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// Copyright 2018-2022 System76 <info@system76.com>
// SPDX-License-Identifier: MIT OR Apache-2.0
//! High level abstraction over the `mount` and `umount2` system calls.
//!
//! If the `loop` feature is enabled (default), additionally supports creating loopback devices
//! automatically when mounting an iso or squashfs file.
//!
//! # Example
//!
//! ```rust,no_run
//! extern crate sys_mount;
//!
//! use std::process::exit;
//! use sys_mount::{
//! Mount,
//! MountFlags,
//! SupportedFilesystems,
//! Unmount,
//! UnmountFlags
//! };
//!
//! fn main() {
//! // Fetch a list of supported file systems.
//! // When mounting, a file system will be selected from this.
//! let supported = SupportedFilesystems::new().unwrap();
//!
//! // Attempt to mount the src device to the dest directory.
//! let mount_result = Mount::builder()
//! .fstype("btrfs")
//! .data("subvol=@home")
//! .mount("/dev/sda1", "/home");
//!
//! match mount_result {
//! Ok(mount) => {
//! // Make the mount temporary, so that it will be unmounted on drop.
//! let mount = mount.into_unmount_drop(UnmountFlags::DETACH);
//! // Do thing with the mounted device.
//! }
//! Err(why) => {
//! eprintln!("failed to mount device: {}", why);
//! exit(1);
//! }
//! }
//! }
extern crate libc;
#[macro_use]
extern crate bitflags;
#[macro_use]
extern crate thiserror;
mod builder;
mod flags;
mod fstype;
mod mount;
mod supported;
mod umount;
pub use self::{builder::*, flags::*, fstype::*, mount::*, supported::*, umount::*};
use libc::swapoff as c_swapoff;
use std::{
ffi::CString,
io::{self, Error, ErrorKind},
os::unix::ffi::OsStrExt,
path::Path,
};
#[derive(Debug, Error)]
pub enum ScopedMountError {
#[error("cannot get list of supported file systems")]
Supported(#[source] io::Error),
#[error("could not mount partition")]
Mount(#[source] io::Error),
}
/// Mount a partition temporarily for the duration of the scoped block within.
///
/// # Errors
///
/// - Fails if the supported file systems cannot be found.
/// - Or if it fails to unmount
pub fn scoped_mount<T, S: FnOnce() -> T>(
source: &Path,
mount_at: &Path,
scope: S,
) -> Result<T, ScopedMountError> {
let supported = SupportedFilesystems::new().map_err(ScopedMountError::Supported)?;
Mount::builder()
.fstype(&supported)
.mount(source, mount_at)
.map_err(ScopedMountError::Mount)?;
let result = scope();
if let Err(why) = unmount(mount_at, UnmountFlags::empty()) {
tracing::warn!("{}: failed to unmount: {}", mount_at.display(), why);
}
Ok(result)
}
/// Unmounts a swap partition using `libc::swapoff`
///
/// # Errors
///
/// - If the destination path is not a valid C String
/// - Or the swapoff function fails
pub fn swapoff<P: AsRef<Path>>(dest: P) -> io::Result<()> {
let Ok(swap) = CString::new(dest.as_ref().as_os_str().as_bytes().to_owned()) else {
return Err(Error::new(
ErrorKind::Other,
format!(
"swap path is not a valid c string: '{}'",
dest.as_ref().display()
)
))
};
match unsafe { c_swapoff(swap.as_ptr()) } {
0 => Ok(()),
_err => Err(Error::new(
ErrorKind::Other,
format!(
"failed to swapoff {}: {}",
dest.as_ref().display(),
Error::last_os_error()
),
)),
}
}
#[inline]
fn to_cstring(data: &[u8]) -> io::Result<CString> {
CString::new(data).map_err(|why| {
io::Error::new(
io::ErrorKind::InvalidData,
format!("failed to create `CString`: {}", why),
)
})
}