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artiq/soc/runtime/flash_storage.c

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/*
* Yann Sionneau <ys@m-labs.hk>, 2015
*/
#include <string.h>
#include <stdio.h>
#include <system.h>
#include <spiflash.h>
#include <generated/mem.h>
#include <generated/csr.h>
#include "log.h"
#include "flash_storage.h"
#if (defined CSR_SPIFLASH_BASE && defined SPIFLASH_PAGE_SIZE)
#define STORAGE_ADDRESS ((char *)(FLASH_BOOT_ADDRESS + 256*1024))
#define STORAGE_SIZE SPIFLASH_SECTOR_SIZE
#define END_MARKER (0xFFFFFFFF)
#define min(a, b) (a>b?b:a)
#define max(a, b) (a>b?a:b)
struct record {
char *key;
unsigned int key_len;
char *value;
unsigned int value_len;
char *raw_record;
unsigned int size;
};
struct iter_state {
char *buffer;
unsigned int seek;
unsigned int buf_len;
};
static unsigned int get_record_size(char *buff)
{
unsigned int record_size;
memcpy(&record_size, buff, 4);
return record_size;
}
static void record_iter_init(struct iter_state *is, char *buffer, unsigned int buf_len)
{
is->buffer = buffer;
is->seek = 0;
is->buf_len = buf_len;
}
static int record_iter_next(struct iter_state *is, struct record *record, int *fatal)
{
if(is->seek >= is->buf_len)
return 0;
record->raw_record = &is->buffer[is->seek];
record->size = get_record_size(record->raw_record);
if(record->size == END_MARKER)
return 0;
if(record->size < 6) {
log("flash_storage might be corrupted: record size is %u (<6) at address %08x", record->size, record->raw_record);
if(fatal)
*fatal = 1;
return 0;
}
if(is->seek > is->buf_len - sizeof(record->size) - 2) { /* 2 is the minimum key length */
log("flash_storage might be corrupted: END_MARKER missing at the end of the storage sector");
if(fatal)
*fatal = 1;
return 0;
}
if(record->size > is->buf_len - is->seek) {
log("flash_storage might be corrupted: invalid record_size %d at address %08x", record->size, record->raw_record);
if(fatal)
*fatal = 1;
return 0;
}
record->key = record->raw_record + sizeof(record->size);
record->key_len = strnlen(record->key, record->size - sizeof(record->size)) + 1;
if(record->key_len == record->size - sizeof(record->size) + 1) {
log("flash_storage might be corrupted: invalid key length at address %08x", record->raw_record);
if(fatal)
*fatal = 1;
return 0;
}
record->value = record->key + record->key_len;
record->value_len = record->size - record->key_len - sizeof(record->size);
is->seek += record->size;
return 1;
}
static unsigned int get_free_space(void)
{
struct iter_state is;
struct record record;
record_iter_init(&is, STORAGE_ADDRESS, STORAGE_SIZE);
while(record_iter_next(&is, &record, NULL));
return STORAGE_SIZE - is.seek;
}
static int is_empty(struct record *record)
{
return record->value_len == 0;
}
static int key_exists(char *buff, const char *key, char *end, char accept_empty,
struct record *found_record)
{
struct iter_state is;
struct record iter_record;
int found = 0;
record_iter_init(&is, buff, end - buff);
while(record_iter_next(&is, &iter_record, NULL)) {
if(strcmp(iter_record.key, key) == 0) {
found = 1;
if(found_record)
*found_record = iter_record;
}
}
if(found && is_empty(found_record) && !accept_empty)
return 0;
if(found)
return 1;
return 0;
}
static char check_for_duplicates(char *buff)
{
struct record record, following_record;
struct iter_state is;
int no_error;
record_iter_init(&is, buff, STORAGE_SIZE);
no_error = record_iter_next(&is, &record, NULL);
while(no_error) {
no_error = record_iter_next(&is, &following_record, NULL);
if(no_error && key_exists(following_record.raw_record, record.key, &buff[STORAGE_SIZE], 1, NULL))
return 1;
record = following_record;
}
return 0;
}
static char check_for_empty_records(char *buff)
{
struct iter_state is;
struct record record;
record_iter_init(&is, buff, STORAGE_SIZE);
while(record_iter_next(&is, &record, NULL))
if(is_empty(&record))
return 1;
return 0;
}
static unsigned int try_to_flush_duplicates(const char *new_key, unsigned int buf_len)
{
unsigned int key_size, new_record_size, ret = 0, can_rollback = 0;
struct record record, previous_record;
char sector_buff[STORAGE_SIZE];
struct iter_state is;
memcpy(sector_buff, STORAGE_ADDRESS, STORAGE_SIZE);
if(check_for_duplicates(sector_buff)
|| key_exists(sector_buff, new_key, &sector_buff[STORAGE_SIZE], 0, NULL)
|| check_for_empty_records(sector_buff)) {
fs_erase();
record_iter_init(&is, sector_buff, STORAGE_SIZE);
while(record_iter_next(&is, &record, NULL)) {
if(is_empty(&record))
continue;
if(!key_exists((char *)STORAGE_ADDRESS, record.key, STORAGE_ADDRESS + STORAGE_SIZE, 1, NULL)) {
struct record rec;
if(!key_exists(sector_buff, record.key, &sector_buff[STORAGE_SIZE], 0, &rec))
continue;
if(strcmp(new_key, record.key) == 0) { // If we are about to write this key we don't keep the old value.
previous_record = rec; // This holds the old record in case we need it back (for instance if new record is too long)
can_rollback = 1;
} else
fs_write(record.key, rec.value, rec.value_len);
}
}
ret = 1;
}
key_size = strlen(new_key) + 1;
new_record_size = key_size + buf_len + sizeof(new_record_size);
if(can_rollback && new_record_size > get_free_space()) {
fs_write(new_key, previous_record.value, previous_record.value_len);
}
return ret;
}
static void write_at_offset(const char *key, const void *buffer,
int buf_len, unsigned int sector_offset)
{
int key_len = strlen(key) + 1;
unsigned int record_size = key_len + buf_len + sizeof(record_size);
unsigned int flash_addr = (unsigned int)STORAGE_ADDRESS + sector_offset;
write_to_flash(flash_addr, (unsigned char *)&record_size, sizeof(record_size));
write_to_flash(flash_addr+sizeof(record_size), (unsigned char *)key, key_len);
write_to_flash(flash_addr+sizeof(record_size)+key_len, buffer, buf_len);
flush_cpu_dcache();
}
int fs_write(const char *key, const void *buffer, unsigned int buf_len)
{
struct record record;
unsigned int key_size = strlen(key) + 1;
unsigned int new_record_size = key_size + sizeof(int) + buf_len;
int no_error, fatal = 0;
struct iter_state is;
record_iter_init(&is, STORAGE_ADDRESS, STORAGE_SIZE);
while((no_error = record_iter_next(&is, &record, &fatal)));
if(fatal)
goto fatal_error;
if(STORAGE_SIZE - is.seek >= new_record_size) {
write_at_offset(key, buffer, buf_len, is.seek);
return 1;
}
if(!try_to_flush_duplicates(key, buf_len)) // storage is full, let's try to free some space up.
return 0; // No duplicates found, cannot write the new key-value record: sector is full.
// Now retrying to write, hoping enough flash was freed.
record_iter_init(&is, STORAGE_ADDRESS, STORAGE_SIZE);
while((no_error = record_iter_next(&is, &record, &fatal)));
if(fatal)
goto fatal_error;
if(STORAGE_SIZE - is.seek >= new_record_size) {
write_at_offset(key, buffer, buf_len, is.seek);
return 1; // We eventually succeeded in writing the record
} else
return 0; // Storage is definitely full.
fatal_error:
log("fatal error: flash storage might be corrupted");
return 0;
}
void fs_erase(void)
{
erase_flash_sector((unsigned int)STORAGE_ADDRESS);
flush_cpu_dcache();
}
unsigned int fs_read(const char *key, void *buffer, unsigned int buf_len, unsigned int *remain)
{
unsigned int read_length = 0;
struct iter_state is;
struct record record;
int fatal = 0;
if(remain)
*remain = 0;
record_iter_init(&is, STORAGE_ADDRESS, STORAGE_SIZE);
while(record_iter_next(&is, &record, &fatal)) {
if(strcmp(record.key, key) == 0) {
memcpy(buffer, record.value, min(record.value_len, buf_len));
read_length = min(record.value_len, buf_len);
if(remain)
*remain = max(0, (int)record.value_len - (int)buf_len);
}
}
if(fatal)
log("fatal error: flash storage might be corrupted");
return read_length;
}
void fs_remove(const char *key)
{
fs_write(key, NULL, 0);
}
#endif /* CSR_SPIFLASH_BASE && SPIFLASH_PAGE_SIZE */
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