3 files changed, 44 insertions, 9 deletions

diff --git a/src/action.rs b/src/action.rs
index 1aeefb6..58effbe 100644
--- a/src/action.rs
+++ b/src/action.rs
@@ -1,5 +1,5 @@
 use crate::config::{self, ConfigCommand, TEMP_CONFIG_PATH, create_config};
-use crate::util::{dir_size, get_editor, is_root, open_in_editor, yn_prompt};
+use crate::util::{dir_size, get_editor, open_in_editor, yn_prompt};
 use git2::Repository;
 use std::fs;
 use std::path::{Path, PathBuf};
@@ -76,7 +76,7 @@ impl Action {
 }
 
 fn add(url: &str) -> Result<(), String> {
-    if !is_root() {
+    if !nix::unistd::geteuid().is_root() {
         return Err("add must be run as root".to_string());
     }
 
@@ -138,7 +138,7 @@ fn autoremove() {
 }
 
 fn remove(packages: Vec<String>) -> Result<(), String> {
-    if !is_root() {
+    if !nix::unistd::geteuid().is_root() {
         return Err("remove must be run as root".to_string());
     }
 
diff --git a/src/config.rs b/src/config.rs
index 7c6cf2b..4976af3 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -1,8 +1,11 @@
 use serde::Deserialize;
 use std::fs;
+use std::os::unix::process::CommandExt;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
+use crate::util::get_invoking_user_env;
+
 pub const TEMP_CONFIG_PATH: &str = "/var/lib/forge/.tmp";
 
 pub enum ConfigCommand {
@@ -66,6 +69,9 @@ pub fn run_config_command(
     command: ConfigCommand,
 ) -> Result<(), String> {
     let config = Config::new(config_path).ok_or("config not found".to_string())?;
+
+    let is_build = matches!(command, ConfigCommand::Build);
+
     let cmd = match command {
         ConfigCommand::Build => config.build,
         ConfigCommand::Install => config.install,
@@ -77,9 +83,23 @@ pub fn run_config_command(
         let cmd_base = parts.next().ok_or("empty command".to_string())?;
         let args: Vec<&str> = parts.collect();
 
-        let status = Command::new(cmd_base)
-            .args(&args)
-            .current_dir(repo_path)
+        let mut command = Command::new(cmd_base);
+        command.args(&args).current_dir(repo_path);
+
+        if is_build {
+            if let Some((uid, gid, home, path)) = get_invoking_user_env() {
+                command.env("HOME", home).env("PATH", path);
+                unsafe {
+                    command.pre_exec(move || {
+                        nix::unistd::setgid(nix::unistd::Gid::from_raw(gid))?;
+                        nix::unistd::setuid(nix::unistd::Uid::from_raw(uid))?;
+                        Ok(())
+                    });
+                }
+            }
+        }
+
+        let status = command
             .status()
             .map_err(|e| format!("failed to execute command: {}", e))?;
 
diff --git a/src/util.rs b/src/util.rs
index 90aacb6..e79124d 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -1,4 +1,3 @@
-use libc;
 use std::env;
 use std::fs;
 use std::io;
@@ -28,8 +27,24 @@ pub fn get_editor() -> String {
         .unwrap_or_else(|_| "nano".to_string())
 }
 
-pub fn is_root() -> bool {
-    unsafe { libc::geteuid() == 0 }
+pub fn get_invoking_user_env() -> Option<(u32, u32, String, String)> {
+    let username = std::env::var("SUDO_USER").ok()?;
+    if username.is_empty() {
+        return None;
+    }
+
+    let user = nix::unistd::User::from_name(&username).ok()??;
+    let uid = user.uid.as_raw();
+    let gid = user.gid.as_raw();
+    let home = user.dir.to_string_lossy().to_string();
+
+    // Reconstruct a sane PATH for the user including common tool locations
+    let path = format!(
+        "{home}/.cargo/bin:{home}/.local/bin:/usr/local/bin:/usr/bin:/bin",
+        home = home
+    );
+
+    Some((uid, gid, home, path))
 }
 
 pub fn open_in_editor(editor: &str, file: &str) -> Result<(), String> {