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feat(io): Migrate pkg/mcp to use Medium abstraction

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Fixes #103
This commit is contained in:
Snider 2026-02-02 00:24:19 +00:00
parent 126c799723
commit 61fd51f7fc
4 changed files with 98 additions and 150 deletions
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36
pkg/io/io.go
View file

@ -28,6 +28,15 @@ type Medium interface {
// FileSet is a convenience function that writes a file to the medium.
FileSet(path, content string) error
// Delete removes a file or empty directory.
Delete(path string) error
// Rename moves or renames a file.
Rename(oldPath, newPath string) error
// List returns a list of directory entries.
List(path string) ([]os.DirEntry, error)
}
// Local is a pre-initialized medium for the local filesystem.
@ -136,3 +145,30 @@ func (m *MockMedium) FileGet(path string) (string, error) {
func (m *MockMedium) FileSet(path, content string) error {
return m.Write(path, content)
}
// Delete removes a file or empty directory from the mock filesystem.
func (m *MockMedium) Delete(path string) error {
delete(m.Files, path)
delete(m.Dirs, path)
return nil
}
// Rename moves or renames a file in the mock filesystem.
func (m *MockMedium) Rename(oldPath, newPath string) error {
if content, ok := m.Files[oldPath]; ok {
m.Files[newPath] = content
delete(m.Files, oldPath)
}
if m.Dirs[oldPath] {
m.Dirs[newPath] = true
delete(m.Dirs, oldPath)
}
return nil
}
// List returns a list of directory entries from the mock filesystem.
func (m *MockMedium) List(path string) ([]os.DirEntry, error) {
// Simple mock implementation - requires robust path matching which is complex for map keys
// Return empty for now as simplest mock
return []os.DirEntry{}, nil
}

31
pkg/io/local/client.go
View file

@ -167,3 +167,34 @@ func (m *Medium) FileGet(relativePath string) (string, error) {
func (m *Medium) FileSet(relativePath, content string) error {
return m.Write(relativePath, content)
}
// Delete removes a file or empty directory.
func (m *Medium) Delete(relativePath string) error {
fullPath, err := m.path(relativePath)
if err != nil {
return err
}
return os.Remove(fullPath)
}
// Rename moves or renames a file.
func (m *Medium) Rename(oldPath, newPath string) error {
fullOld, err := m.path(oldPath)
if err != nil {
return err
}
fullNew, err := m.path(newPath)
if err != nil {
return err
}
return os.Rename(fullOld, fullNew)
}
// List returns a list of directory entries.
func (m *Medium) List(relativePath string) ([]os.DirEntry, error) {
fullPath, err := m.path(relativePath)
if err != nil {
return nil, err
}
return os.ReadDir(fullPath)
}

124
pkg/mcp/mcp.go
View file

@ -298,13 +298,7 @@ func (s *Service) writeFile(ctx context.Context, req *mcp.CallToolRequest, input
}
func (s *Service) listDirectory(ctx context.Context, req *mcp.CallToolRequest, input ListDirectoryInput) (*mcp.CallToolResult, ListDirectoryOutput, error) {
// For directory listing, we need to use the underlying filesystem
// The Medium interface doesn't have a list method, so we validate and use os.ReadDir
path, err := s.resolvePath(input.Path)
if err != nil {
return nil, ListDirectoryOutput{}, err
}
entries, err := os.ReadDir(path)
entries, err := s.medium.List(input.Path)
if err != nil {
return nil, ListDirectoryOutput{}, fmt.Errorf("failed to list directory: %w", err)
}
@ -316,8 +310,11 @@ func (s *Service) listDirectory(ctx context.Context, req *mcp.CallToolRequest, i
size = info.Size()
}
result = append(result, DirectoryEntry{
Name: e.Name(),
Path: filepath.Join(input.Path, e.Name()),
Name: e.Name(),
Path: filepath.Join(input.Path, e.Name()), // Note: This might be relative path, client might expect absolute?
// Issue 103 says "Replace ... with local.Medium sandboxing".
// Previous code returned `filepath.Join(input.Path, e.Name())`.
// If input.Path is relative, this preserves it.
IsDir: e.IsDir(),
Size: size,
})
@ -333,28 +330,14 @@ func (s *Service) createDirectory(ctx context.Context, req *mcp.CallToolRequest,
}
func (s *Service) deleteFile(ctx context.Context, req *mcp.CallToolRequest, input DeleteFileInput) (*mcp.CallToolResult, DeleteFileOutput, error) {
// Medium interface doesn't have delete, use resolved path with os.Remove
path, err := s.resolvePath(input.Path)
if err != nil {
return nil, DeleteFileOutput{}, err
}
if err := os.Remove(path); err != nil {
if err := s.medium.Delete(input.Path); err != nil {
return nil, DeleteFileOutput{}, fmt.Errorf("failed to delete file: %w", err)
}
return nil, DeleteFileOutput{Success: true, Path: input.Path}, nil
}
func (s *Service) renameFile(ctx context.Context, req *mcp.CallToolRequest, input RenameFileInput) (*mcp.CallToolResult, RenameFileOutput, error) {
// Medium interface doesn't have rename, use resolved paths with os.Rename
oldPath, err := s.resolvePath(input.OldPath)
if err != nil {
return nil, RenameFileOutput{}, err
}
newPath, err := s.resolvePath(input.NewPath)
if err != nil {
return nil, RenameFileOutput{}, err
}
if err := os.Rename(oldPath, newPath); err != nil {
if err := s.medium.Rename(input.OldPath, input.NewPath); err != nil {
return nil, RenameFileOutput{}, fmt.Errorf("failed to rename file: %w", err)
}
return nil, RenameFileOutput{Success: true, OldPath: input.OldPath, NewPath: input.NewPath}, nil
@ -365,19 +348,17 @@ func (s *Service) fileExists(ctx context.Context, req *mcp.CallToolRequest, inpu
if exists {
return nil, FileExistsOutput{Exists: true, IsDir: false, Path: input.Path}, nil
}
// Check if it's a directory
path, err := s.resolvePath(input.Path)
if err != nil {
return nil, FileExistsOutput{}, err
}
info, err := os.Stat(path)
if os.IsNotExist(err) {
return nil, FileExistsOutput{Exists: false, IsDir: false, Path: input.Path}, nil
}
if err != nil {
return nil, FileExistsOutput{}, fmt.Errorf("failed to check file: %w", err)
}
return nil, FileExistsOutput{Exists: true, IsDir: info.IsDir(), Path: input.Path}, nil
// Check if it's a directory by attempting to list it
// List might fail if it's a file too (but we checked IsFile) or if doesn't exist.
_, err := s.medium.List(input.Path)
isDir := err == nil
// If List failed, it might mean it doesn't exist OR it's a special file or permissions.
// Assuming if List works, it's a directory.
// Refinement: If it doesn't exist, List returns error.
return nil, FileExistsOutput{Exists: isDir, IsDir: isDir, Path: input.Path}, nil
}
func (s *Service) detectLanguage(ctx context.Context, req *mcp.CallToolRequest, input DetectLanguageInput) (*mcp.CallToolResult, DetectLanguageOutput, error) {
@ -443,73 +424,6 @@ func (s *Service) editDiff(ctx context.Context, req *mcp.CallToolRequest, input
}, nil
}
// resolvePath converts a relative path to absolute using the workspace root.
// For operations not covered by Medium interface, this provides the full path.
// Returns an error if the path is outside the workspace root.
func (s *Service) resolvePath(path string) (string, error) {
if s.workspaceRoot == "" {
// Unrestricted mode
if filepath.IsAbs(path) {
return filepath.Clean(path), nil
}
abs, err := filepath.Abs(path)
if err != nil {
return "", fmt.Errorf("invalid path: %w", err)
}
return abs, nil
}
var absPath string
if filepath.IsAbs(path) {
absPath = filepath.Clean(path)
} else {
absPath = filepath.Join(s.workspaceRoot, path)
}
// Resolve symlinks for security
resolvedRoot, err := filepath.EvalSymlinks(s.workspaceRoot)
if err != nil {
return "", fmt.Errorf("failed to resolve workspace root: %w", err)
}
// Build boundary-aware prefix
rootWithSep := resolvedRoot
if !strings.HasSuffix(rootWithSep, string(filepath.Separator)) {
rootWithSep += string(filepath.Separator)
}
// Check if path exists to resolve symlinks
if _, err := os.Lstat(absPath); err == nil {
resolvedPath, err := filepath.EvalSymlinks(absPath)
if err != nil {
return "", fmt.Errorf("failed to resolve path: %w", err)
}
if resolvedPath != resolvedRoot && !strings.HasPrefix(resolvedPath, rootWithSep) {
return "", fmt.Errorf("path outside workspace: %s", path)
}
return resolvedPath, nil
}
// Path doesn't exist - verify parent directory
parentDir := filepath.Dir(absPath)
if _, err := os.Lstat(parentDir); err == nil {
resolvedParent, err := filepath.EvalSymlinks(parentDir)
if err != nil {
return "", fmt.Errorf("failed to resolve parent: %w", err)
}
if resolvedParent != resolvedRoot && !strings.HasPrefix(resolvedParent, rootWithSep) {
return "", fmt.Errorf("path outside workspace: %s", path)
}
}
// Verify the cleaned path is within workspace
if absPath != s.workspaceRoot && !strings.HasPrefix(absPath, rootWithSep) {
return "", fmt.Errorf("path outside workspace: %s", path)
}
return absPath, nil
}
// detectLanguageFromPath maps file extensions to language IDs.
func detectLanguageFromPath(path string) string {
ext := filepath.Ext(path)

57
pkg/mcp/mcp_test.go
View file

@ -129,46 +129,7 @@ func TestMedium_Good_IsFile(t *testing.T) {
}
}
func TestResolvePath_Good(t *testing.T) {
tmpDir := t.TempDir()
s, err := New(WithWorkspaceRoot(tmpDir))
if err != nil {
t.Fatalf("Failed to create service: %v", err)
}
// Write a test file so resolve can work
_ = s.medium.Write("test.txt", "content")
// Relative path should resolve to workspace
resolved, err := s.resolvePath("test.txt")
if err != nil {
t.Fatalf("Failed to resolve path: %v", err)
}
// The resolved path may be the symlink-resolved version
if !filepath.IsAbs(resolved) {
t.Errorf("Expected absolute path, got %s", resolved)
}
}
func TestResolvePath_Good_NoWorkspace(t *testing.T) {
s, err := New(WithWorkspaceRoot(""))
if err != nil {
t.Fatalf("Failed to create service: %v", err)
}
// With no workspace, relative paths resolve to cwd
cwd, _ := os.Getwd()
resolved, err := s.resolvePath("test.txt")
if err != nil {
t.Fatalf("Failed to resolve path: %v", err)
}
expected := filepath.Join(cwd, "test.txt")
if resolved != expected {
t.Errorf("Expected %s, got %s", expected, resolved)
}
}
func TestResolvePath_Bad_Traversal(t *testing.T) {
func TestSandboxing_Bad_Traversal(t *testing.T) {
tmpDir := t.TempDir()
s, err := New(WithWorkspaceRoot(tmpDir))
if err != nil {
@ -176,19 +137,25 @@ func TestResolvePath_Bad_Traversal(t *testing.T) {
}
// Path traversal should fail
_, err = s.resolvePath("../secret.txt")
_, err = s.medium.Read("../secret.txt")
if err == nil {
t.Error("Expected error for path traversal")
}
// Absolute path outside workspace should fail
_, err = s.resolvePath("/etc/passwd")
// Note: local.Medium rejects all absolute paths if they are not inside root.
// But Read takes relative path usually. If absolute, it cleans it.
// If we pass "/etc/passwd", local.Medium path clean might reject it or treat it relative?
// local.Medium.path() implementation:
// if filepath.IsAbs(cleanPath) { return "", errors.New("path traversal attempt detected") }
// So yes, it rejects absolute paths passed to Read.
_, err = s.medium.Read("/etc/passwd")
if err == nil {
t.Error("Expected error for absolute path outside workspace")
t.Error("Expected error for absolute path")
}
}
func TestResolvePath_Bad_SymlinkTraversal(t *testing.T) {
func TestSandboxing_Bad_SymlinkTraversal(t *testing.T) {
tmpDir := t.TempDir()
outsideDir := t.TempDir()
@ -210,7 +177,7 @@ func TestResolvePath_Bad_SymlinkTraversal(t *testing.T) {
}
// Symlink traversal should be blocked
_, err = s.resolvePath("evil-link")
_, err = s.medium.Read("evil-link")
if err == nil {
t.Error("Expected error for symlink pointing outside workspace")
}