...

+#ifndef OSMO_IS_LITTLE_ENDIAN + #define OSMO_IS_LITTLE_ENDIAN 0 +#endif

I am surprised by this hunk. Our endian.h should define both macros. I think I used the vim search to search for a typo in one of the branches (BSD vs. Linux, LE vs. BE) but it looks good. Do you remember why this was needed?

It isn't needed. It was just added out of habit to make sure it is defined when it is being checked further down. You can remove it, it won't make any difference. Ruben