feat: add the env command

coreutils/src/commands/env.rs

@@ -0,0 +1,78 @@
+use boxutils::args::ArgParser;
+use boxutils::commands::Command;
+
+// note(teesh): this command uses technically unsafe stuff,
+//
+//              HOWEVER: the rust docs state that if you are
+//              running the things we're doing on a single-threaded
+//              application (which rebox, and env are), then you
+//              are fine!
+
+pub struct Env;
+
+impl Env {
+    pub fn clean_unwanted(to_clean: Vec<String>) {
+        for var in to_clean {
+            unsafe {
+                std::env::remove_var(var);
+            }
+        }
+    }
+
+    pub fn maybe_clean_env(maybe: bool) {
+        if !maybe {
+            return;
+        }
+
+        Env::clean_unwanted(std::env::vars().map(|(x, _)| x).collect());
+    }
+
+    pub fn print_all_vars() {
+        for (k, v) in std::env::vars() {
+            println!("{}={}", k, v);
+        }
+    }
+}
+
+impl Command for Env {
+    fn execute(&self) {
+        let args = ArgParser::builder()
+            .add_flag("-i")
+            .add_flag("-0")
+            .add_option_list("-u")
+            .set_seperator("--")
+            .parse_args("env");
+
+        let remove_from_env: Vec<String> = args
+            .get_option_list("-u")
+            .unwrap_or_default()
+            .iter()
+            .map(|a| a.to_string())
+            .collect();
+        let null_terminate = args.get_flag("-0");
+        let clean_env = args.get_flag("-i") | args.get_flag("-");
+        let to_run = args.get_normal_args();
+
+        Env::clean_unwanted(remove_from_env);
+        Env::maybe_clean_env(clean_env);
+
+        if to_run.is_empty() {
+            Env::print_all_vars();
+
+            return;
+        }
+
+        if let Some((command, args)) = to_run.split_first() {
+            std::process::Command::new(command)
+                .args(args)
+                .spawn()
+                .expect("env: failed to start command")
+                .wait()
+                .expect("env: could not wait for command");
+        }
+
+        if null_terminate {
+            print!("\0");
+        }
+    }
+}

coreutils/src/commands/mod.rs

@@ -23,3 +23,4 @@ command!(tee::Tee);
 command!(base64::Base64);
 command!(base32::Base32);
 command!(seq::Seq);
+command!(env::Env);

src/registry.rs

@@ -33,6 +33,7 @@ pub fn get_registry() -> CommandRegistry {
         "base64" => coreutils::commands::Base64,
         "base32" => coreutils::commands::Base32,
         "seq" => coreutils::commands::Seq,
+        "env" => coreutils::commands::Env,
         "box" => Boxcmd
     });