byteclaw/internal/tools/files.go

package tools

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"

	"github.com/crypto/byteclaw/internal/llm"
)

// Workspace confines file access to a root directory using os.Root
// (Go 1.24+), which rejects "..", absolute paths and symlink escapes.
type Workspace struct {
	Dir      string
	MaxBytes int64
}

func (w Workspace) open() (*os.Root, error) {
	if err := os.MkdirAll(w.Dir, 0o750); err != nil {
		return nil, err
	}
	return os.OpenRoot(w.Dir)
}

func cleanRel(p string) (string, error) {
	if p == "" {
		p = "."
	}
	if filepath.IsAbs(p) {
		return "", errors.New("path must be relative to the workspace")
	}
	return filepath.Clean(p), nil
}

type pathArgs struct {
	Path    string `json:"path"`
	Content string `json:"content"`
}

// ---- file_read

type FileRead struct{ Workspace }

func (FileRead) Spec() llm.ToolSpec {
	return llm.ToolSpec{Name: "file_read", Description: "Read a text file inside the workspace.",
		Parameters: obj(map[string]any{"path": map[string]any{"type": "string"}}, "path")}
}

func (f FileRead) Call(_ context.Context, raw json.RawMessage) (string, error) {
	var a pathArgs
	if err := json.Unmarshal(raw, &a); err != nil {
		return "", err
	}
	p, err := cleanRel(a.Path)
	if err != nil {
		return "", err
	}
	root, err := f.open()
	if err != nil {
		return "", err
	}
	defer root.Close()
	fh, err := root.Open(p)
	if err != nil {
		return "", err
	}
	defer fh.Close()
	b, err := io.ReadAll(io.LimitReader(fh, f.MaxBytes+1))
	if err != nil {
		return "", err
	}
	if int64(len(b)) > f.MaxBytes {
		return string(b[:f.MaxBytes]) + "\n[truncated]", nil
	}
	return string(b), nil
}

// ---- file_write

type FileWrite struct{ Workspace }

func (FileWrite) Spec() llm.ToolSpec {
	return llm.ToolSpec{Name: "file_write", Description: "Create or overwrite a text file inside the workspace.",
		Parameters: obj(map[string]any{"path": map[string]any{"type": "string"}, "content": map[string]any{"type": "string"}}, "path", "content")}
}

func (f FileWrite) Call(_ context.Context, raw json.RawMessage) (string, error) {
	var a pathArgs
	if err := json.Unmarshal(raw, &a); err != nil {
		return "", err
	}
	if int64(len(a.Content)) > f.MaxBytes {
		return "", fmt.Errorf("content exceeds %d bytes", f.MaxBytes)
	}
	p, err := cleanRel(a.Path)
	if err != nil {
		return "", err
	}
	if p == "." {
		return "", errors.New("path required")
	}
	root, err := f.open()
	if err != nil {
		return "", err
	}
	defer root.Close()
	if dir := filepath.Dir(p); dir != "." {
		if err := mkdirAll(root, dir); err != nil {
			return "", err
		}
	}
	fh, err := root.OpenFile(p, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0o640)
	if err != nil {
		return "", err
	}
	defer fh.Close()
	if _, err := fh.WriteString(a.Content); err != nil {
		return "", err
	}
	return fmt.Sprintf("wrote %d bytes to %s", len(a.Content), p), nil
}

func mkdirAll(root *os.Root, dir string) error {
	cur := ""
	for _, part := range strings.Split(filepath.ToSlash(dir), "/") {
		cur = filepath.Join(cur, part)
		if err := root.Mkdir(cur, 0o750); err != nil && !errors.Is(err, os.ErrExist) {
			return err
		}
	}
	return nil
}

// ---- file_list

type FileList struct{ Workspace }

func (FileList) Spec() llm.ToolSpec {
	return llm.ToolSpec{Name: "file_list", Description: "List entries of a directory inside the workspace (default: root).",
		Parameters: obj(map[string]any{"path": map[string]any{"type": "string"}})}
}

func (f FileList) Call(_ context.Context, raw json.RawMessage) (string, error) {
	var a pathArgs
	if err := json.Unmarshal(raw, &a); err != nil {
		return "", err
	}
	p, err := cleanRel(a.Path)
	if err != nil {
		return "", err
	}
	root, err := f.open()
	if err != nil {
		return "", err
	}
	defer root.Close()
	d, err := root.Open(p)
	if err != nil {
		return "", err
	}
	defer d.Close()
	ents, err := d.ReadDir(500)
	if err != nil && !errors.Is(err, io.EOF) {
		return "", err
	}
	var sb strings.Builder
	for _, e := range ents {
		name := e.Name()
		if e.IsDir() {
			name += "/"
		}
		sb.WriteString(name + "\n")
	}
	if sb.Len() == 0 {
		return "(empty)", nil
	}
	return sb.String(), nil
}