Re: [PATCH 02/25] qemu-option: move help handling to get_opt_name_value

[Markus Armbruster <armbru@redhat.com>]

Paolo Bonzini <pbonzini@redhat.com> writes:

> Right now, help options are parsed normally and then checked
> specially in opt_validate, but only if coming from
> qemu_opts_parse_noisily.  has_help_option does the check on its own.
>
> opt_validate() has two callers: qemu_opt_set(), which passes null and is
> therefore unaffected, and opts_do_parse(), which is affected.
>
> opts_do_parse() is called by qemu_opts_do_parse(), which passes null and
> is therefore unaffected, and opts_parse().
>
> opts_parse() is called by qemu_opts_parse() and qemu_opts_set_defaults(),
> which pass null and are therefore unaffected, and
> qemu_opts_parse_noisily().
>
> Move the check from opt_validate to the parsing workhorse of QemuOpts,
> get_opt_name_value.  This will come in handy in the next patch, which
> will raise a warning for "-object memory-backend-ram,share" ("flag" option
> with no =on/=off part) but not for "-object memory-backend-ram,help".
>
> As a result:
>
> - opts_parse and opts_do_parse do not return an error anymore
>   when help is requested; qemu_opts_parse_noisily does not have
>   to work around that anymore.
>
> - various crazy ways to request help are not recognized anymore:
>   - "help=..."
>   - "nohelp" (sugar for "help=off")
>   - "?=..."
>   - "no?" (sugar for "?=off")
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  util/qemu-option.c | 38 +++++++++++++++++++++++---------------
>  1 file changed, 23 insertions(+), 15 deletions(-)
>
> diff --git a/util/qemu-option.c b/util/qemu-option.c
> index 91f4120ce1..5f27d4369d 100644
> --- a/util/qemu-option.c
> +++ b/util/qemu-option.c
> @@ -496,8 +496,7 @@ static QemuOpt *opt_create(QemuOpts *opts, const char *name, char *value,
>      return opt;
>  }
>  
> -static bool opt_validate(QemuOpt *opt, bool *help_wanted,
> -                         Error **errp)
> +static bool opt_validate(QemuOpt *opt, Error **errp)
>  {
>      const QemuOptDesc *desc;
>      const QemuOptsList *list = opt->opts->list;
> @@ -505,9 +504,6 @@ static bool opt_validate(QemuOpt *opt, bool *help_wanted,
>      desc = find_desc_by_name(list->desc, opt->name);
>      if (!desc && !opts_accepts_any(list)) {
>          error_setg(errp, QERR_INVALID_PARAMETER, opt->name);
> -        if (help_wanted && is_help_option(opt->name)) {
> -            *help_wanted = true;
> -        }
>          return false;
>      }
>  
> @@ -524,7 +520,7 @@ bool qemu_opt_set(QemuOpts *opts, const char *name, const char *value,
>  {
>      QemuOpt *opt = opt_create(opts, name, g_strdup(value), false);
>  
> -    if (!opt_validate(opt, NULL, errp)) {
> +    if (!opt_validate(opt, errp)) {
>          qemu_opt_del(opt);
>          return false;
>      }
> @@ -760,10 +756,12 @@ void qemu_opts_print(QemuOpts *opts, const char *separator)
>  
>  static const char *get_opt_name_value(const char *params,
>                                        const char *firstname,
> +                                      bool *help_wanted,
>                                        char **name, char **value)
>  {
>      const char *p;
>      size_t len;
> +    bool is_help = false;
>  
>      len = strcspn(params, "=,");
>      if (params[len] != '=') {
> @@ -780,6 +778,7 @@ static const char *get_opt_name_value(const char *params,
>                  *value = g_strdup("off");
>              } else {
>                  *value = g_strdup("on");
> +                is_help = is_help_option(*name);
>              }
>          }
>      } else {
> @@ -791,6 +790,9 @@ static const char *get_opt_name_value(const char *params,
>      }
>  
>      assert(!*p || *p == ',');
> +    if (help_wanted && is_help) {
> +        *help_wanted = true;

Note [1] for later: we only ever set *help_wanted to true.

> +    }
>      if (*p == ',') {
>          p++;
>      }
> @@ -806,7 +808,12 @@ static bool opts_do_parse(QemuOpts *opts, const char *params,
>      QemuOpt *opt;
>  
>      for (p = params; *p;) {
> -        p = get_opt_name_value(p, firstname, &option, &value);
> +        p = get_opt_name_value(p, firstname, help_wanted, &option, &value);
> +        if (help_wanted && *help_wanted) {
> +            g_free(option);
> +            g_free(value);
> +            return false;
> +        }
>          firstname = NULL;
>  
>          if (!strcmp(option, "id")) {
> @@ -817,7 +824,7 @@ static bool opts_do_parse(QemuOpts *opts, const char *params,
>  
>          opt = opt_create(opts, option, value, prepend);
>          g_free(option);
> -        if (!opt_validate(opt, help_wanted, errp)) {
> +        if (!opt_validate(opt, errp)) {
>              qemu_opt_del(opt);
>              return false;
>          }
> @@ -832,7 +839,7 @@ static char *opts_parse_id(const char *params)
>      char *name, *value;
>  
>      for (p = params; *p;) {
> -        p = get_opt_name_value(p, NULL, &name, &value);
> +        p = get_opt_name_value(p, NULL, NULL, &name, &value);
>          if (!strcmp(name, "id")) {
>              g_free(name);
>              return value;
> @@ -848,11 +855,10 @@ bool has_help_option(const char *params)
>  {
>      const char *p;
>      char *name, *value;
> -    bool ret;
> +    bool ret = false;

This initializer is required due to [1].
>  
>      for (p = params; *p;) {
> -        p = get_opt_name_value(p, NULL, &name, &value);
> -        ret = is_help_option(name);
> +        p = get_opt_name_value(p, NULL, &ret, &name, &value);
>          g_free(name);
>          g_free(value);
>          if (ret) {

Works, but I'd prefer get_opt_name_value() to always set *help_wanted
when help_wanted isn't null.  Up to you.

> @@ -937,11 +943,13 @@ QemuOpts *qemu_opts_parse_noisily(QemuOptsList *list, const char *params,
>      QemuOpts *opts;
>      bool help_wanted = false;
>  
> -    opts = opts_parse(list, params, permit_abbrev, false, &help_wanted, &err);
> -    if (err) {
> +    opts = opts_parse(list, params, permit_abbrev, false,
> +                      opts_accepts_any(list) ? NULL : &help_wanted,
> +                      &err);
> +    if (!opts) {
> +        assert(!!err + !!help_wanted == 1);

Either err or help_wanted.  This is logical inequality.  I'd write it as

           assert(!err != !help_wanted);

or maybe as

           assert(!err ^ !help_wanted);

But your artistic license applies.

>          if (help_wanted) {
>              qemu_opts_print_help(list, true);
> -            error_free(err);
>          } else {
>              error_report_err(err);
>          }

Before the patch, we recognize help requests only if they aren't
captured by a (foolishly named) parameter name.

Afterwards, we recognize only sane help requests regardless of
parameters.  In other words:

  - various crazy ways to request help are not recognized anymore:
    - "help=..."
    - "nohelp" (sugar for "help=off")
    - "?=..."
    - "no?" (sugar for "?=off")

  - "help" is recognized as help request even if there is a (foolishly
    named) parameter "help".  No such parameters exist.

Let's add the last item to the commit message, too.

Preferably with the commit message amended:
Reviewed-by: Markus Armbruster <armbru@redhat.com>