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Refactor statvfs module
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 * Use upstream libc FFI declarations and constants
 * Use more Rust-y interface of returning entire struct versus passing it as an
   argument to (f)statvfs.
 * Replace field accesses with accessor methods
 * Flatten vfs module into parent
 * Remove all non-libc-based interfaces for working with the statvfs struct
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@Susurrus
Susurrus committed Aug 10, 2017
1 parent 087aece commit ba5d4ae
Showing 1 changed file with 120 additions and 141 deletions.
261 changes: 120 additions & 141 deletions src/sys/statvfs.rs
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Original file line number Diff line number Diff line change
@@ -1,161 +1,142 @@
//! FFI for statvfs functions
//! Get filesystem statistics
//!
//! See the `vfs::Statvfs` struct for some rusty wrappers
//! See [the man pages](http://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 {Errno, Result, NixPath};
use std::os::unix::io::AsRawFd;

pub mod vfs {
//! Structs related to the `statvfs` and `fstatvfs` functions
//!
//! The `Statvfs` struct has some wrappers methods around the `statvfs` and
//! `fstatvfs` calls.

use libc::{c_ulong,c_int};
use std::os::unix::io::AsRawFd;
use {Result, NixPath};

use super::{statvfs, fstatvfs};

bitflags!(
/// Mount Flags
#[repr(C)]
#[derive(Default)]
pub struct FsFlags: c_ulong {
/// Read Only
const RDONLY = 1;
/// Do not allow the set-uid bits to have an effect
const NOSUID = 2;
/// Do not interpret character or block-special devices
const NODEV = 4;
/// Do not allow execution of binaries on the filesystem
const NOEXEC = 8;
/// All IO should be done synchronously
const SYNCHRONOUS = 16;
/// Allow mandatory locks on the filesystem
const MANDLOCK = 64;
const WRITE = 128;
const APPEND = 256;
const IMMUTABLE = 512;
/// Do not update access times on files
const NOATIME = 1024;
/// Do not update access times on files
const NODIRATIME = 2048;
/// Update access time relative to modify/change time
const RELATIME = 4096;
}
);

/// The posix statvfs struct
///
/// http://linux.die.net/man/2/statvfs
bitflags!(
/// File system mount Flags
#[repr(C)]
#[derive(Debug,Copy,Clone)]
pub struct Statvfs {
/// Filesystem block size. This is the value that will lead to
/// most efficient use of the filesystem
pub f_bsize: c_ulong,
/// Fragment Size -- actual minimum unit of allocation on this
/// filesystem
pub f_frsize: c_ulong,
/// Total number of blocks on the filesystem
pub f_blocks: u64,
/// Number of unused blocks on the filesystem, including those
/// reserved for root
pub f_bfree: u64,
/// Number of blocks available to non-root users
pub f_bavail: u64,
/// Total number of inodes available on the filesystem
pub f_files: u64,
/// Number of inodes available on the filesystem
pub f_ffree: u64,
/// Number of inodes available to non-root users
pub f_favail: u64,
/// File System ID
pub f_fsid: c_ulong,
/// Mount Flags
pub f_flag: FsFlags,
/// Maximum filename length
pub f_namemax: c_ulong,
/// Reserved extra space, OS-dependent
f_spare: [c_int; 6],
}

impl Statvfs {
/// Create a new `Statvfs` object and fill it with information about
/// the mount that contains `path`
pub fn for_path<P: ?Sized + NixPath>(path: &P) -> Result<Statvfs> {
let mut stat = Statvfs::default();
let res = statvfs(path, &mut stat);
res.map(|_| stat)
}

/// Replace information in this struct with information about `path`
pub fn update_with_path<P: ?Sized + NixPath>(&mut self, path: &P) -> Result<()> {
statvfs(path, self)
}

/// Create a new `Statvfs` object and fill it with information from fd
pub fn for_fd<T: AsRawFd>(fd: &T) -> Result<Statvfs> {
let mut stat = Statvfs::default();
let res = fstatvfs(fd, &mut stat);
res.map(|_| stat)
}

/// Replace information in this struct with information about `fd`
pub fn update_with_fd<T: AsRawFd>(&mut self, fd: &T) -> Result<()> {
fstatvfs(fd, self)
}
}

impl Default for Statvfs {
/// Create a statvfs object initialized to all zeros
fn default() -> Self {
Statvfs {
f_bsize: 0,
f_frsize: 0,
f_blocks: 0,
f_bfree: 0,
f_bavail: 0,
f_files: 0,
f_ffree: 0,
f_favail: 0,
f_fsid: 0,
f_flag: FsFlags::default(),
f_namemax: 0,
f_spare: [0, 0, 0, 0, 0, 0],
}
}
#[derive(Default)]
pub struct FsFlags: c_ulong {
/// Read Only
const RDONLY = libc::ST_RDONLY;
/// Do not allow the set-uid bits to have an effect
const NOSUID = libc::ST_NOSUID;
/// Do not interpret character or block-special devices
#[cfg(any(target_os = "android", target_os = "linux"))]
const NODEV = libc::ST_NODEV;
/// Do not allow execution of binaries on the filesystem
#[cfg(any(target_os = "android", target_os = "linux"))]
const NOEXEC = libc::ST_NOEXEC;
/// All IO should be done synchronously
#[cfg(any(target_os = "android", target_os = "linux"))]
const SYNCHRONOUS = libc::ST_SYNCHRONOUS;
/// Allow mandatory locks on the filesystem
#[cfg(any(target_os = "android", target_os = "linux"))]
const MANDLOCK = libc::ST_MANDLOCK;
/// Write on file/directory/symlink
#[cfg(any(target_os = "android", target_os = "linux"))]
const WRITE = libc::ST_WRITE;
/// Append-only file
#[cfg(any(target_os = "android", target_os = "linux"))]
const APPEND = libc::ST_APPEND;
/// Immutable file
#[cfg(any(target_os = "android", target_os = "linux"))]
const IMMUTABLE = libc::ST_IMMUTABLE;
/// Do not update access times on files
#[cfg(any(target_os = "android", target_os = "linux"))]
const NOATIME = libc::ST_NOATIME;
/// Do not update access times on files
#[cfg(any(target_os = "android", target_os = "linux"))]
const NODIRATIME = libc::ST_NODIRATIME;
/// Update access time relative to modify/change time
#[cfg(any(target_os = "android", all(target_os = "linux", not(target_env = "musl"))))]
const RELATIME = libc::ST_RELATIME;
}
);

/// Wrapper around the POSIX `statvfs` struct
///
/// For more information see the [`statvfs(3)` man pages](http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_statvfs.h.html).
// FIXME: Replace with repr(transparent)
#[repr(C)]
pub struct Statvfs(libc::statvfs);

impl Statvfs {
/// get the file system block size
pub fn block_size(&self) -> libc::c_ulong {
self.0.f_bsize
}
}

mod ffi {
use libc::{c_char, c_int};
use sys::statvfs::vfs;
/// Get the fundamental file system block size
pub fn fragment_size(&self) -> libc::c_ulong {
self.0.f_frsize
}

extern {
pub fn statvfs(path: * const c_char, buf: *mut vfs::Statvfs) -> c_int;
pub fn fstatvfs(fd: c_int, buf: *mut vfs::Statvfs) -> c_int;
/// 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
pub fn flags(&self) -> FsFlags {
FsFlags::from_bits_truncate(self.0.f_flag)
}

/// Get the maximum filename length
pub fn name_max(&self) -> libc::c_ulong {
self.0.f_namemax
}

}

/// Fill an existing `Statvfs` object with information about the `path`
pub fn statvfs<P: ?Sized + NixPath>(path: &P, stat: &mut vfs::Statvfs) -> Result<()> {
/// 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: Statvfs = mem::uninitialized();
let res = try!(
path.with_nix_path(|path| ffi::statvfs(path.as_ptr(), stat))
path.with_nix_path(|path| libc::statvfs(path.as_ptr(), &mut stat.0))
);

Errno::result(res).map(drop)
Errno::result(res).map(|_| stat)
}
}

/// Fill an existing `Statvfs` object with information about `fd`
pub fn fstatvfs<T: AsRawFd>(fd: &T, stat: &mut vfs::Statvfs) -> Result<()> {
/// Return a `Statvfs` object with information about `fd`
pub fn fstatvfs<T: AsRawFd>(fd: &T) -> Result<Statvfs> {
unsafe {
Errno::clear();
Errno::result(ffi::fstatvfs(fd.as_raw_fd(), stat)).map(drop)
let mut stat: Statvfs = mem::uninitialized();
Errno::result(libc::fstatvfs(fd.as_raw_fd(), &mut stat.0)).map(|_| stat)
}
}

Expand All @@ -166,14 +147,12 @@ mod test {

#[test]
fn statvfs_call() {
let mut stat = vfs::Statvfs::default();
statvfs("/".as_bytes(), &mut stat).unwrap()
statvfs("/".as_bytes()).unwrap();
}

#[test]
fn fstatvfs_call() {
let mut stat = vfs::Statvfs::default();
let root = File::open("/").unwrap();
fstatvfs(&root, &mut stat).unwrap()
fstatvfs(&root).unwrap();
}
}

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