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/* env.c - Environment variables */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2003,2005,2006,2007,2008,2009 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 3 of the License, or
* (at your option) any later version.
*
* GRUB 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, see <http://www.gnu.org/licenses/>.
*/
#include <grub/env.h>
#include <grub/env_private.h>
#include <grub/misc.h>
#include <grub/mm.h>
/* The initial context. */
static struct grub_env_context initial_context;
/* The current context. */
struct grub_env_context *grub_current_context = &initial_context;
/* 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 efficiently. */
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);
/* Look for the variable in the current context. */
for (var = grub_current_context->vars[idx]; var; var = var->next)
if (grub_strcmp (var->name, name) == 0)
return var;
return 0;
}
static void
grub_env_insert (struct grub_env_context *context,
struct grub_env_var *var)
{
int idx = grub_env_hashval (var->name);
/* Insert the variable into the hashtable. */
var->prevp = &context->vars[idx];
var->next = context->vars[idx];
if (var->next)
var->next->prevp = &(var->next);
context->vars[idx] = var;
}
static void
grub_env_remove (struct grub_env_var *var)
{
/* Remove the entry from the variable table. */
*var->prevp = var->next;
if (var->next)
var->next->prevp = var->prevp;
}
grub_err_t
grub_env_set (const char *name, const char *val)
{
struct grub_env_var *var;
/* If the variable does already exist, just update the variable. */
var = grub_env_find (name);
if (var)
{
char *old = var->value;
if (var->write_hook)
var->value = var->write_hook (var, val);
else
var->value = grub_strdup (val);
if (! var->value)
{
var->value = old;
return grub_errno;
}
grub_free (old);
return GRUB_ERR_NONE;
}
/* The variable does not exist, so create a new one. */
var = grub_zalloc (sizeof (*var));
if (! var)
return grub_errno;
var->name = grub_strdup (name);
if (! var->name)
goto fail;
var->value = grub_strdup (val);
if (! var->value)
goto fail;
grub_env_insert (grub_current_context, var);
return GRUB_ERR_NONE;
fail:
grub_free (var->name);
grub_free (var->value);
grub_free (var);
return grub_errno;
}
const char *
grub_env_get (const char *name)
{
struct grub_env_var *var;
var = grub_env_find (name);
if (! var)
return 0;
if (var->read_hook)
return var->read_hook (var, var->value);
return var->value;
}
void
grub_env_unset (const char *name)
{
struct grub_env_var *var;
var = grub_env_find (name);
if (! var)
return;
if (var->read_hook || var->write_hook)
{
grub_env_set (name, "");
return;
}
grub_env_remove (var);
grub_free (var->name);
grub_free (var->value);
grub_free (var);
}
struct grub_env_var *
grub_env_update_get_sorted (void)
{
struct grub_env_var *sorted_list = 0;
int i;
/* Add variables associated with this context into a sorted list. */
for (i = 0; i < HASHSZ; i++)
{
struct grub_env_var *var;
for (var = grub_current_context->vars[i]; var; var = var->next)
{
struct grub_env_var *p, **q;
for (q = &sorted_list, p = *q; p; q = &((*q)->sorted_next), p = *q)
{
if (grub_strcmp (p->name, var->name) > 0)
break;
}
var->sorted_next = *q;
*q = var;
}
}
return sorted_list;
}
grub_err_t
grub_register_variable_hook (const char *name,
grub_env_read_hook_t read_hook,
grub_env_write_hook_t write_hook)
{
struct grub_env_var *var = grub_env_find (name);
if (! var)
{
if (grub_env_set (name, "") != GRUB_ERR_NONE)
return grub_errno;
var = grub_env_find (name);
/* XXX Insert an assertion? */
}
var->read_hook = read_hook;
var->write_hook = write_hook;
return GRUB_ERR_NONE;
}
grub_err_t
grub_env_export (const char *name)
{
struct grub_env_var *var;
var = grub_env_find (name);
if (! var)
{
grub_err_t err;
err = grub_env_set (name, "");
if (err)
return err;
var = grub_env_find (name);
}
var->global = 1;
return GRUB_ERR_NONE;
}
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