rustc_fs_util/
lib.rs

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1use std::ffi::CString;
2use std::path::{Path, PathBuf, absolute};
3use std::{fs, io};
4
5// Unfortunately, on windows, it looks like msvcrt.dll is silently translating
6// verbatim paths under the hood to non-verbatim paths! This manifests itself as
7// gcc looking like it cannot accept paths of the form `\\?\C:\...`, but the
8// real bug seems to lie in msvcrt.dll.
9//
10// Verbatim paths are generally pretty rare, but the implementation of
11// `fs::canonicalize` currently generates paths of this form, meaning that we're
12// going to be passing quite a few of these down to gcc, so we need to deal with
13// this case.
14//
15// For now we just strip the "verbatim prefix" of `\\?\` from the path. This
16// will probably lose information in some cases, but there's not a whole lot
17// more we can do with a buggy msvcrt...
18//
19// For some more information, see this comment:
20//   https://github.com/rust-lang/rust/issues/25505#issuecomment-102876737
21#[cfg(windows)]
22pub fn fix_windows_verbatim_for_gcc(p: &Path) -> PathBuf {
23    use std::ffi::OsString;
24    use std::path;
25    let mut components = p.components();
26    let prefix = match components.next() {
27        Some(path::Component::Prefix(p)) => p,
28        _ => return p.to_path_buf(),
29    };
30    match prefix.kind() {
31        path::Prefix::VerbatimDisk(disk) => {
32            let mut base = OsString::from(format!("{}:", disk as char));
33            base.push(components.as_path());
34            PathBuf::from(base)
35        }
36        path::Prefix::VerbatimUNC(server, share) => {
37            let mut base = OsString::from(r"\\");
38            base.push(server);
39            base.push(r"\");
40            base.push(share);
41            base.push(components.as_path());
42            PathBuf::from(base)
43        }
44        _ => p.to_path_buf(),
45    }
46}
47
48#[cfg(not(windows))]
49pub fn fix_windows_verbatim_for_gcc(p: &Path) -> PathBuf {
50    p.to_path_buf()
51}
52
53pub enum LinkOrCopy {
54    Link,
55    Copy,
56}
57
58/// Copies `p` into `q`, preferring to use hard-linking if possible.
59/// The result indicates which of the two operations has been performed.
60pub fn link_or_copy<P: AsRef<Path>, Q: AsRef<Path>>(p: P, q: Q) -> io::Result<LinkOrCopy> {
61    // Creating a hard-link will fail if the destination path already exists. We could defensively
62    // call remove_file in this function, but that pessimizes callers who can avoid such calls.
63    // Incremental compilation calls this function a lot, and is able to avoid calls that
64    // would fail the first hard_link attempt.
65
66    let p = p.as_ref();
67    let q = q.as_ref();
68
69    let err = match fs::hard_link(p, q) {
70        Ok(()) => return Ok(LinkOrCopy::Link),
71        Err(err) => err,
72    };
73
74    if err.kind() == io::ErrorKind::AlreadyExists {
75        fs::remove_file(q)?;
76        if fs::hard_link(p, q).is_ok() {
77            return Ok(LinkOrCopy::Link);
78        }
79    }
80
81    // Hard linking failed, fall back to copying.
82    fs::copy(p, q).map(|_| LinkOrCopy::Copy)
83}
84
85#[cfg(any(unix, all(target_os = "wasi", target_env = "p1")))]
86pub fn path_to_c_string(p: &Path) -> CString {
87    use std::ffi::OsStr;
88    #[cfg(unix)]
89    use std::os::unix::ffi::OsStrExt;
90    #[cfg(all(target_os = "wasi", target_env = "p1"))]
91    use std::os::wasi::ffi::OsStrExt;
92
93    let p: &OsStr = p.as_ref();
94    CString::new(p.as_bytes()).unwrap()
95}
96#[cfg(windows)]
97pub fn path_to_c_string(p: &Path) -> CString {
98    CString::new(p.to_str().unwrap()).unwrap()
99}
100
101#[inline]
102pub fn try_canonicalize<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
103    fs::canonicalize(&path).or_else(|_| absolute(&path))
104}
rustc_fs_util/lib.rs

rustc_fs_util/
lib.rs
