From f3d411f821df3caf52a0272d920075655147b1f6 Mon Sep 17 00:00:00 2001
From: Moritz Gmeiner <moritz@gmeiner.net>
Date: Sun, 27 Jul 2025 13:17:04 +0200
Subject: [PATCH] moved low-level code into fat-bits subcrate

---
 .gitignore                          |   4 +-
 Cargo.lock                          |  10 ++-
 Cargo.toml                          |  19 +---
 fat-bits/.gitignore                 |   2 +
 fat-bits/Cargo.lock                 | 130 ++++++++++++++++++++++++++++
 fat-bits/Cargo.toml                 |  15 ++++
 {src => fat-bits/src}/bpb.rs        |  17 ++--
 {src => fat-bits/src}/datetime.rs   |   4 +
 {src => fat-bits/src}/dir.rs        |   1 -
 {src => fat-bits/src}/fat.rs        |   0
 {src => fat-bits/src}/fs_info.rs    |   1 +
 {src => fat-bits/src}/iter.rs       |   0
 {src => fat-bits/src}/lib.rs        |   8 --
 {src => fat-bits/src}/subslice.rs   |   0
 {src => fat-bits/src}/utils.rs      |   0
 fat-dump/Cargo.toml                 |   8 ++
 src/dump.rs => fat-dump/src/main.rs |  14 +--
 17 files changed, 187 insertions(+), 46 deletions(-)
 create mode 100644 fat-bits/.gitignore
 create mode 100644 fat-bits/Cargo.lock
 create mode 100644 fat-bits/Cargo.toml
 rename {src => fat-bits/src}/bpb.rs (98%)
 rename {src => fat-bits/src}/datetime.rs (96%)
 rename {src => fat-bits/src}/dir.rs (99%)
 rename {src => fat-bits/src}/fat.rs (100%)
 rename {src => fat-bits/src}/fs_info.rs (98%)
 rename {src => fat-bits/src}/iter.rs (100%)
 rename {src => fat-bits/src}/lib.rs (96%)
 rename {src => fat-bits/src}/subslice.rs (100%)
 rename {src => fat-bits/src}/utils.rs (100%)
 create mode 100644 fat-dump/Cargo.toml
 rename src/dump.rs => fat-dump/src/main.rs (87%)

diff --git a/.gitignore b/.gitignore
index 54b52f6..0b00ca9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,2 @@
-/target
-/tests
+target/
+tests/
diff --git a/Cargo.lock b/Cargo.lock
index 958e3ac..6ee0b94 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -42,7 +42,7 @@ dependencies = [
 ]
 
 [[package]]
-name = "fat-rs"
+name = "fat-bits"
 version = "0.1.0"
 dependencies = [
  "anyhow",
@@ -53,6 +53,14 @@ dependencies = [
  "thiserror",
 ]
 
+[[package]]
+name = "fat-dump"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "fat-bits",
+]
+
 [[package]]
 name = "num-traits"
 version = "0.2.19"
diff --git a/Cargo.toml b/Cargo.toml
index ee5b3c7..15a1a97 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,16 +1,3 @@
-[package]
-name = "fat-rs"
-version = "0.1.0"
-edition = "2024"
-
-[[bin]]
-name = "dump"
-path = "src/dump.rs"
-
-[dependencies]
-anyhow = "1.0.98"
-bitflags = "2.9.1"
-chrono = { version = "0.4.41", default-features = false, features = ["alloc", "std"] }
-enum_dispatch = "0.3.13"
-static_assertions = "1.1.0"
-thiserror = "2.0.12"
+[workspace]
+resolver = "3"
+members = ["fat-bits", "fat-dump"]
diff --git a/fat-bits/.gitignore b/fat-bits/.gitignore
new file mode 100644
index 0000000..54b52f6
--- /dev/null
+++ b/fat-bits/.gitignore
@@ -0,0 +1,2 @@
+/target
+/tests
diff --git a/fat-bits/Cargo.lock b/fat-bits/Cargo.lock
new file mode 100644
index 0000000..958e3ac
--- /dev/null
+++ b/fat-bits/Cargo.lock
@@ -0,0 +1,130 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "anyhow"
+version = "1.0.98"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e16d2d3311acee920a9eb8d33b8cbc1787ce4a264e85f964c2404b969bdcd487"
+
+[[package]]
+name = "autocfg"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c08606f8c3cbf4ce6ec8e28fb0014a2c086708fe954eaa885384a6165172e7e8"
+
+[[package]]
+name = "bitflags"
+version = "2.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b8e56985ec62d17e9c1001dc89c88ecd7dc08e47eba5ec7c29c7b5eeecde967"
+
+[[package]]
+name = "chrono"
+version = "0.4.41"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c469d952047f47f91b68d1cba3f10d63c11d73e4636f24f08daf0278abf01c4d"
+dependencies = [
+ "num-traits",
+]
+
+[[package]]
+name = "enum_dispatch"
+version = "0.3.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aa18ce2bc66555b3218614519ac839ddb759a7d6720732f979ef8d13be147ecd"
+dependencies = [
+ "once_cell",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "fat-rs"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "bitflags",
+ "chrono",
+ "enum_dispatch",
+ "static_assertions",
+ "thiserror",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
+dependencies = [
+ "autocfg",
+]
+
+[[package]]
+name = "once_cell"
+version = "1.21.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42f5e15c9953c5e4ccceeb2e7382a716482c34515315f7b03532b8b4e8393d2d"
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.95"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "02b3e5e68a3a1a02aad3ec490a98007cbc13c37cbe84a3cd7b8e406d76e7f778"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.40"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1885c039570dc00dcb4ff087a89e185fd56bae234ddc7f056a945bf36467248d"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "static_assertions"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
+
+[[package]]
+name = "syn"
+version = "2.0.104"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "17b6f705963418cdb9927482fa304bc562ece2fdd4f616084c50b7023b435a40"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "thiserror"
+version = "2.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "567b8a2dae586314f7be2a752ec7474332959c6460e02bde30d702a66d488708"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "2.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f7cf42b4507d8ea322120659672cf1b9dbb93f8f2d4ecfd6e51350ff5b17a1d"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a5f39404a5da50712a4c1eecf25e90dd62b613502b7e925fd4e4d19b5c96512"
diff --git a/fat-bits/Cargo.toml b/fat-bits/Cargo.toml
new file mode 100644
index 0000000..1986af5
--- /dev/null
+++ b/fat-bits/Cargo.toml
@@ -0,0 +1,15 @@
+[package]
+name = "fat-bits"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+anyhow = "1.0.98"
+bitflags = "2.9.1"
+chrono = { version = "0.4.41", default-features = false, features = [
+    "alloc",
+    "std",
+] }
+enum_dispatch = "0.3.13"
+static_assertions = "1.1.0"
+thiserror = "2.0.12"
diff --git a/src/bpb.rs b/fat-bits/src/bpb.rs
similarity index 98%
rename from src/bpb.rs
rename to fat-bits/src/bpb.rs
index a1e42cf..26e4223 100644
--- a/src/bpb.rs
+++ b/fat-bits/src/bpb.rs
@@ -22,7 +22,7 @@ impl Display for ExtBpb {
 pub struct Bpb {
     fat_type: FatType,
 
-    jmp_boot: [u8; 3],
+    // jmp_boot: [u8; 3],
     oem_name: [u8; 8],
     bytes_per_sector: u16,
     sectors_per_cluster: u8,
@@ -52,11 +52,11 @@ impl Display for Bpb {
 
         writeln!(f, "")?;
 
-        writeln!(
-            f,
-            "    jmp_boot: [{:#X}, {:#X}, {:#X}]",
-            self.jmp_boot[0], self.jmp_boot[1], self.jmp_boot[2]
-        )?;
+        // writeln!(
+        //     f,
+        //     "    jmp_boot: [{:#X}, {:#X}, {:#X}]",
+        //     self.jmp_boot[0], self.jmp_boot[1], self.jmp_boot[2]
+        // )?;
 
         writeln!(f, "    oem name: \"{}\"", self.oem_name_str().unwrap_or(""))?;
         writeln!(f, "    bytes per sector: {}", self.bytes_per_sector())?;
@@ -90,7 +90,8 @@ impl Bpb {
     pub fn load(bytes: &[u8]) -> anyhow::Result<Bpb> {
         anyhow::ensure!(bytes.len() >= 512, "invalid BPB of len {}", bytes.len());
 
-        let jmp_boot = bytes[..3].try_into().unwrap();
+        // let jmp_boot = bytes[..3].try_into().unwrap();
+
         let oem_name = bytes[3..][..8].try_into().unwrap();
         let bytes_per_sector = load_u16_le(&bytes[11..][..2]);
 
@@ -145,7 +146,7 @@ impl Bpb {
 
         let mut bpb = Bpb {
             fat_type,
-            jmp_boot,
+            // jmp_boot,
             oem_name,
             bytes_per_sector,
             sectors_per_cluster,
diff --git a/src/datetime.rs b/fat-bits/src/datetime.rs
similarity index 96%
rename from src/datetime.rs
rename to fat-bits/src/datetime.rs
index 78cb507..b9672f2 100644
--- a/src/datetime.rs
+++ b/fat-bits/src/datetime.rs
@@ -22,6 +22,7 @@ impl Date {
         Ok(date)
     }
 
+    #[allow(dead_code)]
     pub fn from_day_month_year(day: u8, month: u8, year: u16) -> anyhow::Result<Date> {
         anyhow::ensure!(day <= 31, "invalid day: {}", day);
         anyhow::ensure!(month <= 12, "invalid month: {}", month);
@@ -32,6 +33,7 @@ impl Date {
         Ok(Date { repr })
     }
 
+    #[allow(dead_code)]
     pub fn from_system_time(time: SystemTime) -> anyhow::Result<Date> {
         let datetime: DateTime<Utc> = time.into();
 
@@ -73,6 +75,7 @@ impl Time {
         Ok(time)
     }
 
+    #[allow(dead_code)]
     pub fn from_seconds_minutes_hours(seconds: u8, minutes: u8, hours: u8) -> anyhow::Result<Time> {
         anyhow::ensure!(seconds <= 58 && seconds % 2 == 0, "invalid seconds: {}", seconds);
         anyhow::ensure!(minutes <= 59, "invalid minutes: {}", minutes);
@@ -83,6 +86,7 @@ impl Time {
         Ok(Time { repr })
     }
 
+    #[allow(dead_code)]
     pub fn from_system_time(time: SystemTime) -> anyhow::Result<Time> {
         let datetime: DateTime<Utc> = time.into();
 
diff --git a/src/dir.rs b/fat-bits/src/dir.rs
similarity index 99%
rename from src/dir.rs
rename to fat-bits/src/dir.rs
index 59089ad..e2a0acf 100644
--- a/src/dir.rs
+++ b/fat-bits/src/dir.rs
@@ -5,7 +5,6 @@ use bitflags::bitflags;
 use chrono::{NaiveDate, NaiveDateTime, TimeDelta};
 
 use crate::datetime::{Date, Time};
-use crate::dir;
 use crate::utils::{load_u16_le, load_u32_le};
 
 bitflags! {
diff --git a/src/fat.rs b/fat-bits/src/fat.rs
similarity index 100%
rename from src/fat.rs
rename to fat-bits/src/fat.rs
diff --git a/src/fs_info.rs b/fat-bits/src/fs_info.rs
similarity index 98%
rename from src/fs_info.rs
rename to fat-bits/src/fs_info.rs
index 993052c..f381652 100644
--- a/src/fs_info.rs
+++ b/fat-bits/src/fs_info.rs
@@ -1,5 +1,6 @@
 use crate::utils::load_u32_le;
 
+#[allow(dead_code)]
 pub struct FsInfo {
     free_count: u32,
     next_free: u32,
diff --git a/src/iter.rs b/fat-bits/src/iter.rs
similarity index 100%
rename from src/iter.rs
rename to fat-bits/src/iter.rs
diff --git a/src/lib.rs b/fat-bits/src/lib.rs
similarity index 96%
rename from src/lib.rs
rename to fat-bits/src/lib.rs
index a0f086c..ebeb6ef 100644
--- a/src/lib.rs
+++ b/fat-bits/src/lib.rs
@@ -38,14 +38,6 @@ pub trait SliceLike {
 
 impl SliceLike for &mut [u8] {
     fn read_at_offset(&mut self, offset: u64, buf: &mut [u8]) -> std::io::Result<()> {
-        // anyhow::ensure!(
-        //     offset as usize + buf.len() <= self.len(),
-        //     "reading {} bytes at offset {} is out of bounds for slice of len {}",
-        //     buf.len(),
-        //     offset,
-        //     self.len()
-        // );
-
         if offset as usize + buf.len() > self.len() {
             return Err(std::io::Error::other(anyhow::anyhow!(
                 "reading {} bytes at offset {} is out of bounds for slice of len {}",
diff --git a/src/subslice.rs b/fat-bits/src/subslice.rs
similarity index 100%
rename from src/subslice.rs
rename to fat-bits/src/subslice.rs
diff --git a/src/utils.rs b/fat-bits/src/utils.rs
similarity index 100%
rename from src/utils.rs
rename to fat-bits/src/utils.rs
diff --git a/fat-dump/Cargo.toml b/fat-dump/Cargo.toml
new file mode 100644
index 0000000..23836a8
--- /dev/null
+++ b/fat-dump/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "fat-dump"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+anyhow = "1.0.98"
+fat-bits = { version = "0.1.0", path = "../fat-bits" }
diff --git a/src/dump.rs b/fat-dump/src/main.rs
similarity index 87%
rename from src/dump.rs
rename to fat-dump/src/main.rs
index 908d290..a227756 100644
--- a/src/dump.rs
+++ b/fat-dump/src/main.rs
@@ -1,8 +1,6 @@
-use std::io::Read;
-
-use fat_rs::dir::{DirIter, RegularDirEntry};
-use fat_rs::fat::Fatty as _;
-use fat_rs::{FatFs, SliceLike};
+use fat_bits::dir::{DirIter, RegularDirEntry};
+use fat_bits::fat::Fatty as _;
+use fat_bits::{FatFs, SliceLike};
 
 pub fn main() -> anyhow::Result<()> {
     let args = std::env::args();
@@ -21,7 +19,7 @@ pub fn main() -> anyhow::Result<()> {
 
     // println!("{}", bpb);
 
-    let mut fat_fs = FatFs::load(file)?;
+    let fat_fs = FatFs::load(file)?;
 
     println!("{}", fat_fs.bpb());
     println!();
@@ -35,10 +33,6 @@ pub fn main() -> anyhow::Result<()> {
             * fat_fs.bpb().sectors_per_cluster() as usize
     );
 
-    for dir_entry in fat_fs.root_dir_iter() {
-        println!("{}", dir_entry);
-    }
-
     println!();
     println!();