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/*
* Copyright (C) 2016 Pengutronix, Markus Pargmann <mpa@pengutronix.de>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2, as published by the Free Software Foundation.
*
* This program 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.
*
*/
#include <fcntl.h>
#include <fs.h>
#include <libfile.h>
#include <linux/kernel.h>
#include <malloc.h>
#include <linux/printk.h>
#include "state.h"
struct state_backend_storage_bucket_direct {
struct state_backend_storage_bucket bucket;
ssize_t offset;
ssize_t max_size;
int fd;
struct device *dev;
};
struct __attribute__((__packed__)) state_backend_storage_bucket_direct_meta {
uint32_t magic;
uint32_t written_length;
};
static const uint32_t direct_magic = 0x2354fdf3;
static inline struct state_backend_storage_bucket_direct
*get_bucket_direct(struct state_backend_storage_bucket *bucket)
{
return container_of(bucket, struct state_backend_storage_bucket_direct,
bucket);
}
static int state_backend_bucket_direct_read(struct state_backend_storage_bucket
*bucket, void ** buf_out,
ssize_t * len_out)
{
struct state_backend_storage_bucket_direct *direct =
get_bucket_direct(bucket);
struct state_backend_storage_bucket_direct_meta meta;
uint32_t read_len, header_len = 0;
void *buf;
int ret;
if (lseek(direct->fd, direct->offset, SEEK_SET) != direct->offset) {
dev_err(direct->dev, "Failed to seek file, %d\n", -errno);
return -errno;
}
ret = read_full(direct->fd, &meta, sizeof(meta));
if (ret < 0) {
dev_err(direct->dev, "Failed to read meta data from file, %d\n", ret);
return ret;
}
if (meta.magic == direct_magic) {
read_len = meta.written_length;
if (read_len > direct->max_size) {
dev_err(direct->dev, "Wrong length in meta data\n");
return -EINVAL;
}
header_len = sizeof(meta);
} else {
if (meta.magic != ~0 && !!meta.magic)
bucket->wrong_magic = 1;
if (!IS_ENABLED(CONFIG_STATE_BACKWARD_COMPATIBLE)) {
dev_dbg(direct->dev, "Enable backward compatibility or increase stride size\n");
return dev_err_state_init(direct->dev, meta.magic ? -EINVAL : -ENOMEDIUM,
"No meta data header found\n");
}
read_len = direct->max_size;
if (lseek(direct->fd, direct->offset, SEEK_SET) !=
direct->offset) {
dev_err(direct->dev, "Failed to seek file, %d\n",
-errno);
return -errno;
}
}
buf = xmalloc(read_len);
if (!buf)
return -ENOMEM;
dev_dbg(direct->dev, "Read state from %lld length %d\n", (long long) direct->offset,
header_len + read_len);
ret = read_full(direct->fd, buf, read_len);
if (ret < 0) {
dev_err(direct->dev, "Failed to read from file, %d\n", ret);
free(buf);
return ret;
}
*buf_out = buf;
*len_out = read_len;
return 0;
}
static int state_backend_bucket_direct_write(struct state_backend_storage_bucket
*bucket, const void * buf,
ssize_t len)
{
struct state_backend_storage_bucket_direct *direct =
get_bucket_direct(bucket);
size_t header_len = 0;
int ret;
struct state_backend_storage_bucket_direct_meta meta;
if (lseek(direct->fd, direct->offset, SEEK_SET) != direct->offset) {
dev_err(direct->dev, "Failed to seek file, %d\n", -errno);
return -errno;
}
/* write the meta data only if there is head room */
if (len <= direct->max_size - sizeof(meta)) {
meta.magic = direct_magic;
meta.written_length = len;
ret = write_full(direct->fd, &meta, sizeof(meta));
if (ret < 0) {
dev_err(direct->dev, "Failed to write metadata to file, %d\n", ret);
return ret;
}
header_len = sizeof(meta);
} else {
if (!IS_ENABLED(CONFIG_STATE_BACKWARD_COMPATIBLE)) {
dev_dbg(direct->dev, "Too small stride size: must skip metadata! Increase stride size\n");
return -EINVAL;
}
}
ret = write_full(direct->fd, buf, len);
if (ret < 0) {
dev_err(direct->dev, "Failed to write file, %d\n", ret);
return ret;
}
ret = flush(direct->fd);
if (ret < 0) {
dev_err(direct->dev, "Failed to flush file, %d\n", ret);
return ret;
}
dev_dbg(direct->dev, "Written state to offset %lld length %zu data length %zu\n",
(long long)direct->offset, len + header_len, len);
return 0;
}
static void state_backend_bucket_direct_free(struct
state_backend_storage_bucket
*bucket)
{
struct state_backend_storage_bucket_direct *direct =
get_bucket_direct(bucket);
close(direct->fd);
free(direct);
}
int state_backend_bucket_direct_create(struct device *dev, const char *path,
struct state_backend_storage_bucket **bucket,
off_t offset, ssize_t max_size, bool readonly)
{
int fd;
struct state_backend_storage_bucket_direct *direct;
fd = open(path, readonly ? O_RDONLY : O_RDWR);
if (fd < 0) {
dev_err(dev, "Failed to open file '%s', %d\n", path, -errno);
return -errno;
}
direct = xzalloc(sizeof(*direct));
direct->offset = offset;
direct->max_size = max_size;
direct->fd = fd;
direct->dev = dev;
direct->bucket.read = state_backend_bucket_direct_read;
direct->bucket.write = state_backend_bucket_direct_write;
direct->bucket.free = state_backend_bucket_direct_free;
*bucket = &direct->bucket;
return 0;
}
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