Am 14.04.2020 um 11:10 hat Markus Armbruster geschrieben: > Eric Blake <ebl...@redhat.com> writes: > > > On 4/9/20 10:30 AM, Markus Armbruster wrote: > >> The two turn out to be inconsistent for "a,b,,help". Test case > >> marked /* BUG */. > >> > >> Signed-off-by: Markus Armbruster <arm...@redhat.com> > >> --- > >> tests/test-qemu-opts.c | 38 ++++++++++++++++++++++++++++++++++++++ > >> 1 file changed, 38 insertions(+) > >> > > > >> +static void test_has_help_option(void) > >> +{ > >> + static const struct { > >> + const char *params; > >> + /* expected value of has_help_option() */ > >> + bool expect_has_help_option; > >> + /* expected value of qemu_opt_has_help_opt() with implied=false */ > >> + bool expect_opt_has_help_opt; > >> + /* expected value of qemu_opt_has_help_opt() with implied=true */ > >> + bool expect_opt_has_help_opt_implied; > >> + } test[] = { > >> + { "help", true, true, false },
While we're talking about unintuitive, I feel the result for implied=true is confusing, too. Never noticed it before, but are we really sure that it is the best possible behaviour that '-chardev help' and '-chardev id=foo,help' print two entirely different help texts? I'm not requesting to change anything about this in this series, but just making the point that maybe sometimes the existing behaviour is questionable. > >> + { "helpme", false, false, false }, > >> + { "a,help", true, true, true }, > >> + { "a=0,help,b", true, true, true }, > >> + { "help,b=1", true, true, false }, > >> + { "a,b,,help", false /* BUG */, true, true }, > > > > So which way are you calling the bug? Without looking at the code but > > going off my intuition, I parse this as option 'a' and option > > 'b,help'. The latter is not a normal option name because it contains a > > ',', but is a valid option value. > > > > I agree that we have a bug, but I'm not yet sure in which direction > > the bug lies (should has_help_option be fixed to report true, in which > > case the substring ",help" has precedence over ',,' escaping; or > > should qemu_opt_has_help_opt be fixed to report false, due to treating > > 'b,help' after ',,' escape removal as an invalid option name). So the > > placement of the /* BUG */ comment matters - where you placed it, I'm > > presuming that later in the series you change has_help_option to > > return true, even though that goes against my intuitive parse. > > In addition to the canonical QemuOpts parser opts_do_parse(), we have > several more, and of course they all differ from the canonical one for > corner cases. > > I treat the canonical one as correct, and fix the others by eliminating > the extra parsers. > > The others are: > > * has_help_option() > > Fixed in PATCH 5 by reusing the guts of opts_do_parse(). > > * is_valid_option_list() > > Fixed in PATCH 8 by not parsing. > > * "id" extraction in opts_parse() > > Lazy hack. Fixed in PATCH 3 by reusing the guts of opts_do_parse(). > > Back to your question: the value of has_help_option() differs from the > value of qemu_opt_has_help_opt(). The latter uses the canonical parser, > the former is one of the other parsers. I therefore judge the latter > right and the former wrong. Shouldn't we also consider what users would reasonably expect? Getting it parsed as an empty option name (I assume with a default value of "on"?) certainly looks like something that would surprise most users and, as you can see, even some QEMU developers. Kevin