Create helix-stdx crate for stdlib extensions

helix-stdx is meant to carry extensions to the stdlib or low-level
dependencies that are useful in all other crates. This commit starts
with all of the path functions from helix-core and the CWD tracking that
lived in helix-loader.

The CWD tracking in helix-loader was previously unable to call the
canonicalization functions in helix-core. Switching to our custom
canonicalization code should make no noticeable difference though
since `std::env::current_dir` returns a canonicalized path with
symlinks resolved (at least on unix).

1 files changed, 124 insertions, 0 deletions

diff --git a/helix-stdx/tests/path.rs b/helix-stdx/tests/path.rs
new file mode 100644
index 00000000..cc3c15cb
--- /dev/null
+++ b/helix-stdx/tests/path.rs
@@ -0,0 +1,124 @@
+#![cfg(windows)]
+
+use std::{
+    env::set_current_dir,
+    error::Error,
+    path::{Component, Path, PathBuf},
+};
+
+use helix_stdx::path;
+use tempfile::Builder;
+
+// Paths on Windows are almost always case-insensitive.
+// Normalization should return the original path.
+// E.g. mkdir `CaSe`, normalize(`case`) = `CaSe`.
+#[test]
+fn test_case_folding_windows() -> Result<(), Box<dyn Error>> {
+    // tmp/root/case
+    let tmp_prefix = std::env::temp_dir();
+    set_current_dir(&tmp_prefix)?;
+
+    let root = Builder::new().prefix("root-").tempdir()?;
+    let case = Builder::new().prefix("CaSe-").tempdir_in(&root)?;
+
+    let root_without_prefix = root.path().strip_prefix(&tmp_prefix)?;
+
+    let lowercase_case = format!(
+        "case-{}",
+        case.path()
+            .file_name()
+            .unwrap()
+            .to_string_lossy()
+            .split_at(5)
+            .1
+    );
+    let test_path = root_without_prefix.join(lowercase_case);
+    assert_eq!(
+        path::normalize(&test_path),
+        case.path().strip_prefix(&tmp_prefix)?
+    );
+
+    Ok(())
+}
+
+#[test]
+fn test_normalize_path() -> Result<(), Box<dyn Error>> {
+    /*
+    tmp/root/
+    ├── link -> dir1/orig_file
+    ├── dir1/
+    │   └── orig_file
+    └── dir2/
+        └── dir_link -> ../dir1/
+    */
+
+    let tmp_prefix = std::env::temp_dir();
+    set_current_dir(&tmp_prefix)?;
+
+    // Create a tree structure as shown above
+    let root = Builder::new().prefix("root-").tempdir()?;
+    let dir1 = Builder::new().prefix("dir1-").tempdir_in(&root)?;
+    let orig_file = Builder::new().prefix("orig_file-").tempfile_in(&dir1)?;
+    let dir2 = Builder::new().prefix("dir2-").tempdir_in(&root)?;
+
+    // Create path and delete existing file
+    let dir_link = Builder::new()
+        .prefix("dir_link-")
+        .tempfile_in(&dir2)?
+        .path()
+        .to_owned();
+    let link = Builder::new()
+        .prefix("link-")
+        .tempfile_in(&root)?
+        .path()
+        .to_owned();
+
+    use std::os::windows;
+    windows::fs::symlink_dir(&dir1, &dir_link)?;
+    windows::fs::symlink_file(&orig_file, &link)?;
+
+    // root/link
+    let path = link.strip_prefix(&tmp_prefix)?;
+    assert_eq!(
+        path::normalize(path),
+        path,
+        "input {:?} and symlink last component shouldn't be resolved",
+        path
+    );
+
+    // root/dir2/dir_link/orig_file/../..
+    let path = dir_link
+        .strip_prefix(&tmp_prefix)
+        .unwrap()
+        .join(orig_file.path().file_name().unwrap())
+        .join(Component::ParentDir)
+        .join(Component::ParentDir);
+    let expected = dir_link
+        .strip_prefix(&tmp_prefix)
+        .unwrap()
+        .join(Component::ParentDir);
+    assert_eq!(
+        path::normalize(&path),
+        expected,
+        "input {:?} and \"..\" should not erase the simlink that goes ahead",
+        &path
+    );
+
+    // root/link/.././../dir2/../
+    let path = link
+        .strip_prefix(&tmp_prefix)
+        .unwrap()
+        .join(Component::ParentDir)
+        .join(Component::CurDir)
+        .join(Component::ParentDir)
+        .join(dir2.path().file_name().unwrap())
+        .join(Component::ParentDir);
+    let expected = link
+        .strip_prefix(&tmp_prefix)
+        .unwrap()
+        .join(Component::ParentDir)
+        .join(Component::ParentDir);
+    assert_eq!(path::normalize(&path), expected, "input {:?}", &path);
+
+    Ok(())
+}