1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137

use std::ffi::{OsStr, OsString};
use std::io;
use std::mem;
use std::os::unix::ffi::OsStrExt;
use std::os::unix::io::BorrowedFd;
use std::path::Path;

use rustix::fs as rfs;
use rustix::path::Arg;

use crate::util::allocate_loop;

use std::os::raw::c_char;

#[cfg(not(target_os = "macos"))]
pub const ENOATTR: i32 = rustix::io::Errno::NODATA.raw_os_error();

#[cfg(target_os = "macos")]
pub const ENOATTR: i32 = rustix::io::Errno::NOATTR.raw_os_error();

// Convert an `&mut [u8]` to an `&mut [c_char]`
#[inline]
fn as_listxattr_buffer(buf: &mut [u8]) -> &mut [c_char] {
    // SAFETY: u8 and i8 have the same size and alignment
    unsafe {
        &mut *(buf as *mut [u8] as *mut [c_char])
    }
}

/// An iterator over a set of extended attributes names.
pub struct XAttrs {
    data: Box<[u8]>,
    offset: usize,
}

impl Clone for XAttrs {
    fn clone(&self) -> Self {
        XAttrs {
            data: Vec::from(&*self.data).into_boxed_slice(),
            offset: self.offset,
        }
    }
    fn clone_from(&mut self, other: &XAttrs) {
        self.offset = other.offset;

        let mut data = mem::replace(&mut self.data, Box::new([])).into_vec();
        data.extend(other.data.iter().cloned());
        self.data = data.into_boxed_slice();
    }
}

// Yes, I could avoid these allocations on linux/macos. However, if we ever want to be freebsd
// compatible, we need to be able to prepend the namespace to the extended attribute names.
// Furthermore, borrowing makes the API messy.
impl Iterator for XAttrs {
    type Item = OsString;
    fn next(&mut self) -> Option<OsString> {
        let data = &self.data[self.offset..];
        if data.is_empty() {
            None
        } else {
            // always null terminated (unless empty).
            let end = data.iter().position(|&b| b == 0u8).unwrap();
            self.offset += end + 1;
            Some(OsStr::from_bytes(&data[..end]).to_owned())
        }
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.data.len() == self.offset {
            (0, Some(0))
        } else {
            (1, None)
        }
    }
}

pub fn get_fd(fd: BorrowedFd<'_>, name: &OsStr) -> io::Result<Vec<u8>> {
    allocate_loop(|buf| {
        rfs::fgetxattr(fd, name, buf)
    })
}

pub fn set_fd(fd: BorrowedFd<'_>, name: &OsStr, value: &[u8]) -> io::Result<()> {
    rfs::fsetxattr(fd, name, value, rfs::XattrFlags::empty())?;
    Ok(())
}

pub fn remove_fd(fd: BorrowedFd<'_>, name: &OsStr) -> io::Result<()> {
    rfs::fremovexattr(fd, name)?;
    Ok(())
}

pub fn list_fd(fd: BorrowedFd<'_>) -> io::Result<XAttrs> {
    let vec = allocate_loop(|buf| {
        rfs::flistxattr(fd, as_listxattr_buffer(buf))
    })?;
    Ok(XAttrs {
        data: vec.into_boxed_slice(),
        offset: 0,
    })
}

pub fn get_path(path: &Path, name: &OsStr, deref: bool) -> io::Result<Vec<u8>> {
    let path = path.into_c_str()?;
    let name = name.into_c_str()?;

    allocate_loop(|buf| {
        let getxattr_func = if deref { rfs::getxattr } else { rfs::lgetxattr };
        let size = getxattr_func(&*path, &*name, buf)?;
        io::Result::Ok(size)
    })
}

pub fn set_path(path: &Path, name: &OsStr, value: &[u8], deref: bool) -> io::Result<()> {
    let setxattr_func = if deref { rfs::setxattr } else { rfs::lsetxattr };
    setxattr_func(path, name, value, rfs::XattrFlags::empty())?;
    Ok(())
}

pub fn remove_path(path: &Path, name: &OsStr, deref: bool) -> io::Result<()> {
    let removexattr_func = if deref { rfs::removexattr } else { rfs::lremovexattr };
    removexattr_func(path, name)?;
    Ok(())
}

pub fn list_path(path: &Path, deref: bool) -> io::Result<XAttrs> {
    let listxattr_func = if deref { rfs::listxattr } else { rfs::llistxattr };
    let path = path.as_cow_c_str()?;
    let vec = allocate_loop(|buf| {
        listxattr_func(&*path, as_listxattr_buffer(buf))
    })?;
    Ok(XAttrs {
        data: vec.into_boxed_slice(),
        offset: 0,
    })
}