[PATCH] Implement the mlock2 function

[Florian Weimer]

On 11/27/2017 05:35 PM, Adhemerval Zanella wrote:
> 
> 
> On 27/11/2017 14:07, Florian Weimer wrote:
>> On 11/27/2017 02:11 PM, Adhemerval Zanella wrote:
>>> This is a reasonable approach and I am ok with this patch with the
>>> INLINE_SYSCALL_CALL change. I wonder if it is worth to add a similar
>>> change to p{read,write}v2 to return ENOSUP in the case of ENOSYS.
>>
>> My copy of the manual page says that EINVAL is used there as well.
>>
>> Thanks,
>> Florian
> 
> Indeed manpages [1] states that EINVAL is returned, but our documentation
> states otherwise:
> 
> manual/llio.texi
> 
> 1286 @item EOPNOTSUPP
> 1287
> 1288 @c The default sysdeps/posix code will return it for any flags value
> 1289 @c different than 0.
> 1290 An unsupported @var{flags} was used.
> 
> Also, "tst-preadvwritev" on a 4.13.0-17-generic indeed generates Linux
> EOPNOTSUPP (ENOSUP):
> 
> [pid  7896] preadv2(3,  <unfinished ...>
> [pid  7895] <... rt_sigaction resumed> {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
> [pid  7896] <... preadv2 resumed> [{iov_base=0x7ffca77846d0, iov_len=32}], 1, 0, 0x10 /* RWF_??? */) = -1 EOPNOTSUPP (Operation not supported)
> [pid  7895] wait4(7896,  <unfinished ...>
> [pid  7896] pwritev2(3, [{iov_base="\0\0\0\0\0\0\0\0\241H\363?\244\177\0\0@Gx\247\374\177\0\0\0\0\0\0\0\0\0\0", iov_len=32}], 1, 0, 0x10 /* RWF_??? */) = -1 EOPNOTSUPP (Operation not supported)
> 
> So I think it would be worth to change p{read,write}v2 on GLIBC to
> return EINVAL for invalid flags. I will prepare a patch.
> 
> [1] http://man7.org/linux/man-pages/man2/preadv2.2.html

Typo?  Shouldn't we match the kernel behavior, so fail with EOPNOTSUPP?

(I double-checked, and for mlock2, the kernel does return EINVAL.)

Thanks,
Florian