git-hardening/.crosslink/rules/rust.md

Rust Best Practices

Code Style

• Use rustfmt for formatting (run cargo fmt before committing)
• Use clippy for linting (run cargo clippy -- -D warnings)
• Prefer ? operator over .unwrap() for error handling
• Use anyhow::Result for application errors, thiserror for library errors
• Avoid .clone() unless necessary - prefer references
• Use &str for function parameters, String for owned data

Error Handling

// GOOD: Propagate errors with context
fn read_config(path: &Path) -> Result<Config> {
    let content = fs::read_to_string(path)
        .context("Failed to read config file")?;
    serde_json::from_str(&content)
        .context("Failed to parse config")
}

// BAD: Panic on error
fn read_config(path: &Path) -> Config {
    let content = fs::read_to_string(path).unwrap();  // Don't do this
    serde_json::from_str(&content).unwrap()
}

Memory Safety

• Never use unsafe without explicit justification and review
• Prefer Vec over raw pointers
• Use Arc<Mutex<T>> for shared mutable state across threads
• Avoid static mut - use lazy_static or once_cell instead

Testing

• Write unit tests with #[cfg(test)] modules
• Use tempfile for tests involving filesystem
• Run cargo test before committing
• Use cargo tarpaulin for coverage reports

SQL Injection Prevention

Always use parameterized queries with rusqlite::params![]:

// GOOD
conn.execute("INSERT INTO users (name) VALUES (?1)", params![name])?;

// BAD - SQL injection vulnerability
conn.execute(&format!("INSERT INTO users (name) VALUES ('{}')", name), [])?;