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use std::io::{self, Read};
use std::path::Path;
use std::fs::File;
use std::env;
use rustc::session::Session;
use rustc::session::config::nightly_options;
const FILE_MAGIC: &'static [u8] = b"RSIC";
const HEADER_FORMAT_VERSION: u16 = 0;
const RUSTC_VERSION: Option<&'static str> = option_env!("CFG_VERSION");
pub fn write_file_header<W: io::Write>(stream: &mut W) -> io::Result<()> {
stream.write_all(FILE_MAGIC)?;
stream.write_all(&[(HEADER_FORMAT_VERSION >> 0) as u8,
(HEADER_FORMAT_VERSION >> 8) as u8])?;
let rustc_version = rustc_version();
assert_eq!(rustc_version.len(), (rustc_version.len() as u8) as usize);
stream.write_all(&[rustc_version.len() as u8])?;
stream.write_all(rustc_version.as_bytes())?;
Ok(())
}
pub fn read_file(sess: &Session, path: &Path) -> io::Result<Option<Vec<u8>>> {
if !path.exists() {
return Ok(None);
}
let mut file = File::open(path)?;
{
debug_assert!(FILE_MAGIC.len() == 4);
let mut file_magic = [0u8; 4];
file.read_exact(&mut file_magic)?;
if file_magic != FILE_MAGIC {
report_format_mismatch(sess, path, "Wrong FILE_MAGIC");
return Ok(None)
}
}
{
debug_assert!(::std::mem::size_of_val(&HEADER_FORMAT_VERSION) == 2);
let mut header_format_version = [0u8; 2];
file.read_exact(&mut header_format_version)?;
let header_format_version = (header_format_version[0] as u16) |
((header_format_version[1] as u16) << 8);
if header_format_version != HEADER_FORMAT_VERSION {
report_format_mismatch(sess, path, "Wrong HEADER_FORMAT_VERSION");
return Ok(None)
}
}
{
let mut rustc_version_str_len = [0u8; 1];
file.read_exact(&mut rustc_version_str_len)?;
let rustc_version_str_len = rustc_version_str_len[0] as usize;
let mut buffer = Vec::with_capacity(rustc_version_str_len);
buffer.resize(rustc_version_str_len, 0);
file.read_exact(&mut buffer[..])?;
if &buffer[..] != rustc_version().as_bytes() {
report_format_mismatch(sess, path, "Different compiler version");
return Ok(None);
}
}
let mut data = vec![];
file.read_to_end(&mut data)?;
Ok(Some(data))
}
fn report_format_mismatch(sess: &Session, file: &Path, message: &str) {
debug!("read_file: {}", message);
if sess.opts.debugging_opts.incremental_info {
println!("incremental: ignoring cache artifact `{}`: {}",
file.file_name().unwrap().to_string_lossy(),
message);
}
}
fn rustc_version() -> String {
if nightly_options::is_nightly_build() {
if let Some(val) = env::var_os("RUSTC_FORCE_INCR_COMP_ARTIFACT_HEADER") {
return val.to_string_lossy().into_owned()
}
}
RUSTC_VERSION.expect("Cannot use rustc without explicit version for \
incremental compilation")
.to_string()
}