diff options
Diffstat (limited to 'grub-core/kern/env.c')
| -rw-r--r-- | grub-core/kern/env.c | 238 |
1 files changed, 238 insertions, 0 deletions
diff --git a/grub-core/kern/env.c b/grub-core/kern/env.c new file mode 100644 index 0000000..c408626 --- /dev/null +++ b/grub-core/kern/env.c @@ -0,0 +1,238 @@ +/* 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; +} |