diff --git a/src/librustc_incremental/persist/file_format.rs b/src/librustc_incremental/persist/file_format.rs
new file mode 100644
index 00000000000..79971740f5d
--- /dev/null
+++ b/src/librustc_incremental/persist/file_format.rs
@@ -0,0 +1,105 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! This module defines a generic file format that allows to check if a given
+//! file generated by incremental compilation was generated by a compatible
+//! compiler version. This file format is used for the on-disk version of the
+//! dependency graph and the exported metadata hashes.
+//!
+//! In practice "compatible compiler version" means "exactly the same compiler
+//! version", since the header encodes the git commit hash of the compiler.
+//! Since we can always just ignore the incremental compilation cache and
+//! compiler versions don't change frequently for the typical user, being
+//! conservative here practically has no downside.
+
+use std::io::{self, Read};
+use std::path::Path;
+use std::fs::File;
+
+/// The first few bytes of files generated by incremental compilation
+const FILE_MAGIC: &'static [u8] = b"RSIC";
+
+/// Change this if the header format changes
+const HEADER_FORMAT_VERSION: u16 = 0;
+
+/// A version string that hopefully is always different for compiler versions
+/// with different encodings of incremental compilation artifacts. Contains
+/// the git commit hash.
+const RUSTC_VERSION: &'static str = 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])?;
+ 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(())
+}
+
+/// Reads the contents of a file with a file header as defined in this module.
+///
+/// - Returns `Ok(Some(data))` if the file existed and was generated by a
+/// compatible compiler version. `data` is the entire contents of the file
+/// *after* the header.
+/// - Returns `Ok(None)` if the file did not exist or was generated by an
+/// incompatible version of the compiler.
+/// - Returns `Err(..)` if some kind of IO error occurred while reading the
+/// file.
+pub fn read_file(path: &Path) -> io::Result<Option<Vec<u8>>> {
+ if !path.exists() {
+ return Ok(None);
+ }
+
+ let mut file = File::open(path)?;
+
+ // Check FILE_MAGIC
+ {
+ debug_assert!(FILE_MAGIC.len() == 4);
+ let mut file_magic = [0u8; 4];
+ file.read_exact(&mut file_magic)?;
+ if file_magic != FILE_MAGIC {
+ return Ok(None)
+ }
+ }
+
+ // Check HEADER_FORMAT_VERSION
+ {
+ 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 {
+ return Ok(None)
+ }
+ }
+
+ // Check RUSTC_VERSION
+ {
+ 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() {
+ return Ok(None);
+ }
+ }
+
+ let mut data = vec![];
+ file.read_to_end(&mut data)?;
+
+ Ok(Some(data))
+}
diff --git a/src/librustc_incremental/persist/fs.rs b/src/librustc_incremental/persist/fs.rs
index c9cfaf4f661..2d28afeaebf 100644
--- a/src/librustc_incremental/persist/fs.rs
+++ b/src/librustc_incremental/persist/fs.rs
@@ -345,6 +345,15 @@ pub fn finalize_session_directory(sess: &Session, svh: Svh) {
let _ = garbage_collect_session_directories(sess);
}
+pub fn delete_all_session_dir_contents(sess: &Session) -> io::Result<()> {
+ let sess_dir_iterator = sess.incr_comp_session_dir().read_dir()?;
+ for entry in sess_dir_iterator {
+ let entry = entry?;
+ safe_remove_file(&entry.path())?
+ }
+ Ok(())
+}
+
fn copy_files(target_dir: &Path,
source_dir: &Path,
print_stats_on_success: bool)
diff --git a/src/librustc_incremental/persist/hash.rs b/src/librustc_incremental/persist/hash.rs
index 5a4716e45f6..ca173db15fc 100644
--- a/src/librustc_incremental/persist/hash.rs
+++ b/src/librustc_incremental/persist/hash.rs
@@ -16,12 +16,11 @@ use rustc_data_structures::fnv::FnvHashMap;
use rustc_data_structures::flock;
use rustc_serialize::Decodable;
use rustc_serialize::opaque::Decoder;
-use std::io::{ErrorKind, Read};
-use std::fs::File;
use IncrementalHashesMap;
use super::data::*;
use super::fs::*;
+use super::file_format;
pub struct HashContext<'a, 'tcx: 'a> {
pub tcx: TyCtxt<'a, 'tcx, 'tcx>,
@@ -153,12 +152,9 @@ impl<'a, 'tcx> HashContext<'a, 'tcx> {
let hashes_file_path = metadata_hash_import_path(&session_dir);
- let mut data = vec![];
- match
- File::open(&hashes_file_path)
- .and_then(|mut file| file.read_to_end(&mut data))
+ match file_format::read_file(&hashes_file_path)
{
- Ok(_) => {
+ Ok(Some(data)) => {
match self.load_from_data(cnum, &data, svh) {
Ok(()) => { }
Err(err) => {
@@ -167,18 +163,13 @@ impl<'a, 'tcx> HashContext<'a, 'tcx> {
}
}
}
+ Ok(None) => {
+ // If the file is not found, that's ok.
+ }
Err(err) => {
- match err.kind() {
- ErrorKind::NotFound => {
- // If the file is not found, that's ok.
- }
- _ => {
- self.tcx.sess.err(
- &format!("could not load dep information from `{}`: {}",
- hashes_file_path.display(), err));
- return;
- }
- }
+ self.tcx.sess.err(
+ &format!("could not load dep information from `{}`: {}",
+ hashes_file_path.display(), err));
}
}
}
diff --git a/src/librustc_incremental/persist/load.rs b/src/librustc_incremental/persist/load.rs
index ba15529c81a..db8d3125e51 100644
--- a/src/librustc_incremental/persist/load.rs
+++ b/src/librustc_incremental/persist/load.rs
@@ -18,8 +18,7 @@ use rustc::ty::TyCtxt;
use rustc_data_structures::fnv::{FnvHashSet, FnvHashMap};
use rustc_serialize::Decodable as RustcDecodable;
use rustc_serialize::opaque::Decoder;
-use std::io::Read;
-use std::fs::{self, File};
+use std::fs;
use std::path::{Path};
use IncrementalHashesMap;
@@ -28,6 +27,7 @@ use super::directory::*;
use super::dirty_clean;
use super::hash::*;
use super::fs::*;
+use super::file_format;
pub type DirtyNodes = FnvHashSet<DepNode<DefPathIndex>>;
@@ -94,25 +94,26 @@ fn load_dep_graph_if_exists<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
}
fn load_data(sess: &Session, path: &Path) -> Option<Vec<u8>> {
- if !path.exists() {
- return None;
- }
-
- let mut data = vec![];
- match
- File::open(path)
- .and_then(|mut file| file.read_to_end(&mut data))
- {
- Ok(_) => {
- Some(data)
+ match file_format::read_file(path) {
+ Ok(Some(data)) => return Some(data),
+ Ok(None) => {
+ // The file either didn't exist or was produced by an incompatible
+ // compiler version. Neither is an error.
}
Err(err) => {
sess.err(
&format!("could not load dep-graph from `{}`: {}",
path.display(), err));
- None
}
}
+
+ if let Err(err) = delete_all_session_dir_contents(sess) {
+ sess.err(&format!("could not clear incompatible incremental \
+ compilation session directory `{}`: {}",
+ path.display(), err));
+ }
+
+ None
}
/// Decode the dep graph and load the edges/nodes that are still clean
@@ -331,16 +332,22 @@ fn load_prev_metadata_hashes(tcx: TyCtxt,
debug!("load_prev_metadata_hashes() - File: {}", file_path.display());
- let mut data = vec![];
- if !File::open(&file_path)
- .and_then(|mut file| file.read_to_end(&mut data)).is_ok() {
- debug!("load_prev_metadata_hashes() - Couldn't read file containing \
- hashes at `{}`", file_path.display());
- return
- }
+ let data = match file_format::read_file(&file_path) {
+ Ok(Some(data)) => data,
+ Ok(None) => {
+ debug!("load_prev_metadata_hashes() - File produced by incompatible \
+ compiler version: {}", file_path.display());
+ return
+ }
+ Err(err) => {
+ debug!("load_prev_metadata_hashes() - Error reading file `{}`: {}",
+ file_path.display(), err);
+ return
+ }
+ };
debug!("load_prev_metadata_hashes() - Decoding hashes");
- let mut decoder = Decoder::new(&mut data, 0);
+ let mut decoder = Decoder::new(&data, 0);
let _ = Svh::decode(&mut decoder).unwrap();
let serialized_hashes = SerializedMetadataHashes::decode(&mut decoder).unwrap();
@@ -358,3 +365,4 @@ fn load_prev_metadata_hashes(tcx: TyCtxt,
debug!("load_prev_metadata_hashes() - successfully loaded {} hashes",
serialized_hashes.index_map.len());
}
+
diff --git a/src/librustc_incremental/persist/mod.rs b/src/librustc_incremental/persist/mod.rs
index ba0f71971bb..26fcde05868 100644
--- a/src/librustc_incremental/persist/mod.rs
+++ b/src/librustc_incremental/persist/mod.rs
@@ -21,6 +21,7 @@ mod load;
mod preds;
mod save;
mod work_product;
+mod file_format;
pub use self::fs::finalize_session_directory;
pub use self::fs::in_incr_comp_dir;
diff --git a/src/librustc_incremental/persist/save.rs b/src/librustc_incremental/persist/save.rs
index 896e8a9845e..e6fb1da1982 100644
--- a/src/librustc_incremental/persist/save.rs
+++ b/src/librustc_incremental/persist/save.rs
@@ -28,6 +28,7 @@ use super::hash::*;
use super::preds::*;
use super::fs::*;
use super::dirty_clean;
+use super::file_format;
pub fn save_dep_graph<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
incremental_hashes_map: &IncrementalHashesMap,
@@ -102,6 +103,7 @@ fn save_in<F>(sess: &Session, path_buf: PathBuf, encode: F)
// generate the data in a memory buffer
let mut wr = Cursor::new(Vec::new());
+ file_format::write_file_header(&mut wr).unwrap();
match encode(&mut Encoder::new(&mut wr)) {
Ok(()) => {}
Err(err) => {