81 lines
2.2 KiB
Rust
81 lines
2.2 KiB
Rust
use {
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crate::Error,
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std::io::{Read, Write},
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};
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/// Represents the major and minor numbers of a Unix special Device node
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#[derive(Debug, PartialEq, Eq)]
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pub struct Special {
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pub major: u32,
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pub minor: u32,
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}
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impl Special {
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pub(crate) fn read<T: Read>(reader: &mut T) -> Result<Self, Error> {
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let mut buf = [0; 8];
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reader.read_exact(&mut buf)?;
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let major: [u8; 4] = buf[..4].try_into()?;
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let major = u32::from_le_bytes(major);
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let minor: [u8; 4] = buf[4..].try_into()?;
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let minor = u32::from_le_bytes(minor);
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Ok(Self { major, minor })
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}
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pub(crate) fn write<T: Write>(&self, writer: &mut T) -> Result<(), Error> {
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writer.write_all(&self.major.to_le_bytes())?;
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writer.write_all(&self.minor.to_le_bytes())?;
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Ok(())
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}
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#[cfg(all(target_os = "freebsd", target_arch = "x86_64"))]
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#[allow(clippy::cast_possible_truncation)]
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pub(super) fn from_rdev(rdev: u64) -> Self {
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Self {
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major: ((rdev >> 8) & 0xff) as u32,
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minor: (rdev & 0xffff_00ff) as u32,
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}
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}
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#[cfg(target_os = "linux")]
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#[allow(clippy::cast_possible_truncation)]
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pub(super) fn from_rdev(rdev: u64) -> Self {
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let mut major = 0;
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major |= (rdev & 0x0000_0000_000f_ff00) >> 8;
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major |= (rdev & 0xffff_f000_0000_0000) >> 32;
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let mut minor = 0;
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minor |= rdev & 0x0000_0000_0000_00ff;
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minor |= (rdev & 0x0000_0fff_fff0_0000) >> 12;
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Self {
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major: major as u32,
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minor: minor as u32,
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use std::fs::File;
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#[test]
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fn load_store() {
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{
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let mut fd = File::options()
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.write(true)
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.create(true)
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.truncate(true)
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.open("test/device")
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.unwrap();
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let dev = Special {
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major: 42,
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minor: 69,
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};
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dev.write(&mut fd).unwrap();
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}
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let mut fd = File::open("test/device").unwrap();
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let dev = Special::read(&mut fd).unwrap();
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assert_eq!(dev.major, 42);
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assert_eq!(dev.minor, 69);
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}
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}
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