Cleanup.

algo.

CODE_OF_CONDUCT.md

@@ -0,0 +1,128 @@
+
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+We as members, contributors, and leaders pledge to make participation in our
+community a harassment-free experience for everyone, regardless of age, body
+size, visible or invisible disability, ethnicity, sex characteristics, gender
+identity and expression, level of experience, education, socio-economic status,
+nationality, personal appearance, race, caste, color, religion, or sexual
+identity and orientation.
+
+We pledge to act and interact in ways that contribute to an open, welcoming,
+diverse, inclusive, and healthy community.
+
+## Our Standards
+
+Examples of behavior that contributes to a positive environment for our
+community include:
+
+- Demonstrating empathy and kindness toward other people
+- Being respectful of differing opinions, viewpoints, and experiences
+- Giving and gracefully accepting constructive feedback
+- Accepting responsibility and apologizing to those affected by our mistakes,
+  and learning from the experience
+- Focusing on what is best not just for us as individuals, but for the overall
+  community
+
+Examples of unacceptable behavior include:
+
+- The use of sexualized language or imagery, and sexual attention or advances of
+  any kind
+- Trolling, insulting or derogatory comments, and personal or political attacks
+- Public or private harassment
+- Publishing others' private information, such as a physical or email address,
+  without their explicit permission
+- Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Enforcement Responsibilities
+
+Community leaders are responsible for clarifying and enforcing our standards of
+acceptable behavior and will take appropriate and fair corrective action in
+response to any behavior that they deem inappropriate, threatening, offensive,
+or harmful.
+
+Community leaders have the right and responsibility to remove, edit, or reject
+comments, commits, code, wiki edits, issues, and other contributions that are
+not aligned to this Code of Conduct, and will communicate reasons for moderation
+decisions when appropriate.
+
+## Scope
+
+This Code of Conduct applies within all community spaces, and also applies when
+an individual is officially representing the community in public spaces.
+Examples of representing our community include using an official email address,
+posting via an official social media account, or acting as an appointed
+representative at an online or offline event.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported to the community leaders responsible for enforcement at
+<olivia.a.brooks77@gmail.com>.
+All complaints will be reviewed and investigated promptly and fairly.
+
+All community leaders are obligated to respect the privacy and security of the
+reporter of any incident.
+
+## Enforcement Guidelines
+
+Community leaders will follow these Community Impact Guidelines in determining
+the consequences for any action they deem in violation of this Code of Conduct:
+
+### 1. Correction
+
+**Community Impact**: Use of inappropriate language or other behavior deemed
+unprofessional or unwelcome in the community.
+
+**Consequence**: A private, written warning from community leaders, providing
+clarity around the nature of the violation and an explanation of why the
+behavior was inappropriate. A public apology may be requested.
+
+### 2. Warning
+
+**Community Impact**: A violation through a single incident or series of
+actions.
+
+**Consequence**: A warning with consequences for continued behavior. No
+interaction with the people involved, including unsolicited interaction with
+those enforcing the Code of Conduct, for a specified period of time. This
+includes avoiding interactions in community spaces as well as external channels
+like social media. Violating these terms may lead to a temporary or permanent
+ban.
+
+### 3. Temporary Ban
+
+**Community Impact**: A serious violation of community standards, including
+sustained inappropriate behavior.
+
+**Consequence**: A temporary ban from any sort of interaction or public
+communication with the community for a specified period of time. No public or
+private interaction with the people involved, including unsolicited interaction
+with those enforcing the Code of Conduct, is allowed during this period.
+Violating these terms may lead to a permanent ban.
+
+### 4. Permanent Ban
+
+**Community Impact**: Demonstrating a pattern of violation of community
+standards, including sustained inappropriate behavior, harassment of an
+individual, or aggression toward or disparagement of classes of individuals.
+
+**Consequence**: A permanent ban from any sort of public interaction within the
+community.
+
+## Attribution
+
+This Code of Conduct is adapted from the
+[Contributor Covenant](https://www.contributor-covenant.org/), version 2.1,
+available at
+<https://www.contributor-covenant.org/version/2/1/code_of_conduct/>.
+
+Community Impact Guidelines were inspired by
+[Mozilla's code of conduct enforcement ladder](https://github.com/mozilla/inclusion).
+
+For answers to common questions about this code of conduct, see the FAQ at
+<https://www.contributor-covenant.org/faq/>. Translations are available at
+<https://www.contributor-covenant.org/translations/>.

Cargo.toml

@@ -23,8 +23,11 @@ features = ["derive"]
 version = "1.0"
 features = ["derive"]
 
-[target.'cfg(all(unix, not(target_os = "macos")))'.dependencies]
 # Yes. For one constant, this library is required.
+# Technically, this did a bit more in early testing when I messed about
+# with unsafe ffi disasters trying to solve problems.
+#
 # And yes, I spent time tracking down the first release with that constant.
-# v0.2.25 is almost 9 years old as of writing this comment.
+# v0.2.25 is almost 9 years old as of writing this comment
+[target.'cfg(all(unix, not(target_os = "macos")))'.dependencies]
 libc = "~0.2.25"

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2025 Olivia Bridie Alexandria Millicent Ivette Brooks
+Copyright (c) 2025 Olivia Brooks
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.adoc

@@ -1,41 +0,0 @@
-= kramer
-:toc:
-
-// Hello people reading the README source :)
-
-== Prelude
-
-VERY EARLY ALPHA -- NOT YET FUNCTIONAL
-
-I needed a program to efficiently repair the data on optical discs.
-
-== Goals
-
-* [*] CLI Args
-** [*] Input device
-** [*] Output file (ISO 9660)
-** [*] Repair map file
-** [*] sequence_length
-** [*] brute_passes
-** [*] Sector size override?
-
-* Repair Algorithm
-** Stage 1: Trial
-*** [ ] 1 - From first sector, parse forward to error.
-*** [ ] 2 - From last sector, parse backwards to error.
-*** [ ] 3 - From center of data for trial, parse forward to error or end of remaining trial domain.
-*** [ ] 4 - Stripe-skip remaining data, attempting to read largest trial domains first.
-**** [ ] If data keeps reading good, no skip will occur until an error is reached.
-** Stage 2: Isolation
-*** [ ] From largest to smallest untrustworthy sequence, attempt to read each sequence at half sequence_length.
-*** [ ] Same, but at quarter sequence_length.
-*** [ ] Same, but at eighth sequence_length.
-*** [ ] By sector, parse untrustworthy sequences from start to error, and end to error. Mark mid section for brute force.
-** Stage 3: Brute Force
-*** [ ] Desperately attempt to recover data from marked sections.
-*** [ ] Attempt for brute_passes, retrying all failed sectors.
-
-* [ ] Repair Map
-** [ ] I'll figure out some kind of language for this...
-
-== License

README.md

@@ -0,0 +1,70 @@
+# kramer
+
+`kramer` is a data recovery utility for optical media.
+
+There are plans to change the project name, but during initial development it
+will continue to be referred to as kramer.
+
+This is still in very early development, so expect old maps to no longer work.
+
+## Plans
+
+### Core
+
+- [x] Mapping
+  - [x] Record the state of disc regions.
+  - [x] Recover from saved map.
+  - [x] Backup old map before truncating for new.
+- [ ] Recovery
+  - [x] Initial / Patchworking
+        Technically there is an outstanding issue with sleepy firmware here,
+        but beside that this technically works.
+  - [ ] Isolate
+  - [ ] Scraping
+- [ ] CLI
+  - [x] Arguments
+  - [ ] Recovery progress
+  - [ ] Recovery stats
+- [ ] Documentation, eugh.
+
+### Extra
+
+- [ ] i18n
+  - [ ] English
+  - [ ] French
+- [ ] TUI (akin to `ddrescueview`)
+  - [ ] Visual status map
+  - [ ] Recovery properties
+  - [ ] Recovery progress
+  - [ ] Recovery stats
+
+## Recovery Strategy
+
+### Initial Pass / Patchworking
+
+Tries to read clusters of `max_buffer_size`, marking clusters with errors with
+an increasing `level`.
+
+This works by halving the length of the read buffer until one of two
+conditions is met:
+
+1. `max_buffer_size` has been divided by `max_buffer_subdivision`
+  (like a maximum recursion depth).
+  Effectively, it will keep running `max_buffer_size / isolation_depth;
+  isolation_depth++;` on each pass until `isolation_depth ==
+  max_buffer_subdivision`
+2. `buffer_size <= min_buffer_size`
+3. `buffer_size <= sector_size`
+
+### Isolate
+
+This is where we reach brute forcing territory. `ddrescue` refers to this as
+trimming. `kramer` implements the same technique. However, thanks to the
+patchworking pass, this sector-at-a-time reading can be minimized, hopefully
+reducing wear and overall recovery time on drives with a very short spin-down
+delay.
+
+### Scraping (Stage::BruteForceAndDesperation)
+
+This is the pure brute force, sector-at-a-time read. This has identical
+behaviour to `ddrescue`'s scraping phase.

src/cli.rs

@@ -31,14 +31,16 @@ pub struct Args {
     #[arg(short, long, default_value_t = crate::FB_SECTOR_SIZE)]
     pub sector_size: usize,
 
-    // Behaviour is backwards.
+    // !!! ArgAction behaviour is backwards !!!
     // ArgAction::SetFalse by default evaluates to true,
     // ArgAction::SetTrue by default evaluates to false.
+    //
     /// Upon encountering a read error, reopen the source file before continuing.
     #[arg(short, long, action = ArgAction::SetTrue)]
     pub reopen_on_error: bool,
 
     /// Use O_DIRECT to bypass kernel buffer when reading.
+    //
     // BSD seems to support O_DIRECT, but MacOS for certain does not.
     #[cfg(all(unix, not(target_os = "macos")))]
     #[arg(short, long = "direct", action = ArgAction::SetFalse)]

src/io.rs

@@ -1,9 +1,11 @@
 use std::fs::{File, OpenOptions};
 use std::io::{self, Seek, SeekFrom};
+use std::ops::Index;
+use std::path::Path;
 
 use crate::cli::CONFIG;
 
-use anyhow::Context;
+use anyhow::{Context, anyhow};
 
 /// Get length of data stream.
 /// Physical length of data stream in bytes
@@ -64,10 +66,21 @@ pub fn load_map_read() -> std::io::Result<File> {
 }
 
 pub fn load_map_write() -> anyhow::Result<File> {
+    // Attempt to check if a map exists on the disk.
+    // If so, make a backup of it.
+    //
+    // This should be recoverable by just skipping over this error and logging a warning,
+    // but for now it will be an error condition.
+    if std::fs::exists(crate::path::MAP_PATH.clone())
+        .context("Could not check if map exists in fs to make a backup.")?
+    {
+        backup(crate::path::MAP_PATH.clone())?;
+    }
+
     OpenOptions::new()
         .write(true)
         .create(true)
-        .truncate(true) // Wipe old map. Should really make a backup first.
+        .truncate(true) // Wipe old map, in case we skip over backing up the old one.
         .open(crate::path::MAP_PATH.clone())
         .with_context(|| {
             format!(
@@ -77,9 +90,23 @@ pub fn load_map_write() -> anyhow::Result<File> {
         })
 }
 
+fn backup<P: AsRef<Path>>(path: P) -> std::io::Result<()> {
+    std::fs::rename(
+        &path,
+        format!("{}.bak", path.as_ref().to_path_buf().display()),
+    )
+}
+
+#[derive(Debug)]
 #[repr(C, align(512))]
 pub struct DirectIOBuffer(pub [u8; crate::MAX_BUFFER_SIZE]);
 
+impl DirectIOBuffer {
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
+
 impl Default for DirectIOBuffer {
     fn default() -> Self {
         Self([crate::FB_NULL_VALUE; _])
@@ -91,3 +118,37 @@ impl From<[u8; crate::MAX_BUFFER_SIZE]> for DirectIOBuffer {
         Self(value)
     }
 }
+
+impl TryFrom<&[u8]> for DirectIOBuffer {
+    type Error = anyhow::Error;
+
+    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
+        if value.len() > crate::MAX_BUFFER_SIZE {
+            return Err(anyhow!("Provided slice is larger than MAX_BUFFER_SIZE."));
+        }
+
+        Ok(Self(value.try_into()?))
+    }
+}
+
+impl AsRef<[u8]> for DirectIOBuffer {
+    fn as_ref(&self) -> &[u8] {
+        &self.0
+    }
+}
+
+impl AsMut<[u8]> for DirectIOBuffer {
+    fn as_mut(&mut self) -> &mut [u8] {
+        &mut self.0
+    }
+}
+
+impl<Idx> Index<Idx> for DirectIOBuffer
+where
+    Idx: std::slice::SliceIndex<[u8], Output = [u8]>,
+{
+    type Output = Idx::Output;
+    fn index(&self, index: Idx) -> &Self::Output {
+        &self.0.as_slice()[index]
+    }
+}

src/mapping/cluster.rs

@@ -3,6 +3,8 @@ use super::{Domain, Stage};
 use serde::{Deserialize, Serialize};
 
 /// A map for data stored in memory for processing and saving to disk.
+// derived Ord impl *should* use self.domain.start to sort? Not sure.
+// Use `sort_by_key()` to be safe.
 #[derive(Clone, Copy, Debug, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Cluster {
     pub domain: Domain,

src/mapping/map.rs

@@ -1,6 +1,8 @@
 use std::fs::File;
 use std::io::Write;
 
+use crate::mapping::cluster;
+
 use super::{Cluster, Domain, DomainOverlap, Stage};
 
 use anyhow;
@@ -30,7 +32,7 @@ impl Default for MapFile {
             domain: Domain::default(),
             map: vec![Cluster {
                 domain: Domain::default(),
-                stage: Stage::Untested,
+                stage: Stage::Patchwork { depth: 0 },
             }],
         }
     }
@@ -81,18 +83,8 @@ impl MapFile {
         let mut recover_stage = Stage::Damaged;
 
         for cluster in self.map.iter() {
-            match cluster.stage {
-                Stage::Untested => return Stage::Untested,
-                Stage::ForIsolation { .. } => {
-                    if recover_stage == Stage::Damaged || cluster.stage < recover_stage {
-                        // Note that recover_stage after first condition is
-                        // only ever Stage::ForIsolation(_), thus PartialEq,
-                        // PartialOrd are useful for comparing the internal value.
-                        recover_stage = cluster.stage
-                    }
-                }
-                Stage::Damaged => (),
-                Stage::Intact => (),
+            if cluster.stage < recover_stage {
+                recover_stage = cluster.stage;
             }
         }
 
@@ -116,52 +108,29 @@ impl MapFile {
     /// Defragments cluster groups.
     /// I.E. check forwards every cluster from current until stage changes,
     /// then group at once.
-    pub fn defrag(&mut self) -> &mut Self {
+    pub fn defrag(&mut self) {
+        self.map.sort_by_key(|c| c.domain.start);
+
         let mut new_map: Vec<Cluster> = vec![];
+        let mut idx = 0;
+        let mut master;
+        while idx < self.map.len() - 1 {
+            master = self.map[idx];
 
-        // Fetch first cluster.
-        let mut start_cluster = self.map.iter().find(|c| c.domain.start == 0).unwrap();
-
-        // Even though this would be initialized by its first read,
-        // the compiler won't stop whining, and idk how to assert that to it.
-        let mut end_cluster = Cluster::default();
-        let mut new_cluster: Cluster;
-
-        let mut stage_common: bool;
-        let mut is_finished = false;
-
-        while !is_finished {
-            stage_common = true;
-
-            // Start a new cluster based on the cluster following
-            // the end of last new_cluster.
-            new_cluster = start_cluster.to_owned();
-
-            // While stage is common, and not finished,
-            // find each trailing cluster.
-            while stage_common && !is_finished {
-                end_cluster = start_cluster.to_owned();
-
-                if end_cluster.domain.end != self.domain.end {
-                    start_cluster = self
-                        .map
-                        .iter()
-                        .find(|c| end_cluster.domain.end == c.domain.start)
-                        .unwrap();
-
-                    stage_common = new_cluster.stage == start_cluster.stage
-                } else {
-                    is_finished = true;
+            for c in self.map[idx + 1..self.map.len()].into_iter() {
+                if c.stage != master.stage {
+                    break;
                 }
+
+                idx += 1;
             }
 
-            // Set the new ending, encapsulating any clusters of common stage.
-            new_cluster.domain.end = end_cluster.domain.end;
-            new_map.push(new_cluster);
+            master.domain.end = self.map[idx].domain.end;
+            new_map.push(master);
+            idx += 1;
         }
 
         self.map = new_map;
-        self
     }
 
     /// Extend the domain of the MapFile.
@@ -622,7 +591,7 @@ mod tests {
         let mut map = MapFile {
             map: vec![Cluster {
                 domain: Domain { start: 0, end: 3 },
-                stage: Stage::Untested,
+                stage: Stage::Patchwork { depth: 0 },
             }],
             ..Default::default()
         };
@@ -726,17 +695,16 @@ mod tests {
 
         // If this fails here, there's something SERIOUSLY wrong.
         assert!(
-            mf_stage == Stage::Untested,
+            mf_stage == Stage::Patchwork { depth: 0 },
             "Determined stage to be {:?}, when {:?} was expeccted.",
             mf_stage,
-            Stage::Untested
+            Stage::Patchwork { depth: 0 }
         );
 
         let stages = vec![
             Stage::Damaged,
-            Stage::ForIsolation { level: 1 },
-            Stage::ForIsolation { level: 0 },
-            Stage::Untested,
+            Stage::Patchwork { depth: 1 },
+            Stage::Patchwork { depth: 0 },
         ];
 
         mf.map = vec![];
@@ -762,20 +730,17 @@ mod tests {
 
         mf.map = vec![
             *Cluster::default().set_stage(Stage::Damaged),
-            *Cluster::default().set_stage(Stage::ForIsolation { level: 0 }),
-            *Cluster::default().set_stage(Stage::ForIsolation { level: 1 }),
+            *Cluster::default().set_stage(Stage::Patchwork { depth: 1 }),
             Cluster::default(),
             Cluster::default(),
-            *Cluster::default().set_stage(Stage::ForIsolation { level: 1 }),
-            *Cluster::default().set_stage(Stage::ForIsolation { level: 0 }),
+            *Cluster::default().set_stage(Stage::Patchwork { depth: 1 }),
             *Cluster::default().set_stage(Stage::Damaged),
         ];
 
         let stages = vec![
             Stage::Damaged,
-            Stage::ForIsolation { level: 1 },
-            Stage::ForIsolation { level: 0 },
-            Stage::Untested,
+            Stage::Patchwork { depth: 1 },
+            Stage::Patchwork { depth: 0 },
         ];
 
         for stage in stages {
@@ -803,63 +768,84 @@ mod tests {
             map: vec![
                 Cluster {
                     domain: Domain { start: 0, end: 1 },
-                    stage: Stage::Untested,
+                    stage: Stage::Patchwork { depth: 0 },
                 },
                 Cluster {
                     domain: Domain { start: 1, end: 2 },
-                    stage: Stage::Untested,
+                    stage: Stage::Patchwork { depth: 0 },
                 },
                 Cluster {
                     domain: Domain { start: 2, end: 3 },
-                    stage: Stage::Untested,
+                    stage: Stage::Patchwork { depth: 0 },
                 },
                 Cluster {
                     domain: Domain { start: 3, end: 4 },
-                    stage: Stage::ForIsolation { level: 0 },
+                    stage: Stage::Isolate,
                 },
                 Cluster {
                     domain: Domain { start: 4, end: 5 },
-                    stage: Stage::ForIsolation { level: 0 },
+                    stage: Stage::Isolate,
                 },
                 Cluster {
                     domain: Domain { start: 5, end: 6 },
-                    stage: Stage::ForIsolation { level: 1 },
+                    stage: Stage::Patchwork { depth: 1 },
                 },
                 Cluster {
                     domain: Domain { start: 6, end: 7 },
-                    stage: Stage::ForIsolation { level: 0 },
+                    stage: Stage::Patchwork { depth: 0 },
                 },
                 Cluster {
                     domain: Domain { start: 7, end: 8 },
                     stage: Stage::Damaged,
                 },
+                Cluster {
+                    domain: Domain { start: 8, end: 10 },
+                    stage: Stage::Intact,
+                },
+                Cluster {
+                    domain: Domain { start: 10, end: 11 },
+                    stage: Stage::BruteForceAndDesperation,
+                },
+                Cluster {
+                    domain: Domain { start: 11, end: 12 },
+                    stage: Stage::BruteForceAndDesperation,
+                },
             ],
         };
 
         let expected = vec![
             Cluster {
                 domain: Domain { start: 0, end: 3 },
-                stage: Stage::Untested,
+                stage: Stage::Patchwork { depth: 0 },
             },
             Cluster {
                 domain: Domain { start: 3, end: 5 },
-                stage: Stage::ForIsolation { level: 0 },
+                stage: Stage::Isolate,
             },
             Cluster {
                 domain: Domain { start: 5, end: 6 },
-                stage: Stage::ForIsolation { level: 1 },
+                stage: Stage::Patchwork { depth: 1 },
             },
             Cluster {
                 domain: Domain { start: 6, end: 7 },
-                stage: Stage::ForIsolation { level: 0 },
+                stage: Stage::Patchwork { depth: 0 },
             },
             Cluster {
                 domain: Domain { start: 7, end: 8 },
                 stage: Stage::Damaged,
             },
+            Cluster {
+                domain: Domain { start: 8, end: 10 },
+                stage: Stage::Intact,
+            },
+            Cluster {
+                domain: Domain { start: 10, end: 12 },
+                stage: Stage::BruteForceAndDesperation,
+            },
         ];
 
         mf.defrag();
+        mf.map.sort_by_key(|c| c.domain.start);
 
         let received = mf.map;
 

src/mapping/stage.rs

@@ -2,15 +2,17 @@ use serde::{Deserialize, Serialize};
 
 #[derive(Clone, Copy, Debug, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
 pub enum Stage {
-    Untested,
-    ForIsolation { level: u8 },
+    // Don't mess with the order.
+    Patchwork { depth: usize },
+    Isolate,
+    BruteForceAndDesperation,
     Damaged,
     Intact,
 }
 
 impl Default for Stage {
     fn default() -> Self {
-        Stage::Untested
+        Stage::Patchwork { depth: 0 }
     }
 }
 

src/recovery.rs

@@ -43,19 +43,15 @@ impl Recover {
 
     /// Recover media.
     pub fn run(&mut self) -> anyhow::Result<usize> {
-        // From start, read to end or error.
-        //
-        // If all data recovered, return early.
-        // Else, read from end to error.
-
         let mut is_finished = false;
 
         while !is_finished {
             self.map.defrag();
 
             match self.map.get_stage() {
-                Stage::Untested => self.copy_untested()?,
-                Stage::ForIsolation { .. } => todo!(),
+                Stage::Patchwork { depth } => self.copy_patchwork(depth)?,
+                Stage::Isolate => todo!(),
+                Stage::BruteForceAndDesperation => todo!(),
                 Stage::Damaged | Stage::Intact => {
                     println!("Cannot recover further.");
 
@@ -89,39 +85,52 @@ impl Recover {
     }
 
     /// Attempt to copy all untested blocks.
-    fn copy_untested(&mut self) -> anyhow::Result<()> {
-        let mut buf = DirectIOBuffer::default();
+    fn copy_patchwork(&mut self, mut depth: usize) -> anyhow::Result<()> {
+        let mut buf = DirectIOBuffer::new();
+        let mut buf_capacity = self.get_buf_capacity() as usize;
 
-        for untested in self.map.get_clusters(Stage::Untested) {
-            // Caching.
-            let mut read_position: usize;
-            let mut cluster: Cluster;
-            let mut buf_capacity = self.get_buf_capacity() as usize;
+        while self.map.get_stage() == (Stage::Patchwork { depth }) {
+            // Order of these two expressions matters, stupid.
+            buf_capacity /= depth;
+            depth += 1;
 
-            dbg!(untested.domain);
-            read_position = untested.domain.start;
+            for cluster in self.map.get_clusters(Stage::Patchwork { depth }) {
+                self.read_domain(buf.as_mut(), cluster.domain, buf_capacity, Stage::Isolate)?;
+            }
+        }
 
-            while read_position < untested.domain.end {
-                dbg!(read_position);
+        Ok(())
+    }
 
-                buf_capacity = buf_capacity.min(untested.domain.end - read_position);
+    fn read_domain(
+        &mut self,
+        buf: &mut [u8],
+        domain: Domain,
+        mut buf_capacity: usize,
+        next_stage: Stage,
+    ) -> anyhow::Result<()> {
+        let mut cluster;
+        let mut read_position = domain.start;
 
-                cluster = Cluster {
-                    domain: Domain {
-                        start: read_position,
-                        end: read_position + buf_capacity,
-                    },
-                    stage: Stage::Intact,
-                };
+        while read_position < domain.end {
+            buf_capacity = buf_capacity.min(domain.end - read_position);
 
-                if let Err(err) = self.input.read_exact(&mut buf.0) {
-                    // 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
-                    // values are potentially invalid.
-                    //
-                    // That padding should have a cli arg to control it.
+            cluster = Cluster {
+                domain: Domain {
+                    start: read_position,
+                    end: read_position + buf_capacity,
+                },
+                stage: Stage::Intact,
+            };
 
+            match self.read_sectors(buf.as_mut()) {
+                Ok(bytes) => {
+                    self.output
+                        .write_all(&buf[0..bytes])
+                        .context("Failed to write data to output file")?;
+                    read_position += bytes;
+                }
+                Err(err) => {
                     println!("Hit error: {:?}", err);
                     if CONFIG.reopen_on_error {
                         self.reload_input()
@@ -135,26 +144,14 @@ impl Recover {
                         .seek_relative(buf_capacity as i64)
                         .context("Failed to seek output by buf_capacity to skip previous error")?;
 
-                    // I don't remember what level was for.
-                    cluster.stage = Stage::ForIsolation { level: 1 };
+                    cluster.stage = next_stage.clone();
                 }
-
-                if cluster.stage == Stage::Intact {
-                    self.output
-                        .write_all(&buf.0[0..buf_capacity])
-                        .context("Failed to write data to output file")?;
-                }
-
-                self.map.update(cluster);
-                self.map.write_to(&mut crate::io::load_map_write()?)?;
-                read_position += buf_capacity;
             }
+
+            self.map.update(cluster);
+            self.map.write_to(&mut crate::io::load_map_write()?)?;
         }
 
-        drop(buf);
-
-        self.map.write_to(&mut crate::io::load_map_write()?)?;
-
         Ok(())
     }
 
@@ -172,6 +169,25 @@ impl Recover {
         self.input.seek(SeekFrom::Start(seek_pos))?;
         Ok(())
     }
+
+    fn read_sectors(&mut self, mut buf: &mut [u8]) -> std::io::Result<usize> {
+        let mut raw_buf = vec![crate::FB_NULL_VALUE; buf.len()];
+        let result = self.input.read(&mut raw_buf);
+
+        if result.is_err() {
+            return result;
+        } else if let Ok(mut bytes) = result
+            && bytes >= CONFIG.sector_size
+        {
+            // Remember that this is integer division (floor division)
+            bytes = (bytes / CONFIG.sector_size) * CONFIG.sector_size;
+            buf.write_all(&raw_buf[..bytes]).unwrap();
+
+            return Ok(bytes);
+        } else {
+            return Ok(0);
+        }
+    }
 }
 
 #[cfg(test)]