ impl Drop for Guard<'_> {
     }
 }
 
-pub(crate) unsafe fn append_to_string_unchecked<F>(buf: &mut ArrayString<8192>, f: F) -> usize
-where
-    F: FnOnce(&mut ArrayVec<u8, 8192>) -> usize,
-{
-    let mut buf_vec = ArrayVec::<u8, 8192>::new();
-    for u in buf.as_bytes() {
-        buf_vec.push(*u);
-    }
-    let mut g = Guard { len: buf.len(), buf: &mut buf_vec };
-    let ret = f(g.buf);
-    //std::str::from_utf8_unchecked(&g.buf[g.len..]); // Do we  need it? (https://doc.rust-lang.org/src/std/io/mod.rs.html#342-349)
-    g.len = g.buf.len();
-    ret
-}
-
 pub trait UnsafeBufRead: Read {
     fn consume(&mut self, amt: usize);
     fn fill_buf(&mut self) -> Result<&[u8], Error>;
@@ -39,8 +24,14 @@ pub trait UnsafeBufRead: Read {
         read_until(self, byte, buf)
     }
 
-    fn read_line(&mut self, buf: &mut ArrayString<8192>) -> Result<usize, Error> {
-        unsafe { Ok(append_to_string_unchecked(buf, |b| read_until(self, b'\n', b).unwrap())) }
+    fn read_line(&mut self, buf: &mut ArrayString<8192>) -> usize {
+        let mut buf_vec = ArrayVec::<u8, 8192>::new();
+        for u in buf.as_bytes() {
+            buf_vec.push(*u);
+        }
+        let return_val = read_until(self, b'\n', &mut buf_vec).unwrap();
+        unsafe { buf.push_str(std::str::from_utf8_unchecked(buf_vec.as_slice())) };
+        return_val
     }
 
     fn lines(self) -> UnsafeLines<Self>
@@ -62,17 +53,13 @@ impl<B: UnsafeBufRead> Iterator for UnsafeLines<B> {
     fn next(&mut self) -> Option<Result<ArrayString<8192>, CifError>> {
         let mut buf = ArrayString::<8192>::new();
         match self.buf.read_line(&mut buf) {
-            Ok(0) => None,
-            Ok(_n) => {
+            0 => None,
+            _n => {
                 if buf.ends_with('\n') {
                     buf.pop();
-                    if buf.ends_with('\r') {
-                        buf.pop();
-                    }
                 }
                 Some(Ok(buf))
             }
-            Err(e) => Some(Err(CifError::IoError(e))),
         }
     }
 }

src/unsafe_std/bufreader.rs

@@ -1,11 +1,8 @@
 // https://doc.rust-lang.org/src/std/io/buffered/bufreader.rs.html
 
 use crate::unsafe_std::bufread::UnsafeBufRead;
-use crate::CifError;
-use arrayvec::{ArrayString, ArrayVec};
-use std::io::{Error, Read};
+use std::io::Read;
 
-#[derive(Debug)]
 pub struct UnsafeBufReader<R> {
     inner: R,
     buf: Box<[u8]>,
@@ -15,8 +12,12 @@ pub struct UnsafeBufReader<R> {
 
 impl<R: Read> UnsafeBufReader<R> {
     pub fn new(inner: R) -> UnsafeBufReader<R> {
+        UnsafeBufReader::with_capacity(8192, inner)
+    }
+
+    pub fn with_capacity(capacity: usize, inner: R) -> UnsafeBufReader<R> {
         unsafe {
-            let mut buf = std::boxed::Box::new_uninit_slice(8192).assume_init();
+            let mut buf = Box::new_uninit_slice(capacity).assume_init();
             inner.initializer().initialize(&mut buf);
             UnsafeBufReader { inner, buf, pos: 0, cap: 0 }
         }
@@ -33,9 +34,6 @@ impl<R> UnsafeBufReader<R> {
 
 impl<R: Read> Read for UnsafeBufReader<R> {
     fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
-        // If we don't have any buffered data and we're doing a massive read
-        // (larger than our internal buffer), bypass our internal buffer
-        // entirely.
         if self.pos == self.cap && buf.len() >= self.buf.len() {
             self.discard_buffer();
             return self.inner.read(buf)
@@ -63,3 +61,15 @@ impl<R: Read> UnsafeBufRead for UnsafeBufReader<R> {
         self.pos = std::cmp::min(self.pos + amt, self.cap);
     }
 }
+
+impl<R> std::fmt::Debug for UnsafeBufReader<R>
+where
+    R: std::fmt::Debug,
+{
+    fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        fmt.debug_struct("BufReader")
+            .field("reader", &self.inner)
+            .field("buffer", &format_args!("{}/{}", self.cap - self.pos, self.buf.len()))
+            .finish()
+    }
+}