Invoke NPM only if the global installation dir is in the home directory (fix #21)

src/main.rs

@@ -6,6 +6,7 @@ extern crate termion;
 
 mod git;
 mod linux;
+mod npm;
 mod report;
 mod steps;
 mod terminal;
@@ -16,7 +17,7 @@ use git::Git;
 use report::{Report, Reporter};
 use std::collections::HashSet;
 use std::env::home_dir;
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use std::process::ExitStatus;
 use steps::*;
 use terminal::Terminal;
@@ -46,6 +47,19 @@ fn home_path(p: &str) -> PathBuf {
     path
 }
 
+fn is_ancestor(ancestor: &Path, path: &Path) -> bool {
+    let mut p = path;
+    while let Some(parent) = p.parent() {
+        if parent == ancestor {
+            return true;
+        }
+
+        p = parent;
+    }
+
+    false
+}
+
 #[cfg(unix)]
 fn tpm() -> Option<PathBuf> {
     let mut path = home_dir().unwrap();
@@ -129,9 +143,13 @@ fn main() -> Result<(), Error> {
         }
     }
 
-    if let Ok(npm) = which("npm") {
-        terminal.print_separator("Node Package Manager");
-        run_npm(&npm).report("Node Package Manager", &mut reports);
+    if let Ok(npm) = which("npm").map(npm::NPM::new) {
+        if let Ok(npm_root) = npm.root() {
+            if is_ancestor(&home_dir().unwrap(), &npm_root) {
+                terminal.print_separator("Node Package Manager");
+                npm.upgrade().report("Node Package Manager", &mut reports);
+            }
+        }
     }
 
     if let Ok(apm) = which("apm") {

src/npm.rs

@@ -0,0 +1,32 @@
+use super::Check;
+use failure;
+use std::path::PathBuf;
+use std::process::Command;
+
+pub struct NPM {
+    command: PathBuf,
+}
+
+impl NPM {
+    pub fn new(command: PathBuf) -> Self {
+        Self { command }
+    }
+
+    pub fn root(&self) -> Result<PathBuf, failure::Error> {
+        let output = Command::new(&self.command).args(&["root", "-g"]).output()?;
+
+        output.status.check()?;
+
+        Ok(PathBuf::from(&String::from_utf8(output.stdout)?))
+    }
+
+    pub fn upgrade(&self) -> Result<(), failure::Error> {
+        Command::new(&self.command)
+            .args(&["update", "-g"])
+            .spawn()?
+            .wait()?
+            .check()?;
+
+        Ok(())
+    }
+}

src/steps.rs

@@ -73,16 +73,6 @@ pub fn run_vim(
     Ok(())
 }
 
-pub fn run_npm(npm: &PathBuf) -> Result<(), failure::Error> {
-    Command::new(&npm)
-        .args(&["update", "-g"])
-        .spawn()?
-        .wait()?
-        .check()?;
-
-    Ok(())
-}
-
 pub fn run_apm(apm: &PathBuf) -> Result<(), failure::Error> {
     Command::new(&apm)
         .args(&["upgrade", "--confirm=false"])