103 lines
2.9 KiB
Rust
103 lines
2.9 KiB
Rust
use collections::BTreeMap;
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use core::cmp;
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use core::sync::atomic::{AtomicUsize, Ordering};
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use spin::RwLock;
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use syscall::error::*;
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use syscall::flag::{SEEK_SET, SEEK_CUR, SEEK_END};
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use syscall::scheme::Scheme;
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struct Handle {
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data: &'static [u8],
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seek: usize
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}
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pub struct EnvScheme {
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next_id: AtomicUsize,
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files: BTreeMap<&'static [u8], &'static [u8]>,
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handles: RwLock<BTreeMap<usize, Handle>>
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}
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impl EnvScheme {
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pub fn new() -> EnvScheme {
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let mut files: BTreeMap<&'static [u8], &'static [u8]> = BTreeMap::new();
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files.insert(b"HOME", b"initfs:");
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files.insert(b"PWD", b"initfs:");
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files.insert(b"COLUMNS", b"80");
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files.insert(b"LINES", b"30");
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EnvScheme {
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next_id: AtomicUsize::new(0),
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files: files,
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handles: RwLock::new(BTreeMap::new())
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}
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}
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}
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impl Scheme for EnvScheme {
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fn open(&self, path: &[u8], _flags: usize) -> Result<usize> {
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let data = self.files.get(path).ok_or(Error::new(ENOENT))?;
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let id = self.next_id.fetch_add(1, Ordering::SeqCst);
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self.handles.write().insert(id, Handle {
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data: data,
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seek: 0
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});
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Ok(id)
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}
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fn dup(&self, file: usize) -> Result<usize> {
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let (data, seek) = {
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let handles = self.handles.read();
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let handle = handles.get(&file).ok_or(Error::new(EBADF))?;
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(handle.data, handle.seek)
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};
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let id = self.next_id.fetch_add(1, Ordering::SeqCst);
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self.handles.write().insert(id, Handle {
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data: data,
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seek: seek
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});
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Ok(id)
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}
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fn read(&self, file: usize, buffer: &mut [u8]) -> Result<usize> {
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let mut handles = self.handles.write();
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let mut handle = handles.get_mut(&file).ok_or(Error::new(EBADF))?;
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let mut i = 0;
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while i < buffer.len() && handle.seek < handle.data.len() {
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buffer[i] = handle.data[handle.seek];
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i += 1;
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handle.seek += 1;
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}
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Ok(i)
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}
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fn seek(&self, id: usize, pos: usize, whence: usize) -> Result<usize> {
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let mut handles = self.handles.write();
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let mut handle = handles.get_mut(&id).ok_or(Error::new(EBADF))?;
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handle.seek = match whence {
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SEEK_SET => cmp::min(handle.data.len(), pos),
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SEEK_CUR => cmp::max(0, cmp::min(handle.data.len() as isize, handle.seek as isize + pos as isize)) as usize,
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SEEK_END => cmp::max(0, cmp::min(handle.data.len() as isize, handle.data.len() as isize + pos as isize)) as usize,
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_ => return Err(Error::new(EINVAL))
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};
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Ok(handle.seek)
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}
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fn fsync(&self, _file: usize) -> Result<usize> {
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Ok(0)
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}
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fn close(&self, file: usize) -> Result<usize> {
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self.handles.write().remove(&file).ok_or(Error::new(EBADF)).and(Ok(0))
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}
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}
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