DirectIO is working! Also a bit more cleanup.

src/io.rs

@@ -20,39 +20,12 @@ pub fn get_stream_length<S: Seek>(stream: &mut S) -> io::Result<u64> {
     len
 }
 
-/*
- * IO Error Poisoning:
- *
- *
- * Attempt 1:
- *
- * Wrap C calls w/ `ffi`. Most importantly, execute the `close()` through C.
- *
- *
- * Attempt 2:
- *
- * Return to using safe-on-the-surface Rust, but attempt to execute the reads
- * via a separate thread, hoping that the observed poisoning goes away with the
- * thread being closed and doesn't affect the main thread.
- *
- * May need `mpsc` to transfer data without spawning a thread on every read.
- */
-
 pub fn load_input() -> anyhow::Result<File> {
     OpenOptions::new()
         .read(true)
         .custom_flags(libc::O_DIRECT)
         .open(&CONFIG.input)
         .with_context(|| format!("Failed to open input file: {}", &CONFIG.input.display()))
-
-    /*
-    use std::ffi::CString;
-    use std::os::fd::FromRawFd;
-
-    let path = CString::new(CONFIG.input.to_str().unwrap().to_owned()).unwrap();
-    let flags = libc::O_DIRECT | libc::O_RDONLY;
-    let f = unsafe { File::from_raw_fd(libc::open(path.as_ptr(), flags)) };
-    */
 }
 
 pub fn load_output() -> anyhow::Result<File> {
@@ -88,3 +61,18 @@ pub fn load_map_write() -> anyhow::Result<File> {
             )
         })
 }
+
+#[repr(C, align(512))]
+pub struct DirectIOBuffer(pub [u8; crate::MAX_BUFFER_SIZE]);
+
+impl Default for DirectIOBuffer {
+    fn default() -> Self {
+        Self([crate::FB_NULL_VALUE; _])
+    }
+}
+
+impl From<[u8; crate::MAX_BUFFER_SIZE]> for DirectIOBuffer {
+    fn from(value: [u8; crate::MAX_BUFFER_SIZE]) -> Self {
+        Self(value)
+    }
+}