[V13,1/6] add def_value_str in QemuOptDesc struct and rewrite qemu_opts_print

qemu_opts_print has no user now, so can re-write the function safely.

qemu_opts_print will be used while using "qemu-img create", it will
produce the same output as previous code.

The behavior of this function has changed:

1. Print every possible option, whether a value has been set or not.
2. Option descriptors may provide a default value.
3. Print to stdout instead of stderr.

Previously the behavior was to print every option that has been set.
Options that have not been set would be skipped.

Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
---
v12->v13
1) re-write commit message.

v11->v12
1) make def_value_str become the real default value string in opt_set
function.

v10->v11:
1) print all values that have actually been assigned while accept-any
cases.

v7->v8:
1) print "elements => accept any params" while opts_accepts_any() ==
true.
2) since def_print_str is the default value if an option isn't set,
so rename it to def_value_str.


 include/qemu/option.h |  3 ++-
 util/qemu-option.c    | 33 +++++++++++++++++++++++++++------
 2 files changed, 29 insertions(+), 7 deletions(-)

Dong Xu Wang <wdongxu@linux.vnet.ibm.com> writes:

> qemu_opts_print has no user now, so can re-write the function safely.
>
> qemu_opts_print will be used while using "qemu-img create", it will
> produce the same output as previous code.
>
> The behavior of this function has changed:
>
> 1. Print every possible option, whether a value has been set or not.
> 2. Option descriptors may provide a default value.
> 3. Print to stdout instead of stderr.
>
> Previously the behavior was to print every option that has been set.
> Options that have not been set would be skipped.
>
> Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
> ---
> v12->v13
> 1) re-write commit message.
>
> v11->v12
> 1) make def_value_str become the real default value string in opt_set
> function.
>
> v10->v11:
> 1) print all values that have actually been assigned while accept-any
> cases.
>
> v7->v8:
> 1) print "elements => accept any params" while opts_accepts_any() ==
> true.
> 2) since def_print_str is the default value if an option isn't set,
> so rename it to def_value_str.
>
>
>  include/qemu/option.h |  3 ++-
>  util/qemu-option.c    | 33 +++++++++++++++++++++++++++------
>  2 files changed, 29 insertions(+), 7 deletions(-)
>
> diff --git a/include/qemu/option.h b/include/qemu/option.h
> index bdb6d21..b928ab0 100644
> --- a/include/qemu/option.h
> +++ b/include/qemu/option.h
> @@ -96,6 +96,7 @@ typedef struct QemuOptDesc {
>      const char *name;
>      enum QemuOptType type;
>      const char *help;
> +    const char *def_value_str;
>  } QemuOptDesc;
>  
>  struct QemuOptsList {
> @@ -152,7 +153,7 @@ QDict *qemu_opts_to_qdict(QemuOpts *opts, QDict *qdict);
>  void qemu_opts_absorb_qdict(QemuOpts *opts, QDict *qdict, Error **errp);
>  
>  typedef int (*qemu_opts_loopfunc)(QemuOpts *opts, void *opaque);
> -int qemu_opts_print(QemuOpts *opts, void *dummy);
> +int qemu_opts_print(QemuOpts *opts);
>  int qemu_opts_foreach(QemuOptsList *list, qemu_opts_loopfunc func, void *opaque,
>                        int abort_on_failure);
>  
> diff --git a/util/qemu-option.c b/util/qemu-option.c
> index 8b74bf1..57cdd57 100644
> --- a/util/qemu-option.c
> +++ b/util/qemu-option.c
> @@ -646,6 +646,7 @@ static void opt_set(QemuOpts *opts, const char *name, const char *value,
>      }
>      opt->desc = desc;
>      opt->str = g_strdup(value);
> +    opt->str = g_strdup(value ?: desc->def_value_str);

Memory leak.  Did you forget to delete the previous line?  You do it in
PATCH 4/6, plugging the leak...

>      qemu_opt_parse(opt, &local_err);
>      if (error_is_set(&local_err)) {
>          error_propagate(errp, local_err);

opt_set() now accepts a null value argument, and so do its callers
qemu_opt_set(), qemu_opt_set_err(), qemu_opts_set().  Why?

> @@ -860,16 +861,36 @@ void qemu_opts_del(QemuOpts *opts)
>      g_free(opts);
>  }
>  
> -int qemu_opts_print(QemuOpts *opts, void *dummy)
> +int qemu_opts_print(QemuOpts *opts)
>  {
>      QemuOpt *opt;
> +    QemuOptDesc *desc = opts->list->desc;
>  
> -    fprintf(stderr, "%s: %s:", opts->list->name,
> -            opts->id ? opts->id : "<noid>");
> -    QTAILQ_FOREACH(opt, &opts->head, next) {
> -        fprintf(stderr, " %s=\"%s\"", opt->name, opt->str);
> +    if (desc[0].name == NULL) {
> +        QTAILQ_FOREACH(opt, &opts->head, next) {
> +            printf("%s=\"%s\" ", opt->name, opt->str);
> +        }
> +        return 0;
> +    }
> +    for (; desc && desc->name; desc++) {
> +        const char *value = desc->def_value_str;
> +        QemuOpt *opt;
> +
> +        opt = qemu_opt_find(opts, desc->name);
> +        if (opt) {
> +            value = opt->str;
> +        }
> +
> +        if (!value) {
> +            continue;
> +        }
> +
> +        if (desc->type == QEMU_OPT_STRING) {
> +            printf("%s='%s' ", desc->name, value);
> +        } else {
> +            printf("%s=%s ", desc->name, value);
> +        }
>      }
> -    fprintf(stderr, "\n");
>      return 0;
>  }