This patch was fed back to the upstream community:
http://code.google.com/p/libarchive/issues/detail?id=287
Given the response "I just committed your patch.", it should
no longer be needed with the next release.
--- libarchive/libarchive/archive_write_set_format_ar.c.orig Mon Mar 26 19:49:00 2012
+++ libarchive/libarchive/archive_write_set_format_ar.c Tue Nov 27 17:48:04 2012
@@ -165,7 +165,7 @@
* Reject files with empty name.
*/
pathname = archive_entry_pathname(entry);
- if (*pathname == '\0') {
+ if (pathname == NULL || *pathname == '\0') {
archive_set_error(&a->archive, EINVAL,
"Invalid filename");
return (ARCHIVE_WARN);