//! `sys/mman.h` implementation.
//!
//! See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/sys_mman.h.html>.

use crate::{
    c_str::{CStr, CString},
    error::{Errno, ResultExt},
    header::{fcntl, unistd},
    platform::{ERRNO, Pal, Sys, types::*},
};

pub use self::sys::*;

#[cfg(target_os = "linux")]
#[path = "linux.rs"]
pub mod sys;

#[cfg(target_os = "redox")]
#[path = "redox.rs"]
pub mod sys;

pub const MADV_NORMAL: c_int = 0;
pub const MADV_RANDOM: c_int = 1;
pub const MADV_SEQUENTIAL: c_int = 2;
pub const MADV_WILLNEED: c_int = 3;
pub const MADV_DONTNEED: c_int = 4;

pub const MAP_SHARED: c_int = 0x0001;
pub const MAP_PRIVATE: c_int = 0x0002;
pub const MAP_TYPE: c_int = 0x000F;
pub const MAP_ANON: c_int = 0x0020;
pub const MAP_ANONYMOUS: c_int = MAP_ANON;
pub const MAP_STACK: c_int = 0x20000;
pub const MAP_FAILED: *mut c_void = usize::wrapping_neg(1) as *mut c_void;

pub const MREMAP_MAYMOVE: c_int = 1;

pub const MS_ASYNC: c_int = 0x0001;
pub const MS_INVALIDATE: c_int = 0x0002;
pub const MS_SYNC: c_int = 0x0004;

pub const MCL_CURRENT: c_int = 1;
pub const MCL_FUTURE: c_int = 2;

pub const POSIX_MADV_NORMAL: c_int = 0;
pub const POSIX_MADV_RANDOM: c_int = 1;
pub const POSIX_MADV_SEQUENTIAL: c_int = 2;
pub const POSIX_MADV_WILLNEED: c_int = 3;
pub const POSIX_MADV_WONTNEED: c_int = 4;

/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man2/madvise.2.html>.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn madvise(addr: *mut c_void, len: size_t, flags: c_int) -> c_int {
    Sys::madvise(addr, len, flags)
        .map(|()| 0)
        .or_minus_one_errno()
}

/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/mlock.html>.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn mlock(addr: *const c_void, len: usize) -> c_int {
    Sys::mlock(addr, len).map(|()| 0).or_minus_one_errno()
}

/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/mlockall.html>.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn mlockall(flags: c_int) -> c_int {
    Sys::mlockall(flags).map(|()| 0).or_minus_one_errno()
}

/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/mmap.html>.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn mmap(
    addr: *mut c_void,
    len: size_t,
    prot: c_int,
    flags: c_int,
    fildes: c_int,
    off: off_t,
) -> *mut c_void {
    match Sys::mmap(addr, len, prot, flags, fildes, off) {
        Ok(ptr) => ptr,
        Err(Errno(errno)) => {
            ERRNO.set(errno);
            MAP_FAILED
        }
    }
}

/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/mprotect.html>.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn mprotect(addr: *mut c_void, len: size_t, prot: c_int) -> c_int {
    Sys::mprotect(addr, len, prot)
        .map(|()| 0)
        .or_minus_one_errno()
}

/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man2/mremap.2.html>.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn mremap(
    old_address: *mut c_void,
    old_size: usize,
    new_size: usize,
    flags: c_int,
    mut __valist: ...
) -> *mut c_void {
    let new_address = __valist.arg::<*mut c_void>();
    match Sys::mremap(old_address, old_size, new_size, flags, new_address) {
        Ok(ptr) => ptr,
        Err(Errno(errno)) => {
            ERRNO.set(errno);
            MAP_FAILED
        }
    }
}

/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/msync.html>.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn msync(addr: *mut c_void, len: size_t, flags: c_int) -> c_int {
    Sys::msync(addr, len, flags)
        .map(|()| 0)
        .or_minus_one_errno()
}

/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/mlock.html>.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn munlock(addr: *const c_void, len: usize) -> c_int {
    Sys::munlock(addr, len).map(|()| 0).or_minus_one_errno()
}

/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/mlockall.html>.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn munlockall() -> c_int {
    Sys::munlockall().map(|()| 0).or_minus_one_errno()
}

/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/munmap.html>.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn munmap(addr: *mut c_void, len: size_t) -> c_int {
    Sys::munmap(addr, len).map(|()| 0).or_minus_one_errno()
}

#[cfg(target_os = "linux")]
static SHM_PATH: &'static [u8] = b"/dev/shm/";

#[cfg(target_os = "redox")]
static SHM_PATH: &'static [u8] = b"/scheme/shm/";

unsafe fn shm_path(name: *const c_char) -> CString {
    let name_c = CStr::from_ptr(name);

    let mut path = SHM_PATH.to_vec();

    let mut skip_slash = true;
    for &b in name_c.to_bytes() {
        if skip_slash {
            if b == b'/' {
                continue;
            } else {
                skip_slash = false;
            }
        }
        path.push(b);
    }

    CString::from_vec_unchecked(path)
}

/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/shm_open.html>.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn shm_open(name: *const c_char, oflag: c_int, mode: mode_t) -> c_int {
    let path = shm_path(name);
    fcntl::open(path.as_ptr(), oflag, mode)
}

/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/shm_unlink.html>.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn shm_unlink(name: *const c_char) -> c_int {
    let path = shm_path(name);
    unistd::unlink(path.as_ptr())
}