73 lines
1.7 KiB
Rust
73 lines
1.7 KiB
Rust
// SPDX-License-Identifier: MPL-2.0
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use crate::{
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events::IoEvents,
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fs::{
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device::{Device, DeviceId, DeviceType},
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inode_handle::FileIo,
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},
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prelude::*,
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process::signal::{PollHandle, Pollable},
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util::random::getrandom,
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};
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pub struct Urandom;
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impl Urandom {
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pub fn getrandom(writer: &mut VmWriter) -> Result<usize> {
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const IO_CAPABILITY: usize = 4096;
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if !writer.has_avail() {
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return Ok(0);
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}
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let mut buffer = vec![0; writer.avail().min(IO_CAPABILITY)];
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let mut written_bytes = 0;
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while writer.has_avail() {
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getrandom(&mut buffer[..writer.avail().min(IO_CAPABILITY)]);
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match writer.write_fallible(&mut VmReader::from(buffer.as_slice())) {
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Ok(len) => written_bytes += len,
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Err((err, 0)) if written_bytes == 0 => return Err(err.into()),
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Err((_, len)) => return Ok(written_bytes + len),
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}
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}
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Ok(written_bytes)
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}
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}
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impl Device for Urandom {
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fn type_(&self) -> DeviceType {
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DeviceType::Char
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}
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fn id(&self) -> DeviceId {
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// The same value as Linux
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DeviceId::new(1, 9)
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}
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fn open(&self) -> Result<Option<Arc<dyn FileIo>>> {
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Ok(Some(Arc::new(Urandom)))
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}
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}
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impl Pollable for Urandom {
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fn poll(&self, mask: IoEvents, _poller: Option<&mut PollHandle>) -> IoEvents {
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let events = IoEvents::IN | IoEvents::OUT;
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events & mask
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}
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}
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impl FileIo for Urandom {
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fn read(&self, writer: &mut VmWriter) -> Result<usize> {
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Self::getrandom(writer)
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}
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fn write(&self, reader: &mut VmReader) -> Result<usize> {
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let len = reader.remain();
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reader.skip(len);
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Ok(len)
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}
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}
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