s3: fix if-match error

.github/workflows/test-s3-over-https-using-awscli.yml

@@ -77,3 +77,12 @@ jobs:
           aws --no-verify-ssl s3 cp --no-progress s3://bucket/test-multipart downloaded
           diff -q generated downloaded
           rm -f generated downloaded
+
+      - name: Test GetObject with If-Match
+        run: |
+          set -e
+          dd if=/dev/urandom of=generated bs=1M count=32
+          ETAG=$(aws --no-verify-ssl s3api put-object --bucket bucket --key test-get-obj --body generated | jq -r .ETag)
+          aws --no-verify-ssl s3api get-object --bucket bucket --key test-get-obj --if-match ${ETAG:1:32} downloaded
+          diff -q generated downloaded
+          rm -f downloaded

weed/s3api/s3api_object_handlers_put.go

@@ -1085,6 +1085,9 @@ func (s3a *S3ApiServer) getObjectETag(entry *filer_pb.Entry) string {
 	if etagBytes, hasETag := entry.Extended[s3_constants.ExtETagKey]; hasETag {
 		return string(etagBytes)
 	}
+	if entry.Attributes.Md5 != nil {
+		return fmt.Sprintf("\"%x\"", entry.Attributes.Md5)
+	}
 	// Fallback: calculate ETag from chunks
 	return s3a.calculateETagFromChunks(entry.Chunks)
 }