Probably won't work.

src/io.rs

@@ -1,6 +1,7 @@
+use std::ffi::CString;
 use std::fs::{File, OpenOptions};
 use std::io::{self, Seek, SeekFrom};
-use std::os::unix::fs::OpenOptionsExt;
+use std::os::fd::{AsRawFd, FromRawFd, IntoRawFd};
 
 use crate::cli::CONFIG;
 
@@ -20,12 +21,22 @@ 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.
+ *
+ * I cannot seem to execute `close()`... one hopes that reassigning will drop
+ * calling `close()` on the old fd, but I don't know.
+ */
+
 pub fn load_input() -> anyhow::Result<File> {
-    OpenOptions::new()
+    let path = CString::new(CONFIG.input.to_str().unwrap().to_owned())?;
-        .read(true)
+    let flags = libc::O_RDONLY | libc::O_DIRECT;
-        .custom_flags(libc::O_DIRECT)
+    Ok(unsafe { File::from_raw_fd(libc::open(path.as_ptr(), flags)) })
-        .open(&CONFIG.input)
-        .with_context(|| format!("Failed to open input file: {}", &CONFIG.input.display()))
 }
 
 pub fn load_output() -> anyhow::Result<File> {
@@ -61,18 +72,3 @@ 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)
-    }
-}

src/main.rs

@@ -11,8 +11,6 @@ use anyhow;
 const FB_SECTOR_SIZE: usize = 2048;
 const FB_NULL_VALUE: u8 = 0;
 
-const MAX_BUFFER_SIZE: usize = FB_SECTOR_SIZE * 16;
-
 fn main() -> anyhow::Result<()> {
     let mut recover_tool = Recover::new()?;
     recover_tool.run()?;

src/mapping/cluster.rs

@@ -21,7 +21,6 @@ impl Default for Cluster {
 impl Cluster {
     /// Breaks apart into a vec of clusters,
     /// each of cluster_size, excepting last.
-    #[allow(dead_code)]
     pub fn subdivide(&mut self, cluster_len: usize) -> Vec<Cluster> {
         let domain_len = self.domain.len();
         let mut start = self.domain.start;
@@ -50,8 +49,6 @@ impl Cluster {
         clusters
     }
 
-    // This is used in unit tests at present. Ideally it probably shouldn't exist.
-    #[allow(dead_code)]
     pub fn set_stage(&mut self, stage: Stage) -> &mut Self {
         self.stage = stage;
         self

src/mapping/domain.rs

@@ -16,7 +16,6 @@ impl Default for Domain {
 
 impl Domain {
     /// Return length of domain in sectors.
-    #[allow(dead_code)]
     pub fn len(self) -> usize {
         self.end - self.start
     }

src/recovery.rs

@@ -2,13 +2,13 @@ use std::fs::File;
 use std::io::{BufWriter, Read, Seek, SeekFrom, Write};
 use std::usize;
 
-use anyhow::Context;
+use anyhow::{Context, anyhow};
 
 use crate::cli::CONFIG;
-use crate::io::DirectIOBuffer;
 use crate::mapping::prelude::*;
 
 #[derive(Debug)]
+#[allow(dead_code)]
 pub struct Recover {
     input: File,
     output: BufWriter<File>,
@@ -90,12 +90,11 @@ impl Recover {
 
     /// Attempt to copy all untested blocks.
     fn copy_untested(&mut self) -> anyhow::Result<()> {
-        let mut buf = DirectIOBuffer::default();
-
         for untested in self.map.get_clusters(Stage::Untested) {
             // Caching.
             let mut read_position: usize;
             let mut cluster: Cluster;
+            let mut buf: Vec<u8>;
             let mut buf_capacity = self.get_buf_capacity() as usize;
 
             dbg!(untested.domain);
@@ -105,6 +104,7 @@ impl Recover {
                 dbg!(read_position);
 
                 buf_capacity = buf_capacity.min(untested.domain.end - read_position);
+                buf = vec![crate::FB_NULL_VALUE; buf_capacity];
 
                 cluster = Cluster {
                     domain: Domain {
@@ -114,7 +114,7 @@ impl Recover {
                     stage: Stage::Intact,
                 };
 
-                if let Err(err) = self.input.read_exact(&mut buf.0) {
+                if let Err(err) = self.input.read_exact(&mut buf) {
                     // If buf were zeroed out before every read, one could theoretically recover
                     // part of that read given the assumption that all null values from the end to
                     // the first non-null value are unread, and some further padding from the last
@@ -141,7 +141,7 @@ impl Recover {
 
                 if cluster.stage == Stage::Intact {
                     self.output
-                        .write_all(&buf.0[0..buf_capacity])
+                        .write_all(&buf[0..buf_capacity])
                         .context("Failed to write data to output file")?;
                 }
 
@@ -151,8 +151,6 @@ impl Recover {
             }
         }
 
-        drop(buf);
-
         self.map.write_to(&mut crate::io::load_map_write()?)?;
 
         Ok(())
@@ -161,7 +159,7 @@ impl Recover {
     /// Set buffer capacity as cluster length in bytes.
     /// Varies depending on the recovery stage.
     fn get_buf_capacity(&mut self) -> u64 {
-        crate::MAX_BUFFER_SIZE.min(CONFIG.sector_size * CONFIG.cluster_length) as u64
+        CONFIG.sector_size as u64 * CONFIG.cluster_length as u64
     }
 
     /// Reloads the input and restores the seek position.