Yegappan wrote:
> On Thu, Aug 9, 2018 at 12:52 PM, Bram Moolenaar <b...@moolenaar.net> wrote:
> >
> > Patch 8.1.0261
> > Problem: Coverity complains about a negative array index.
> > Solution: When qf_id2nr() cannot find the list then don't set qf_curlist.
> > Files: src/quickfix.c
> >
> >
> > *** ../vim-8.1.0260/src/quickfix.c 2018-08-09 21:19:15.774436077 +0200
> > --- src/quickfix.c 2018-08-09 21:49:36.929501416 +0200
> > ***************
> > *** 4339,4352 ****
> > }
> >
> > /*
> > * Jump to the first entry if there is one.
> > */
> > static void
> > qf_jump_first(qf_info_T *qi, int_u save_qfid, int forceit)
> > {
> > ! // If autocommands changed the current list, then restore it
> > ! if (qi->qf_lists[qi->qf_curlist].qf_id != save_qfid)
> > ! qi->qf_curlist = qf_id2nr(qi, save_qfid);
> >
> > // Autocommands might have cleared the list, check for it
> > if (!qf_list_empty(qi, qi->qf_curlist))
> > --- 4335,4365 ----
> > }
> >
> > /*
> > + * If the current list is not "save_qfid" and we can find the list with
> > that ID
> > + * then make it the current list.
> > + * This is used when autocommands may have changed the current list.
> > + */
> > + static void
> > + qf_restore_list(qf_info_T *qi, int_u save_qfid)
> > + {
> > + int curlist;
> > +
> > + if (qi->qf_lists[qi->qf_curlist].qf_id != save_qfid)
> > + {
> > + curlist = qf_id2nr(qi, save_qfid);
> > + if (curlist >= 0)
> > + qi->qf_curlist = curlist;
> > + // else: what if the list can't be found?
> >
>
> In all the places where qf_restore_list() is currently invoked, there
> is a call to
> qflist_valid() to check whether the list with the specified id is
> present or not.
> If the list is not present, then qf_restore_list() is not called. But
> in the future,
> someone might call qf_restore_list() without first checking whether the list
> is still present in the stack or not.
Yes, so the current construction is brittle, if someone makes changes
and forgets to call qflist_valid() then things break. That's basically
what Coverity complains about: unless you are careful qf_curlist becomes
negative.
We should move qflist_valid() into qf_restore_list(), and let it return
FAIL when the list isn't valid. Then the caller must deal with the
failure. This also applies to qf_jump_first() indirectly.
Can you make it work like that?
--
Shaw's Principle: Build a system that even a fool can use, and
only a fool will want to use it.
/// Bram Moolenaar -- b...@moolenaar.net -- http://www.Moolenaar.net \\\
/// sponsor Vim, vote for features -- http://www.Vim.org/sponsor/ \\\
\\\ an exciting new programming language -- http://www.Zimbu.org ///
\\\ help me help AIDS victims -- http://ICCF-Holland.org ///
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