Fix Libc.getpwuid usage and use addenv for environment variables

- Fix Libc.getpwuid to use UInt conversion for the uid parameter
- Use addenv instead of command interpolation for setting PATH and HOME
- Properly retrieve user home directory from Libc.Passwd object

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: Keno

src/tools/bash.jl

@@ -4,23 +4,17 @@ Bash command execution tool for MCP
 
 # Helper function to get user's home directory using getpwuid
 function get_user_home(uid::Int)
-    # Use Libc.getpwuid to get user info
-    passwd = Libc.getpwuid(uid)
+    # Use Libc.getpwuid to get user info - it returns a Libc.Passwd object or nothing
+    # Convert to UInt as getpwuid expects unsigned
+    passwd_info = Libc.getpwuid(UInt(uid))
 
-    if passwd == C_NULL
+    if passwd_info === nothing
         # Failed to get user info, return nothing
         return nothing
     end
 
-    # Extract home directory from the passwd struct
-    # The Libc.Passwd struct has the homedir field
-    pwd = unsafe_load(passwd)
-    
-    if pwd.homedir == C_NULL
-        return nothing
-    end
-    
-    return unsafe_string(pwd.homedir)
+    # Libc.getpwuid returns a Libc.Passwd object with homedir field already as a string
+    return passwd_info.homedir
 end
 
 mutable struct BashTool <: MCPTool
@@ -78,19 +72,24 @@ function execute(tool::BashTool, params::Dict)
             # Get target user's home directory
             user_home = get_user_home(tool.uid)
 
-            # Build environment variables to set
-            env_vars = ["PATH=$current_path"]
+            # Build the sudo command
+            # -E: preserve environment variables (but PATH and HOME are still reset by sudo)
+            # -u #uid: run as the specified UID (# prefix tells sudo it's a UID not username)
+            # sh -c: use shell to run the command
+            cmd = Cmd(`sudo -E -u "#$(tool.uid)" sh -c $command`, ignorestatus=true, dir=tool.working_dir)
+            
+            # Add environment variables that sudo resets
+            # Since sudo passes through -E, we can use addenv to set them
+            env_dict = Dict{String,String}()
+            env_dict["PATH"] = current_path
             if user_home !== nothing
-                push!(env_vars, "HOME=$user_home")
+                env_dict["HOME"] = user_home
             end
-            env_str = join(env_vars, " ")
 
-            # Use sudo to switch to the specified uid
-            # -E: preserve environment variables (but PATH and HOME are still reset by sudo)
-            # -u #uid: run as the specified UID (# prefix tells sudo it's a UID not username)
-            # env PATH=... HOME=...: explicitly restore PATH and HOME inside sudo
-            # Note: This requires the process to have appropriate permissions
-            cmd = Cmd(`sudo -E -u "#$(tool.uid)" env $env_str sh -c $command`, ignorestatus=true, dir=tool.working_dir)
+            # Apply environment variables
+            if !isempty(env_dict)
+                cmd = addenv(cmd, env_dict)
+            end
         else
             # Use Cmd with ignorestatus to capture all output regardless of exit code
             cmd = Cmd(`sh -c $command`, ignorestatus=true, dir=tool.working_dir)