pipedash-core 0.3.0

use std::{
    ffi::OsString,
    sync::{
        Mutex,
        MutexGuard,
        PoisonError,
    },
};

static ENV_LOCK: Mutex<()> = Mutex::new(());

pub(crate) struct EnvGuard {
    saved: Vec<(&'static str, Option<OsString>)>,
    _lock: MutexGuard<'static, ()>,
}

impl EnvGuard {
    pub(crate) fn set(vars: &[(&'static str, Option<&str>)]) -> Self {
        let lock = ENV_LOCK.lock().unwrap_or_else(PoisonError::into_inner);
        let saved = vars
            .iter()
            .map(|(name, value)| {
                let previous = std::env::var_os(name);
                match value {
                    Some(value) => std::env::set_var(name, value),
                    None => std::env::remove_var(name),
                }
                (*name, previous)
            })
            .collect();

        Self { saved, _lock: lock }
    }
}

impl Drop for EnvGuard {
    fn drop(&mut self) {
        for (name, previous) in self.saved.drain(..) {
            match previous {
                Some(value) => std::env::set_var(name, value),
                None => std::env::remove_var(name),
            }
        }
    }
}