fix(archive): custom create archive function which preserves symlinks

worker/cache/cache.go

@@ -1,14 +1,16 @@
 package cache
 
 import (
+	"archive/tar"
+	"compress/gzip"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
 
 	api "github.com/bleenco/abstruse/pb"
 	"github.com/bleenco/abstruse/pkg/fs"
-	"github.com/mholt/archiver/v3"
 )
 
 func SaveCache(job *api.Job, dir string) (string, error) {
@@ -21,15 +23,70 @@ func SaveCache(job *api.Job, dir string) (string, error) {
 		}
 	}
 
-	cwd, err := os.Getwd()
+	return out, createArchive(job.GetCache(), out)
+}
+
+func createArchive(folders []string, outPath string) error {
+	out, err := os.Create(outPath)
 	if err != nil {
-		return out, err
+		return err
 	}
-	defer os.Chdir(cwd)
+	defer out.Close()
+
+	gw := gzip.NewWriter(out)
+	defer gw.Close()
+
+	tw := tar.NewWriter(gw)
+	defer tw.Close()
+
+	for _, folder := range folders {
+		folder = filepath.Join(filepath.Dir(outPath), folder)
+		if err := filepath.Walk(folder, func(path string, info os.FileInfo, err error) error {
+			if info.IsDir() {
+				return nil
+			}
+
+			if err != nil {
+				return err
+			}
+
+			link := ""
+			if info.Mode()&os.ModeSymlink != 0 {
+				link, err = os.Readlink(path)
+				if err != nil {
+					return err
+				}
+			}
 
-	if err := os.Chdir(dir); err != nil {
-		return out, err
+			header, err := tar.FileInfoHeader(info, link)
+			if err != nil {
+				return err
+			}
+
+			header.Name = strings.TrimPrefix(path, fmt.Sprintf("%s/", filepath.Dir(outPath)))
+
+			if err := tw.WriteHeader(header); err != nil {
+				return err
+			}
+
+			switch header.Typeflag {
+			case tar.TypeLink, tar.TypeSymlink, tar.TypeChar, tar.TypeBlock, tar.TypeDir, tar.TypeFifo:
+			default:
+				file, err := os.Open(path)
+				if err != nil {
+					return err
+				}
+
+				if _, err := io.Copy(tw, file); err != nil {
+					return err
+				}
+			}
+
+			return nil
+		}); err != nil {
+			return err
+		}
 	}
 
-	return out, archiver.Archive(job.GetCache(), out)
+	return nil
 }