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#[cfg(target_os = "freebsd")]
use crate::Error;
use crate::{Errno, NixPath, Result};
use libc::c_int;
#[cfg(target_os = "freebsd")]
use libc::{c_char, c_uint, c_void};
#[cfg(target_os = "freebsd")]
use std::{
borrow::Cow,
ffi::{CStr, CString},
fmt, io,
marker::PhantomData,
};
libc_bitflags!(
/// Used with [`Nmount::nmount`].
pub struct MntFlags: c_int {
/// ACL support enabled.
#[cfg(any(target_os = "netbsd", target_os = "freebsd"))]
MNT_ACLS;
/// All I/O to the file system should be done asynchronously.
MNT_ASYNC;
/// dir should instead be a file system ID encoded as “FSID:val0:val1”.
#[cfg(target_os = "freebsd")]
MNT_BYFSID;
/// Force a read-write mount even if the file system appears to be
/// unclean.
MNT_FORCE;
/// GEOM journal support enabled.
#[cfg(target_os = "freebsd")]
MNT_GJOURNAL;
/// MAC support for objects.
#[cfg(target_os = "freebsd")]
MNT_MULTILABEL;
/// Disable read clustering.
#[cfg(freebsdlike)]
MNT_NOCLUSTERR;
/// Disable write clustering.
#[cfg(freebsdlike)]
MNT_NOCLUSTERW;
/// Enable NFS version 4 ACLs.
#[cfg(target_os = "freebsd")]
MNT_NFS4ACLS;
/// Do not update access times.
MNT_NOATIME;
/// Disallow program execution.
MNT_NOEXEC;
/// Do not honor setuid or setgid bits on files when executing them.
MNT_NOSUID;
/// Do not follow symlinks.
#[cfg(freebsdlike)]
MNT_NOSYMFOLLOW;
/// Mount read-only.
MNT_RDONLY;
/// Causes the vfs subsystem to update its data structures pertaining to
/// the specified already mounted file system.
MNT_RELOAD;
/// Create a snapshot of the file system.
///
#[cfg(target_os = "freebsd")]
MNT_SNAPSHOT;
/// Using soft updates.
#[cfg(any(freebsdlike, netbsdlike))]
MNT_SOFTDEP;
/// Directories with the SUID bit set chown new files to their own
/// owner.
#[cfg(freebsdlike)]
MNT_SUIDDIR;
/// All I/O to the file system should be done synchronously.
MNT_SYNCHRONOUS;
/// Union with underlying fs.
#[cfg(any(
target_os = "freebsd",
target_os = "netbsd"
))]
MNT_UNION;
/// Indicates that the mount command is being applied to an already
/// mounted file system.
MNT_UPDATE;
/// Check vnode use counts.
#[cfg(target_os = "freebsd")]
MNT_NONBUSY;
}
);
/// The Error type of [`Nmount::nmount`].
///
/// It wraps an [`Errno`], but also may contain an additional message returned
/// by `nmount(2)`.
#[cfg(target_os = "freebsd")]
#[derive(Debug)]
pub struct NmountError {
errno: Error,
errmsg: Option<String>,
}
#[cfg(target_os = "freebsd")]
impl NmountError {
/// Returns the additional error string sometimes generated by `nmount(2)`.
pub fn errmsg(&self) -> Option<&str> {
self.errmsg.as_deref()
}
/// Returns the inner [`Error`]
pub const fn error(&self) -> Error {
self.errno
}
fn new(error: Error, errmsg: Option<&CStr>) -> Self {
Self {
errno: error,
errmsg: errmsg.map(CStr::to_string_lossy).map(Cow::into_owned),
}
}
}
#[cfg(target_os = "freebsd")]
impl std::error::Error for NmountError {}
#[cfg(target_os = "freebsd")]
impl fmt::Display for NmountError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
if let Some(errmsg) = &self.errmsg {
write!(f, "{:?}: {}: {}", self.errno, errmsg, self.errno.desc())
} else {
write!(f, "{:?}: {}", self.errno, self.errno.desc())
}
}
}
#[cfg(target_os = "freebsd")]
impl From<NmountError> for io::Error {
fn from(err: NmountError) -> Self {
err.errno.into()
}
}
/// Result type of [`Nmount::nmount`].
#[cfg(target_os = "freebsd")]
pub type NmountResult = std::result::Result<(), NmountError>;
/// Mount a FreeBSD file system.
///
/// The `nmount(2)` system call works similarly to the `mount(8)` program; it
/// takes its options as a series of name-value pairs. Most of the values are
/// strings, as are all of the names. The `Nmount` structure builds up an
/// argument list and then executes the syscall.
///
/// # Examples
///
/// To mount `target` onto `mountpoint` with `nullfs`:
/// ```
/// # use nix::unistd::Uid;
/// # use ::sysctl::{CtlValue, Sysctl};
/// # let ctl = ::sysctl::Ctl::new("vfs.usermount").unwrap();
/// # if !Uid::current().is_root() && CtlValue::Int(0) == ctl.value().unwrap() {
/// # return;
/// # };
/// use nix::mount::{MntFlags, Nmount, unmount};
/// use std::ffi::CString;
/// use tempfile::tempdir;
///
/// let mountpoint = tempdir().unwrap();
/// let target = tempdir().unwrap();
///
/// let fstype = CString::new("fstype").unwrap();
/// let nullfs = CString::new("nullfs").unwrap();
/// Nmount::new()
/// .str_opt(&fstype, &nullfs)
/// .str_opt_owned("fspath", mountpoint.path().to_str().unwrap())
/// .str_opt_owned("target", target.path().to_str().unwrap())
/// .nmount(MntFlags::empty()).unwrap();
///
/// unmount(mountpoint.path(), MntFlags::empty()).unwrap();
/// ```
///
/// # See Also
#[cfg(target_os = "freebsd")]
#[derive(Debug, Default)]
pub struct Nmount<'a> {
// n.b. notgull: In reality, this is a list that contains
// both mutable and immutable pointers.
// Be careful using this.
iov: Vec<libc::iovec>,
is_owned: Vec<bool>,
marker: PhantomData<&'a ()>,
}
#[cfg(target_os = "freebsd")]
impl<'a> Nmount<'a> {
/// Helper function to push a slice onto the `iov` array.
fn push_slice(&mut self, val: &'a [u8], is_owned: bool) {
self.iov.push(libc::iovec {
iov_base: val.as_ptr().cast_mut().cast(),
iov_len: val.len(),
});
self.is_owned.push(is_owned);
}
/// Helper function to push a pointer and its length onto the `iov` array.
fn push_pointer_and_length(
&mut self,
val: *const u8,
len: usize,
is_owned: bool,
) {
self.iov.push(libc::iovec {
iov_base: val as *mut _,
iov_len: len,
});
self.is_owned.push(is_owned);
}
/// Helper function to push a `nix` path as owned.
fn push_nix_path<P: ?Sized + NixPath>(&mut self, val: &P) {
val.with_nix_path(|s| {
let len = s.to_bytes_with_nul().len();
let ptr = s.to_owned().into_raw() as *const u8;
self.push_pointer_and_length(ptr, len, true);
})
.unwrap();
}
/// Add an opaque mount option.
///
/// Some file systems take binary-valued mount options. They can be set
/// with this method.
///
/// # Safety
///
/// Unsafe because it will cause `Nmount::nmount` to dereference a raw
/// pointer. The user is responsible for ensuring that `val` is valid and
/// its lifetime outlives `self`! An easy way to do that is to give the
/// value a larger scope than `name`
///
/// # Examples
/// ```
/// use libc::c_void;
/// use nix::mount::Nmount;
/// use std::ffi::CString;
/// use std::mem;
///
/// // Note that flags outlives name
/// let mut flags: u32 = 0xdeadbeef;
/// let name = CString::new("flags").unwrap();
/// let p = &mut flags as *mut u32 as *mut c_void;
/// let len = mem::size_of_val(&flags);
/// let mut nmount = Nmount::new();
/// unsafe { nmount.mut_ptr_opt(&name, p, len) };
/// ```
pub unsafe fn mut_ptr_opt(
&mut self,
name: &'a CStr,
val: *mut c_void,
len: usize,
) -> &mut Self {
self.push_slice(name.to_bytes_with_nul(), false);
self.push_pointer_and_length(val.cast(), len, false);
self
}
/// Add a mount option that does not take a value.
///
/// # Examples
/// ```
/// use nix::mount::Nmount;
/// use std::ffi::CString;
///
/// let read_only = CString::new("ro").unwrap();
/// Nmount::new()
/// .null_opt(&read_only);
/// ```
pub fn null_opt(&mut self, name: &'a CStr) -> &mut Self {
self.push_slice(name.to_bytes_with_nul(), false);
self.push_slice(&[], false);
self
}
/// Add a mount option that does not take a value, but whose name must be
/// owned.
///
///
/// This has higher runtime cost than [`Nmount::null_opt`], but is useful
/// when the name's lifetime doesn't outlive the `Nmount`, or it's a
/// different string type than `CStr`.
///
/// # Examples
/// ```
/// use nix::mount::Nmount;
///
/// let read_only = "ro";
/// let mut nmount: Nmount<'static> = Nmount::new();
/// nmount.null_opt_owned(read_only);
/// ```
pub fn null_opt_owned<P: ?Sized + NixPath>(
&mut self,
name: &P,
) -> &mut Self {
self.push_nix_path(name);
self.push_slice(&[], false);
self
}
/// Add a mount option as a [`CStr`].
///
/// # Examples
/// ```
/// use nix::mount::Nmount;
/// use std::ffi::CString;
///
/// let fstype = CString::new("fstype").unwrap();
/// let nullfs = CString::new("nullfs").unwrap();
/// Nmount::new()
/// .str_opt(&fstype, &nullfs);
/// ```
pub fn str_opt(&mut self, name: &'a CStr, val: &'a CStr) -> &mut Self {
self.push_slice(name.to_bytes_with_nul(), false);
self.push_slice(val.to_bytes_with_nul(), false);
self
}
/// Add a mount option as an owned string.
///
/// This has higher runtime cost than [`Nmount::str_opt`], but is useful
/// when the value's lifetime doesn't outlive the `Nmount`, or it's a
/// different string type than `CStr`.
///
/// # Examples
/// ```
/// use nix::mount::Nmount;
/// use std::path::Path;
///
/// let mountpoint = Path::new("/mnt");
/// Nmount::new()
/// .str_opt_owned("fspath", mountpoint.to_str().unwrap());
/// ```
pub fn str_opt_owned<P1, P2>(&mut self, name: &P1, val: &P2) -> &mut Self
where
P1: ?Sized + NixPath,
P2: ?Sized + NixPath,
{
self.push_nix_path(name);
self.push_nix_path(val);
self
}
/// Create a new `Nmount` struct with no options
pub fn new() -> Self {
Self::default()
}
/// Actually mount the file system.
pub fn nmount(&mut self, flags: MntFlags) -> NmountResult {
const ERRMSG_NAME: &[u8] = b"errmsg\0";
let mut errmsg = vec![0u8; 255];
// nmount can return extra error information via a "errmsg" return
// argument.
self.push_slice(ERRMSG_NAME, false);
// SAFETY: we are pushing a mutable iovec here, so we can't use
// the above method
self.iov.push(libc::iovec {
iov_base: errmsg.as_mut_ptr().cast(),
iov_len: errmsg.len(),
});
let niov = self.iov.len() as c_uint;
let iovp = self.iov.as_mut_ptr();
let res = unsafe { libc::nmount(iovp, niov, flags.bits()) };
match Errno::result(res) {
Ok(_) => Ok(()),
Err(error) => {
let errmsg = if errmsg[0] == 0 {
None
} else {
CStr::from_bytes_until_nul(&errmsg[..]).ok()
};
Err(NmountError::new(error, errmsg))
}
}
}
}
#[cfg(target_os = "freebsd")]
impl<'a> Drop for Nmount<'a> {
fn drop(&mut self) {
for (iov, is_owned) in self.iov.iter().zip(self.is_owned.iter()) {
if *is_owned {
// Free the owned string. Safe because we recorded ownership,
// and Nmount does not implement Clone.
unsafe {
drop(CString::from_raw(iov.iov_base as *mut c_char));
}
}
}
}
}
/// Unmount the file system mounted at `mountpoint`.
///
/// Useful flags include
/// * `MNT_FORCE` - Unmount even if still in use.
#[cfg_attr(
target_os = "freebsd",
doc = "
* `MNT_BYFSID` - `mountpoint` is not a path, but a file system ID
encoded as `FSID:val0:val1`, where `val0` and `val1`
are the contents of the `fsid_t val[]` array in decimal.
The file system that has the specified file system ID
will be unmounted. See
[`statfs`](crate::sys::statfs::statfs) to determine the
`fsid`.
"
)]
pub fn unmount<P>(mountpoint: &P, flags: MntFlags) -> Result<()>
where
P: ?Sized + NixPath,
{
let res = mountpoint.with_nix_path(|cstr| unsafe {
libc::unmount(cstr.as_ptr(), flags.bits())
})?;
Errno::result(res).map(drop)
}