Bug: links are relative to linkdir, not rootdir

abspath.go

@@ -48,7 +48,8 @@ func (abs absPath) Canonical() (absPath, error) {
 	return absPath(result), nil
 }
 
-// Join appends more path elements to abs, like filepath.Join.
+// Join appends more path elements to abs, like filepath.Join. This will clean
+// the final path (e.g. resolve ".." elements).
 func (abs absPath) Join(elems ...string) absPath {
 	all := make([]string, 0, 1+len(elems))
 	all = append(all, abs.String())

main.go

@@ -1277,7 +1277,7 @@ func (git *repoSync) publishSymlink(ctx context.Context, worktree worktree) erro
 		return fmt.Errorf("error making symlink dir: %w", err)
 	}
 
-	// newDir is absolute, so we need to change it to a relative path.  This is
+	// linkDir is absolute, so we need to change it to a relative path.  This is
 	// so it can be volume-mounted at another path and the symlink still works.
 	targetRelative, err := filepath.Rel(linkDir, targetPath.String())
 	if err != nil {
@@ -1573,7 +1573,8 @@ func (git *repoSync) currentWorktree() (worktree, error) {
 	if filepath.IsAbs(target) {
 		return worktree(target), nil
 	}
-	return worktree(git.root.Join(target)), nil
+	linkDir, _ := git.link.Split()
+	return worktree(absPath(linkDir).Join(target)), nil
 }
 
 // SyncRepo syncs the repository to the desired ref, publishes it via the link,

test_e2e.sh

@@ -411,36 +411,6 @@ function e2e::init_root_fails_sanity() {
     assert_file_eq "$ROOT/link/file" "$FUNCNAME"
 }
 
-##############################################
-# Test init with an absolute-path link
-##############################################
-function e2e::sync_absolute_link() {
-    GIT_SYNC \
-        --one-time \
-        --repo="file://$REPO" \
-        --root="$ROOT/root" \
-        --link="$ROOT/other/dir/link"
-    assert_file_absent "$ROOT/root/link"
-    assert_link_exists "$ROOT/other/dir/link"
-    assert_file_exists "$ROOT/other/dir/link/file"
-    assert_file_eq "$ROOT/other/dir/link/file" "$FUNCNAME"
-}
-
-##############################################
-# Test init with a subdir-path link
-##############################################
-function e2e::sync_subdir_link() {
-    GIT_SYNC \
-        --one-time \
-        --repo="file://$REPO" \
-        --root="$ROOT" \
-        --link="other/dir/link"
-    assert_file_absent "$ROOT/link"
-    assert_link_exists "$ROOT/other/dir/link"
-    assert_file_exists "$ROOT/other/dir/link/file"
-    assert_file_eq "$ROOT/other/dir/link/file" "$FUNCNAME"
-}
-
 ##############################################
 # Test non-zero exit with a bad ref
 ##############################################
@@ -539,6 +509,96 @@ function e2e::sync_head() {
     assert_metric_eq "${METRIC_FETCH_COUNT}" 3
 }
 
+##############################################
+# Test sync with an absolute-path link
+##############################################
+function e2e::sync_head_absolute_link() {
+    # First sync
+    echo "$FUNCNAME 1" > "$REPO/file"
+    git -C "$REPO" commit -qam "$FUNCNAME 1"
+
+    GIT_SYNC \
+        --period=100ms \
+        --repo="file://$REPO" \
+        --ref=HEAD \
+        --root="$ROOT/root" \
+        --link="$ROOT/other/dir/link" \
+        &
+    wait_for_sync "${MAXWAIT}"
+    assert_file_absent "$ROOT/root/link"
+    assert_link_exists "$ROOT/other/dir/link"
+    assert_file_exists "$ROOT/other/dir/link/file"
+    assert_file_eq "$ROOT/other/dir/link/file" "$FUNCNAME 1"
+    assert_metric_eq "${METRIC_GOOD_SYNC_COUNT}" 1
+    assert_metric_eq "${METRIC_FETCH_COUNT}" 1
+
+    # Move HEAD forward
+    echo "$FUNCNAME 2" > "$REPO/file"
+    git -C "$REPO" commit -qam "$FUNCNAME 2"
+    wait_for_sync "${MAXWAIT}"
+    assert_file_absent "$ROOT/root/link"
+    assert_link_exists "$ROOT/other/dir/link"
+    assert_file_exists "$ROOT/other/dir/link/file"
+    assert_file_eq "$ROOT/other/dir/link/file" "$FUNCNAME 2"
+    assert_metric_eq "${METRIC_GOOD_SYNC_COUNT}" 2
+    assert_metric_eq "${METRIC_FETCH_COUNT}" 2
+
+    # Move HEAD backward
+    git -C "$REPO" reset -q --hard HEAD^
+    wait_for_sync "${MAXWAIT}"
+    assert_file_absent "$ROOT/root/link"
+    assert_link_exists "$ROOT/other/dir/link"
+    assert_file_exists "$ROOT/other/dir/link/file"
+    assert_file_eq "$ROOT/other/dir/link/file" "$FUNCNAME 1"
+    assert_metric_eq "${METRIC_GOOD_SYNC_COUNT}" 3
+    assert_metric_eq "${METRIC_FETCH_COUNT}" 3
+}
+
+##############################################
+# Test sync with a subdir-path link
+##############################################
+function e2e::sync_head_subdir_link() {
+    # First sync
+    echo "$FUNCNAME 1" > "$REPO/file"
+    git -C "$REPO" commit -qam "$FUNCNAME 1"
+
+    GIT_SYNC \
+        --period=100ms \
+        --repo="file://$REPO" \
+        --ref=HEAD \
+        --root="$ROOT" \
+        --link="other/dir/link" \
+        &
+    wait_for_sync "${MAXWAIT}"
+    assert_file_absent "$ROOT/link"
+    assert_link_exists "$ROOT/other/dir/link"
+    assert_file_exists "$ROOT/other/dir/link/file"
+    assert_file_eq "$ROOT/other/dir/link/file" "$FUNCNAME 1"
+    assert_metric_eq "${METRIC_GOOD_SYNC_COUNT}" 1
+    assert_metric_eq "${METRIC_FETCH_COUNT}" 1
+
+    # Move HEAD forward
+    echo "$FUNCNAME 2" > "$REPO/file"
+    git -C "$REPO" commit -qam "$FUNCNAME 2"
+    wait_for_sync "${MAXWAIT}"
+    assert_file_absent "$ROOT/link"
+    assert_link_exists "$ROOT/other/dir/link"
+    assert_file_exists "$ROOT/other/dir/link/file"
+    assert_file_eq "$ROOT/other/dir/link/file" "$FUNCNAME 2"
+    assert_metric_eq "${METRIC_GOOD_SYNC_COUNT}" 2
+    assert_metric_eq "${METRIC_FETCH_COUNT}" 2
+
+    # Move HEAD backward
+    git -C "$REPO" reset -q --hard HEAD^
+    wait_for_sync "${MAXWAIT}"
+    assert_file_absent "$ROOT/link"
+    assert_link_exists "$ROOT/other/dir/link"
+    assert_file_exists "$ROOT/other/dir/link/file"
+    assert_file_eq "$ROOT/other/dir/link/file" "$FUNCNAME 1"
+    assert_metric_eq "${METRIC_GOOD_SYNC_COUNT}" 3
+    assert_metric_eq "${METRIC_FETCH_COUNT}" 3
+}
+
 ##############################################
 # Test worktree-cleanup
 ##############################################