zoi-core 1.26.0

/// Manages the "Sysroot" (System Root) for Zoi operations.
///
/// A Sysroot allows Zoi to operate on an external directory as if it were
/// the primary system root (`/`). This is a powerful feature for:
/// - Bootstrapping: Creating a bootable OS image or container from the
///   outside.
/// - Cross-Installation: Installing packages for an embedded system or
///   another partition.
/// - Isolation: Testing installations without affecting the current host
///   system.
///
/// When a sysroot is set, Zoi transparently redirects all absolute and
/// relative paths to reside within this target directory.
use std::path::{Component, PathBuf};
use std::sync::{OnceLock, RwLock};

/// Provides thread-safe access to the optional global sysroot path.
fn sysroot_store() -> &'static RwLock<Option<PathBuf>> {
    static SYSROOT: OnceLock<RwLock<Option<PathBuf>>> = OnceLock::new();
    SYSROOT.get_or_init(|| RwLock::new(None))
}

/// Sets or replaces the global sysroot path.
pub fn set_sysroot(path: PathBuf) {
    if let Ok(mut guard) = sysroot_store().write() {
        *guard = Some(path);
    }
}

/// Clears the global sysroot path.
pub fn clear_sysroot() {
    if let Ok(mut guard) = sysroot_store().write() {
        *guard = None;
    }
}

/// Returns the global sysroot path if it has been set.
pub fn get_sysroot() -> Option<PathBuf> {
    sysroot_store().read().ok().and_then(|g| g.clone())
}

/// Prepends the sysroot to the given path if a sysroot is set.
/// If the path is absolute, it is made relative to the current root before
/// joining.
pub fn apply_sysroot(path: impl Into<PathBuf>) -> PathBuf {
    let path = path.into();
    if let Some(root) = get_sysroot() {
        let mut applied = root.clone();
        for component in path.components() {
            match component {
                Component::Prefix(_)
                | Component::RootDir
                | Component::CurDir => {}
                Component::ParentDir => {
                    // Never allow a relative path to pop above the configured
                    // sysroot. This keeps callers safe even when metadata
                    // contains `..` components.
                    if applied != root {
                        applied.pop();
                    }
                }
                Component::Normal(name) => applied.push(name)
            }
        }
        applied
    } else {
        path
    }
}