bin/60287: [patch] NSS does not handle NSS_STATUS_TRYAGAIN
Jacques A. Vidrine
nectar at FreeBSD.org
Thu Dec 18 19:43:53 PST 2003
On Fri, Dec 19, 2003 at 02:14:33PM +1100, Lachlan O'Dea wrote:
> Are you certain that the module should actually set errno? At the
> moment, nss_ldap does return ERANGE, but not in errno.
Well, NSS modules do not set errno directly but rather use the supplied
errnop argument. But yes, it must set errno.
> In the LDAP
> case, getgrent seems to end up calling:
> _nss_ldap_getgrent_r (struct group *result,
> char *buffer, size_t buflen, int *errnop)
> In the buffer too small case, *errnop _is_ set to ERANGE.
Not that I saw... I was looking for what nss_ldap does after checking
`bytesleft', e.g. from _nss_ldap_parse_gr:
if (bytesleft (buffer, buflen, char *) <
(dn_mems_c + 1) * sizeof (char *))
I believe it should do `*errnop = ERANGE' in this case.
> This ends up
> being checked by libc before it expands the buffer in getgr in
> In any case, I don't think my patch needs to be changed? I think you're
> saying that the errno code tells us why TRYAGAIN was returned. But
> regardless of why, TRYAGAIN implies that the operation can be, well,
> tried again. So we never want to set the terminate flag in the TRYAGAIN
> case, regardless of the errno value.
No. The behavior of `TRYAGAIN' depends upon what is set in
/etc/nsswitch.conf, and has nothing whatsoever to do with the
FreeBSD-specific implementation of getgrent which is layered on top
of getgrent_r. The actual fix is multifold:
1. the GNU libc compat stuff should not set the terminator in
the NS_RETURN case
2. the GNU libc compat stuff should `translate' the condition
`result == NSS_STATUS_TRYAGAIN && *errnop == ERANGE' into
`result == NS_RETURN && *errnop == ERANGE'
3. nss_ldap should set ERANGE when it is given a buffer that is
too small, as required by the GNU libc documentation
I'll be happy to discuss further when I return! Cheers,
Jacques Vidrine . NTT/Verio SME . FreeBSD UNIX . Heimdal
nectar at celabo.org . jvidrine at verio.net . nectar at freebsd.org . nectar at kth.se
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