Re: [SSSD] [PATCH] SYSDB: sysdb_search_object_by_sid returns ENOENT

[Pavel Reichl]

On 12/12/2014 03:02 PM, Lukas Slebodnik wrote:
> On (12/12/14 14:25), Pavel Reichl wrote:
> > On 12/11/2014 06:35 PM, Michal Židek wrote:
> > > I think that smaller nesting levels are better.
> > >
> > > In general I would do
> > >
> > > if (ret == SPECIFIC_CODE) {
> > >    specific_error_handle_block
> > > } else (ret != EOK) {
> > >    general_error_handle_block
> > > }
> > >
> > > If there are many specific error codes that need to be addressed,
> > > use switch, but 1-2 else-ifs are ok to me.
> > >
> > > This pattern can be used if common_to_all_erros_action exists (and is
> > > something more than just goto done):
> > >
> > > if (ret != EOK) {
> > >    if (ret == SPECIFIC_CODE) {
> > >        specific_error_handle_block
> > >    }
> > >    common_to_all_errors_action;
> > > }
> > >
> > > So I would slightly prefer Lukas's solution over Pavel's.
> > >
> > > In this particullar case I would do:
> > > if (ret == ENOENT) {
> > >     ....
> > > } else if (ret != EOK) {
> > >     ....
> > > }
> > >
> > > Michal
> >
> > OK, thank you both for opinions and for comments.
> >
> > Please see updated patch.
> >
> > Thanks!
>
> Two questions/comments are inline.
> > From 94eade7b3c0c0729f5d4a322061c7c9688bd8130 Mon Sep 17 00:00:00 2001
> > From: Pavel Reichl 
> > Date: Tue, 9 Dec 2014 11:01:13 +0000
> > Subject: [PATCH 2/2] SYSDB: sysdb_search_object_by_sid returns ENOENT
> >
> > sysdb_search_object_by_sid returns ENOENT if no results are found.
> >
> > Part od solution for:
> > https://fedorahosted.org/sssd/ticket/1991
> >
> > Fixes:
> > https://fedorahosted.org/sssd/ticket/2520
> >
> > src/db/sysdb.h                 |  2 +-
> > src/db/sysdb_ops.c             | 68 ++++++------------------------------------
> > src/responder/nss/nsssrv_cmd.c | 27 ++++++++---------
> > src/responder/pac/pacsrv_cmd.c | 29 ++++++++++--------
> > src/tests/sysdb-tests.c        |  5 +---
> > 5 files changed, 40 insertions(+), 91 deletions(-)
> > errno_t sysdb_search_object_by_uuid(TALLOC_CTX *mem_ctx,
> > diff --git a/src/responder/nss/nsssrv_cmd.c b/src/responder/nss/nsssrv_cmd.c
> > index ea58920bc3611c84958e8d0aca0e122d90c68e5c..3c5d450714fb3f7655cd32aeef900b4f5e9782c7 100644
> > --- a/src/responder/nss/nsssrv_cmd.c
> > +++ b/src/responder/nss/nsssrv_cmd.c
> > @@ -4491,7 +4491,19 @@ static errno_t nss_cmd_getbysid_search(struct nss_dom_ctx *dctx)
> >  ret = sysdb_search_object_by_sid(cmdctx, dom, cmdctx->secid, NULL,
> >                                   &dctx->res);
> > if (ret != EOK) {
> > if (ret == ENOENT) {
> >    if (!dctx->check_provider) {
> >        DEBUG(SSSDBG_OP_FAILURE, "No results for getbysid call.\n");
> >        /* set negative cache only if not result of cache check */
> >        ret = sss_ncache_set_sid(nctx->ncache, false, cmdctx->secid);
> >        if (ret != EOK) {
> >            DEBUG(SSSDBG_MINOR_FAILURE,
> >                  "Cannot set negative cache for %s\n", cmdctx->secid);
> >        }
> >    }
> >    return ENOENT;
>
> You changed behaviour with this nesting if statements.
> ENOENT will be returned every time. Previously it was returned just in case of
> true condition (dctx->res->count == 0 && !dctx->check_provider)
> Could you explain such change?

Because otherwise 'res' is accessed in case of ENOENT which implies 
segfault in nss_cmd_getbysid_send_reply() or even earlier in 
check_cache(), if I read the code correctly.
> > } else if (ret != EOK) {
> >     DEBUG(SSSDBG_CRIT_FAILURE, "Failed to make request to our cache!\n");
> >     return EIO;
> > }
> >
> > @@ -4502,19 +4514,6 @@ static errno_t nss_cmd_getbysid_search(struct nss_dom_ctx *dctx)
> >          return ENOENT;
> >      }
> > if (dctx->res->count == 0 && !dctx->check_provider) {
> >    DEBUG(SSSDBG_OP_FAILURE, "No results for getbysid call.\n");
> >    /* set negative cache only if not result of cache check */
> >    ret = sss_ncache_set_sid(nctx->ncache, false, cmdctx->secid);
> >    if (ret != EOK) {
> >        DEBUG(SSSDBG_MINOR_FAILURE,
> >              "Cannot set negative cache for %s\n", cmdctx->secid);
> >    }
> >    return ENOENT;
> > }
>
> ^^^^
> @see removed code.
> >  /* if this is a caching provider (or if we haven't checked the cache
> >   * yet) then verify that the cache is uptodate */
> >  if (dctx->check_provider) {
> >
> > diff --git a/src/responder/pac/pacsrv_cmd.c b/src/responder/pac/pacsrv_cmd.c
> > index cc92592893899b1fa269188facc1a8154f80991d..07d2f0cf79b70429dc7cf2784a8e31d651e5095f 100644
> > --- a/src/responder/pac/pacsrv_cmd.c
> > +++ b/src/responder/pac/pacsrv_cmd.c
> > @@ -911,10 +911,13 @@ pac_store_membership(struct pac_req_ctx *pr_ctx,
> >  ret = sysdb_search_object_by_sid(tmp_ctx, grp_dom, grp_sid_str,
> >                                   group_attrs, &group);
> > if (ret != EOK) {
> >    DEBUG(SSSDBG_TRACE_INTERNAL, "sysdb_search_object_by_sid " \
> >                                  "for SID [%s] failed [%d][%s].\n",
> >                                  grp_sid_str, ret, strerror(ret));
> > if (ret == ENOENT) {
> >    DEBUG(SSSDBG_OP_FAILURE, "Unexpected number of groups returned.\n");
>                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>                                  This message can be little bit confusing.
>        We exactly know what's wrong. There isn't such object for SID.
>        It's better to be clear.
>
> LS
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