[PATCH 2/2] globalvar: add helpers for stashing global variables

[Sascha Hauer]

On Thu, Mar 12, 2026 at 03:43:16PM +0100, Ahmad Fatoum wrote:
> Configuring a FIT image boot with overlays involves setting not only
> global.bootm.* variables, but also global.of.overlay.* variables.
> 
> For use in custom boot entry functions, provide functions for stashing
> and restoring a set of variables. This allows dry run and boot fallback
> behavior to not affect later boot attempts.

Looks generally good. I assume this is to replace the .dyn. type
variables, right?

Can we the a user before applying this?

Sascha

> 
> Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
> ---
>  common/globalvar.c  | 77 +++++++++++++++++++++++++++++++++++++++++++++
>  include/globalvar.h |  3 ++
>  2 files changed, 80 insertions(+)
> 
> diff --git a/common/globalvar.c b/common/globalvar.c
> index c2b0d5b4bbad..e168d6055347 100644
> --- a/common/globalvar.c
> +++ b/common/globalvar.c
> @@ -461,6 +461,83 @@ int globalvar_set(const char *name, const char *val)
>  	return dev_set_param(&global_device, name, val);
>  }
>  
> +struct globalvar_stashed {
> +	const char *key;
> +	const char *value;
> +	struct list_head list;
> +};
> +
> +static void globalvar_stashed_free(struct globalvar_stashed *elem)
> +{
> +	list_del(&elem->list);
> +	free_const(elem->key);
> +	free_const(elem->value);
> +	free(elem);
> +}
> +
> +int globalvar_stash_push(struct list_head *stash, ...)
> +{
> +	struct globalvar_stashed *elem, *safe;
> +	const char *name;
> +	int ret = -ENOMEM;
> +	va_list args;
> +	LIST_HEAD(tmp);
> +
> +	va_start(args, stash);
> +
> +	while ((name = va_arg(args, const char *))) {
> +		const char *value;
> +
> +		elem = calloc(1, sizeof(*elem));
> +		if (!elem)
> +			goto out;
> +
> +		list_add_tail(&elem->list, &tmp);
> +
> +		elem->key = strdup_const(name);
> +		if (!elem->key)
> +			goto out;
> +
> +		value = globalvar_get(name);
> +		if (!value) {
> +			ret = -EINVAL;
> +			goto out;
> +		}
> +
> +		elem->value = strdup_const(value);
> +		if (!elem->value)
> +			goto out;
> +	}
> +
> +	list_splice_tail(&tmp, stash);
> +
> +	ret = 0;
> +out:
> +	va_end(args);
> +
> +	if (ret) {
> +		list_for_each_entry_safe(elem, safe, &tmp, list)
> +			globalvar_stashed_free(elem);
> +	}
> +
> +	return ret;
> +}
> +
> +int globalvar_stash_pop(struct list_head *stash)
> +{
> +	struct globalvar_stashed *elem, *tmp;
> +	int err = 0;
> +
> +	list_for_each_entry_safe(elem, tmp, stash, list) {
> +		int ret = globalvar_set(elem->key, elem->value);
> +		if (ret)
> +			err = ret;
> +		globalvar_stashed_free(elem);
> +	}
> +
> +	return err;
> +}
> +
>  static int globalvar_simple_set(struct bobject *bobj, struct param_d *p,
>  				const char *val)
>  {
> diff --git a/include/globalvar.h b/include/globalvar.h
> index 413cf72002a0..1d39849ddbab 100644
> --- a/include/globalvar.h
> +++ b/include/globalvar.h
> @@ -24,6 +24,9 @@ char *globalvar_get_match(const char *match, const char *separator);
>  void globalvar_set_match(const char *match, const char *val);
>  int globalvar_set(const char *name, const char *val);
>  
> +int globalvar_stash_push(struct list_head *stash, ...) __attribute__((sentinel));
> +int globalvar_stash_pop(struct list_head *stash);
> +
>  int globalvar_add_simple_string(const char *name, char **value);
>  int globalvar_add_simple_int(const char *name, int *value,
>  			     const char *format);
> -- 
> 2.47.3
> 
> 
> 

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