Re: commit: ldap/libraries/liblber io.c

[Hallvard B Furuseth <h.b.furuseth@usit.uio.no>]

Looking closer now that I'm awake...

Howard Chu writes:
>Hallvard B Furuseth wrote:
>>Howard Chu writes:
>>>> Keep the sock_errset() if returning LBER_DEFAULT and sblen<   0?
>>> No. ber_int_sb_read() will cause errno to already be set if it cannot
>>> fulfill the request.
>>
>> Sorry, I meant sblen>= 0 of course.  That can be a read() result which
>> does not set errno.
>
> No, doesn't matter. A blocking read that returns 0 means of course that the
> connection was closed.

But the caller doesn't know that.  What it knows is that ber_get_next()
returned LBER_DEFAULT.  Anyway, that part of the code seems to be gone
now.

> A non-blocking read that returns 0 will set errno.

Not on my host (Linux).  And not in the Posix spec that I can see.


In any case, it looks like the error number handling is incomplete:

ber_get_next() can do sock_errset(0) before calling ber_int_sb_read()
and returning LBER_DEFAULT if zero result, however that function can set
errno spuriously and then return zero.  At least in an EINTR loop there
or in sb_rdahead_read().  I don't know if the read OS call itself is one
of the functions which can set errno (or WSASetLastError) spuriously on
some OSes.

ber_get_next() can return LBER_DEFAULT due to memory allocation error, I
don't suppose that does sock_errset().  Haven't checked if all variants
set errno either before failing.

On the caller side, slapd/connection.c treats all other return values
than LDAP_TAG_MESSAGE as LBER_DEFAULT and examines sock_errno().
libldap/result.c does Debug() before reading sock_errno().  Debug() can
change errno.

-- 
Hallvard