This patch comes from in-house and has been submitted upstream:

--- groff-1.22.3/src/libs/libbib/index.cpp.org 2014-11-04 17:38:35.183524522 +0900

+++ groff-1.22.3/src/libs/libbib/index.cpp 2016-07-07 09:41:11.572149218 +0900

@@ -158,6 +158,10 @@

}

mtime = sb.st_mtime;

int size = int(sb.st_size);

+ if (size == 0) {

+ error("`%1' is an empty file", name);

+ return 0;

+ }

char *addr;

map_addr = mapread(fd, size);

if (map_addr) {