Some small fixes

src/symbols/npm.rs

@@ -13,7 +13,7 @@ pub struct Install<'a, T: AsRef<Path>, C: CommandRunner> {
 
 impl<'a, T: AsRef<Path>, C: CommandRunner> Install<'a, T, C> {
   pub fn new(target: T, command_runner: &'a C) -> Self {
-    Install {
+    Self {
       target,
       command_runner,
     }
@@ -36,9 +36,9 @@ impl<T: AsRef<Path>, C: CommandRunner> Symbol for Install<'_, T, C> {
     if !self.target.as_ref().exists() {
       return Ok(false);
     }
-    let output = self
+    let result = self
       .command_runner
-      .get_output(
+      .run_with_args(
         "sh",
         args![
           "-c",
@@ -46,7 +46,12 @@ impl<T: AsRef<Path>, C: CommandRunner> Symbol for Install<'_, T, C> {
         ],
       )
       .await?;
-    Ok(!String::from_utf8(output).unwrap().contains("(empty)"))
+    Ok(
+      result.status.success()
+        && !String::from_utf8(result.stdout)
+          .unwrap()
+          .contains("(empty)"),
+    )
   }
 
   async fn execute(&self) -> Result<(), Box<dyn Error>> {

src/symbols/user.rs

@@ -1,7 +1,12 @@
 use crate::command_runner::CommandRunner;
 use crate::symbols::Symbol;
 use async_trait::async_trait;
+use once_cell::sync::Lazy;
 use std::error::Error;
+use tokio::sync::Semaphore;
+
+pub type Wait = Lazy<Semaphore>;
+static WAIT: Wait = Lazy::new(|| Semaphore::new(1));
 
 #[derive(Debug)]
 pub struct User<U, C> {
@@ -33,6 +38,9 @@ impl<U: AsRef<str>, C: CommandRunner> Symbol for User<U, C> {
   }
 
   async fn execute(&self) -> Result<(), Box<dyn Error>> {
+    // adduser is not reentrant because finding the next uid
+    // and creating the account is not an atomic operation
+    let wait = WAIT.acquire().await;
     self
       .command_runner
       .run_successfully(