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/*
* Block device emulated on standard files
*
* Copyright (c) 2017 Christopher Haster
* Distributed under the MIT license
*/
#include "emubd/lfs_emubd.h"
#include "emubd/lfs_cfg.h"
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <limits.h>
#include <dirent.h>
#include <sys/stat.h>
// Block device emulated on existing filesystem
lfs_error_t lfs_emubd_create(lfs_emubd_t *emu, const char *path) {
memset(&emu->info, 0, sizeof(emu->info));
memset(&emu->stats, 0, sizeof(emu->stats));
// Allocate buffer for creating children files
size_t pathlen = strlen(path);
emu->path = malloc(pathlen + 1 + LFS_NAME_MAX + 1);
if (!emu->path) {
return -ENOMEM;
}
strcpy(emu->path, path);
emu->path[pathlen] = '/';
emu->path[pathlen + 1 + LFS_NAME_MAX] = '\0';
emu->child = &emu->path[pathlen+1];
strncpy(emu->child, "config", LFS_NAME_MAX);
// Load config, erroring if it doesn't exist
lfs_cfg_t cfg;
int err = lfs_cfg_create(&cfg, emu->path);
if (err) {
return err;
}
emu->info.read_size = lfs_cfg_getu(&cfg, "read_size", 0);
emu->info.write_size = lfs_cfg_getu(&cfg, "write_size", 0);
emu->info.erase_size = lfs_cfg_getu(&cfg, "erase_size", 0);
emu->info.total_size = lfs_cfg_getu(&cfg, "total_size", 0);
lfs_cfg_destroy(&cfg);
return 0;
}
void lfs_emubd_destroy(lfs_emubd_t *emu) {
free(emu->path);
}
lfs_error_t lfs_emubd_read(lfs_emubd_t *emu, uint8_t *buffer,
lfs_ino_t ino, lfs_off_t off, lfs_size_t size) {
// Check if read is valid
if (!(off % emu->info.read_size == 0 &&
size % emu->info.read_size == 0 &&
((lfs_lsize_t)ino*emu->info.erase_size + off + size
< emu->info.total_size))) {
return -EINVAL;
}
// Zero out buffer for debugging
memset(buffer, 0, size);
// Iterate over blocks until enough data is read
while (size > 0) {
snprintf(emu->child, LFS_NAME_MAX, "%d", ino);
size_t count = lfs_min(emu->info.erase_size - off, size);
FILE *f = fopen(emu->path, "rb");
if (!f && errno != ENOENT) {
return -errno;
}
if (f) {
int err = fseek(f, off, SEEK_SET);
if (err) {
return -errno;
}
size_t res = fread(buffer, 1, count, f);
if (res < count && !feof(f)) {
return -errno;
}
err = fclose(f);
if (err) {
return -errno;
}
}
size -= count;
buffer += count;
ino += 1;
off = 0;
}
emu->stats.read_count += 1;
return 0;
}
lfs_error_t lfs_emubd_write(lfs_emubd_t *emu, const uint8_t *buffer,
lfs_ino_t ino, lfs_off_t off, lfs_size_t size) {
// Check if write is valid
if (!(off % emu->info.write_size == 0 &&
size % emu->info.write_size == 0 &&
((lfs_lsize_t)ino*emu->info.erase_size + off + size
< emu->info.total_size))) {
return -EINVAL;
}
// Iterate over blocks until enough data is read
while (size > 0) {
snprintf(emu->child, LFS_NAME_MAX, "%d", ino);
size_t count = lfs_min(emu->info.erase_size - off, size);
FILE *f = fopen(emu->path, "r+b");
if (!f && errno == ENOENT) {
f = fopen(emu->path, "w+b");
if (!f) {
return -errno;
}
}
int err = fseek(f, off, SEEK_SET);
if (err) {
return -errno;
}
size_t res = fwrite(buffer, 1, count, f);
if (res < count) {
return -errno;
}
err = fclose(f);
if (err) {
return -errno;
}
size -= count;
buffer += count;
ino += 1;
off = 0;
}
emu->stats.write_count += 1;
return 0;
}
lfs_error_t lfs_emubd_erase(lfs_emubd_t *emu,
lfs_ino_t ino, lfs_off_t off, lfs_size_t size) {
// Check if erase is valid
if (!(off % emu->info.erase_size == 0 &&
size % emu->info.erase_size == 0 &&
((lfs_lsize_t)ino*emu->info.erase_size + off + size
< emu->info.total_size))) {
return -EINVAL;
}
// Iterate and erase blocks
while (size > 0) {
snprintf(emu->child, LFS_NAME_MAX, "%d", ino);
struct stat st;
int err = stat(emu->path, &st);
if (err && errno != ENOENT) {
return -errno;
}
if (!err && S_ISREG(st.st_mode)) {
int err = unlink(emu->path);
if (err) {
return -errno;
}
}
size -= emu->info.erase_size;
ino += 1;
off = 0;
}
emu->stats.erase_count += 1;
return 0;
}
lfs_error_t lfs_emubd_sync(lfs_emubd_t *emu) {
// Always in sync
return 0;
}
lfs_error_t lfs_emubd_info(lfs_emubd_t *emu, struct lfs_bd_info *info) {
*info = emu->info;
return 0;
}
lfs_error_t lfs_emubd_stats(lfs_emubd_t *emu, struct lfs_bd_stats *stats) {
*stats = emu->stats;
return 0;
}
// Wrappers for void*s
static lfs_error_t lfs_emubd_bd_read(void *bd, uint8_t *buffer,
lfs_ino_t ino, lfs_off_t off, lfs_size_t size) {
return lfs_emubd_read((lfs_emubd_t*)bd, buffer, ino, off, size);
}
static lfs_error_t lfs_emubd_bd_write(void *bd, const uint8_t *buffer,
lfs_ino_t ino, lfs_off_t off, lfs_size_t size) {
return lfs_emubd_write((lfs_emubd_t*)bd, buffer, ino, off, size);
}
static lfs_error_t lfs_emubd_bd_erase(void *bd,
lfs_ino_t ino, lfs_off_t off, lfs_size_t size) {
return lfs_emubd_erase((lfs_emubd_t*)bd, ino, off, size);
}
static lfs_error_t lfs_emubd_bd_sync(void *bd) {
return lfs_emubd_sync((lfs_emubd_t*)bd);
}
static lfs_error_t lfs_emubd_bd_info(void *bd, struct lfs_bd_info *info) {
return lfs_emubd_info((lfs_emubd_t*)bd, info);
}
const struct lfs_bd_ops lfs_emubd_ops = {
.read = lfs_emubd_bd_read,
.write = lfs_emubd_bd_write,
.erase = lfs_emubd_bd_erase,
.sync = lfs_emubd_bd_sync,
.info = lfs_emubd_bd_info,
};
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