Merge pull request #1425 from EliahKagan/strange-symlink-targets

Always fall back to creating file symlinks on Windows

Author: Byron

gix-fs/src/symlink.rs

@@ -41,12 +41,7 @@ pub fn create(original: &Path, link: &Path) -> io::Result<()> {
     use std::os::windows::fs::{symlink_dir, symlink_file};
     // TODO: figure out if links to links count as files or whatever they point at
     let orig_abs = link.parent().expect("dir for link").join(original);
-    let is_dir = match std::fs::metadata(orig_abs) {
-        Ok(m) => m.is_dir(),
-        Err(err) if err.kind() == io::ErrorKind::NotFound => false,
-        Err(err) => return Err(err),
-    };
-    if is_dir {
+    if orig_abs.is_dir() {
         symlink_dir(original, link)
     } else {
         symlink_file(original, link)

gix-index/tests/fixtures/make_traverse_literal_separators.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+set -eu -o pipefail
+
+git init -q
+
+# On Windows, the target is an invalid file name.
+qmarks_oid=$(echo -n "???" | git hash-object -w --stdin)
+
+git update-index --index-info <<EOF
+120000 $qmarks_oid	dangling-qmarks-symlink
+EOF
+
+git commit -m "dangling symlinks with Windows invalid target in index"

gix-worktree-state/tests/fixtures/generated-archives/make_dangling_symlink_to_windows_invalid.tar

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+set -eu -o pipefail
+
+git init -q
+
+# On Windows, the target is a reserved legacy DOS device name.
+con_oid=$(echo -n "CON" | git hash-object -w --stdin)
+
+git update-index --index-info <<EOF
+120000 $con_oid	dangling-con-symlink
+EOF
+
+git commit -m "dangling symlinks with Widnows reserved target in index"

gix-worktree-state/tests/fixtures/generated-archives/make_dangling_symlink_to_windows_reserved.tar

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+set -eu -o pipefail
+
+git init -q
+
+target_oid=$(echo -n "." | git hash-object -w --stdin)
+
+git update-index --index-info <<EOF
+120000 $target_oid	symlink
+EOF
+
+git commit -m "symlink in index, points to directory"

gix-worktree-state/tests/fixtures/generated-archives/make_dir_symlink.tar

@@ -268,29 +268,71 @@ fn symlinks_become_files_if_disabled() -> crate::Result {
 }
 
 #[test]
-fn dangling_symlinks_can_be_created() -> crate::Result {
+fn symlinks_to_directories_are_usable() -> crate::Result {
     let opts = opts_from_probe();
     if !opts.fs.symlink {
-        eprintln!("Skipping dangling symlink test on filesystem that doesn't support it");
+        eprintln!("Skipping directory symlink test on filesystem that doesn't support it");
         return Ok(());
     }
 
     let (_source_tree, destination, _index, outcome) =
-        checkout_index_in_tmp_dir(opts.clone(), "make_dangling_symlink", None)?;
+        checkout_index_in_tmp_dir(opts.clone(), "make_dir_symlink", None)?;
     let worktree_files = dir_structure(&destination);
     let worktree_files_stripped = stripped_prefix(&destination, &worktree_files);
 
-    assert_eq!(worktree_files_stripped, paths(["dangling"]));
+    assert_eq!(worktree_files_stripped, paths(["symlink"]));
     let symlink_path = &worktree_files[0];
     assert!(symlink_path
         .symlink_metadata()
-        .expect("dangling symlink is on disk")
+        .expect("symlink is on disk")
         .is_symlink());
-    assert_eq!(std::fs::read_link(symlink_path)?, Path::new("non-existing-target"));
+    assert!(symlink_path
+        .metadata()
+        .expect("metadata accessible through symlink")
+        .is_dir());
+    assert_eq!(std::fs::read_link(symlink_path)?, Path::new("."));
     assert!(outcome.collisions.is_empty());
     Ok(())
 }
 
+#[test]
+fn dangling_symlinks_can_be_created() -> crate::Result {
+    let opts = opts_from_probe();
+    if !opts.fs.symlink {
+        eprintln!("Skipping dangling symlink test on filesystem that doesn't support it");
+        return Ok(());
+    }
+
+    for (fixture, symlink_name, target_name) in [
+        ("make_dangling_symlink", "dangling", "non-existing-target"),
+        (
+            "make_dangling_symlink_to_windows_invalid",
+            "dangling-qmarks-symlink",
+            "???",
+        ),
+        (
+            "make_dangling_symlink_to_windows_reserved",
+            "dangling-con-symlink",
+            "CON",
+        ),
+    ] {
+        let (_source_tree, destination, _index, outcome) = checkout_index_in_tmp_dir(opts.clone(), fixture, None)?;
+        let worktree_files = dir_structure(&destination);
+        let worktree_files_stripped = stripped_prefix(&destination, &worktree_files);
+
+        assert_eq!(worktree_files_stripped, paths([symlink_name]));
+        let symlink_path = &worktree_files[0];
+        assert!(symlink_path
+            .symlink_metadata()
+            .expect("dangling symlink is on disk")
+            .is_symlink());
+        assert_eq!(std::fs::read_link(symlink_path)?, Path::new(target_name));
+        assert!(outcome.collisions.is_empty());
+    }
+
+    Ok(())
+}
+
 #[test]
 fn allow_or_disallow_symlinks() -> crate::Result {
     let mut opts = opts_from_probe();