Ignore cyclic skill links on Windows

2 files · +23 -1

M packages/agent/skills/skills.go +9 -1


@@ -33,6 +33,7 @@ import (
33	33		"io/fs"
34	34		"os"
35	35		"path/filepath"
	36	+	"runtime"
36	37		"sort"
37	38		"strings"
38	39		"syscall"

@@ -248,7 +249,7 @@ func scanSource(source Source) ([]*Skill, []error) {
248	249		if statErr != nil {
249	250		// Dangling and cyclic links are not skills. Anything
250	251		// else (permissions, I/O) is worth reporting.
251		-	if !errors.Is(statErr, fs.ErrNotExist) && !errors.Is(statErr, syscall.ELOOP) {
	252	+	if !errors.Is(statErr, fs.ErrNotExist) && !symlinkLoopError(statErr) {
252	253		errs = append(errs, fmt.Errorf("%s: %w", path, statErr))
253	254		}
254	255		continue

@@ -287,6 +288,13 @@ func scanSource(source Source) ([]*Skill, []error) {
287	288		return out, errs
288	289		}
289	290
	291	+	func symlinkLoopError(err error) bool {
	292	+	// Windows reports cyclic links as ERROR_CANT_RESOLVE_FILENAME (1921),
	293	+	// rather than ELOOP. syscall does not export a name for this error.
	294	+	return errors.Is(err, syscall.ELOOP) \|\|
	295	+	(runtime.GOOS == "windows" && errors.Is(err, syscall.Errno(1921)))
	296	+	}
	297	+
290	298		// deriveName builds a skill name for a SKILL.md file that carries no
291	299		// frontmatter `name`, from its directory path relative to the source root.
292	300		func deriveName(root, path string) (string, error) {

 	"io/fs"
 	"os"
 	"path/filepath"
+	"runtime"
 	"sort"
 	"strings"
 	"syscall"
 				if statErr != nil {
 					// Dangling and cyclic links are not skills. Anything
 					// else (permissions, I/O) is worth reporting.
-					if !errors.Is(statErr, fs.ErrNotExist) && !errors.Is(statErr, syscall.ELOOP) {
+					if !errors.Is(statErr, fs.ErrNotExist) && !symlinkLoopError(statErr) {
 						errs = append(errs, fmt.Errorf("%s: %w", path, statErr))
 					}
 					continue
 	return out, errs
 }
+func symlinkLoopError(err error) bool {
+	// Windows reports cyclic links as ERROR_CANT_RESOLVE_FILENAME (1921),
+	// rather than ELOOP. syscall does not export a name for this error.
+	return errors.Is(err, syscall.ELOOP) ||
+		(runtime.GOOS == "windows" && errors.Is(err, syscall.Errno(1921)))
+}
 // deriveName builds a skill name for a SKILL.md file that carries no
 // frontmatter `name`, from its directory path relative to the source root.
 func deriveName(root, path string) (string, error) {

M packages/agent/skills/skills_test.go +14 -0

@@ -1,10 +1,12 @@
1	1		package skills
2	2
3	3		import (
	4	+	"fmt"
4	5		"os"
5	6		"path/filepath"
6	7		"runtime"
7	8		"strings"
	9	+	"syscall"
8	10		"testing"
9	11		)
10	12

@@ -246,6 +248,18 @@ func TestDiscoverSourcesIgnoresCyclicSymlink(t *testing.T) {
246	248		}
247	249		}
248	250
	251	+	func TestSymlinkLoopError(t *testing.T) {
	252	+	if !symlinkLoopError(fmt.Errorf("stat: %w", syscall.ELOOP)) {
	253	+	t.Error("ELOOP should be ignored")
	254	+	}
	255	+	if runtime.GOOS == "windows" && !symlinkLoopError(fmt.Errorf("stat: %w", syscall.Errno(1921))) {
	256	+	t.Error("Windows cyclic-link error should be ignored")
	257	+	}
	258	+	if symlinkLoopError(fmt.Errorf("stat: %w", os.ErrPermission)) {
	259	+	t.Error("permission errors must still be reported")
	260	+	}
	261	+	}
	262	+
249	263		func mustEvalSymlinks(t *testing.T, path string) string {
250	264		t.Helper()
251	265		resolved, err := filepath.EvalSymlinks(path)

@@ -1,10 +1,12 @@
1	package skills	1		package skills
2		2
3	import (	3		import (
		4	+	"fmt"
4	"os"	5		"os"
5	"path/filepath"	6		"path/filepath"
6	"runtime"	7		"runtime"
7	"strings"	8		"strings"
		9	+	"syscall"
8	"testing"	10		"testing"
9	)	11		)
10		12

@@ -246,6 +248,18 @@ func TestDiscoverSourcesIgnoresCyclicSymlink(t *testing.T) {
246	}	248		}
247	}	249		}
248		250
		251	+	func TestSymlinkLoopError(t *testing.T) {
		252	+	if !symlinkLoopError(fmt.Errorf("stat: %w", syscall.ELOOP)) {
		253	+	t.Error("ELOOP should be ignored")
		254	+	}
		255	+	if runtime.GOOS == "windows" && !symlinkLoopError(fmt.Errorf("stat: %w", syscall.Errno(1921))) {
		256	+	t.Error("Windows cyclic-link error should be ignored")
		257	+	}
		258	+	if symlinkLoopError(fmt.Errorf("stat: %w", os.ErrPermission)) {
		259	+	t.Error("permission errors must still be reported")
		260	+	}
		261	+	}
		262	+
249	func mustEvalSymlinks(t *testing.T, path string) string {	263		func mustEvalSymlinks(t *testing.T, path string) string {
250	t.Helper()	264		t.Helper()
251	resolved, err := filepath.EvalSymlinks(path)	265		resolved, err := filepath.EvalSymlinks(path)