Files
wasmtime/crates/wasi-common/src/string_array.rs
2020-09-02 17:16:39 -07:00

146 lines
4.6 KiB
Rust

use crate::Error;
use std::collections::HashMap;
use std::convert::TryInto;
use std::ffi::{CString, OsString};
use wiggle::GuestPtr;
#[derive(Debug, Eq, Hash, PartialEq)]
pub enum PendingString {
Bytes(Vec<u8>),
OsString(OsString),
}
impl From<Vec<u8>> for PendingString {
fn from(bytes: Vec<u8>) -> Self {
Self::Bytes(bytes)
}
}
impl From<OsString> for PendingString {
fn from(s: OsString) -> Self {
Self::OsString(s)
}
}
impl PendingString {
pub fn into_string(self) -> Result<String, StringArrayError> {
let res = match self {
Self::Bytes(v) => String::from_utf8(v)?,
#[cfg(unix)]
Self::OsString(s) => {
use std::os::unix::ffi::OsStringExt;
String::from_utf8(s.into_vec())?
}
#[cfg(windows)]
Self::OsString(s) => {
use std::os::windows::ffi::OsStrExt;
let bytes: Vec<u16> = s.encode_wide().collect();
String::from_utf16(&bytes)?
}
};
Ok(res)
}
}
#[derive(Debug, thiserror::Error)]
pub enum StringArrayError {
/// Provided sequence of bytes contained an unexpected NUL byte.
#[error("provided sequence contained an unexpected NUL byte")]
Nul(#[from] std::ffi::NulError),
/// Too many elements: must fit into u32
#[error("too many elements")]
NumElements,
/// Element size: must fit into u32
#[error("element too big")]
ElemSize,
/// Cumulative element size: must fit into u32
#[error("cumulative element size too big")]
CumElemSize,
/// Provided sequence of bytes was not a valid UTF-8.
#[error("provided sequence is not valid UTF-8: {0}")]
InvalidUtf8(#[from] std::string::FromUtf8Error),
/// Provided sequence of bytes was not a valid UTF-16.
///
/// This error is expected to only occur on Windows hosts.
#[error("provided sequence is not valid UTF-16: {0}")]
InvalidUtf16(#[from] std::string::FromUtf16Error),
}
pub struct StringArray {
elems: Vec<CString>,
pub number_elements: u32,
pub cumulative_size: u32,
}
impl StringArray {
pub fn from_pending_vec(elems: Vec<PendingString>) -> Result<Self, StringArrayError> {
let elems = elems
.into_iter()
.map(|arg| arg.into_string())
.collect::<Result<Vec<String>, StringArrayError>>()?;
Self::from_strings(elems)
}
pub fn from_pending_map(
elems: HashMap<PendingString, PendingString>,
) -> Result<Self, StringArrayError> {
let mut pairs = Vec::new();
for (k, v) in elems.into_iter() {
let mut pair = k.into_string()?;
pair.push('=');
pair.push_str(&v.into_string()?);
pairs.push(pair);
}
Self::from_strings(pairs)
}
pub fn from_strings(elems: Vec<String>) -> Result<Self, StringArrayError> {
let elems = elems
.into_iter()
.map(|s| CString::new(s))
.collect::<Result<Vec<CString>, _>>()?;
let number_elements = elems
.len()
.try_into()
.map_err(|_| StringArrayError::NumElements)?;
let mut cumulative_size: u32 = 0;
for elem in elems.iter() {
let elem_bytes = elem
.as_bytes_with_nul()
.len()
.try_into()
.map_err(|_| StringArrayError::ElemSize)?;
cumulative_size = cumulative_size
.checked_add(elem_bytes)
.ok_or(StringArrayError::CumElemSize)?;
}
Ok(Self {
elems,
number_elements,
cumulative_size,
})
}
pub fn write_to_guest<'a>(
&self,
buffer: &GuestPtr<'a, u8>,
element_heads: &GuestPtr<'a, GuestPtr<'a, u8>>,
) -> Result<(), Error> {
let element_heads = element_heads.as_array(self.number_elements);
let buffer = buffer.as_array(self.cumulative_size);
let mut cursor = 0;
for (elem, head) in self.elems.iter().zip(element_heads.iter()) {
let bytes = elem.as_bytes_with_nul();
let len: u32 = bytes.len().try_into()?;
let elem_buffer = buffer
.get_range(cursor..(cursor + len))
.ok_or(Error::Inval)?; // Elements don't fit in buffer provided
elem_buffer.copy_from_slice(bytes)?;
head?.write(
elem_buffer
.get(0)
.expect("all elem buffers at least length 1"),
)?;
cursor += len;
}
Ok(())
}
}