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|
use std::{
ffi::{OsStr, OsString},
os::unix::{
ffi::OsStrExt,
io::{AsRawFd, IntoRawFd, RawFd},
net::UnixStream,
},
process::Command,
};
use nix::{
self, cmsg_space,
fcntl::{fcntl, FcntlArg, FdFlag},
sys::socket::{recvmsg, ControlMessageOwned, MsgFlags},
};
use quick_error::quick_error;
use super::Start;
use crate::util::{from_nix_error, DumbFd};
quick_error! {
#[derive(Debug)]
pub enum MountError {
Io(err: std::io::Error) { from() }
Fusermount { display("fusermount failed") }
}
}
#[derive(Default)]
pub struct Options(OsString);
impl Options {
pub fn fs_name<O: AsRef<OsStr>>(&mut self, fs_name: O) -> &mut Self {
self.push_key_value("fsname", fs_name)
}
pub fn read_only(&mut self) -> &mut Self {
self.push("ro")
}
pub fn push<O: AsRef<OsStr>>(&mut self, option: O) -> &mut Self {
self.push_parts(&[option.as_ref()])
}
pub fn push_key_value<K, V>(&mut self, key: K, value: V) -> &mut Self
where
K: AsRef<OsStr>,
V: AsRef<OsStr>,
{
let (key, value) = (key.as_ref(), value.as_ref());
let assert_valid = |part: &OsStr| {
let bytes = part.as_bytes();
assert!(
!bytes.is_empty() && bytes.iter().all(|b| !matches!(*b, b',' | b'=')),
"invalid key or value: {}",
part.to_string_lossy()
);
};
assert_valid(key);
assert_valid(value);
self.push_parts(&[key, OsStr::new("="), value])
}
fn push_parts(&mut self, segment: &[&OsStr]) -> &mut Self {
if !self.0.is_empty() {
self.0.push(",");
}
let start = self.0.as_bytes().len();
segment.iter().for_each(|part| self.0.push(part));
let bytes = self.0.as_bytes();
let last = bytes.len() - 1;
assert!(
last >= start && bytes[start] != b',' && bytes[last] != b',',
"invalid option string: {}",
OsStr::from_bytes(&bytes[start..]).to_string_lossy()
);
self
}
}
impl<O: AsRef<OsStr>> Extend<O> for Options {
fn extend<I: IntoIterator<Item = O>>(&mut self, iter: I) {
iter.into_iter().for_each(|option| {
self.push(option);
});
}
}
pub fn mount_sync<M>(mountpoint: M, options: &Options) -> Result<Start, MountError>
where
M: AsRef<OsStr>,
{
let (left_side, right_side) = UnixStream::pair()?;
// The fusermount protocol requires us to preserve right_fd across execve()
let right_fd = right_side.as_raw_fd();
fcntl(
right_fd,
FcntlArg::F_SETFD(
FdFlag::from_bits(fcntl(right_fd, FcntlArg::F_GETFD).unwrap()).unwrap()
& !FdFlag::FD_CLOEXEC,
),
)
.unwrap();
let mut command = Command::new("fusermount3");
if !options.0.is_empty() {
command.args(&[OsStr::new("-o"), &options.0, mountpoint.as_ref()]);
} else {
command.arg(mountpoint);
};
let mut fusermount = command.env("_FUSE_COMMFD", right_fd.to_string()).spawn()?;
// recvmsg() should fail if fusermount exits (last open fd is closed)
drop(right_side);
let session_fd = (|| {
let mut buffer = cmsg_space!(RawFd);
let message = recvmsg(
left_side.as_raw_fd(),
&[],
Some(&mut buffer),
MsgFlags::empty(),
)
.map_err(from_nix_error)?;
let session_fd = match message.cmsgs().next() {
Some(ControlMessageOwned::ScmRights(fds)) => fds.into_iter().next(),
_ => None,
};
session_fd.ok_or(MountError::Fusermount)
})();
match session_fd {
Ok(session_fd) => {
let fusermount_fd = DumbFd(left_side.into_raw_fd());
let session_fd = DumbFd(session_fd);
Ok(Start {
fusermount_fd,
session_fd,
})
}
Err(error) => {
drop(left_side);
fusermount.wait()?;
Err(error)
}
}
}
|
