utmp fallback not complete enough

[Alastair Hughes]

I've just tried to build busybox 1.24.0 against musl, however the build fails because musl does not define _PATH_WTMP in utmpx.h (it's defined in utmp.h).

This is caused by commit 86a7f18f211af1abda5c855d2674b0fcb53de524 (*: Switch to POSIX utmpx API), and the workaround for uclibc (7d86384b246434e72533332f7f409a7aa9efeacb (include: Fallback to UTMP unless there is UTMPX support)) does not work for musl, as it only checks for __UCLIBC__ or __GLIBC__.

I'm not sure what would be an appropriate fix; POSIX appears to not include _PATH_WTMP [1] at all? What would be a good way of fixing this?

Alastair Hughes

[1]: http://pubs.opengroup.org/onlinepubs/009695399/basedefs/utmpx.h.html