Embed the game data so the disks are not needed at run time

build.rs unpacks the ADF images next to Cargo.toml (or in
SKIDS_EMBED_DIR) with the same ADF/LHA readers the game uses and packs
the files into the executable. At run time the built-in data loads
first and anything given with --data, or found next to the executable,
overrides it. The embed feature is on by default; builds without it
behave as before and ask for --data. CI now runs the binary from an
empty directory.

.github/workflows/build.yml

@@ -31,11 +31,14 @@ jobs:
         run: cargo test --release
       - name: Build
         run: cargo build --release
-      - name: Check against the game data
+      - name: Check the binary runs without the disks
         shell: bash
         run: |
-          ./target/release/${{ matrix.bin }} info --data .
-          ./target/release/${{ matrix.bin }} bench --data . --seconds 60
+          mkdir -p "$RUNNER_TEMP/standalone"
+          cp target/release/${{ matrix.bin }} "$RUNNER_TEMP/standalone/"
+          cd "$RUNNER_TEMP/standalone"
+          ./${{ matrix.bin }} info
+          ./${{ matrix.bin }} bench --seconds 60
       - uses: actions/upload-artifact@v4
         with:
           name: ${{ matrix.artifact }}

Cargo.toml

@@ -8,10 +8,13 @@ readme = "README.md"
 repository = "https://github.com/andydixon/skids"
 
 [features]
-default = ["audio"]
+default = ["audio", "embed"]
 # Procedural engine/skid sound via cpal. Disable with --no-default-features
 # on Linux machines without the ALSA development headers.
 audio = ["dep:cpal"]
+# Build the game data from the ADF images next to Cargo.toml (or in
+# SKIDS_EMBED_DIR) into the executable, so it runs without the disks.
+embed = []
 
 [dependencies]
 minifb = "0.28"

README.md

@@ -3,10 +3,14 @@
 A cross-platform (Windows, macOS, Linux) engine written in Rust that plays
 *Super Skidmarks* (Acid Software, 1995) on the original Amiga data.
 
-It reads the game's ADF disk images directly: it unpacks the LHA archives
-on them, decrunches the CrunchMania-packed files, and decodes the planar
-track graphics and AGA sprite banks. No game assets are compiled into the
-program; you supply the disks.
+At build time it reads the game's ADF disk images from this repository:
+it unpacks the LHA archives on them and builds the game files into the
+executable. At run time it decrunches the CrunchMania-packed files and
+decodes the planar track graphics and AGA sprite banks. The finished
+program is a single self-contained file, with no disks needed to play.
+
+Because the binary carries the original game data, anyone you give a build
+to also gets the game data.
 
 ## What works
 
@@ -44,11 +48,17 @@ far.
 ## Running
 
 ```sh
-cargo run --release -- --data /path/to/adfs
+cargo run --release
 ```
 
-Without `--data`, the game looks in the current directory and then next to
-the executable, so running it from this repository's root just works.
+The built executable (`target/release/skids`, or `skids.exe` on Windows)
+runs on its own from anywhere.
+
+`--data DIR` adds to or overrides the built-in data with more ADF images,
+LHA archives, or extracted `track/`, `vehicles/` and `palettes/` folders.
+Without `--data`, a folder like that in the current directory or next to
+the executable is picked up automatically. That means dropping disk 1 or
+real palette files next to the game just works.
 
 | Action      | Player 1                              | Player 2 |
 |-------------|---------------------------------------|----------|
@@ -79,12 +89,18 @@ You need a stable Rust toolchain.
   without sound (no ALSA needed), use `cargo build --release --no-default-features`.
 - **macOS / Windows:** `cargo build --release` works as is.
 
+The build embeds the data from the `*.adf` files next to `Cargo.toml`. To
+use images from somewhere else, set `SKIDS_EMBED_DIR=/path/to/adfs`. To
+build without embedding, so the game needs `--data` at run time, use
+`--no-default-features --features audio`.
+
 GitHub Actions builds all three platforms on every push
 (`.github/workflows/build.yml`).
 
 ## Layout
 
 ```
+build.rs       unpacks the ADFs and embeds the game files at build time
 src/formats/   ADF (OFS/FFS), LHA and CrunchMania readers
 src/data/      track, vehicle and palette decoding; locating the game files
 src/game/      physics, AI and race rules

build.rs

@@ -0,0 +1,84 @@
+//! Embeds the game data in the executable so it runs without the disks.
+//!
+//! The ADF images next to Cargo.toml (or in `SKIDS_EMBED_DIR`) are unpacked
+//! at build time and the files inside their LHA archives are packed into
+//! `$OUT_DIR/embedded.bin`, which `src/data/embedded.rs` includes. If no
+//! images are found the pack is empty and the game asks for `--data`.
+//! Disable with `--no-default-features --features audio`.
+
+#[path = "src/formats/mod.rs"]
+#[allow(dead_code)]
+mod formats;
+
+use formats::{adf::Adf, lha};
+use std::env;
+use std::fs;
+use std::path::PathBuf;
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-env-changed=SKIDS_EMBED_DIR");
+    let out = PathBuf::from(env::var("OUT_DIR").unwrap()).join("embedded.bin");
+
+    let mut files: Vec<(String, Vec<u8>)> = Vec::new();
+    if env::var_os("CARGO_FEATURE_EMBED").is_some() {
+        let dir = env::var_os("SKIDS_EMBED_DIR")
+            .map(PathBuf::from)
+            .unwrap_or_else(|| PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap()));
+        println!("cargo:rerun-if-changed={}", dir.display());
+        let mut images: Vec<PathBuf> = fs::read_dir(&dir)
+            .map(|rd| rd.flatten().map(|e| e.path()).collect())
+            .unwrap_or_default();
+        images.retain(|p| p.extension().is_some_and(|e| e.eq_ignore_ascii_case("adf")));
+        images.sort();
+        for image in images {
+            println!("cargo:rerun-if-changed={}", image.display());
+            let name = image.display().to_string();
+            let disk = match fs::read(&image)
+                .map_err(|e| e.to_string())
+                .and_then(|d| Adf::open(d).map_err(|e| e.to_string()))
+                .and_then(|a| a.files().map_err(|e| e.to_string()))
+            {
+                Ok(f) => f,
+                Err(e) => {
+                    println!("cargo:warning=skipping {name}: {e}");
+                    continue;
+                }
+            };
+            for f in disk {
+                if !f.path.to_lowercase().ends_with(".lha") {
+                    files.push((f.path, f.data));
+                    continue;
+                }
+                match lha::parse(&f.data) {
+                    Ok(entries) => {
+                        for e in entries {
+                            if let Some(d) = e.data {
+                                files.push((e.path, d));
+                            }
+                        }
+                    }
+                    Err(e) => println!("cargo:warning=skipping {name}/{}: {e}", f.path),
+                }
+            }
+        }
+        if files.is_empty() {
+            println!(
+                "cargo:warning=no Super Skidmarks ADF images in {}; the game will need --data",
+                dir.display()
+            );
+        }
+    }
+
+    // Pack: "SKIDPAK1", u32 count, then per file u16 name length, name,
+    // u32 data length, data. All little-endian.
+    let mut pack = b"SKIDPAK1".to_vec();
+    pack.extend_from_slice(&(files.len() as u32).to_le_bytes());
+    for (name, data) in &files {
+        pack.extend_from_slice(&(name.len() as u16).to_le_bytes());
+        pack.extend_from_slice(name.as_bytes());
+        pack.extend_from_slice(&(data.len() as u32).to_le_bytes());
+        pack.extend_from_slice(data);
+    }
+    fs::write(out, pack).unwrap();
+}

src/data/embedded.rs

@@ -0,0 +1,25 @@
+//! Game files built into the executable by `build.rs`.
+
+static PACK: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/embedded.bin"));
+
+/// Every embedded file as (archive path, contents). Empty when the build
+/// found no disk images.
+pub fn files() -> Vec<(String, &'static [u8])> {
+    parse(PACK).unwrap_or_default()
+}
+
+fn parse(d: &'static [u8]) -> Option<Vec<(String, &'static [u8])>> {
+    let rest = d.strip_prefix(b"SKIDPAK1")?;
+    let (count, mut rest) = rest.split_at_checked(4)?;
+    let count = u32::from_le_bytes(count.try_into().ok()?);
+    let mut out = Vec::with_capacity(count as usize);
+    for _ in 0..count {
+        let (len, r) = rest.split_at_checked(2)?;
+        let (name, r) = r.split_at_checked(u16::from_le_bytes(len.try_into().ok()?) as usize)?;
+        let (len, r) = r.split_at_checked(4)?;
+        let (data, r) = r.split_at_checked(u32::from_le_bytes(len.try_into().ok()?) as usize)?;
+        out.push((String::from_utf8_lossy(name).into_owned(), data));
+        rest = r;
+    }
+    Some(out)
+}

src/data/mod.rs

@@ -1,9 +1,12 @@
 //! Locates and decodes the original game data.
 //!
-//! Data can be supplied as the original ADF images, as the LHA archives taken
-//! off them, or as an already-extracted directory tree containing `track/` and
-//! `vehicles/`. Nothing from the original game is embedded in this program.
+//! The default build embeds the data from the ADF images it was built
+//! alongside (see `build.rs`), so no disks are needed at run time. Extra or
+//! replacement data can still be supplied as ADF images, the LHA archives
+//! from them, or an extracted tree with `track/`, `vehicles/` and `palettes/`.
+//! Files on disk override the built-in ones.
 
+pub mod embedded;
 pub mod palette;
 pub mod track;
 pub mod vehicle;
@@ -25,12 +28,18 @@ pub struct FileSet {
 }
 
 impl FileSet {
-    pub fn scan(root: &Path) -> FileSet {
+    pub fn embedded() -> FileSet {
         let mut fs_ = FileSet::default();
-        fs_.scan_dir(root, 0);
+        for (path, data) in embedded::files() {
+            fs_.add(&path, data.to_vec());
+        }
         fs_
     }
 
+    pub fn scan(&mut self, root: &Path) {
+        self.scan_dir(root, 0);
+    }
+
     fn scan_dir(&mut self, dir: &Path, depth: usize) {
         let Ok(rd) = fs::read_dir(dir) else {
             self.warnings
@@ -116,8 +125,12 @@ pub struct GameData {
 }
 
 impl GameData {
-    pub fn load(root: &Path) -> Result<GameData, String> {
-        let files = FileSet::scan(root);
+    /// Loads the built-in data, overlaid with whatever is under `dir`.
+    pub fn load(dir: Option<&Path>) -> Result<GameData, String> {
+        let mut files = FileSet::embedded();
+        if let Some(dir) = dir {
+            files.scan(dir);
+        }
         let mut warnings = files.warnings.clone();
 
         let mut track_files = Vec::new();
@@ -145,9 +158,9 @@ impl GameData {
 
         if track_files.is_empty() || vehicles.is_empty() {
             return Err(format!(
-                "no usable game data under {} (found {} track files, {} vehicles).\n\
-                 Point --data at a folder containing the Super Skidmarks ADF images.{}",
-                root.display(),
+                "no usable game data (found {} track files, {} vehicles).\n\
+                 This build has no data built in: point --data at a folder containing the \
+                 Super Skidmarks ADF images, or rebuild with the images next to Cargo.toml.{}",
                 track_files.len(),
                 vehicles.len(),
                 if warnings.is_empty() {

src/main.rs

@@ -30,9 +30,11 @@ USAGE:
     skids trace   [--data DIR] --out FILE.png [--track N] [--seconds S]
                                                   draw the computer cars' paths on a track
 
-The data directory should hold the Super Skidmarks ADF images (or the LHA
-archives from them, or extracted track/ and vehicles/ folders). It defaults to
-the current directory, then the directory the executable is in.
+The game data is built into the executable, so no disks are needed. --data
+adds to or overrides it with ADF images, LHA archives, or extracted track/,
+vehicles/ and palettes/ folders (e.g. disk 1, or real palettes). Without
+--data, a folder like that in the current directory or next to the
+executable is picked up automatically.
 
 CONTROLS:
     Player 1: arrow keys (or W A S D in one-player games)
@@ -83,9 +85,12 @@ fn parse_args() -> Result<Args, String> {
     Ok(a)
 }
 
-fn find_data(explicit: Option<PathBuf>) -> PathBuf {
-    if let Some(p) = explicit {
-        return p;
+/// An explicit --data directory, or a nearby folder that looks like it holds
+/// game data (e.g. disk 1 dropped next to the executable). The built-in data
+/// is always loaded first, so finding nothing is fine.
+fn find_data(explicit: Option<PathBuf>) -> Option<PathBuf> {
+    if explicit.is_some() {
+        return explicit;
     }
     let looks_right = |d: &Path| {
         std::fs::read_dir(d).is_ok_and(|rd| {
@@ -103,10 +108,7 @@ fn find_data(explicit: Option<PathBuf>) -> PathBuf {
         candidates.push(dir);
     }
     candidates.push(PathBuf::from("data"));
-    candidates
-        .into_iter()
-        .find(|d| looks_right(d))
-        .unwrap_or_else(|| PathBuf::from("."))
+    candidates.into_iter().find(|d| looks_right(d))
 }
 
 fn main() -> ExitCode {
@@ -125,7 +127,7 @@ fn main() -> ExitCode {
         }
     };
     let root = find_data(args.data.clone());
-    let data = match GameData::load(&root) {
+    let data = match GameData::load(root.as_deref()) {
         Ok(d) => d,
         Err(e) => {
             eprintln!("{e}");
@@ -137,7 +139,7 @@ fn main() -> ExitCode {
     }
     let result = match args.cmd.as_str() {
         "info" => {
-            info(&data);
+            info(&data, root.as_deref());
             Ok(())
         }
         "extract" => extract(&data, args.out.as_deref()),
@@ -155,7 +157,13 @@ fn main() -> ExitCode {
     }
 }
 
-fn info(data: &GameData) {
+fn info(data: &GameData, dir: Option<&Path>) {
+    let built_in = data::embedded::files().len();
+    match (built_in, dir) {
+        (0, Some(d)) => println!("Data: {}", d.display()),
+        (n, Some(d)) => println!("Data: built in ({n} files), plus {}", d.display()),
+        (n, None) => println!("Data: built in ({n} files)"),
+    }
     println!("Tracks:");
     for (f, s) in data.track_list() {
         let tf = &data.track_files[f];