//! Get filesystem statistics

//!

//! See [the man pages](https://pubs.opengroup.org/onlinepubs/9699919799/functions/fstatvfs.html)

//! for more details.

use std::mem;

use std::os::unix::io::AsRawFd;

use libc::{self, c_ulong};

use crate::{errno::Errno, NixPath, Result};

#[cfg(not(target_os = "redox"))]

libc_bitflags!(

    /// File system mount Flags

    #[repr(C)]

    #[derive(Default)]

    pub struct FsFlags: c_ulong {

        /// Read Only

        #[cfg(not(target_os = "haiku"))]

        ST_RDONLY;

        /// Do not allow the set-uid bits to have an effect

        #[cfg(not(target_os = "haiku"))]

        ST_NOSUID;

        /// Do not interpret character or block-special devices

        #[cfg(any(target_os = "android", target_os = "linux"))]

        #[cfg_attr(docsrs, doc(cfg(all())))]

        ST_NODEV;

        /// Do not allow execution of binaries on the filesystem

        #[cfg(any(target_os = "android", target_os = "linux"))]

        #[cfg_attr(docsrs, doc(cfg(all())))]

        ST_NOEXEC;

        /// All IO should be done synchronously

        #[cfg(any(target_os = "android", target_os = "linux"))]

        #[cfg_attr(docsrs, doc(cfg(all())))]

        ST_SYNCHRONOUS;

        /// Allow mandatory locks on the filesystem

        #[cfg(any(target_os = "android", target_os = "linux"))]

        #[cfg_attr(docsrs, doc(cfg(all())))]

        ST_MANDLOCK;

        /// Write on file/directory/symlink

        #[cfg(target_os = "linux")]

        #[cfg_attr(docsrs, doc(cfg(all())))]

        ST_WRITE;

        /// Append-only file

        #[cfg(target_os = "linux")]

        #[cfg_attr(docsrs, doc(cfg(all())))]

        ST_APPEND;

        /// Immutable file

        #[cfg(target_os = "linux")]

        #[cfg_attr(docsrs, doc(cfg(all())))]

        ST_IMMUTABLE;

        /// Do not update access times on files

        #[cfg(any(target_os = "android", target_os = "linux"))]

        #[cfg_attr(docsrs, doc(cfg(all())))]

        ST_NOATIME;

        /// Do not update access times on files

        #[cfg(any(target_os = "android", target_os = "linux"))]

        #[cfg_attr(docsrs, doc(cfg(all())))]

        ST_NODIRATIME;

        /// Update access time relative to modify/change time

        #[cfg(any(target_os = "android", all(target_os = "linux", not(target_env = "musl"))))]

        #[cfg_attr(docsrs, doc(cfg(all())))]

        ST_RELATIME;

    }

);

/// Wrapper around the POSIX `statvfs` struct

///

/// For more information see the [`statvfs(3)` man pages](https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_statvfs.h.html).

#[repr(transparent)]

#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]

pub struct Statvfs(libc::statvfs);

impl Statvfs {

    /// get the file system block size

    pub fn block_size(&self) -> c_ulong {

        self.0.f_bsize

    }

    /// Get the fundamental file system block size

    pub fn fragment_size(&self) -> c_ulong {

        self.0.f_frsize

    }

    /// Get the number of blocks.

    ///

    /// Units are in units of `fragment_size()`

    pub fn blocks(&self) -> libc::fsblkcnt_t {

        self.0.f_blocks

    }

    /// Get the number of free blocks in the file system

    pub fn blocks_free(&self) -> libc::fsblkcnt_t {

        self.0.f_bfree

    }

    /// Get the number of free blocks for unprivileged users

    pub fn blocks_available(&self) -> libc::fsblkcnt_t {

        self.0.f_bavail

    }

    /// Get the total number of file inodes

    pub fn files(&self) -> libc::fsfilcnt_t {

        self.0.f_files

    }

    /// Get the number of free file inodes

    pub fn files_free(&self) -> libc::fsfilcnt_t {

        self.0.f_ffree

    }

    /// Get the number of free file inodes for unprivileged users

    pub fn files_available(&self) -> libc::fsfilcnt_t {

        self.0.f_favail

    }

    /// Get the file system id

    pub fn filesystem_id(&self) -> c_ulong {

        self.0.f_fsid

    }

    /// Get the mount flags

    #[cfg(not(target_os = "redox"))]

    #[cfg_attr(docsrs, doc(cfg(all())))]

    pub fn flags(&self) -> FsFlags {

        FsFlags::from_bits_truncate(self.0.f_flag)

    }

    /// Get the maximum filename length

    pub fn name_max(&self) -> c_ulong {

        self.0.f_namemax

    }

}

/// Return a `Statvfs` object with information about the `path`

pub fn statvfs<P: ?Sized + NixPath>(path: &P) -> Result<Statvfs> {

    unsafe {

        Errno::clear();

        let mut stat = mem::MaybeUninit::<libc::statvfs>::uninit();

        let res = path.with_nix_path(|path| {

            libc::statvfs(path.as_ptr(), stat.as_mut_ptr())

        })?;

        Errno::result(res).map(|_| Statvfs(stat.assume_init()))

    }

}

/// Return a `Statvfs` object with information about `fd`

pub fn fstatvfs<T: AsRawFd>(fd: &T) -> Result<Statvfs> {

    unsafe {

        Errno::clear();

        let mut stat = mem::MaybeUninit::<libc::statvfs>::uninit();

        Errno::result(libc::fstatvfs(fd.as_raw_fd(), stat.as_mut_ptr()))

            .map(|_| Statvfs(stat.assume_init()))

    }

}

#[cfg(test)]

mod test {

    use crate::sys::statvfs::*;

    use std::fs::File;

    #[test]

    fn statvfs_call() {

        statvfs(&b"/"[..]).unwrap();

    }

    #[test]

    fn fstatvfs_call() {

        let root = File::open("/").unwrap();

        fstatvfs(&root).unwrap();

    }

}