Failed test '$! is ENOENT for a readlink(undef)' (freebsd 13 + 14 only?)

[eserte]

On some of my smokers (freebsd 13 + 14 with zfs) t/readlink.t fails like this:

# Failed test '$! is ENOENT for a readlink(undef)'
# at t/readlink.t line 52.
# +-----+----+-------+
# | GOT | OP | CHECK |
# +-----+----+-------+
# | 22  | eq | 2     |
# +-----+----+-------+

# Failed test '$! is ENOENT for a readlink(undef)'
# at t/readlink.t line 58.
# +-----+----+-------+
# | GOT | OP | CHECK |
# +-----+----+-------+
# | 22  | eq | 2     |
# +-----+----+-------+
# Seeded srand with seed '20211227' from local date.
t/readlink.t ............ 
Dubious, test returned 2 (wstat 512, 0x200)
Failed 2/32 subtests 

The problem can be reproduced with a oneliner:

$ perl -e 'readlink(undef); warn "$!"'
Invalid argument at -e line 1.

On freebsd 12 and older (and linux systems) it looks differently:

$ perl -e 'readlink(undef); warn "$!"'
No such file or directory at -e line 1.

[toddr]

We think this is fixed on 0.027

[eserte]

Well, now it fails for my non-zfs freebsd smokers the other way around:

# Failed test '$! is EINVAL for a readlink(undef)'
# at t/readlink.t line 52.
# +-----+----+-------+
# | GOT | OP | CHECK |
# +-----+----+-------+
# | 2   | eq | 22    |
# +-----+----+-------+

# Failed test '$! is EINVAL for a readlink(undef)'
# at t/readlink.t line 63.
# +-----+----+-------+
# | GOT | OP | CHECK |
# +-----+----+-------+
# | 2   | eq | 22    |
# +-----+----+-------+
# Seeded srand with seed '20220217' from local date.
t/readlink.t ...................... 
Dubious, test returned 2 (wstat 512, 0x200)
Failed 2/32 subtests 

So the difference is zfs, not freebsd in general.

[eserte]

Well, actually it's not zfs that makes the difference, but different FreeBSD versions. Following truss log snippets while running readlink.t:

• FreeBSD 12:

38819: 0.984243129 0.000011053 readlink("",0x7fffffffe2c0,1023) ERR#2 'No such file or directory'

• FreeBSD 14:

23719: 0.355629434 0.000008947 readlink("",0x820e3bef0,1023) ERR#22 'Invalid argument'

Probably it's easiest to accept both, EINVAL and ENOENT here.