The man page for statfs(2) is using macros which are glibc implementation internals (not part of the public interface) for defining struct statfs. This leads programmers to believe they should use these macros in applications (a cast to __SWORD_TYPE has recently appeared in util-linux; see link [1] below) and __SWORD_TYPE isn't even the correct type on glibc/x32. Note that glibc also has the signedness of these members wrong; in the kernel, they're rightfully unsigned for 32-bit and only signed on 64-bit (where it doesn't matter). musl does not have this mismatch; we use unsigned types where they make sense (e.g. storing unsigned filesystem magic numbers that don't fit in signed 32-bit). Since the types of these fields are such a mess, I think the man page should refrain from documenting specific types, and should include advice on safe usage, including how to safely compare f_type -- on glibc, the value will wrongly be negative for many filesystems, and although default integer promotions will fix this for direct comparison with the fs magic constants, the safe way to use f_type seems to be explicitly casting it to uint32_t. Rich [1] https://git.kernel.org/cgit/utils/util-linux/util-linux.git/tree/sys-utils/switch_root.c#n179 -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
