grub/kern/env.c
okuji 4b13b216f4 2004-04-04 Yoshinori K. Okuji <okuji@enbug.org>
All symbols prefixed with PUPA_ and pupa_ are renamed to GRUB_
	and grub_, respectively. Because the conversion is trivial and
	mechanical, I omit the details here. Please refer to the CVS
	if you need more information.
2004-04-04 13:46:03 +00:00

209 lines
4.6 KiB
C

/* env.c - Environment variables */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2003 Free Software Foundation, Inc.
*
* GRUB is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <grub/env.h>
#include <grub/misc.h>
#include <grub/mm.h>
/* XXX: What would be a good size for the hashtable? */
#define HASHSZ 123
/* A hashtable for quick lookup of variables. */
static struct grub_env_var *grub_env[HASHSZ];
/* The variables in a sorted list. */
static struct grub_env_var *grub_env_sorted;
/* Return the hash representation of the string S. */
static unsigned int grub_env_hashval (const char *s)
{
unsigned int i = 0;
/* XXX: This can be done much more effecient. */
while (*s)
i += 5 * *(s++);
return i % HASHSZ;
}
static struct grub_env_var *
grub_env_find (const char *name)
{
struct grub_env_var *var;
int idx = grub_env_hashval (name);
for (var = grub_env[idx]; var; var = var->next)
if (! grub_strcmp (var->name, name))
return var;
return 0;
}
grub_err_t
grub_env_set (const char *var, const char *val)
{
int idx = grub_env_hashval (var);
struct grub_env_var *env;
struct grub_env_var *sort;
struct grub_env_var **sortp;
/* If the variable does already exist, just update the variable. */
env = grub_env_find (var);
if (env)
{
char *old = env->value;
env->value = grub_strdup (val);
if (! env->name)
{
env->value = old;
return grub_errno;
}
if (env->write_hook)
(env->write_hook) (env);
grub_free (old);
return 0;
}
/* The variable does not exist, create it. */
env = grub_malloc (sizeof (struct grub_env_var));
if (! env)
return grub_errno;
grub_memset (env, 0, sizeof (struct grub_env_var));
env->name = grub_strdup (var);
if (! env->name)
goto fail;
env->value = grub_strdup (val);
if (! env->name)
goto fail;
/* Insert it in the hashtable. */
env->prevp = &grub_env[idx];
env->next = grub_env[idx];
if (grub_env[idx])
grub_env[idx]->prevp = &env->next;
grub_env[idx] = env;
/* Insert it in the sorted list. */
sortp = &grub_env_sorted;
sort = grub_env_sorted;
while (sort)
{
if (grub_strcmp (sort->name, var) > 0)
break;
sortp = &sort->sort_next;
sort = sort->sort_next;
}
env->sort_prevp = sortp;
env->sort_next = sort;
if (sort)
sort->sort_prevp = &env->sort_next;
*sortp = env;
fail:
if (grub_errno)
{
grub_free (env->name);
grub_free (env->value);
grub_free (env);
}
return 0;
}
char *
grub_env_get (const char *name)
{
struct grub_env_var *env;
env = grub_env_find (name);
if (! env)
return 0;
if (env->read_hook)
{
char *val;
env->read_hook (env, &val);
return val;
}
return env->value;
}
void
grub_env_unset (const char *name)
{
struct grub_env_var *env;
env = grub_env_find (name);
if (! env)
return;
/* XXX: It is not possible to unset variables with a read or write
hook. */
if (env->read_hook || env->write_hook)
return;
*env->prevp = env->next;
if (env->next)
env->next->prevp = env->prevp;
*env->sort_prevp = env->sort_next;
if (env->sort_next)
env->sort_next->sort_prevp = env->sort_prevp;
grub_free (env->name);
grub_free (env->value);
grub_free (env);
return;
}
void
grub_env_iterate (int (* func) (struct grub_env_var *var))
{
struct grub_env_var *env;
for (env = grub_env_sorted; env; env = env->sort_next)
if (func (env))
return;
}
grub_err_t
grub_register_variable_hook (const char *var,
grub_err_t (*read_hook) (struct grub_env_var *var, char **),
grub_err_t (*write_hook) (struct grub_env_var *var))
{
struct grub_env_var *env = grub_env_find (var);
if (! env)
if (grub_env_set (var, "") != GRUB_ERR_NONE)
return grub_errno;
env = grub_env_find (var);
/* XXX Insert an assertion? */
env->read_hook = read_hook;
env->write_hook = write_hook;
return GRUB_ERR_NONE;
}