wip 2

host-recipes/gcc-bootstrap.star

@@ -1,23 +1,22 @@
-name = "gcc"
 version = "16.1.0"
 revision = 1
-description = "GNU GCC cross-compiler (bootstrap stage, C/C++ only)"
-license = "GPL-3.0-or-later"
-
-source = {
-    "url": f"https://ftp.gnu.org/gnu/gcc/gcc-{version}/gcc-{version}.tar.xz",
-    "sha256": "50efb4d94c3397aff3b0d61a5abd748b4dd31d9d3f2ab7be05b171d36a510f79",
-    "strip_components": 1,
-}
-
+metadata = meta(
+    description = "GNU GCC cross-compiler (bootstrap stage, C/C++ only)",
+    license = "GPL-3.0-or-later",
+)
+source = tarball_source(
+    url = f"https://ftp.gnu.org/gnu/gcc/gcc-{version}/gcc-{version}.tar.xz",
+    sha256 = "50efb4d94c3397aff3b0d61a5abd748b4dd31d9d3f2ab7be05b171d36a510f79",
+    strip_components = 1,
+)
 host_deps = ["binutils"]
 
 def configure(ctx):
     ctx.run([
         ctx.source_dir + "/configure",
+        "--target=" + options.target_triple,
         "--prefix=" + ctx.prefix,
-        "--target=" + OPTIONS.target_triple,
-        "--with-sysroot=" + ctx.prefix + "/" + OPTIONS.target_triple,
+        "--with-sysroot=" + ctx.sysroot,
         "--without-headers",
         "--with-newlib",
         "--enable-languages=c,c++",
@@ -33,9 +32,9 @@ def configure(ctx):
         "--disable-libvtv",
         "--disable-multilib",
     ], env = {
-        "CFLAGS": OPTIONS.host_cflags,
-        "CXXFLAGS": OPTIONS.host_cxxflags,
-        "LDFLAGS": OPTIONS.host_ldflags,
+        "CFLAGS": options.host_cflags,
+        "CXXFLAGS": options.host_cxxflags,
+        "LDFLAGS": options.host_ldflags,
     })
 
 def build(ctx):
@@ -44,5 +43,5 @@ def build(ctx):
     ctx.run(["make", jobs, "all-target-libgcc"])
 
 def install(ctx, pkg):
-    ctx.run(["make", "DESTDIR=" + pkg.destdir, "install-gcc"])
-    ctx.run(["make", "DESTDIR=" + pkg.destdir, "install-target-libgcc"])
+    ctx.run(["make", "install-gcc"], env = {"DESTDIR": pkg.dest_dir})
+    ctx.run(["make", "install-target-libgcc"], env = {"DESTDIR": pkg.dest_dir})

src/builder.rs

@@ -1 +1,178 @@
-pub struct Builder;
+use std::{
+    fs,
+    path::{Path, PathBuf},
+    process::Command,
+};
+
+use anyhow::{Context, bail};
+use sha2::{Digest, Sha256};
+
+use crate::{
+    config::Config,
+    graph::{TaskPlan, TaskPlanner},
+    log,
+    recipe::RecipeSet,
+};
+
+#[derive(Debug)]
+pub struct Builder {
+    root: PathBuf,
+    config: Config,
+    container_ready: bool,
+}
+
+impl Builder {
+    pub fn new(root: PathBuf, config: Config) -> Self {
+        Self {
+            root,
+            config,
+            container_ready: false,
+        }
+    }
+
+    pub fn build(
+        &mut self,
+        recipes: &RecipeSet,
+        requested: &[String],
+        rebuild: bool,
+        dry_run: bool,
+    ) -> anyhow::Result<()> {
+        let plan = TaskPlanner::new(&self.root, &self.config.arch, recipes)
+            .build_plan(requested, rebuild)?;
+        self.print_plan(&plan);
+        if !dry_run {
+            bail!("task execution is not implemented yet");
+        }
+        Ok(())
+    }
+
+    pub fn fetch(
+        &mut self,
+        recipes: &RecipeSet,
+        requested: &[String],
+        dry_run: bool,
+    ) -> anyhow::Result<()> {
+        let plan =
+            TaskPlanner::new(&self.root, &self.config.arch, recipes).fetch_plan(requested)?;
+        self.print_plan(&plan);
+        if !dry_run {
+            bail!("task execution is not implemented yet");
+        }
+        Ok(())
+    }
+
+    pub fn ensure_container_ready(&mut self) -> anyhow::Result<()> {
+        if !self.container_ready {
+            self.ensure_container_image(&self.abs_config_path(&self.config.container_dockerfile))?;
+            self.container_ready = true;
+        }
+
+        Ok(())
+    }
+
+    fn ensure_container_image(&self, dockerfile: &Path) -> anyhow::Result<()> {
+        if !dockerfile.exists() {
+            bail!(
+                "configured container Dockerfile does not exist: {}",
+                dockerfile.display()
+            );
+        }
+
+        let hash = self.container_build_hash(dockerfile)?;
+        let stamp = self.root.join("build/container-image.hash");
+        if fs::read_to_string(&stamp).ok().as_deref() == Some(hash.as_str())
+            && self.container_image_exists()?
+        {
+            log::skip(
+                "image",
+                &format!("using cached {}", self.config.container_image),
+            );
+            return Ok(());
+        }
+
+        log::step(
+            "image",
+            &format!(
+                "building {} from {}",
+                self.config.container_image,
+                dockerfile.display()
+            ),
+        );
+        let runtime = self.config.container_runtime.as_str();
+        let status = Command::new(runtime)
+            .arg("build")
+            .arg("-f")
+            .arg(dockerfile)
+            .arg("-t")
+            .arg(&self.config.container_image)
+            .arg(&self.root)
+            .status()
+            .with_context(|| {
+                format!(
+                    "failed to build container image `{}` from {}",
+                    self.config.container_image,
+                    dockerfile.display()
+                )
+            })?;
+        if !status.success() {
+            bail!(
+                "container image build failed for `{}` with {status}",
+                self.config.container_image
+            );
+        }
+
+        fs::create_dir_all(stamp.parent().unwrap())?;
+        fs::write(stamp, hash)?;
+        Ok(())
+    }
+
+    fn container_image_exists(&self) -> anyhow::Result<bool> {
+        let runtime = self.config.container_runtime.as_str();
+        let status = Command::new(runtime)
+            .arg("image")
+            .arg("exists")
+            .arg(&self.config.container_image)
+            .status()
+            .with_context(|| {
+                format!(
+                    "failed to inspect container image `{}`",
+                    self.config.container_image
+                )
+            })?;
+        Ok(status.success())
+    }
+
+    fn container_build_hash(&self, dockerfile: &Path) -> anyhow::Result<String> {
+        let mut hasher = Sha256::new();
+        hasher.update(fs::read(dockerfile)?);
+        hasher.update(self.config.container_image.as_bytes());
+        Ok(hex::encode(hasher.finalize()))
+    }
+
+    fn print_plan(&self, plan: &TaskPlan) {
+        if plan.is_empty() {
+            log::skip("plan", "nothing to do");
+            return;
+        }
+
+        log::step(
+            "plan",
+            &format!(
+                "{} active task(s), {} edge(s)",
+                plan.order().len(),
+                plan.dependency_count()
+            ),
+        );
+        for task in plan.order() {
+            println!("{task}");
+        }
+    }
+
+    fn abs_config_path(&self, path: &Path) -> PathBuf {
+        if path.is_absolute() {
+            path.to_path_buf()
+        } else {
+            self.root.join(path)
+        }
+    }
+}

src/cli.rs

@@ -46,6 +46,8 @@ struct BuildCommand {
 enum Command {
     Fetch(FetchCommand),
     Build(BuildCommand),
+    #[command(about = "Create or refresh the configured build container image")]
+    Image,
 }
 
 pub fn run() -> anyhow::Result<()> {
@@ -53,11 +55,23 @@ pub fn run() -> anyhow::Result<()> {
 
     let root_path = cli.root.canonicalize().unwrap_or(cli.root);
     let config = Config::load(&root_path.join("config.star"))?;
-    let lib = eval::eval_lib(&root_path.join("lib"), Some(&config.options))?;
-    let recipes = RecipeSet::load(&root_path, &config.options, lib.as_ref())?;
 
     match cli.command {
-        Command::Fetch { .. } => todo!(),
-        Command::Build { .. } => todo!(),
+        Command::Fetch(command) => {
+            let lib = eval::eval_lib(&root_path.join("lib"), Some(&config.options))?;
+            let recipes = RecipeSet::load(&root_path, &config.options, lib.as_ref())?;
+            let mut builder = Builder::new(root_path, config);
+            builder.fetch(&recipes, &command.recipes, command.dry_run)
+        }
+        Command::Build(command) => {
+            let lib = eval::eval_lib(&root_path.join("lib"), Some(&config.options))?;
+            let recipes = RecipeSet::load(&root_path, &config.options, lib.as_ref())?;
+            let mut builder = Builder::new(root_path, config);
+            builder.build(&recipes, &command.recipes, command.rebuild, command.dry_run)
+        }
+        Command::Image => {
+            let mut builder = Builder::new(root_path, config);
+            builder.ensure_container_ready()
+        }
     }
 }

src/config.rs

@@ -12,14 +12,31 @@ use crate::{
 
 #[derive(Debug)]
 pub enum ContainerRuntime {
+    Docker,
     Podman,
 }
 
+impl ContainerRuntime {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            Self::Docker => "docker",
+            Self::Podman => "podman",
+        }
+    }
+}
+
+impl std::fmt::Display for ContainerRuntime {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(self.as_str())
+    }
+}
+
 impl TryFrom<&str> for ContainerRuntime {
     type Error = anyhow::Error;
 
     fn try_from(value: &str) -> anyhow::Result<Self> {
         match value {
+            "docker" => Ok(Self::Docker),
             "podman" => Ok(Self::Podman),
             _ => anyhow::bail!("invalid runtime: {value}"),
         }

src/graph.rs

@@ -0,0 +1,552 @@
+use std::{
+    collections::{BTreeMap, BTreeSet},
+    fmt, fs,
+    path::{Path, PathBuf},
+};
+
+use anyhow::{Context, bail};
+use sha2::{Digest, Sha256};
+
+use crate::recipe::{OutputPackage, Recipe, RecipeKind, RecipeSet};
+
+#[derive(Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
+pub enum TaskId {
+    FetchSources(String),
+    PrepareSources(String),
+    ConfigureRecipe(String),
+    BuildRecipe(String),
+    InstallPackageFiles(String),
+    ProduceApk(String),
+    InstallHostRecipe(String),
+}
+
+impl fmt::Display for TaskId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::FetchSources(recipe) => write!(f, "fetch sources {recipe}"),
+            Self::PrepareSources(recipe) => write!(f, "prepare sources {recipe}"),
+            Self::ConfigureRecipe(recipe) => write!(f, "configure {recipe}"),
+            Self::BuildRecipe(recipe) => write!(f, "build {recipe}"),
+            Self::InstallPackageFiles(output) => write!(f, "install package files {output}"),
+            Self::ProduceApk(output) => write!(f, "produce apk {output}"),
+            Self::InstallHostRecipe(recipe) => write!(f, "install host recipe {recipe}"),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct TaskPlan {
+    dependencies: BTreeMap<TaskId, Vec<TaskId>>,
+    order: Vec<TaskId>,
+}
+
+impl TaskPlan {
+    pub fn order(&self) -> &[TaskId] {
+        &self.order
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.order.is_empty()
+    }
+
+    pub fn dependency_count(&self) -> usize {
+        self.dependencies.values().map(Vec::len).sum()
+    }
+
+    #[cfg(test)]
+    pub fn dependencies(&self, task: &TaskId) -> Option<&[TaskId]> {
+        self.dependencies.get(task).map(Vec::as_slice)
+    }
+}
+
+pub struct TaskPlanner<'a> {
+    root: &'a Path,
+    arch: &'a str,
+    recipes: &'a RecipeSet,
+    force: bool,
+    dependencies: BTreeMap<TaskId, Vec<TaskId>>,
+    inactive: BTreeSet<TaskId>,
+    visiting: BTreeSet<TaskId>,
+    visited: BTreeSet<TaskId>,
+}
+
+impl<'a> TaskPlanner<'a> {
+    pub fn new(root: &'a Path, arch: &'a str, recipes: &'a RecipeSet) -> Self {
+        Self {
+            root,
+            arch,
+            recipes,
+            force: false,
+            dependencies: BTreeMap::new(),
+            inactive: BTreeSet::new(),
+            visiting: BTreeSet::new(),
+            visited: BTreeSet::new(),
+        }
+    }
+
+    pub fn build_plan(mut self, requests: &[String], force: bool) -> anyhow::Result<TaskPlan> {
+        self.force = force;
+        for request in requests {
+            let recipe = self.recipes.recipe(request)?;
+            match recipe.kind() {
+                RecipeKind::Package => {
+                    for output in recipe.outputs() {
+                        self.visit(TaskId::ProduceApk(output.key()))?;
+                    }
+                }
+                RecipeKind::HostPackage => {
+                    self.visit(TaskId::InstallHostRecipe(recipe.key()))?;
+                }
+            }
+        }
+        self.into_plan()
+    }
+
+    pub fn fetch_plan(mut self, requests: &[String]) -> anyhow::Result<TaskPlan> {
+        for request in requests {
+            let recipe = self.recipes.recipe(request)?;
+            self.visit(TaskId::FetchSources(recipe.key()))?;
+        }
+        self.into_plan()
+    }
+
+    fn visit(&mut self, task: TaskId) -> anyhow::Result<()> {
+        if self.visited.contains(&task) || self.inactive.contains(&task) {
+            return Ok(());
+        }
+        if !self.is_active(&task)? {
+            self.inactive.insert(task);
+            return Ok(());
+        }
+        if !self.visiting.insert(task.clone()) {
+            bail!("task dependency cycle involving `{task}`");
+        }
+
+        let dependencies = self.dependencies(&task)?;
+        let mut active_dependencies = Vec::new();
+        for dependency in dependencies {
+            self.visit(dependency.clone())?;
+            if self.dependencies.contains_key(&dependency) {
+                active_dependencies.push(dependency);
+            }
+        }
+
+        self.visiting.remove(&task);
+        self.visited.insert(task.clone());
+        self.dependencies.insert(task, active_dependencies);
+        Ok(())
+    }
+
+    fn into_plan(self) -> anyhow::Result<TaskPlan> {
+        let mut order = Vec::new();
+        let mut visiting = BTreeSet::new();
+        let mut visited = BTreeSet::new();
+        for task in self.dependencies.keys() {
+            topo_visit(
+                task,
+                &self.dependencies,
+                &mut visiting,
+                &mut visited,
+                &mut order,
+            )?;
+        }
+        Ok(TaskPlan {
+            dependencies: self.dependencies,
+            order,
+        })
+    }
+
+    fn dependencies(&self, task: &TaskId) -> anyhow::Result<Vec<TaskId>> {
+        match task {
+            TaskId::FetchSources(_) => Ok(Vec::new()),
+            TaskId::PrepareSources(recipe) => Ok(vec![TaskId::FetchSources(recipe.clone())]),
+            TaskId::ConfigureRecipe(recipe) => {
+                let recipe = self.recipes.recipe(recipe)?;
+                let mut deps = vec![TaskId::PrepareSources(recipe.key())];
+                deps.extend(
+                    recipe
+                        .host_deps()
+                        .iter()
+                        .map(|dep| TaskId::InstallHostRecipe(RecipeKind::HostPackage.key(dep))),
+                );
+                deps.extend(
+                    recipe
+                        .build_deps()
+                        .iter()
+                        .chain(recipe.deps().iter())
+                        .map(|dep| TaskId::ProduceApk(dep.clone())),
+                );
+                Ok(deps)
+            }
+            TaskId::BuildRecipe(recipe) => Ok(vec![TaskId::ConfigureRecipe(recipe.clone())]),
+            TaskId::InstallPackageFiles(output) => {
+                let output = self.recipes.output(output)?;
+                Ok(vec![TaskId::BuildRecipe(output.recipe().to_owned())])
+            }
+            TaskId::ProduceApk(output) => {
+                let output = self.recipes.output(output)?;
+                let recipe = self.recipes.recipe(output.recipe())?;
+                let mut deps = vec![TaskId::InstallPackageFiles(output.key())];
+                deps.extend(
+                    recipe
+                        .deps()
+                        .iter()
+                        .chain(recipe.run_deps().iter())
+                        .map(|dep| TaskId::ProduceApk(dep.clone())),
+                );
+                Ok(deps)
+            }
+            TaskId::InstallHostRecipe(recipe) => {
+                self.recipes.recipe(recipe)?;
+                Ok(vec![TaskId::BuildRecipe(recipe.clone())])
+            }
+        }
+    }
+
+    fn is_active(&self, task: &TaskId) -> anyhow::Result<bool> {
+        match task {
+            TaskId::FetchSources(recipe) => self.fetch_sources_active(self.recipes.recipe(recipe)?),
+            TaskId::PrepareSources(recipe) => {
+                self.prepare_sources_active(self.recipes.recipe(recipe)?)
+            }
+            TaskId::ConfigureRecipe(recipe) => {
+                self.recipe_task_active(self.recipes.recipe(recipe)?, "configure")
+            }
+            TaskId::BuildRecipe(recipe) => {
+                self.recipe_task_active(self.recipes.recipe(recipe)?, "build")
+            }
+            TaskId::InstallPackageFiles(output) => {
+                let output = self.recipes.output(output)?;
+                let recipe = self.recipes.recipe(output.recipe())?;
+                self.output_task_active(recipe, output, "install")
+            }
+            TaskId::ProduceApk(output) => {
+                let output = self.recipes.output(output)?;
+                let recipe = self.recipes.recipe(output.recipe())?;
+                self.produce_apk_active(recipe, output)
+            }
+            TaskId::InstallHostRecipe(recipe) => {
+                let recipe = self.recipes.recipe(recipe)?;
+                self.install_host_recipe_active(recipe)
+            }
+        }
+    }
+
+    fn fetch_sources_active(&self, recipe: &Recipe) -> anyhow::Result<bool> {
+        Ok(recipe.sources().entries().iter().any(|(_, source)| {
+            source.is_unknown_cache_key() || !self.source_cache_path(source.cache_key()).exists()
+        }))
+    }
+
+    fn prepare_sources_active(&self, recipe: &Recipe) -> anyhow::Result<bool> {
+        if self.force {
+            return Ok(true);
+        }
+        let want_version = format!("{}-r{}", recipe.version(), recipe.revision());
+        if fs::read_to_string(self.source_stamp(recipe, "version"))
+            .ok()
+            .as_deref()
+            != Some(want_version.as_str())
+        {
+            return Ok(true);
+        }
+        if self.recipe_has_patches(recipe)? && !self.source_stamp(recipe, "patched").exists() {
+            return Ok(true);
+        }
+        Ok(false)
+    }
+
+    fn recipe_task_active(&self, recipe: &Recipe, kind: &str) -> anyhow::Result<bool> {
+        if self.force {
+            return Ok(true);
+        }
+        Ok(fs::read_to_string(self.recipe_task_stamp(recipe, kind))
+            .ok()
+            .as_deref()
+            != Some(self.recipe_fingerprint(recipe)?.as_str()))
+    }
+
+    fn output_task_active(
+        &self,
+        recipe: &Recipe,
+        output: &OutputPackage,
+        kind: &str,
+    ) -> anyhow::Result<bool> {
+        if self.force {
+            return Ok(true);
+        }
+        Ok(fs::read_to_string(self.output_task_stamp(output, kind))
+            .ok()
+            .as_deref()
+            != Some(self.output_fingerprint(recipe, output)?.as_str()))
+    }
+
+    fn produce_apk_active(&self, recipe: &Recipe, output: &OutputPackage) -> anyhow::Result<bool> {
+        if self.force {
+            return Ok(true);
+        }
+        if !self.apk_path(recipe, output).exists() {
+            return Ok(true);
+        }
+        Ok(fs::read_to_string(self.output_task_stamp(output, "apk"))
+            .ok()
+            .as_deref()
+            != Some(self.output_fingerprint(recipe, output)?.as_str()))
+    }
+
+    fn install_host_recipe_active(&self, recipe: &Recipe) -> anyhow::Result<bool> {
+        if self.force {
+            return Ok(true);
+        }
+        if !self.host_install_dir(recipe).exists() {
+            return Ok(true);
+        }
+        Ok(
+            fs::read_to_string(self.recipe_task_stamp(recipe, "host-install"))
+                .ok()
+                .as_deref()
+                != Some(self.recipe_fingerprint(recipe)?.as_str()),
+        )
+    }
+
+    fn recipe_fingerprint(&self, recipe: &Recipe) -> anyhow::Result<String> {
+        let mut hasher = Sha256::new();
+        hasher.update(self.arch.as_bytes());
+        hasher.update(recipe.key().as_bytes());
+        hasher.update(recipe.version().as_bytes());
+        hasher.update(recipe.revision().to_le_bytes());
+        hasher.update(
+            fs::read(recipe.path())
+                .with_context(|| format!("reading recipe {}", recipe.path().display()))?,
+        );
+        for (name, source) in recipe.sources().entries() {
+            hasher.update(name.unwrap_or("").as_bytes());
+            hasher.update(source.url().as_bytes());
+            hasher.update(source.cache_key().as_bytes());
+        }
+        for patch in self.recipe_patches(recipe)? {
+            hasher.update(patch.display().to_string().as_bytes());
+            hasher
+                .update(fs::read(&patch).with_context(|| format!("reading {}", patch.display()))?);
+        }
+        Ok(hex::encode(hasher.finalize()))
+    }
+
+    fn output_fingerprint(
+        &self,
+        recipe: &Recipe,
+        output: &OutputPackage,
+    ) -> anyhow::Result<String> {
+        let mut hasher = Sha256::new();
+        hasher.update(self.recipe_fingerprint(recipe)?.as_bytes());
+        hasher.update(output.key().as_bytes());
+        Ok(hex::encode(hasher.finalize()))
+    }
+
+    fn recipe_has_patches(&self, recipe: &Recipe) -> anyhow::Result<bool> {
+        Ok(!self.recipe_patches(recipe)?.is_empty())
+    }
+
+    fn recipe_patches(&self, recipe: &Recipe) -> anyhow::Result<Vec<PathBuf>> {
+        let patches_dir = recipe.dir().join("patches");
+        if !patches_dir.exists() {
+            return Ok(Vec::new());
+        }
+        let mut patches = Vec::new();
+        for entry in fs::read_dir(&patches_dir)
+            .with_context(|| format!("reading patches directory {}", patches_dir.display()))?
+        {
+            let entry = entry?;
+            let path = entry.path();
+            if path.is_file() {
+                patches.push(path);
+            }
+        }
+        patches.sort();
+        Ok(patches)
+    }
+
+    fn source_cache_path(&self, key: &str) -> PathBuf {
+        self.root.join("build/cache/sources").join(key)
+    }
+
+    fn source_stamp(&self, recipe: &Recipe, kind: &str) -> PathBuf {
+        self.root
+            .join("build/sources")
+            .join(format!("{}.{kind}", recipe.slug()))
+    }
+
+    fn recipe_task_stamp(&self, recipe: &Recipe, kind: &str) -> PathBuf {
+        self.root
+            .join("build/tasks")
+            .join(format!("{}.{kind}", recipe.slug()))
+    }
+
+    fn output_task_stamp(&self, output: &OutputPackage, kind: &str) -> PathBuf {
+        self.root
+            .join("build/tasks")
+            .join(format!("{}.{kind}", output.key().replace(':', "-")))
+    }
+
+    fn apk_path(&self, recipe: &Recipe, output: &OutputPackage) -> PathBuf {
+        self.root.join("build/pkgs").join(self.arch).join(format!(
+            "{}-{}-r{}.apk",
+            output.name(),
+            recipe.version(),
+            recipe.revision()
+        ))
+    }
+
+    fn host_install_dir(&self, recipe: &Recipe) -> PathBuf {
+        self.root
+            .join("build/host-pkgs")
+            .join(recipe.slug())
+            .join("usr/local")
+    }
+}
+
+fn topo_visit(
+    task: &TaskId,
+    dependencies: &BTreeMap<TaskId, Vec<TaskId>>,
+    visiting: &mut BTreeSet<TaskId>,
+    visited: &mut BTreeSet<TaskId>,
+    order: &mut Vec<TaskId>,
+) -> anyhow::Result<()> {
+    if visited.contains(task) {
+        return Ok(());
+    }
+    if !visiting.insert(task.clone()) {
+        bail!("task dependency cycle involving `{task}`");
+    }
+    for dependency in dependencies.get(task).into_iter().flatten() {
+        topo_visit(dependency, dependencies, visiting, visited, order)?;
+    }
+    visiting.remove(task);
+    visited.insert(task.clone());
+    order.push(task.clone());
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use std::fs;
+
+    use tempfile::TempDir;
+
+    use crate::{config::Config, eval, recipe::RecipeSet};
+
+    use super::{TaskId, TaskPlanner};
+
+    fn write_config(root: &TempDir) {
+        fs::write(
+            root.path().join("config.star"),
+            r#"
+container_runtime = "podman"
+container_image = "local/test:latest"
+container_dockerfile = "Dockerfile"
+arch = "x86_64"
+options = dict(target_arch = arch)
+"#,
+        )
+        .unwrap();
+        fs::write(root.path().join("Dockerfile"), "FROM scratch\n").unwrap();
+    }
+
+    fn write_recipe(root: &TempDir, dir: &str, name: &str, extra: &str) {
+        let recipe_dir = root.path().join(dir);
+        fs::create_dir_all(&recipe_dir).unwrap();
+        fs::write(
+            recipe_dir.join(format!("{name}.star")),
+            format!(
+                r#"
+version = "1.0"
+revision = 1
+source = tarball_source(url = "file:///tmp/{name}.tar", sha256 = "hash-{name}")
+{extra}
+def build(ctx):
+    ctx.run(["true"])
+def install(ctx, pkg):
+    ctx.run(["true"])
+"#
+            ),
+        )
+        .unwrap();
+    }
+
+    fn load(root: &TempDir) -> (Config, RecipeSet) {
+        let config = Config::load(&root.path().join("config.star")).unwrap();
+        let lib = eval::eval_lib(&root.path().join("lib"), Some(&config.options)).unwrap();
+        let recipes = RecipeSet::load(root.path(), &config.options, lib.as_ref()).unwrap();
+        (config, recipes)
+    }
+
+    #[test]
+    fn inactive_seed_does_not_pull_dependencies() {
+        let root = TempDir::new().unwrap();
+        write_config(&root);
+        write_recipe(&root, "recipes", "dep", "");
+        write_recipe(&root, "recipes", "app", r#"deps = ["dep"]"#);
+        let (config, recipes) = load(&root);
+
+        let planner = TaskPlanner::new(root.path(), &config.arch, &recipes);
+        let output = recipes.output("app").unwrap();
+        let recipe = recipes.recipe(output.recipe()).unwrap();
+        fs::create_dir_all(root.path().join("build/pkgs/x86_64")).unwrap();
+        fs::write(root.path().join("build/pkgs/x86_64/app-1.0-r1.apk"), "").unwrap();
+        fs::create_dir_all(root.path().join("build/tasks")).unwrap();
+        fs::write(
+            root.path().join("build/tasks/app.apk"),
+            planner.output_fingerprint(recipe, output).unwrap(),
+        )
+        .unwrap();
+
+        let plan = TaskPlanner::new(root.path(), &config.arch, &recipes)
+            .build_plan(&["app".to_owned()], false)
+            .unwrap();
+        assert!(plan.is_empty());
+    }
+
+    #[test]
+    fn active_target_recipe_keeps_edges_and_topo_order() {
+        let root = TempDir::new().unwrap();
+        write_config(&root);
+        write_recipe(&root, "recipes", "app", "");
+        let (config, recipes) = load(&root);
+
+        let plan = TaskPlanner::new(root.path(), &config.arch, &recipes)
+            .build_plan(&["app".to_owned()], false)
+            .unwrap();
+        assert_eq!(
+            plan.order(),
+            &[
+                TaskId::FetchSources("app".to_owned()),
+                TaskId::PrepareSources("app".to_owned()),
+                TaskId::ConfigureRecipe("app".to_owned()),
+                TaskId::BuildRecipe("app".to_owned()),
+                TaskId::InstallPackageFiles("app".to_owned()),
+                TaskId::ProduceApk("app".to_owned()),
+            ]
+        );
+        assert_eq!(
+            plan.dependencies(&TaskId::ProduceApk("app".to_owned())),
+            Some([TaskId::InstallPackageFiles("app".to_owned())].as_slice())
+        );
+    }
+
+    #[test]
+    fn host_dependencies_are_installed_as_host_recipes() {
+        let root = TempDir::new().unwrap();
+        write_config(&root);
+        write_recipe(&root, "host-recipes", "binutils", "");
+        write_recipe(&root, "recipes", "app", r#"host_deps = ["binutils"]"#);
+        let (config, recipes) = load(&root);
+
+        let plan = TaskPlanner::new(root.path(), &config.arch, &recipes)
+            .build_plan(&["app".to_owned()], false)
+            .unwrap();
+        assert!(
+            plan.order()
+                .contains(&TaskId::InstallHostRecipe("host:binutils".to_owned()))
+        );
+    }
+}

src/log.rs

@@ -0,0 +1,26 @@
+use std::{io::IsTerminal, sync::LazyLock};
+
+static IS_STDERR_TERMINAL: LazyLock<bool> = LazyLock::new(|| std::io::stderr().is_terminal());
+
+const ARROW: &str = "==>";
+
+fn emit(color: &str, action: &str, details: &str) {
+    if *IS_STDERR_TERMINAL {
+        eprintln!("\x1b[{color}m{ARROW} \x1b[1m{action} \x1b[0m{details}");
+    } else {
+        eprintln!("{ARROW} {action} {details}");
+    }
+}
+
+pub fn step(action: &str, details: &str) {
+    emit("1;34", action, details);
+}
+
+pub fn skip(action: &str, details: &str) {
+    emit("1;33", action, details);
+}
+
+#[allow(dead_code)]
+pub fn info(action: &str, details: &str) {
+    emit("1;32", action, details);
+}

src/main.rs

@@ -2,6 +2,8 @@ mod builder;
 mod cli;
 mod config;
 mod eval;
+mod graph;
+mod log;
 mod options;
 mod recipe;
 

src/recipe/mod.rs

@@ -36,6 +36,10 @@ impl RecipeKind {
             Self::HostPackage => format!("host:{name}"),
         }
     }
+
+    pub fn slug(self, name: &str) -> String {
+        self.key(name).replace(':', "-")
+    }
 }
 
 #[derive(Debug)]
@@ -44,7 +48,25 @@ pub enum Sources {
     Multiple(HashMap<String, source::Source>),
 }
 
+impl Sources {
+    pub fn entries(&self) -> Vec<(Option<&str>, &source::Source)> {
+        match self {
+            Self::Single(source) => vec![(None, source)],
+            Self::Multiple(sources) => {
+                let mut entries = sources
+                    .iter()
+                    .map(|(name, source)| (Some(name.as_str()), source))
+                    .collect::<Vec<_>>();
+                entries.sort_by_key(|(name, _)| *name);
+                entries
+            }
+        }
+    }
+}
+
 pub struct Recipe {
+    /// Recipe name without namespace prefix.
+    name: String,
     /// Path to the recipe's .star file.
     path: PathBuf,
     /// What kind of a recipe is that?
@@ -173,6 +195,7 @@ impl Recipe {
         let phases = RecipePhases::load(&module)?;
 
         Ok(Recipe {
+            name: name.to_owned(),
             path: path.to_path_buf(),
             kind,
             version,
@@ -190,6 +213,58 @@ impl Recipe {
     pub fn phases(&self) -> &RecipePhases {
         &self.phases
     }
+
+    pub fn key(&self) -> String {
+        self.kind.key(&self.name)
+    }
+
+    pub fn slug(&self) -> String {
+        self.kind.slug(&self.name)
+    }
+
+    pub fn dir(&self) -> &Path {
+        self.path.parent().unwrap_or_else(|| Path::new("."))
+    }
+
+    pub fn path(&self) -> &Path {
+        &self.path
+    }
+
+    pub fn kind(&self) -> RecipeKind {
+        self.kind
+    }
+
+    pub fn version(&self) -> &str {
+        &self.version
+    }
+
+    pub fn revision(&self) -> i32 {
+        self.revision
+    }
+
+    pub fn sources(&self) -> &Sources {
+        &self.sources
+    }
+
+    pub fn outputs(&self) -> &[OutputPackage] {
+        &self.outputs
+    }
+
+    pub fn host_deps(&self) -> &[String] {
+        &self.host_deps
+    }
+
+    pub fn build_deps(&self) -> &[String] {
+        &self.build_deps
+    }
+
+    pub fn deps(&self) -> &[String] {
+        &self.deps
+    }
+
+    pub fn run_deps(&self) -> &[String] {
+        &self.run_deps
+    }
 }
 
 fn optional_string_list(module: &Module, key: &str) -> anyhow::Result<Vec<String>> {
@@ -281,6 +356,20 @@ pub struct OutputPackage {
     metadata: Metadata,
 }
 
+impl OutputPackage {
+    pub fn key(&self) -> String {
+        self.name.clone()
+    }
+
+    pub fn recipe(&self) -> &str {
+        &self.recipe
+    }
+
+    pub fn name(&self) -> &str {
+        &self.name
+    }
+}
+
 #[derive(Debug)]
 pub struct RecipeSet {
     recipes: HashMap<String, Recipe>,
@@ -329,6 +418,18 @@ impl RecipeSet {
 
         Ok(Self { recipes, outputs })
     }
+
+    pub fn recipe(&self, key: &str) -> anyhow::Result<&Recipe> {
+        self.recipes
+            .get(key)
+            .ok_or_else(|| anyhow::anyhow!("unknown recipe `{key}`"))
+    }
+
+    pub fn output(&self, key: &str) -> anyhow::Result<&OutputPackage> {
+        self.outputs
+            .get(key)
+            .ok_or_else(|| anyhow::anyhow!("unknown output package `{key}`"))
+    }
 }
 
 /// Find all recipe `.star` files under `dir`, returning a map of recipe name

src/recipe/source.rs

@@ -89,3 +89,23 @@ starlark::starlark_simple_value!(Source);
 
 #[starlark_value(type = "source")]
 impl<'v> StarlarkValue<'v> for Source {}
+
+impl Source {
+    pub fn url(&self) -> &str {
+        match self {
+            Self::Tarball(source) => source.url(),
+            Self::Git(source) => source.url(),
+        }
+    }
+
+    pub fn cache_key(&self) -> &str {
+        match self {
+            Self::Tarball(source) => source.sha256(),
+            Self::Git(source) => source.commit(),
+        }
+    }
+
+    pub fn is_unknown_cache_key(&self) -> bool {
+        matches!(self.cache_key(), "?" | "???")
+    }
+}