fix: build image layer for dir symlink

.gitignore

@@ -15,7 +15,7 @@
 *.out
 
 # Dependency directories (remove the comment below to include it)
-# vendor/
+/vendor
 
 # Go workspace file
 go.work

pkg/backend/build/builder.go

@@ -17,6 +17,7 @@
 package build
 
 import (
+	"archive/tar"
 	"bytes"
 	"context"
 	"encoding/json"
@@ -26,6 +27,7 @@
 	"os"
 	"path/filepath"
 	"strconv"
+	"strings"
 	"sync"
 	"syscall"
 	"time"
@@ -123,12 +125,56 @@
 }
 
 func (ab *abstractBuilder) BuildLayer(ctx context.Context, mediaType, workDir, path string, hooks hooks.Hooks) (ocispec.Descriptor, error) {
+	logrus.Debugf("BuildLayer:  mediaType %s, workDir %s, path %s", mediaType, workDir, path)
 	info, err := os.Stat(path)
 	if err != nil {
 		return ocispec.Descriptor{}, fmt.Errorf("failed to get file info: %w", err)
 	}
 
 	if info.IsDir() {
+		lInfo, err := os.Lstat(path)
+		if err != nil {
+			return ocispec.Descriptor{}, fmt.Errorf("failed to get file info: %w", err)
+		}
+		isSymlink := lInfo.Mode()&os.ModeSymlink != 0
+		if isSymlink {
+			// 对于符号链接，获取其指向的目标信息
+			dstLinkPath, err := os.Readlink(path)
+			if err != nil {
+				return ocispec.Descriptor{}, fmt.Errorf("failed to read symlink: %w", err)
+			}
+
+			workDirPath, err := filepath.Abs(workDir)
+			if err != nil {
+				return ocispec.Descriptor{}, fmt.Errorf("failed to get absolute path of workDir: %w", err)
+			}
+
+			// Gets the relative path of the file as annotation.
+			//nolint:typecheck
+			relPath, err := filepath.Rel(workDirPath, path)
+			if err != nil {
+				return ocispec.Descriptor{}, fmt.Errorf("failed to get relative path: %w", err)
+			}
+			logrus.Debugf("builder: starting build layer for synlink %s, target path %s", relPath, dstLinkPath)
+
+			// build layer for the target of symbolic link.
+			reader := strings.NewReader("")
+			hash := sha256.New()
+			size, err := io.Copy(hash, reader)
+			if err != nil {
+				return ocispec.Descriptor{}, fmt.Errorf("failed to copy content to hash: %w", err)
+			}
+			digest := fmt.Sprintf("sha256:%x", hash.Sum(nil))
+			desc, err := ab.strategy.OutputLayer(ctx, mediaType, relPath, digest, size, reader, hooks)
+			if err != nil {
+				return desc, err
+			}
+			// Add file metadata to descriptor.
+			if err := addFileMetadata(&desc, path, relPath); err != nil {
+				return desc, err
+			}
+			return desc, nil
+		}
 		return ocispec.Descriptor{}, fmt.Errorf("%s is a directory and not supported yet", path)
 	}
 
@@ -432,11 +478,27 @@
 	// Set Typeflag.
 	switch {
 	case info.Mode().IsRegular():
-		metadata.Typeflag = 0 // Regular file
+		metadata.Typeflag = tar.TypeReg // Regular file
 	case info.Mode().IsDir():
-		metadata.Typeflag = 5 // Directory
+		metadata.Typeflag = tar.TypeDir // Directory
+		lInfo, err := os.Lstat(path)
+		if err != nil {
+			return metadata, fmt.Errorf("failed to get file info: %w", err)
+		}
+		isSymlink := lInfo.Mode()&os.ModeSymlink != 0
+		if isSymlink {
+			// 对于符号链接，获取其指向的目标信息
+			dstLinkPath, err := os.Readlink(path)
+			if err != nil {
+				return metadata, fmt.Errorf("failed to read symlink: %w", err)
+			}
+			logrus.Debugf("builder: symlink detected for file %s -> %s", path, dstLinkPath)
+			metadata.Typeflag = tar.TypeSymlink // Symlink
+			metadata.DstLinkPath = dstLinkPath
+		}
+
 	case info.Mode()&os.ModeSymlink != 0:
-		metadata.Typeflag = 2 // Symlink
+		metadata.Typeflag = tar.TypeSymlink // Symlink
 	default:
 		return metadata, errors.New("unknown file typeflag")
 	}

pkg/backend/extract.go

@@ -17,12 +17,15 @@
 package backend
 
 import (
+	"archive/tar"
 	"bufio"
 	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
+	"os"
+	"path/filepath"
 
 	legacymodelspec "github.com/dragonflyoss/model-spec/specs-go/v1"
 	modelspec "github.com/modelpack/model-spec/specs-go/v1"
@@ -114,22 +117,57 @@ func exportModelArtifact(ctx context.Context, store storage.Storage, manifest oc
 
 // extractLayer extracts the layer to the output directory.
 func extractLayer(desc ocispec.Descriptor, outputDir string, reader io.Reader) error {
-	var filepath string
+	var filePath string
 	if desc.Annotations != nil {
 		if desc.Annotations[modelspec.AnnotationFilepath] != "" {
-			filepath = desc.Annotations[modelspec.AnnotationFilepath]
+			filePath = desc.Annotations[modelspec.AnnotationFilepath]
 		} else {
-			filepath = desc.Annotations[legacymodelspec.AnnotationFilepath]
+			filePath = desc.Annotations[legacymodelspec.AnnotationFilepath]
 		}
 
 	}
 
+	// load symlink from annotation if exists
+	var fileMetadata *modelspec.FileMetadata
+	// Try to retrieve the file metadata from annotation for raw file.
+	if desc.Annotations != nil {
+		fileMetadataStr := desc.Annotations[modelspec.AnnotationFileMetadata]
+		if fileMetadataStr == "" {
+			fileMetadataStr = desc.Annotations[legacymodelspec.AnnotationFileMetadata]
+		}
+
+		if fileMetadataStr != "" {
+			if err := json.Unmarshal([]byte(fileMetadataStr), &fileMetadata); err != nil {
+				return err
+			}
+		}
+	}
+	if fileMetadata != nil {
+		if fileMetadata.Typeflag == tar.TypeSymlink && len(fileMetadata.DstLinkPath) > 0 {
+			// handle file metadata
+
+			dstFullPath := filepath.Join(outputDir, fileMetadata.DstLinkPath)
+			if err := os.MkdirAll(dstFullPath, 0755); err != nil && !os.IsExist(err) {
+				return fmt.Errorf("failed to create directory %s: %w", dstFullPath, err)
+			}
+			fullPath := filepath.Join(outputDir, filePath)
+			if err := os.Remove(fullPath); err != nil && !os.IsNotExist(err) {
+				return fmt.Errorf("failed to remove file %s: %w", fullPath, err)
+			}
+			if err := os.Symlink(fileMetadata.DstLinkPath, fullPath); err != nil {
+				return fmt.Errorf("failed to create symlink from %s to %s: %w", fullPath, dstFullPath, err)
+			}
+			logrus.Debugf("extract: created symlink from %s to %s", fullPath, dstFullPath)
+			return nil
+		}
+	}
+
 	codec, err := pkgcodec.New(pkgcodec.TypeFromMediaType(desc.MediaType))
 	if err != nil {
 		return fmt.Errorf("failed to create codec for media type %s: %w", desc.MediaType, err)
 	}
 
-	if err := codec.Decode(outputDir, filepath, reader, desc); err != nil {
+	if err := codec.Decode(outputDir, filePath, reader, desc); err != nil {
 		if errors.Is(err, pkgcodec.ErrAlreadyUpToDate) {
 			return err
 		}