On 07/13/12 18:51, Luiz Capitulino wrote: > On Wed, 13 Jun 2012 10:22:36 +0200 > Laszlo Ersek wrote: >> Repeating an optarg is supported; > > I see that the current code supports this too, but why? Something > like this should fail: > > -netdev type=tap,vhost=on,vhost=off,id=guest1,script=qemu-ifup-switch > Also, you're using a queue to support the repeating of optargs, > right? I think this could be simplified if we just don't support > that. I hate repeated options with a passion, but SLIRP's hostfwd and guestfwd depend on repetition. When the outermost opts_start_struct() is invoked and I shovel the optargs into the queues, I can't yet know what's going to be used in repeated form and what not. If you prefer I can change lookup_scalar() as follows. For reference: >> +static GQueue * >> +lookup_distinct(const OptsVisitor *ov, const char *name, Error **errp) >> +{ >> + GQueue *list; >> + >> + list = g_hash_table_lookup(ov->unprocessed_opts, name); >> + if (!list) { >> + error_set(errp, QERR_MISSING_PARAMETER, name); >> + } >> + return list; >> +} >> +static void >> +opts_start_optional(Visitor *v, bool *present, const char *name, >> + Error **errp) >> +{ >> + OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v); >> + >> + /* we only support a single mandatory scalar field in a list node */ >> + assert(ov->repeated_opts == NULL); >> + *present = (lookup_distinct(ov, name, NULL) != NULL); >> +} >> +static const QemuOpt * >> +lookup_scalar(const OptsVisitor *ov, const char *name, Error **errp) >> +{ >> + if (ov->repeated_opts == NULL) { >> + GQueue *list; >> + >> + /* the last occurrence of any QemuOpt takes effect when queried by name >> + */ >> + list = lookup_distinct(ov, name, errp; >> + return list ? g_queue_peek_tail(list) : NULL; We're outside of list traversal in this branch, meaning the optarg is allowed exactly once. (Optional optargs are first handled by opts_start_optional().) If lookup_distinct() succeeds here, then rather than returning the last occurrence, I could check the depth of the queue (== 1 or > 1), and set an error for > 1. However QemuOpts definitely supports repeated optargs now (otherwise slirp hostfwd/guestfwd wouldn't work). qemu_opt_foreach() is used for iteration (with QTAILQ_FOREACH()), while qemu_opt_find() -- and thus its direct callers -- rely on QTAILQ_FOREACH_REVERSE() and the first match. Optargs of an option are apparently chained like this: qemu_opts_parse() [qemu-option.c] opts_parse(..., defaults=false) opts_do_parse(..., prepend=false) opt_set(..., prepend=false, ...) QTAILQ_INSERT_TAIL() "-option arg=val1,arg=val2,arg=val3" is therefore linked into the corresponding QemuOpts instance in the same order, and qemu_opt_find() will return "arg=val3". I also use g_queue_push_tail() and g_queue_peek_tail(), so I think we're compatible. >> + } >> + return g_queue_peek_head(ov->repeated_opts); >> +} Continuing slightly out of order: >> +/* mimics qemu-option.c::parse_option_bool() */ >> +static void >> +opts_type_bool(Visitor *v, bool *obj, const char *name, Error **errp) >> +{ >> + OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v); >> + const QemuOpt *opt; >> + >> + opt = lookup_scalar(ov, name, errp); >> + if (!opt) { >> + return; >> + } >> + >> + if (opt->str) { >> + if (strcmp(opt->str, "on") == 0 || >> + strcmp(opt->str, "yes") == 0 || >> + strcmp(opt->str, "y") == 0) { >> + *obj = true; >> + } else if (strcmp(opt->str, "off") == 0 || >> + strcmp(opt->str, "no") == 0 || >> + strcmp(opt->str, "n") == 0) { >> + *obj = false; > > The current code only accepts 'on' or 'off', no reason to change that. > >> + } else { >> + error_set(errp, QERR_INVALID_PARAMETER_VALUE, opt->name, >> + "on|yes|y|off|no|n"); >> + return; >> + } >> + } else { >> + *obj = true; >> + } >> + >> + processed(ov, name); >> +} This function is used for "bool" generally. The following optargs were all unified as "bool": - slirp/restrict: originally QEMU_OPT_STRING, net_init_slirp() accepting all of "on|yes|y|off|no|n" - tap/vnet_hdr: originally QEMU_OPT_BOOL, parse_option_bool() accepting "on|off". - tap/vhost: ditto - tap/vhostforce: ditto So I took the union (nothing should break that used to work). The leading comment rather means that the structure of parse_option_bool() is followed: - optarg values meaning "true": true - optarg values meaning "false": false - other optarg values: error - no optarg value at all: true >> +static void >> +opts_start_struct(Visitor *v, void **obj, const char *kind, >> + const char *name, size_t size, Error **errp) >> +{ >> + OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v); >> + const QemuOpt *opt; >> + >> + *obj = g_malloc0(size); >> + if (ov->depth++ > 0) { >> + return; >> + } >> + >> + ov->unprocessed_opts = g_hash_table_new_full(&g_str_hash, &g_str_equal, >> + NULL, &destroy_list); >> + QTAILQ_FOREACH(opt, &ov->opts_root->head, next) { >> + GQueue *list; >> + >> + list = g_hash_table_lookup(ov->unprocessed_opts, opt->name); >> + if (list == NULL) { >> + list = g_queue_new(); >> + >> + /* GHashTable will never try to free the keys -- we supplied NULL >> + * as "key_destroy_func" above. Thus cast away key const-ness in >> + * order to suppress gcc's warning. */ >> + g_hash_table_insert(ov->unprocessed_opts, (gpointer)opt->name, >> + list); >> + } >> + >> + /* Similarly, destroy_list() doesn't call g_queue_free_full(). */ >> + g_queue_push_tail(list, (gpointer)opt); >> + } >> +} > > This doesn't insert the opts id into the hash, so opts_type_str() > will fail to find the id when the generated code visits it here: > > void visit_type_Netdev(Visitor *m, Netdev ** obj, const char *name, Error **errp) > { > if (!error_is_set(errp)) { > Error *err = NULL; > visit_start_struct(m, (void **)obj, "Netdev", name, sizeof(Netdev), &err); > if (!err) { > assert(!obj || *obj); > visit_type_str(m, obj ? &(*obj)->id : NULL, "id", &err); <--------- > [...] > *groan* You're right. opts_do_parse() makes an exception with "id" and doesn't call opt_set() for any occurrence of it. Would you accept the attached fix, split up and squashed into previous parts appropriately? Thanks! Laszlo