nvram.h

#ifndef INCLUDE_NVRAM_H
#define INCLUDE_NVRAM_H

// Gets the ID of the semaphore. If uninitialized, will initialize both the semaphore and NVRAM.
static int sem_get();
// Locks the binary semaphore. Will block.
static void sem_lock();
// Unlocks the binary semaphore.
static void sem_unlock();

// Sets default NVRAM values using the built-in NVRAM_DEFAULTS table.
static int nvram_set_default_builtin(void);
// Sets default NVRAM values using the override values from OVERRIDE_POINT. Will hold lock.
static int nvram_set_default_image(void);
// Sets default NVRAM values from external table defined in NVRAM_DEFAULTS_PATH.
static int nvram_set_default_table(const char *tbl[]);

/* The following functions form the standard NVRAM API. Functions that return integers
 * will generally return E_SUCCESS/E_FAILURE, with the exception of nvram_get_int(). */

// Initializes NVRAM with default values. Will hold lock.
int nvram_init(void);
// Restores original NVRAM default values.
int nvram_reset(void);
// Clears NVRAM values. Will hold lock.
int nvram_clear(void);
// Pretends to close NVRAM, does nothing.
int nvram_close(void);
// Pretends to commit NVRAM, actually synchronizes file system.
int nvram_commit(void);

// Given a key, gets the corresponding NVRAM value. If key is non-existent, returns NULL.
// Will dynamically allocate memory, so the user should call free().
// On MIPS, will use $a1 as key if $a0 is NULL.
char *nvram_get(const char *key);
// Given a key, gets the corresponding NVRAM value. If key is non-existent, returns "".
// Will dynamically allocate memory.
char *nvram_safe_get(const char *key);
// Given a key, gets the corresponding NVRAM value. If key is non-existent, returns val.
// Otherwise, returns NULL. Will dynamically allocate memory.
char *nvram_default_get(const char *key, const char *val);
// Given a key, gets the corresponding NVRAM value into a user-supplied buffer.
// Will hold lock.
int nvram_get_buf(const char *key, char *buf, size_t sz);
// Given a key, gets the corresponding NVRAM value as integer. If key is non-existent, returns E_FAILURE.
// Will hold lock.
int nvram_get_int(const char *key);
// Gets all NVRAM keys and values into a user-supplied buffer, of the format "key=value...".
// Will hold lock.
int nvram_getall(char *buf, size_t len);

// Given a key and value, sets the corresponding NVRAM value. Will hold lock.
int nvram_set(const char *key, const char *val);
// Given a key and value as integer, sets the corresponding NVRAM value. Will hold lock.
int nvram_set_int(const char *key, const int val);
// Given a key, unsets the corresponding NVRAM value. Will hold lock.
int nvram_unset(const char *key);
// Reloads default NVRAM values.
int nvram_set_default(void);

// Adds a list entry to a NVRAM value.
int nvram_list_add(const char *key, const char *val);
// Checks whether a list entry exists in a NVRAM value. If the magic argument
// is equal to LIST_MAGIC, will either return a pointer to the match or NULL.
char *nvram_list_exist(const char *key, const char *val, int magic);
// Deletes a list entry from a NVRAM value.
int nvram_list_del(const char *key, const char *val);

// Given a key, checks whether the corresponding NVRAM value matches val.
int nvram_match(const char *key, const char *val);
// Given a key, checks whether the corresponding NVRAM value does not match val.
int nvram_invmatch(const char *key, const char *val);

#endif