d586574b1f
building up a bunch of deferred errors in the CtxBuilder sucks. so does reporting errors right away. Idk what to do here?
72 lines
2.2 KiB
Rust
72 lines
2.2 KiB
Rust
use crate::Error;
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use wiggle::GuestPtr;
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pub struct StringArray {
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elems: Vec<String>,
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}
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#[derive(Debug, thiserror::Error)]
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pub enum StringArrayError {
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#[error("Number of elements exceeds 2^32")]
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NumberElements,
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#[error("Element size exceeds 2^32")]
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ElementSize,
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#[error("Cumulative size exceeds 2^32")]
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CumulativeSize,
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}
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impl StringArray {
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pub fn new() -> Self {
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StringArray { elems: Vec::new() }
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}
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pub fn push(&mut self, elem: String) -> Result<(), StringArrayError> {
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if self.elems.len() + 1 > std::u32::MAX as usize {
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return Err(StringArrayError::NumberElements);
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}
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if elem.as_bytes().len() + 1 > std::u32::MAX as usize {
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return Err(StringArrayError::ElementSize);
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}
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if self.cumulative_size() as usize + elem.as_bytes().len() + 1 > std::u32::MAX as usize {
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return Err(StringArrayError::CumulativeSize);
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}
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self.elems.push(elem);
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Ok(())
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}
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pub fn number_elements(&self) -> u32 {
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self.elems.len() as u32
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}
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pub fn cumulative_size(&self) -> u32 {
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self.elems
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.iter()
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.map(|e| e.as_bytes().len() + 1)
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.sum::<usize>() as u32
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}
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pub fn write_to_guest<'a>(
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&self,
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buffer: &GuestPtr<'a, u8>,
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element_heads: &GuestPtr<'a, GuestPtr<'a, u8>>,
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) -> Result<(), Error> {
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let element_heads = element_heads.as_array(self.number_elements());
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let buffer = buffer.as_array(self.cumulative_size());
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let mut cursor = 0;
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for (elem, head) in self.elems.iter().zip(element_heads.iter()) {
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let bytes = elem.as_bytes();
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let len = bytes.len() as u32;
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{
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let elem_buffer = buffer
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.get_range(cursor..(cursor + len))
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.ok_or(Error::Inval)?; // Elements don't fit in buffer provided
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elem_buffer.copy_from_slice(bytes)?;
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}
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buffer.get(cursor + len).ok_or(Error::Inval)?.write(0)?; // 0 terminate
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head?.write(buffer.get(cursor).expect("already validated"))?;
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cursor += len + 1;
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}
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Ok(())
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}
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}
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