Re: [Qemu-devel] [RFC v2 1/7] qemu-option: qemu_opt_set_bool(): fix code duplication

[Paolo Bonzini <pbonzini@redhat.com>]

Il 27/09/2012 07:14, Dong Xu Wang ha scritto:
> Call qemu_opt_set() instead of duplicating opt_set().
> 
> It will set opt->str in qemu_opt_set_bool, without opt->str, there
> will be some potential bugs.
> 
> These are uses of opt->str, and what happens when it isn't set:
> 
> * qemu_opt_get(): returns NULL, which means "not set".  Bug can bite
>   when value isn't the default value.
> 
> * qemu_opt_parse(): passes NULL to parse_option_bool(), which treats it
>   like "on".  Wrong if the value is actually false.  Bug can bite when
>   qemu_opts_validate() runs after qemu_opt_set_bool().
> 
> * qemu_opt_del(): passes NULL to g_free(), which is just fine.
> 
> * qemu_opt_foreach(): passes NULL to the callback, which is unlikely to
>   be prepared for it.
> 
> * qemu_opts_print(): prints NULL, which crashes on some systems.
> 
> * qemu_opts_to_qdict(): passes NULL to qstring_from_str(), which
>   crashes.
> 
> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
> ---
>  qemu-option.c |   28 +---------------------------
>  1 files changed, 1 insertions(+), 27 deletions(-)
> 
> diff --git a/qemu-option.c b/qemu-option.c
> index 27891e7..0b81e77 100644
> --- a/qemu-option.c
> +++ b/qemu-option.c
> @@ -667,33 +667,7 @@ void qemu_opt_set_err(QemuOpts *opts, const char *name, const char *value,
>  
>  int qemu_opt_set_bool(QemuOpts *opts, const char *name, bool val)
>  {
> -    QemuOpt *opt;
> -    const QemuOptDesc *desc = opts->list->desc;
> -    int i;
> -
> -    for (i = 0; desc[i].name != NULL; i++) {
> -        if (strcmp(desc[i].name, name) == 0) {
> -            break;
> -        }
> -    }
> -    if (desc[i].name == NULL) {
> -        if (i == 0) {
> -            /* empty list -> allow any */;
> -        } else {
> -            qerror_report(QERR_INVALID_PARAMETER, name);
> -            return -1;
> -        }
> -    }
> -
> -    opt = g_malloc0(sizeof(*opt));
> -    opt->name = g_strdup(name);
> -    opt->opts = opts;
> -    QTAILQ_INSERT_TAIL(&opts->head, opt, next);
> -    if (desc[i].name != NULL) {
> -        opt->desc = desc+i;
> -    }
> -    opt->value.boolean = !!val;
> -    return 0;
> +    return qemu_opt_set(opts, name, val ? "on" : "off");

This now calls qemu_opt_parse, which won't work if you have opt->desc =
NULL.

Instead of this patch, using the new functions you create in patch 2
should be enough to limit the code duplication in qemu_opt_set_bool.

Paolo

>  }
>  
>  int qemu_opt_foreach(QemuOpts *opts, qemu_opt_loopfunc func, void *opaque,
>