Hi On Tue, Aug 17, 2021 at 12:56 PM Michal Privoznik <mpriv...@redhat.com> wrote:
> When opening a path that starts with "/dev/fdset/" the control > jumps into qemu_parse_fdset() and then into > monitor_fdset_dup_fd_add(). In here, corresponding fdset is found > and then all FDs from the set are iterated over trying to find an > FD that matches expected access mode. For instance, if caller > wants O_WRONLY then the FD set has to contain an O_WRONLY FD. > > If no such FD is found then errno is set to EACCES which results > in very misleading error messages, for instance: > > Could not dup FD for /dev/fdset/3 flags 441: Permission denied > > There is no permission issue, the problem is that there was no FD > within given fdset that was in expected access mode. Therefore, > let's set errno to EBADFD, which gives us somewhat better > error messages: > > Could not dup FD for /dev/fdset/3 flags 441: File descriptor in bad state > > Signed-off-by: Michal Privoznik <mpriv...@redhat.com> > I am not sure this is any better. If you try to open a read-only file, the system also reports EACCES (Permission denied). This is what the current code models, I believe. > --- > monitor/misc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/monitor/misc.c b/monitor/misc.c > index ffe7966870..a0eda0d574 100644 > --- a/monitor/misc.c > +++ b/monitor/misc.c > @@ -1347,7 +1347,7 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int > flags) > } > > if (fd == -1) { > - errno = EACCES; > + errno = EBADFD; > return -1; > } > > -- > 2.31.1 > >