rust/src/librustc_fs_util/lib.rs
2018-08-09 10:00:25 -06:00

129 lines
4.1 KiB
Rust

// Copyright 2018 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.
use std::path::{Path, PathBuf};
use std::ffi::CString;
use std::fs;
use std::io;
// Unfortunately, on windows, it looks like msvcrt.dll is silently translating
// verbatim paths under the hood to non-verbatim paths! This manifests itself as
// gcc looking like it cannot accept paths of the form `\\?\C:\...`, but the
// real bug seems to lie in msvcrt.dll.
//
// Verbatim paths are generally pretty rare, but the implementation of
// `fs::canonicalize` currently generates paths of this form, meaning that we're
// going to be passing quite a few of these down to gcc, so we need to deal with
// this case.
//
// For now we just strip the "verbatim prefix" of `\\?\` from the path. This
// will probably lose information in some cases, but there's not a whole lot
// more we can do with a buggy msvcrt...
//
// For some more information, see this comment:
// https://github.com/rust-lang/rust/issues/25505#issuecomment-102876737
#[cfg(windows)]
pub fn fix_windows_verbatim_for_gcc(p: &Path) -> PathBuf {
use std::path;
use std::ffi::OsString;
let mut components = p.components();
let prefix = match components.next() {
Some(path::Component::Prefix(p)) => p,
_ => return p.to_path_buf(),
};
match prefix.kind() {
path::Prefix::VerbatimDisk(disk) => {
let mut base = OsString::from(format!("{}:", disk as char));
base.push(components.as_path());
PathBuf::from(base)
}
path::Prefix::VerbatimUNC(server, share) => {
let mut base = OsString::from(r"\\");
base.push(server);
base.push(r"\");
base.push(share);
base.push(components.as_path());
PathBuf::from(base)
}
_ => p.to_path_buf(),
}
}
#[cfg(not(windows))]
pub fn fix_windows_verbatim_for_gcc(p: &Path) -> PathBuf {
p.to_path_buf()
}
pub enum LinkOrCopy {
Link,
Copy,
}
/// Copy `p` into `q`, preferring to use hard-linking if possible. If
/// `q` already exists, it is removed first.
/// The result indicates which of the two operations has been performed.
pub fn link_or_copy<P: AsRef<Path>, Q: AsRef<Path>>(p: P, q: Q) -> io::Result<LinkOrCopy> {
let p = p.as_ref();
let q = q.as_ref();
if q.exists() {
fs::remove_file(&q)?;
}
match fs::hard_link(p, q) {
Ok(()) => Ok(LinkOrCopy::Link),
Err(_) => {
match fs::copy(p, q) {
Ok(_) => Ok(LinkOrCopy::Copy),
Err(e) => Err(e),
}
}
}
}
#[derive(Debug)]
pub enum RenameOrCopyRemove {
Rename,
CopyRemove,
}
/// Rename `p` into `q`, preferring to use `rename` if possible.
/// If `rename` fails (rename may fail for reasons such as crossing
/// filesystem), fallback to copy & remove
pub fn rename_or_copy_remove<P: AsRef<Path>, Q: AsRef<Path>>(p: P,
q: Q)
-> io::Result<RenameOrCopyRemove> {
let p = p.as_ref();
let q = q.as_ref();
match fs::rename(p, q) {
Ok(()) => Ok(RenameOrCopyRemove::Rename),
Err(_) => {
match fs::copy(p, q) {
Ok(_) => {
fs::remove_file(p)?;
Ok(RenameOrCopyRemove::CopyRemove)
}
Err(e) => Err(e),
}
}
}
}
#[cfg(unix)]
pub fn path2cstr(p: &Path) -> CString {
use std::os::unix::prelude::*;
use std::ffi::OsStr;
let p: &OsStr = p.as_ref();
CString::new(p.as_bytes()).unwrap()
}
#[cfg(windows)]
pub fn path2cstr(p: &Path) -> CString {
CString::new(p.to_str().unwrap()).unwrap()
}