feat: Follow symlinks while walking files

[0xbe7a]

I am using pixi with detached environments. I have a postinstall task that runs pip install --no-build-isolation --no-deps --disable-pip-version-check -e .. I want to specify an output for this task that checks if the package is installed in .pixi/envs/defaults/... so that I can cache this task. This currently fails because the Walker used does not follow symlinks, and .pixi just points to my detached environments via a symlink. This PR enables resolving symlinks and adds a test for that.

[Hofer-Julian]

Symlinks require dev mode or admin rights on Windows to work. Maybe @baszalmstra can test whether this test works on a "normal" machine

[ruben-arts]

It does indeed not work on my machine:

thread 'task::file_hashes::test::compute_hashes' panicked at src\task\file_hashes.rs:204:18:
called `Result::unwrap()` on an `Err` value: Os { code: 1314, kind: Uncategorized, message: "A required privilege is not held by the client." }

[ruben-arts]

@0xbe7a We can simply add a check if the symlink happened on windows, and only then assert. e.g.:

diff --git a/src/task/file_hashes.rs b/src/task/file_hashes.rs
index 25f5d405..eebc424e 100644
--- a/src/task/file_hashes.rs
+++ b/src/task/file_hashes.rs
@@ -198,10 +198,14 @@ mod test {
             std::os::unix::fs::symlink(symlinked_dir.path(), target_dir.path().join("link"))
                 .unwrap();
         }
+
+        // On Windows this test can fail, so we need to check if the symlink was created successfully.
+        // This works in our CI but might not work on all Windows systems.
+        #[allow(unused_assignments)]
+        let mut symlink_on_windows = false;
         #[cfg(windows)]
         {
-            std::os::windows::fs::symlink_dir(symlinked_dir.path(), target_dir.path().join("link"))
-                .unwrap();
+            symlink_on_windows = std::os::windows::fs::symlink_dir(symlinked_dir.path(), target_dir.path().join("link")).is_ok();
         }
 
         write(symlinked_dir.path().join("main.rs"), "fn main() {}").unwrap();
@@ -237,13 +241,15 @@ mod test {
             Some("2c806b6ebece677c")
         );

-        assert_matches!(
-            hashes
-                .files
-                .get(Path::new("link/main.rs"))
-                .map(String::as_str),
-            Some("2c806b6ebece677c")
-        );
+        if symlink_on_windows || cfg!(unix) {
+            assert_matches!(
+                hashes
+                    .files
+                    .get(Path::new("link/main.rs"))
+                    .map(String::as_str),
+                Some("2c806b6ebece677c")
+            );
+        }

         #[cfg(unix)]
         {his works for me and I guess it's still tested on CI

[ruben-arts]

Thank you @0xbe7a