Mounted files showed up owned by 4294967295 (^uint32(0)) on OpenBSD.
vfsflags_unix.go, which calls unix.Geteuid()/unix.Getegid() to get the
real uid/gid, only builds for linux, darwin and freebsd; OpenBSD fell
through to vfsflags_non_unix.go's zero-value stub instead.
OpenBSD has no linux/darwin/freebsd-specific fields here, just the same
POSIX Geteuid/Getegid/Umask calls golang.org/x/sys/unix already ships
for openbsd on every arch, so this just adds openbsd to both build tags
rather than needing a separate file.
Cross-compiled for GOOS=openbsd (arm64, amd64) and go vet clean; ran the
existing vfs test suite on darwin, no regressions. Not yet verified on a
live OpenBSD mount, only that the right uid/gid syscalls now get called
in this codepath.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>