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use std::io::{Read, Write};
use std::ptr;
use std::str;
use flate2::Compression;
use flate2::read::DeflateDecoder;
use flate2::write::DeflateEncoder;
pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
pub const RLIB_BYTECODE_OBJECT_VERSION: u8 = 2;
pub const RLIB_BYTECODE_EXTENSION: &str = "bc.z";
pub fn encode(identifier: &str, bytecode: &[u8]) -> Vec<u8> {
let mut encoded = Vec::new();
encoded.extend_from_slice(RLIB_BYTECODE_OBJECT_MAGIC);
encoded.extend_from_slice(&[RLIB_BYTECODE_OBJECT_VERSION, 0, 0, 0]);
let identifier_len = identifier.len();
encoded.extend_from_slice(&[
(identifier_len >> 0) as u8,
(identifier_len >> 8) as u8,
(identifier_len >> 16) as u8,
(identifier_len >> 24) as u8,
]);
encoded.extend_from_slice(identifier.as_bytes());
let deflated_size_pos = encoded.len();
encoded.extend_from_slice(&[0, 0, 0, 0, 0, 0, 0, 0]);
let before = encoded.len();
DeflateEncoder::new(&mut encoded, Compression::fast())
.write_all(bytecode)
.unwrap();
let after = encoded.len();
let bytecode_len = (after - before) as u64;
encoded[deflated_size_pos + 0] = (bytecode_len >> 0) as u8;
encoded[deflated_size_pos + 1] = (bytecode_len >> 8) as u8;
encoded[deflated_size_pos + 2] = (bytecode_len >> 16) as u8;
encoded[deflated_size_pos + 3] = (bytecode_len >> 24) as u8;
encoded[deflated_size_pos + 4] = (bytecode_len >> 32) as u8;
encoded[deflated_size_pos + 5] = (bytecode_len >> 40) as u8;
encoded[deflated_size_pos + 6] = (bytecode_len >> 48) as u8;
encoded[deflated_size_pos + 7] = (bytecode_len >> 56) as u8;
if encoded.len() % 2 == 1 {
encoded.push(0);
}
return encoded
}
pub struct DecodedBytecode<'a> {
identifier: &'a str,
encoded_bytecode: &'a [u8],
}
impl<'a> DecodedBytecode<'a> {
pub fn new(data: &'a [u8]) -> Result<DecodedBytecode<'a>, String> {
if !data.starts_with(RLIB_BYTECODE_OBJECT_MAGIC) {
return Err("magic bytecode prefix not found".to_string())
}
let data = &data[RLIB_BYTECODE_OBJECT_MAGIC.len()..];
if !data.starts_with(&[RLIB_BYTECODE_OBJECT_VERSION, 0, 0, 0]) {
return Err("wrong version prefix found in bytecode".to_string())
}
let data = &data[4..];
if data.len() < 4 {
return Err("bytecode corrupted".to_string())
}
let identifier_len = unsafe {
u32::from_le(ptr::read_unaligned(data.as_ptr() as *const u32)) as usize
};
let data = &data[4..];
if data.len() < identifier_len {
return Err("bytecode corrupted".to_string())
}
let identifier = match str::from_utf8(&data[..identifier_len]) {
Ok(s) => s,
Err(_) => return Err("bytecode corrupted".to_string())
};
let data = &data[identifier_len..];
if data.len() < 8 {
return Err("bytecode corrupted".to_string())
}
let bytecode_len = unsafe {
u64::from_le(ptr::read_unaligned(data.as_ptr() as *const u64)) as usize
};
let data = &data[8..];
if data.len() < bytecode_len {
return Err("bytecode corrupted".to_string())
}
let encoded_bytecode = &data[..bytecode_len];
Ok(DecodedBytecode {
identifier,
encoded_bytecode,
})
}
pub fn bytecode(&self) -> Vec<u8> {
let mut data = Vec::new();
DeflateDecoder::new(self.encoded_bytecode).read_to_end(&mut data).unwrap();
return data
}
pub fn identifier(&self) -> &'a str {
self.identifier
}
}