nonlinux runtime start

build.zig

@@ -1,4 +1,7 @@
 const std = @import("std");
+const crun_content = @embedFile("src/tools/crun");
+
+
 
 // Although this function looks imperative, note that its job is to
 // declaratively construct a build graph that will be executed by an external
@@ -18,7 +21,6 @@ pub fn build(b: *std.Build) void {
     // set a preferred release mode, allowing the user to decide how to optimize.
     const optimize = b.standardOptimizeOption(.{});
 
-    // const clap = b.addModule("clap", .{ .root_source_file = .{ .path = "lib/zig-clap/clap.zig" } });
 
     const runtime = b.addExecutable(.{
         .name = "runtime",
@@ -26,8 +28,6 @@ pub fn build(b: *std.Build) void {
         .target = target,
         .optimize = optimize,
         .link_libc = true,
-        // necessary to link in bigger file
-        // .code_model = .medium,
     });
 
     const dockerc = b.addExecutable(.{
@@ -38,35 +38,35 @@ pub fn build(b: *std.Build) void {
         .link_libc = true,
     });
 
+    const init = b.addExecutable(.{
+        .name = "init",
+        .root_source_file = .{ .path = "src/init.zig" },
+        .target = target,
+        .optimize = optimize,
+        // for std.c.environ
+        .link_libc = true,
+    });
+
+    const cpio = b.addWriteFiles();
+    _ = cpio.addCopyFile(init.getEmittedBin(), "init");
+    _ = cpio.add("etc/resolv.conf", "nameserver 1.1.1.1\n");
+    _ = cpio.add("crun", crun_content);
+
+    const mkdir = b.addSystemCommand(&.{"mkdir", "dev", "bundle", "mnt", "proc", "run", "sys", "tmp"});
+    mkdir.setCwd(cpio.getDirectory());
+
+    const findCommand = b.addSystemCommand(&.{"find", ".", "-print0"});
+    findCommand.setCwd(cpio.getDirectory());
+    findCommand.step.dependOn(&mkdir.step);
+
+    const cpioCommand = b.addSystemCommand(&.{"cpio", "--null", "-ov", "--format=newc"});
+    cpioCommand.setCwd(cpio.getDirectory());
+    cpioCommand.setStdIn(.{.lazy_path=findCommand.captureStdOut()});
+
+
     dockerc.root_module.addAnonymousImport("runtime", .{ .root_source_file = runtime.getEmittedBin() });
+    dockerc.root_module.addAnonymousImport("cpio", .{ .root_source_file = cpioCommand.captureStdOut() });
 
     b.installArtifact(dockerc);
-
-    // This declares intent for the executable to be installed into the
-    // standard location when the user invokes the "install" step (the default
-    // step when running `zig build`).
-    // b.installArtifact(exe);
-
-    // This *creates* a Run step in the build graph, to be executed when another
-    // step is evaluated that depends on it. The next line below will establish
-    // such a dependency.
-    // const run_cmd = b.addRunArtifact(exe);
-
-    // By making the run step depend on the install step, it will be run from the
-    // installation directory rather than directly from within the cache directory.
-    // This is not necessary, however, if the application depends on other installed
-    // files, this ensures they will be present and in the expected location.
-    // run_cmd.step.dependOn(b.getInstallStep());
-
-    // This allows the user to pass arguments to the application in the build
-    // command itself, like this: `zig build run -- arg1 arg2 etc`
-    // if (b.args) |args| {
-    //     run_cmd.addArgs(args);
-    // }
-
-    // This creates a build step. It will be visible in the `zig build --help` menu,
-    // and can be selected like this: `zig build run`
-    // This will evaluate the `run` step rather than the default, which is "install".
-    // const run_step = b.step("run", "Run the app");
-    // run_step.dependOn(&run_cmd.step);
+    b.installArtifact(init);
 }

src/init.zig

@@ -0,0 +1,24 @@
+const std = @import("std");
+
+pub fn main() !void {
+    // TODO: check the return value of mount
+
+    _ = std.posix.linux.mount("proc", "/proc", "proc", 0, 0);
+    _ = std.posix.linux.mount("sysfs", "/sys", "sysfs", 0, 0);
+    _ = std.posix.linux.mount("cgroup2", "/sys/fs/cgroup", "cgroup2", 0, 0);
+    _ = std.posix.linux.mount("tmpfs", "/run", "tmpfs", 0, 0);
+
+    try std.fs.makeDirAbsolute("/run/upper");
+    try std.fs.makeDirAbsolute("/run/work");
+
+    _ = std.posix.linux.mount("dev", "/dev", "devtmpfs", 0, 0);
+    _ = std.posix.linux.mount("/dev/sda", "/bundle", "squashfs", std.posix.linux.MS.RDONLY, 0);
+    _ = std.posix.linux.mount("overlay", "/mnt", "overlay", std.posix.linux.MS.RDONLY, @intFromPtr("lowerdir=/bundle,upperdir=/run/upper,workdir=/run/work"));
+
+    const argv = &[_:null]?[*:0]const u8{
+        "/crun", "run", "-b", "/mnt", "--no-pivot", "crun_docker_c_id", null,
+    };
+
+    // TODO: make sure this never returns
+    _ = std.posix.linux.execve("/crun", argv, std.c.environ);
+}

src/nonlinux_runtime.zig

@@ -0,0 +1,5 @@
+
+
+pub fn main() !void {
+
+}