libarchive 3.5.1 checks for strnlen. It is available on all Windows platforms.
@@ -180,6 +180,7 @@ if(WIN32)
set(HAVE_STRERROR_R 0)
set(HAVE_STRNCMPI 0)
set(HAVE_STRNCPY_S 1)
+ set(HAVE_STRNLEN 1)
set(HAVE_STROPTS_H 0)
set(HAVE__STRTOI64 1)
set(HAVE_STRTOLL 1)