Re: [PATCH 1/2] Exporting variables to upper levels

[Avnish Chouhan <avnish@linux.ibm.com>]

> Message: 4
> Date: Mon, 26 May 2025 19:22:38 +0200
> From: Jiří 'bindiff' Wolker <projects@jwo.cz>
> To: grub-devel@gnu.org
> Subject: [PATCH 1/2] Exporting variables to upper levels
> Message-ID: <853421b8-f534-45a9-9c21-0769148fc4a5@jwo.cz>
> Content-Type: text/plain; charset=UTF-8; format=flowed
> 
> This adds new options ‘-g’ and ‘-u’ to the ‘export’ command.
> 
> By default, the ‘export’ command exports the variables to
> lower environment context nesting levels, but not to the upper levels.
> This behavior is left unchanged from the original version.
> 
> Using of the ‘-g’ option allows exporting of the given variable(s)
> even to the upper levels.
> 
> The ‘-u’ option complements the default behavior of ‘export’ command:
> It causes the variable to become local, i.e., un-exported.
> ---
>   grub-core/kern/env.c       | 11 ++++--
>   grub-core/normal/context.c | 70 
> ++++++++++++++++++++++++++++++--------
>   include/grub/env.h         | 11 +++++-
>   3 files changed, 75 insertions(+), 17 deletions(-)
> 
> diff --git a/grub-core/kern/env.c b/grub-core/kern/env.c
> index 764068896..6b60c71de 100644
> --- a/grub-core/kern/env.c
> +++ b/grub-core/kern/env.c
> @@ -231,7 +231,8 @@ grub_register_variable_hook (const char *name,
>   }
>    grub_err_t
> -grub_env_export (const char *name)
> +grub_env_set_export_mode (const char *name,
> +			  enum grub_env_var_export mode)

Hi Jiří,

This above statement would be better in one line!

grub_env_set_export_mode (const char *name, enum grub_env_var_export 
mode)

>   {
>     struct grub_env_var *var;
>   @@ -245,7 +246,13 @@ grub_env_export (const char *name)
>   	return err;
>         var = grub_env_find (name);
>       }
> -  var->global = 1;
> +  var->global = mode;
>      return GRUB_ERR_NONE;
>   }
> +
> +grub_err_t
> +grub_env_export (const char *name)
> +{
> +  return grub_env_set_export_mode (name, grub_env_var_exported);
> +}
> diff --git a/grub-core/normal/context.c b/grub-core/normal/context.c
> index ba185e915..8abe5065c 100644
> --- a/grub-core/normal/context.c
> +++ b/grub-core/normal/context.c
> @@ -22,6 +22,7 @@
>   #include <grub/misc.h>
>   #include <grub/mm.h>
>   #include <grub/command.h>
> +#include <grub/extcmd.h>
>   #include <grub/normal.h>
>   #include <grub/i18n.h>
>   @@ -88,7 +89,7 @@ grub_env_new_context (int export_all)
>   		grub_env_context_close ();
>   		return grub_errno;
>   	      }
> -	    grub_env_export (var->name);
> +	    grub_env_set_export_mode (var->name, var->global);
>   	    grub_register_variable_hook (var->name, var->read_hook,
> var->write_hook);
>   	  }
>       }
> @@ -115,31 +116,52 @@ grub_err_t
>   grub_env_context_close (void)
>   {
>     struct grub_env_context *context;
> +  struct grub_env_context *original_context;
>     int i;
>     struct menu_pointer *menu;
> +  grub_err_t last_err = GRUB_ERR_NONE;
>      if (! grub_current_context->prev)
>       return grub_error (GRUB_ERR_BAD_ARGUMENT,
>   		       "cannot close the initial context");
>   -  /* Free the variables associated with this context.  */
> +  /* Restore the previous context.  */
> +  original_context = grub_current_context;
> +  context = grub_current_context->prev;
> +  grub_current_context = context;
> +
> +  /* Re-export global variables to the upper context. */
> +
>     for (i = 0; i < HASHSZ; i++)
>       {
>         struct grub_env_var *p, *q;
>   -      for (p = grub_current_context->vars[i]; p; p = q)
> +      for (p = original_context->vars[i]; p; p = q)
>   	{
>   	  q = p->next;
> +
> +	  /* Copy global variables to the upper context. */
> +	  if (p->global == grub_env_var_global) {

Please move '{' to next line!

> +	    if (grub_env_set (p->name, p->value) != GRUB_ERR_NONE)
> +	      {
> +		last_err = grub_errno;
> +	      }

Brackets are not required here!

> +	    else
> +	      {
> +		grub_env_set_export_mode (p->name, p->global);
> +		grub_register_variable_hook (p->name, p->read_hook, p->write_hook);
> +	      }
> +	  }
> +
> +	  /* Free the variables associated with this context.  */
>             grub_free (p->name);
>   	  grub_free (p->value);
>   	  grub_free (p);
>   	}
>       }
>   -  /* Restore the previous context.  */
> -  context = grub_current_context->prev;
> -  grub_free (grub_current_context);
> -  grub_current_context = context;
> +  /* Free the previous context. */
> +  grub_free (original_context);
>      menu = current_menu->prev;
>     if (current_menu->menu)
> @@ -181,34 +203,54 @@ grub_env_extractor_close (int source)
>     return err;
>   }
>   -static grub_command_t export_cmd;
> +static grub_extcmd_t export_cmd;
>    static grub_err_t
> -grub_cmd_export (struct grub_command *cmd __attribute__ ((unused)),
> +grub_cmd_export (grub_extcmd_context_t ctxt,
>   		 int argc, char **args)
>   {
> +  struct grub_arg_list *state = ctxt->state;
>     int i;
>   +  enum grub_env_var_export mode = grub_env_var_exported;
> +  if (state[0].set)
> +    mode = grub_env_var_local;
> +  if (state[1].set)
> +    mode = grub_env_var_global;
> +  if (state[0].set && state[1].set)
> +    return grub_error (GRUB_ERR_BAD_ARGUMENT,
> +		       N_("canot use both -u and -a at once"));

Indention seems off here!

return grub_error (GRUB_ERR_BAD_ARGUMENT,
                    N_("canot use both -u and -a at once"));

> +
>     if (argc < 1)
>       return grub_error (GRUB_ERR_BAD_ARGUMENT,
>   		       N_("one argument expected"));
>      for (i = 0; i < argc; i++)
> -    grub_env_export (args[i]);
> +    grub_env_set_export_mode (args[i], mode);
>      return 0;
>   }
>   +static const struct grub_arg_option export_options[] =
> +  {
> +    {"unexport", 'u', 0, N_("Undo exporting the variable."), 0, 0},
> +    {"global", 'g', 0, N_("Export also to parent contexts."), 0, 0},
> +    {0, 0, 0, 0, 0, 0}
> +  };
> +
>   void
>   grub_context_init (void)
>   {
> -  export_cmd = grub_register_command ("export", grub_cmd_export,
> -				      N_("ENVVAR [ENVVAR] ..."),
> -				      N_("Export variables."));
> +  export_cmd = grub_register_extcmd ("export", grub_cmd_export,
> +				     GRUB_COMMAND_ACCEPT_DASH
> +				     | GRUB_COMMAND_OPTIONS_AT_START,
> +				     N_("[-u|-g] ENVVAR [ENVVAR] ..."),
> +				     N_("Export variables."),
> +				     export_options);

Same as mentioned above!

>   }
>    void
>   grub_context_fini (void)
>   {
> -  grub_unregister_command (export_cmd);
> +  grub_unregister_extcmd (export_cmd);
>   }
> diff --git a/include/grub/env.h b/include/grub/env.h
> index 6b9379a30..4634c09d3 100644
> --- a/include/grub/env.h
> +++ b/include/grub/env.h
> @@ -31,6 +31,13 @@ typedef const char *(*grub_env_read_hook_t) (struct
> grub_env_var *var,
>   typedef char *(*grub_env_write_hook_t) (struct grub_env_var *var,
>   					const char *val);
>   +enum grub_env_var_export
> +{
> +  grub_env_var_local    = 0,
> +  grub_env_var_exported = 1,
> +  grub_env_var_global   = 2,
> +};
> +
>   struct grub_env_var
>   {
>     char *name;
> @@ -40,7 +47,7 @@ struct grub_env_var
>     struct grub_env_var *next;
>     struct grub_env_var **prevp;
>     struct grub_env_var *sorted_next;
> -  int global;
> +  enum grub_env_var_export global;
>   };
>    grub_err_t EXPORT_FUNC(grub_env_set) (const char *name, const char 
> *val);
> @@ -58,6 +65,8 @@ grub_err_t EXPORT_FUNC(grub_register_variable_hook)
> (const char *name,
>   grub_err_t grub_env_context_open (void);
>   grub_err_t grub_env_context_close (void);
>   grub_err_t EXPORT_FUNC(grub_env_export) (const char *name);
> +grub_err_t EXPORT_FUNC(grub_env_set_export_mode) (const char *name,
> +						  enum grub_env_var_export mode);

Same as mentioned above!

Thank you!

Regards,
Avnish Chouhan


>    void grub_env_unset_menu (void);
>   grub_menu_t grub_env_get_menu (void);
> --
> 2.45.3
> 

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