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#![deny(missing_docs)]
#![doc = include_str!("../README.md")]
#![cfg_attr(test, deny(warnings))]

use clap::Parser;

#[cfg(unix)]
extern crate privdrop;

use std::ffi::OsString;
#[cfg(feature = "chroot")]
use std::path::PathBuf;

/// Error type for this crate
#[derive(Debug, thiserror::Error)]
pub enum Error {
    /// Error variant if privileges could not be dropped
    #[cfg(unix)]
    #[error("Privileges could not be dropped")]
    PrivDrop(#[from] privdrop::PrivDropError),
}

#[cfg(unix)]
mod supported {
    use super::*;

    /// Drop permissions of a CLI using clap.
    #[derive(Parser, Debug)]
    pub struct Permission {
        /// Change the process user
        #[clap(short = 'u', long = "user", value_parser)]
        user: Option<OsString>,
        /// Change the process group
        #[clap(short = 'g', long = "group", value_parser)]
        group: Option<OsString>,
        /// Change the process root directory
        #[cfg(feature = "chroot")]
        #[clap(long = "chroot", value_parser)]
        chroot: Option<PathBuf>,
    }

    impl Permission {
        /// Drop privileges.
        pub fn drop(self) -> Result<(), Error> {
            let mut drop = privdrop::PrivDrop::default();

            if let Some(user) = self.user {
                drop = drop.user(&user);
            }

            if let Some(group) = self.group {
                drop = drop.group(&group);
            }

            #[cfg(feature = "chroot")]
            {
                if let Some(chroot) = self.chroot {
                    drop = drop.chroot(&chroot);
                }
            }

            drop.apply()?;
            Ok(())
        }

        /// Get the user.
        pub fn user(&self) -> &Option<OsString> {
            &self.user
        }

        /// Get the group.
        pub fn group(&self) -> &Option<OsString> {
            &self.group
        }

        /// Get the chroot directory.
        #[cfg(feature = "chroot")]
        pub fn chroot(&self) -> &Option<PathBuf> {
            &self.chroot
        }
    }
}

#[cfg(not(unix))]
mod stub {
    use super::*;

    /// Drop permissions of a CLI using clap.
    #[derive(Parser, Debug)]
    pub struct Permission {}

    impl Permission {
        /// Drop privileges.
        pub fn drop(self) -> Result<(), Error> {
            Ok(())
        }

        /// Get the user.
        pub fn user(&self) -> &Option<OsString> {
            &None
        }

        /// Get the group.
        pub fn group(&self) -> &Option<OsString> {
            &None
        }

        /// Get the chroot directory.
        #[cfg(feature = "chroot")]
        pub fn chroot(&self) -> &Option<PathBuf> {
            &None
        }
    }
}

#[cfg(unix)]
pub use supported::*;

#[cfg(not(unix))]
pub use stub::*;