Implement getUserInfo function to read environment variables

[f0ssel]

Summary

Implemented the getUserInfo() function in the CLI package to read environment variables and populate the UserInfo struct with appropriate user information for both sudo and non-sudo scenarios. This centralizes environment variable access and provides the data needed for proper user context handling throughout the application.

Implementation Details

Core Functions Added

• getUserInfo() - Main function that detects sudo usage and returns appropriate UserInfo
• getCurrentUserInfo() - Helper function for non-sudo scenarios
• getConfigDir(homeDir) - Helper function for config directory logic with XDG support

Environment Variables Handled

• SUDO_USER - Detects if running under sudo and gets original username
• SUDO_UID - Original user ID (parsed to integer)
• SUDO_GID - Original group ID (parsed to integer)
• XDG_CONFIG_HOME - XDG config directory path for proper config location

UserInfo Struct Population

The function properly populates all UserInfo fields:

type UserInfo struct {
    Username  string  // Original user or current user
    Uid       int     // Parsed integer UID  
    Gid       int     // Parsed integer GID
    HomeDir   string  // User's home directory
    ConfigDir string  // XDG_CONFIG_HOME/coder_jail or ~/.config/coder_jail
}

Key Features

Sudo Detection & Handling

• ✅ Automatic sudo detection via SUDO_USER environment variable
• ✅ Original user lookup when running under sudo
• ✅ Proper credential parsing from SUDO_UID and SUDO_GID
• ✅ Graceful fallbacks when user lookup fails

Configuration Directory Logic

• ✅ XDG Base Directory support - Uses XDG_CONFIG_HOME when available
• ✅ Standard fallback - Falls back to ~/.config/coder_jail
• ✅ Cross-platform compatibility - Works on both Linux and macOS

Error Handling

• ✅ Comprehensive error handling with graceful fallbacks
• ✅ No panics - All errors handled gracefully
• ✅ Fallback to current user when sudo user lookup fails

Code Cleanup

Removed all commented environment variable code that was no longer needed:

• namespace/linux.go - Removed 36+ lines of commented sudo handling code
• namespace/macos.go - Removed 26+ lines of commented sudo handling code
• tls/tls.go - Removed entire commented getConfigDir() function (37+ lines)

Testing

• ✅ All existing tests pass
• ✅ Code compiles successfully on all platforms
• ✅ No breaking changes to external interfaces
• ✅ Environment variables centralized in CLI package only

Benefits

• 🏗️ Better Architecture: Environment variable access centralized in CLI package
• 🧪 Improved Testability: User information can be easily mocked for testing
• 🔒 Security: Proper handling of sudo context and user credentials
• ⚡ Performance: No redundant environment variable reads
• 🛠️ Maintainability: Clean, well-documented code with proper error handling
• 🌐 Cross-platform: Works consistently across Linux and macOS

Usage

The getUserInfo() function is called once during CLI initialization and provides the user context needed by:

• TLS certificate management (for config directory)
• Namespace setup (for user credentials)
• Environment variable restoration (for original user context)