1 files changed, 90 insertions, 0 deletions
diff --git a/vendor/gix-path/src/realpath.rs b/vendor/gix-path/src/realpath.rs
new file mode 100644
index 000000000..807cb74cc
--- /dev/null
+++ b/vendor/gix-path/src/realpath.rs
@@ -0,0 +1,90 @@
+/// The error returned by [`realpath()`][super::realpath()].
+#[derive(Debug, thiserror::Error)]
+#[allow(missing_docs)]
+pub enum Error {
+    #[error("The maximum allowed number {} of symlinks in path is exceeded", .max_symlinks)]
+    MaxSymlinksExceeded { max_symlinks: u8 },
+    #[error(transparent)]
+    ReadLink(std::io::Error),
+    #[error(transparent)]
+    CurrentWorkingDir(std::io::Error),
+    #[error("Empty is not a valid path")]
+    EmptyPath,
+    #[error("Ran out of path components while following parent component '..'")]
+    MissingParent,
+}
+
+/// The default amount of symlinks we may follow when resolving a path in [`realpath()`][crate::realpath()].
+pub const MAX_SYMLINKS: u8 = 32;
+
+pub(crate) mod function {
+    use std::path::{
+        Component::{CurDir, Normal, ParentDir, Prefix, RootDir},
+        Path, PathBuf,
+    };
+
+    use super::Error;
+    use crate::realpath::MAX_SYMLINKS;
+
+    /// Check each component of `path` and see if it is a symlink. If so, resolve it.
+    /// Do not fail for non-existing components, but assume these are as is.
+    ///
+    /// If `path` is relative, the current working directory be used to make it absolute.
+    pub fn realpath(path: impl AsRef<Path>) -> Result<PathBuf, Error> {
+        let cwd = path
+            .as_ref()
+            .is_relative()
+            .then(std::env::current_dir)
+            .unwrap_or_else(|| Ok(PathBuf::default()))
+            .map_err(Error::CurrentWorkingDir)?;
+        realpath_opts(path, cwd, MAX_SYMLINKS)
+    }
+
+    /// The same as [`realpath()`], but allow to configure `max_symlinks` to configure how many symbolic links we are going to follow.
+    /// This serves to avoid running into cycles or doing unreasonable amounts of work.
+    pub fn realpath_opts(path: impl AsRef<Path>, cwd: impl AsRef<Path>, max_symlinks: u8) -> Result<PathBuf, Error> {
+        let path = path.as_ref();
+        if path.as_os_str().is_empty() {
+            return Err(Error::EmptyPath);
+        }
+
+        let mut real_path = PathBuf::new();
+        if path.is_relative() {
+            real_path.push(cwd);
+        }
+
+        let mut num_symlinks = 0;
+        let mut path_backing: PathBuf;
+        let mut components = path.components();
+        while let Some(component) = components.next() {
+            match component {
+                part @ RootDir | part @ Prefix(_) => real_path.push(part),
+                CurDir => {}
+                ParentDir => {
+                    if !real_path.pop() {
+                        return Err(Error::MissingParent);
+                    }
+                }
+                Normal(part) => {
+                    real_path.push(part);
+                    if real_path.is_symlink() {
+                        num_symlinks += 1;
+                        if num_symlinks > max_symlinks {
+                            return Err(Error::MaxSymlinksExceeded { max_symlinks });
+                        }
+                        let mut link_destination = std::fs::read_link(real_path.as_path()).map_err(Error::ReadLink)?;
+                        if link_destination.is_absolute() {
+                            // pushing absolute path to real_path resets it to the pushed absolute path
+                        } else {
+                            assert!(real_path.pop(), "we just pushed a component");
+                        }
+                        link_destination.extend(components);
+                        path_backing = link_destination;
+                        components = path_backing.components();
+                    }
+                }
+            }
+        }
+        Ok(real_path)
+    }
+}