Updated comments

README.md

@@ -1,52 +1,14 @@
-This is a starting point for Rust solutions to the
-["Build Your Own Docker" Challenge](https://codecrafters.io/challenges/docker).
+# codecrafters-docker-rust
+My code for CodeCrafter's ["Build Your Own Docker" Challenge](https://codecrafters.io/challenges/docker).
 
-In this challenge, you'll build a program that can pull an image from
-[Docker Hub](https://hub.docker.com/) and execute commands in it. Along the way,
-we'll learn about [chroot](https://en.wikipedia.org/wiki/Chroot),
-[kernel namespaces](https://en.wikipedia.org/wiki/Linux_namespaces), the
-[docker registry API](https://docs.docker.com/registry/spec/api/) and much more.
-
-**Note**: If you're viewing this repo on GitHub, head over to
-[codecrafters.io](https://codecrafters.io) to signup for early access.
-
-# Passing the first stage
-
-The entry point for your Docker implementation is `src/main.rs`. Study and
-uncomment the relevant code, and push your changes to pass the first stage:
-
-```sh
-git add .
-git commit -m "pass 1st stage" # any msg
-git push origin master
-```
-
-That's all!
-
-# Stage 2 & beyond
-
-Note: This section is for stages 2 and beyond.
-
-You'll use linux-specific syscalls in this challenge. so we'll run your code
-_inside_ a Docker container.
-
-Please ensure you have [Docker installed](https://docs.docker.com/get-docker/)
-locally.
-
-Next, add a [shell alias](https://shapeshed.com/unix-alias/):
+## Requirements
+- docker
 
+## Getting started
 ```sh
 alias mydocker='docker build -t mydocker . && docker run --cap-add="SYS_ADMIN" mydocker'
+mydocker run debian:latest /bin/sh -c "ls -la /"
 ```
 
-(The `--cap-add="SYS_ADMIN"` flag is required to create
-[PID Namespaces](https://man7.org/linux/man-pages/man7/pid_namespaces.7.html))
-
-You can now execute your program like this:
-
-```sh
-mydocker run ubuntu:latest /usr/local/bin/docker-explorer echo hey
-```
-
-This command compiles your Rust project, so it might be slow the first time you
-run it. Subsequent runs will be fast.
+Note: The `--cap-add="SYS_ADMIN"` flag is required to create
+[PID Namespaces](https://man7.org/linux/man-pages/man7/pid_namespaces.7.html)

src/main.rs

@@ -9,7 +9,7 @@ fn main() {
     let command = &args[3];
     let command_args = &args[4..];
 
-    let base_path = std::env::temp_dir().join("mydocker");
+    let base_path = std::env::temp_dir().join("docker");
 
     // prevent cryptic "no such file or directory" error inside chroot
     std::fs::create_dir_all(base_path.join("dev")).unwrap();
@@ -19,14 +19,14 @@ fn main() {
     let mut reg = registry::Registry::default();
     reg.pull(&image, base_path.to_str().unwrap());
 
-    // copy over binary into chroot
+    // copy over binary into chroot directory
     let command_path = path::Path::new(command).strip_prefix("/").unwrap();
     std::fs::create_dir_all(base_path.join(command_path.parent().unwrap()))
         .expect("Failed to create directory for executed binary");
     std::fs::copy(command, base_path.join(command_path))
         .expect("Failed copying executed binary to chroot directory");
 
-    // create and change into chroot
+    // create and change into chroot directory
     let cbase_path = CString::new(base_path.to_str().unwrap().to_owned()).unwrap();
     unsafe {
         libc::chroot(cbase_path.as_ptr());
@@ -35,6 +35,7 @@ fn main() {
     // ensure that directory changed to root of jail
     std::env::set_current_dir("/").expect("Failed to change to root dir");
 
+    // `unshare` puts the next created process in a seperate PID namespace
     unsafe {
         libc::unshare(libc::CLONE_NEWPID);
     }
@@ -44,10 +45,8 @@ fn main() {
         .output()
         .unwrap();
 
-    let std_out = std::str::from_utf8(&output.stdout).unwrap();
-    print!("{}", std_out);
-    let std_err = std::str::from_utf8(&output.stderr).unwrap();
-    eprint!("{}", std_err);
+    print!("{}", std::str::from_utf8(&output.stdout).unwrap());
+    eprint!("{}", std::str::from_utf8(&output.stderr).unwrap());
 
     std::process::exit(output.status.code().unwrap_or(1));
 }

src/registry.rs

@@ -1,4 +1,4 @@
-// TODO: Enable derive feature
+// TODO: Enable derive feature and convert dynamic to typed json
 
 pub struct Registry {
     http_client: reqwest::blocking::Client,
@@ -60,7 +60,7 @@ impl Registry {
             let layer_path = temp_path.join(digest);
             std::fs::write(layer_path.to_owned(), blob).unwrap();
 
-            // TODO: handle exit code of untar
+            // TODO: handle exit code
             std::process::Command::new("tar")
                 .args(["-xf", layer_path.to_str().unwrap(), "-C", destination])
                 .output()