shitbox/unix-mode/src/lib.rs

//! Functions for parsing and managing permissions
mod bit;
mod parser;
mod who;
use std::fmt::{self, Write};

pub use {
    bit::Bit,
    parser::{ParseError, Parser},
    who::Who,
};

/// Gets the umask for the current user
#[must_use]
pub fn get_umask() -> u32 {
    let mask = unsafe { libc::umask(0) };
    let _mask = unsafe { libc::umask(mask) };
    mask
}

/// Functions for extracting information about Unix modes
pub trait Mode {
    /// Returns a string representing permissions in symbolic format
    /// including file type
    fn mode_string_full(&self) -> Result<String, fmt::Error>;

    /// Returns a string representing permissions in symbolic format
    /// minus file type
    fn mode_string(&self) -> Result<String, fmt::Error>;
}

impl Mode for u32 {
    fn mode_string_full(&self) -> Result<String, fmt::Error> {
        let b = if self & 0o40000 != 0 && self & 0o20000 != 0 {
            'b'
        } else if self & 0o40000 != 0 {
            'd'
        } else if self & 0o20000 != 0 {
            'c'
        } else {
            '-'
        };
        let mut s = String::new();
        write!(s, "{b}")?;
        [
            Bit::URead,
            Bit::UWrite,
            Bit::UExec,
            Bit::GRead,
            Bit::GWrite,
            Bit::GExec,
            Bit::ORead,
            Bit::OWrite,
            Bit::OExec,
        ]
        .iter()
        .try_for_each(|b| write!(s, "{}", b.as_char(*self)))?;
        Ok(s)
    }

    fn mode_string(&self) -> Result<String, fmt::Error> {
        let mut s = String::new();
        [
            Bit::URead,
            Bit::UWrite,
            Bit::UExec,
            Bit::GRead,
            Bit::GWrite,
            Bit::GExec,
            Bit::ORead,
            Bit::OWrite,
            Bit::OExec,
        ]
        .iter()
        .try_for_each(|b| write!(s, "{}", b.as_char(*self)))?;
        Ok(s)
    }
}

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

    #[test]
    fn getumask() {
        let mask = unsafe { libc::umask(0o22) };
        assert_eq!(get_umask(), 0o022);
        unsafe {
            libc::umask(mask);
        }
    }

    #[test]
    fn display_bits_dir() {
        let m: u32 = 0o40755;
        let s = m.mode_string_full().unwrap();
        assert_eq!(s.as_str(), "drwxr-xr-x")
    }

    #[test]
    fn display_bits_char() {
        let m: u32 = 0o20666;
        let s = m.mode_string_full().unwrap();
        assert_eq!(s.as_str(), "crw-rw-rw-")
    }

    #[test]
    fn display_bits_block() {
        let m: u32 = 0o60660;
        let s = m.mode_string_full().unwrap();
        assert_eq!(s.as_str(), "brw-rw----")
    }

    #[test]
    fn display_bits_file() {
        let m: u32 = 0o100644;
        let s = m.mode_string_full().unwrap();
        assert_eq!(s.as_str(), "-rw-r--r--")
    }

    #[test]
    fn display_bits_suid() {
        let m: u32 = 0o104755;
        let s = m.mode_string_full().unwrap();
        assert_eq!(s.as_str(), "-rwsr-xr-x")
    }

    #[test]
    fn display_bits_sgid() {
        let m: u32 = 0o102755;
        let s = m.mode_string_full().unwrap();
        assert_eq!(s.as_str(), "-rwxr-sr-x")
    }

    #[test]
    fn display_bits_sticky() {
        let m: u32 = 0o41777;
        let s = m.mode_string_full().unwrap();
        assert_eq!(s.as_str(), "drwxrwxrwt")
    }
}