conditionally set tar header on go >= 1.10

post-processor/vagrant/tar_fix.go

@@ -0,0 +1,9 @@
+// +build !go1.10
+
+package vagrant
+
+import "archive/tar"
+
+func setHeaderFormat(header *tar.Header) {
+	// no-op
+}

post-processor/vagrant/tar_fix_go110.go

@@ -0,0 +1,12 @@
+// +build go1.10
+
+package vagrant
+
+import "archive/tar"
+
+func setHeaderFormat(header *tar.Header) {
+	// We have to set the Format explicitly because of a bug in
+	// libarchive. This affects eg. the tar in macOS listing huge
+	// files with zero byte length.
+	header.Format = tar.FormatGNU
+}

post-processor/vagrant/util.go

@@ -126,10 +126,8 @@ func DirToBox(dst, dir string, ui packer.Ui, level int) error {
 			return err
 		}
 
-		// We have to set the Format explicitly because of a bug in
+		// workaround for large archive formats on go >=1.10
-		// libarchive. This affects eg. the tar in macOS listing huge
+		setHeaderFormat(header)
-		// files with zero byte length.
-		header.Format = tar.FormatGNU
 
 		// We have to set the Name explicitly because it is supposed to
 		// be a relative path to the root. Otherwise, the tar ends up