feat: Make STFS API public

Also: Happy new year :)

pkg/cache/write.go

@@ -0,0 +1,76 @@
+package cache
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/mattetti/filebuffer"
+	"github.com/pojntfx/stfs/pkg/config"
+	"github.com/spf13/afero"
+)
+
+type fileWithSize struct {
+	afero.File
+}
+
+func (f fileWithSize) Size() (int64, error) {
+	info, err := f.Stat()
+	if err != nil {
+		return -1, err
+	}
+
+	return info.Size(), nil
+}
+
+type filebufferWithSize struct {
+	*filebuffer.Buffer
+}
+
+func (f filebufferWithSize) Size() (int64, error) {
+	return int64(f.Buff.Len()), nil
+}
+
+func (f filebufferWithSize) Sync() error {
+	// No need to sync a in-memory buffer
+	return nil
+}
+
+func (f filebufferWithSize) Truncate(size int64) error {
+	f.Buff.Truncate(int(size))
+
+	return nil
+}
+
+func NewCacheWrite(
+	root string,
+	cacheType string,
+) (cache WriteCache, cleanup func() error, err error) {
+	switch cacheType {
+	case config.WriteCacheTypeMemory:
+		buff := &filebufferWithSize{filebuffer.New([]byte{})}
+
+		return buff, func() error {
+			buff = nil
+
+			return nil
+		}, nil
+	case config.WriteCacheTypeFile:
+		tmpdir := filepath.Join(root, "io")
+
+		if err := os.MkdirAll(tmpdir, os.ModePerm); err != nil {
+			return nil, nil, err
+		}
+
+		f, err := ioutil.TempFile(tmpdir, "*")
+		if err != nil {
+			return nil, nil, err
+		}
+
+		return fileWithSize{f}, func() error {
+			return os.Remove(f.Name())
+		}, nil
+	default:
+		return nil, nil, config.ErrWriteCacheTypeUnsupported
+	}
+}