xtask to build stages 1-3

xtask/src/build.rs

@@ -0,0 +1,164 @@
+use std::{
+    ffi::OsStr,
+    fs,
+    path::{Path, PathBuf},
+    process::{Command, Output, Stdio},
+};
+
+use eyre::{WrapErr, eyre};
+
+use crate::Context;
+
+const NASM_COMMON_FLAGS: &[&str] = &["-werror"];
+
+pub fn build(ctx: &Context) -> Result<(), eyre::Error> {
+    let stage_1_src_dir = ctx.workspace.join("stage_1");
+    let stage_2_src_dir = ctx.workspace.join("stage_2");
+    let stage_3_src_dir = ctx.workspace.join("stage_3");
+
+    let build_dir = ctx.workspace.join("build");
+    let stage_1_build_dir = build_dir.join("stage_1");
+    let stage_2_build_dir = build_dir.join("stage_2");
+
+    mkdir_if_missing(&build_dir)?;
+    mkdir_if_missing(&stage_1_build_dir)?;
+    mkdir_if_missing(&stage_2_build_dir)?;
+
+    build_stage_1(ctx, &stage_1_build_dir, &stage_1_src_dir)?;
+    build_stage_2(ctx, &stage_2_build_dir, &stage_2_src_dir)?;
+    build_stage_3(ctx, &stage_3_src_dir)?;
+
+    Ok(())
+}
+
+fn build_stage_1(ctx: &Context, build_dir: &Path, src_dir: &Path) -> Result<(), eyre::Error> {
+    let src_paths = ls_with_extension(src_dir, "s")?;
+
+    let [src_path] = &*src_paths else {
+        return Err(eyre!(
+            "expected exactly one stage 1 source file, found {}",
+            src_paths.len()
+        ));
+    };
+
+    let out_path = build_dir.join("s1.bin");
+    
+    let include_dir = ctx.workspace.join("include");
+
+    Command::new("nasm")
+        .args(["-f", "bin"])
+        .args(NASM_COMMON_FLAGS)
+        .arg("-I")
+        .arg(&include_dir)
+        .arg("-o")
+        .arg(&out_path)
+        .arg(src_path)
+        .stdout(Stdio::inherit())
+        .stderr(Stdio::inherit())
+        .run_ok()?;
+
+    Ok(())
+}
+
+fn build_stage_2(ctx: &Context, build_dir: &Path, src_dir: &Path) -> Result<(), eyre::Error> {
+    let include_dir = ctx.workspace.join("include");
+    let src_paths = ls_with_extension(src_dir, "s")?;
+    let mut obj_paths = Vec::new();
+
+    for src_path in src_paths {
+        let Some(file_stem) = src_path.file_stem() else {
+            continue;
+        };
+        
+        let obj_path = build_dir.join(file_stem).with_extension("o");
+        
+        Command::new("nasm")
+            .args(["-f", "elf"])
+            .args(NASM_COMMON_FLAGS)
+            .arg("-I")
+            .arg(&include_dir)
+            .arg("-o")
+            .arg(&obj_path)
+            .arg(src_path)
+            .stdout(Stdio::inherit())
+            .stderr(Stdio::inherit())
+            .run_ok()?;
+
+        obj_paths.push(obj_path);
+    }
+
+    let linker_file_path = src_dir.join("link.ld");
+    let bin_path = build_dir.join("s2.bin");
+    
+    Command::new("ld")
+        .args(["-m", "elf_i386"])
+        .arg("-T")
+        .arg(&linker_file_path)
+        .arg("-o")
+        .arg(bin_path)
+        .args(&obj_paths)
+        .stdout(Stdio::inherit())
+        .stderr(Stdio::inherit())
+        .run_ok()?;
+    
+    Ok(())
+}
+
+fn build_stage_3(ctx: &Context, stage_3_src_dir: &Path) -> Result<(), eyre::Error> {
+    Command::new(ctx.cargo)
+        .arg("build")
+        .arg("--release")
+        .current_dir(stage_3_src_dir)
+        .stdout(Stdio::inherit())
+        .stderr(Stdio::inherit())
+        .run_ok()?;
+
+    Ok(())
+}
+
+fn mkdir_if_missing(path: &Path) -> Result<(), eyre::Error> {
+    let exists = fs::exists(path)
+        .wrap_err_with(|| format!("failed to check if {} exists", path.to_string_lossy()))?;
+
+    if !exists {
+        fs::create_dir(path)
+            .wrap_err_with(|| format!("failed to create {}", path.to_string_lossy()))?;
+    }
+
+    Ok(())
+}
+
+fn ls_with_extension(path: &Path, ext: &str) -> Result<Vec<PathBuf>, eyre::Error> {
+    let read_dir = fs::read_dir(path)
+        .wrap_err_with(|| format!("failed to read {}", path.to_string_lossy()))?;
+
+    let mut paths = Vec::new();
+
+    for dir in read_dir {
+        let dir = dir.wrap_err_with(|| format!("failed to read {}", path.to_string_lossy()))?;
+
+        if dir.path().extension() == Some(OsStr::new(ext)) {
+            paths.push(dir.path());
+        }
+    }
+
+    Ok(paths)
+}
+
+trait CommandExt {
+    fn run_ok(&mut self) -> Result<Output, eyre::Error>;
+}
+
+impl CommandExt for Command {
+    fn run_ok(&mut self) -> Result<Output, eyre::Error> {
+        let output = self
+            .output()
+            .wrap_err_with(|| format!("failed to run {:?}", self))?;
+
+        if !output.status.success() {
+            return Err(eyre!("command failed: {:?}", self));
+        }
+
+        Ok(output)
+    }
+}

xtask/src/main.rs

@@ -1,83 +1,44 @@
-use std::{env, error::Error, fmt, path::{Path, PathBuf}, process::ExitCode};
+use std::{
+    env,
+    path::{Path, PathBuf},
+};
 
+use eyre::{ContextCompat, eyre};
+
+mod build;
 mod mkimg;
 
-fn main() -> ExitCode {
-    match xtask() {
-        Ok(()) => ExitCode::SUCCESS,
-        Err(err) => {
-            eprintln!("{}", err);
-            ExitCode::FAILURE
-        }
-    }
-}
-
-fn xtask() -> Result<(), XtaskError> {
+fn main() -> Result<(), eyre::Error> {
     let mut args = env::args_os().skip(1);
 
-    let task = args
-        .next()
-        .ok_or_else(|| XtaskError::with_message("no task provided".to_owned()))?;
+    let task = args.next().context("no task provided")?;
 
-    let task = task.to_str().ok_or_else(|| {
-        XtaskError::with_message(format!("invalid utf-8 \"{}\"", task.to_string_lossy()))
-    })?;
+    let task = task
+        .to_str()
+        .with_context(|| format!("invalid utf-8 \"{}\"", task.to_string_lossy()))?;
 
-    let manifest_dir = PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").ok_or_else(|| {
-        XtaskError::with_message("CARGO_MANIFEST_DIR not set".to_owned())
-    })?);
+    let manifest_dir =
+        PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").context("CARGO_MANIFEST_DIR not set")?);
 
-    let workspace_dir = manifest_dir.parent().ok_or_else(|| {
-        XtaskError::with_message("invalid CARGO_MANIFEST_DIR".to_owned())
-    })?;
+    let workspace_dir = manifest_dir
+        .parent()
+        .context("invalid CARGO_MANIFEST_DIR")?;
+
+    let cargo_path = PathBuf::from(env::var_os("CARGO").context("CARGO not set")?);
 
     let ctx = Context {
         workspace: workspace_dir,
+        cargo: &cargo_path,
     };
 
     match task {
-        "mkimg" => mkimg::mkimg_bios_gpt(ctx),
-        _ => Err(XtaskError::with_message(format!("unknown task \"{}\"", task))),
+        "build" => build::build(&ctx),
+        "mkimg" => mkimg::mkimg_bios_gpt(&ctx),
+        _ => Err(eyre!("unknown task \"{}\"", task)),
     }
 }
 
 struct Context<'a> {
     workspace: &'a Path,
+    cargo: &'a Path,
 }
-
-#[derive(Debug)]
-struct XtaskError {
-    message: String,
-    parent: Option<Box<dyn Error>>,
-}
-
-impl XtaskError {
-    fn with_message(message: String) -> Self {
-        Self {
-            message,
-            parent: None,
-        }
-    }
-
-    fn wrap_with_message<E>(err: E, message: String) -> Self
-    where
-        E: Error + 'static,
-    {
-        Self {
-            message,
-            parent: Some(Box::new(err)),
-        }
-    }
-}
-
-impl fmt::Display for XtaskError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}", self.message)?;
-        if let Some(parent) = &self.parent {
-            write!(f, ": {}", parent)?;
-        }
-        Ok(())
-    }
-}
-
-impl Error for XtaskError {}

xtask/src/mkimg.rs

@@ -1,12 +1,8 @@
-use crate::{Context, XtaskError};
+use crate::Context;
 
 const BLOCK_SIZE: u64 = 512;
 const PARTITION_ENTRY_SIZE: u64 = 128;
 
-const ATTR_REQUIRED: u64 = 1 >> 0;
-const ATTR_NO_BLOCK_IO_PROTO: u64 = 1 >> 1;
-const ATTR_LEGACY_BIOS_BOOTABLE: u64 = 1 >> 2;
-
 // LBA 0: MBR
 // LBA 1: partition header
 // LBA 2..33: partition table entries
@@ -23,9 +19,7 @@ struct Partition {
     name: String,
 }
 
-
-
-pub fn mkimg_bios_gpt(ctx: Context) -> Result<(), XtaskError> {
+pub fn mkimg_bios_gpt(ctx: &Context) -> Result<(), eyre::Error> {
     println!("dir={}", ctx.workspace.to_string_lossy());
 
     Ok(())