nix 0.20.0

use libc::{self, c_ulong, c_int};
use crate::{Result, NixPath};
use crate::errno::Errno;

libc_bitflags!(
    pub struct MsFlags: c_ulong {
        /// Mount read-only
        MS_RDONLY;
        /// Ignore suid and sgid bits
        MS_NOSUID;
        /// Disallow access to device special files
        MS_NODEV;
        /// Disallow program execution
        MS_NOEXEC;
        /// Writes are synced at once
        MS_SYNCHRONOUS;
        /// Alter flags of a mounted FS
        MS_REMOUNT;
        /// Allow mandatory locks on a FS
        MS_MANDLOCK;
        /// Directory modifications are synchronous
        MS_DIRSYNC;
        /// Do not update access times
        MS_NOATIME;
        /// Do not update directory access times
        MS_NODIRATIME;
        /// Linux 2.4.0 - Bind directory at different place
        MS_BIND;
        MS_MOVE;
        MS_REC;
        MS_SILENT;
        MS_POSIXACL;
        MS_UNBINDABLE;
        MS_PRIVATE;
        MS_SLAVE;
        MS_SHARED;
        MS_RELATIME;
        MS_KERNMOUNT;
        MS_I_VERSION;
        MS_STRICTATIME;
        MS_ACTIVE;
        MS_NOUSER;
        MS_RMT_MASK;
        MS_MGC_VAL;
        MS_MGC_MSK;
    }
);

libc_bitflags!(
    pub struct MntFlags: c_int {
        MNT_FORCE;
        MNT_DETACH;
        MNT_EXPIRE;
    }
);

pub fn mount<P1: ?Sized + NixPath, P2: ?Sized + NixPath, P3: ?Sized + NixPath, P4: ?Sized + NixPath>(
        source: Option<&P1>,
        target: &P2,
        fstype: Option<&P3>,
        flags: MsFlags,
        data: Option<&P4>) -> Result<()> {

    fn with_opt_nix_path<P, T, F>(p: Option<&P>, f: F) -> Result<T>
        where P: ?Sized + NixPath,
              F: FnOnce(*const libc::c_char) -> T
    {
        match p {
            Some(path) => path.with_nix_path(|p_str| f(p_str.as_ptr())),
            None => Ok(f(std::ptr::null()))
        }
    }

    let res = with_opt_nix_path(source, |s| {
        target.with_nix_path(|t| {
            with_opt_nix_path(fstype, |ty| {
                with_opt_nix_path(data, |d| {
                    unsafe {
                        libc::mount(
                            s,
                            t.as_ptr(),
                            ty,
                            flags.bits,
                            d as *const libc::c_void
                        )
                    }
                })
            })
        })
    })????;

    Errno::result(res).map(drop)
}

pub fn umount<P: ?Sized + NixPath>(target: &P) -> Result<()> {
    let res = target.with_nix_path(|cstr| {
        unsafe { libc::umount(cstr.as_ptr()) }
    })?;

    Errno::result(res).map(drop)
}

pub fn umount2<P: ?Sized + NixPath>(target: &P, flags: MntFlags) -> Result<()> {
    let res = target.with_nix_path(|cstr| {
        unsafe { libc::umount2(cstr.as_ptr(), flags.bits) }
    })?;

    Errno::result(res).map(drop)
}