doos 0.1.0: user-level overlayfs containers with slirp networking

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/container.hpp

@@ -0,0 +1,67 @@
+#pragma once
+#include <sys/types.h>
+
+#include <filesystem>
+#include <optional>
+#include <string>
+#include <vector>
+
+#include "network.hpp"
+
+namespace doos {
+
+class Container {
+public:
+    Container(std::filesystem::path dir, std::string name) : dir_(std::move(dir)), name_(std::move(name)) {}
+
+    static void validateName(const std::string& name);
+
+    const std::string& name() const { return name_; }
+    const std::filesystem::path& dir() const { return dir_; }
+    std::filesystem::path rootfs() const { return dir_ / "rootfs"; }
+    std::filesystem::path layer(const std::string& hostDir) const;  // layers/<name>/{upper,work}
+    std::filesystem::path privateDir(const std::string& hostDir) const;
+    std::filesystem::path lockFile() const { return dir_ / "lock"; }
+    std::filesystem::path pidFile() const { return dir_ / "pid"; }
+    std::filesystem::path metaFile() const { return dir_ / "meta"; }
+
+    NetMode net() const { return net_; }
+    long created() const { return created_; }
+
+    void create(NetMode net);  // writes layout and meta
+    void load();               // reads meta
+
+    // Process id (outside view) of the container's init, if it is alive.
+    std::optional<pid_t> runningPid() const;
+    void recordPid(pid_t pid) const;
+    void clearPid() const;
+
+    // Creates the (empty) mountpoint skeleton and layer dirs. Idempotent.
+    void prepareLayout() const;
+
+private:
+    std::filesystem::path dir_;
+    std::string name_;
+    NetMode net_ = NetMode::Slirp;
+    long created_ = 0;
+};
+
+class Store {
+public:
+    explicit Store(std::filesystem::path root);
+    static Store fromEnvironment();
+
+    std::vector<Container> list() const;
+    // Returns the container and whether it was created by this call.
+    std::pair<Container, bool> getOrCreate(const std::string& name, std::optional<NetMode> net);
+    // Dry-run unless confirmed. Returns a human-readable report line.
+    std::string remove(const std::string& name, bool confirmed);
+
+    const std::filesystem::path& root() const { return root_; }
+
+private:
+    std::filesystem::path containersDir() const { return root_ / "containers"; }
+    std::filesystem::path root_;
+};
+
+}  // namespace doos