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/* SPDX-License-Identifier: LGPL-3.0-or-later */
/*
* meta_reader.c
*
* Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
*/
#define SQFS_BUILDING_DLL
#include "config.h"
#include "sqfs/meta_reader.h"
#include "sqfs/compressor.h"
#include "sqfs/error.h"
#include "sqfs/block.h"
#include "sqfs/io.h"
#include "util.h"
#include <stdlib.h>
#include <string.h>
struct sqfs_meta_reader_t {
sqfs_object_t base;
sqfs_u64 start;
sqfs_u64 limit;
size_t data_used;
/* The location of the current block in the image */
sqfs_u64 block_offset;
/* The location of the next block after the current one */
sqfs_u64 next_block;
/* A byte offset into the uncompressed data of the current block */
size_t offset;
/* The underlying file descriptor to read from */
sqfs_file_t *file;
/* A pointer to the compressor to use for extracting data */
sqfs_compressor_t *cmp;
/* The raw data read from the input file */
sqfs_u8 data[SQFS_META_BLOCK_SIZE];
/* The uncompressed data read from the input file */
sqfs_u8 scratch[SQFS_META_BLOCK_SIZE];
};
static void meta_reader_destroy(sqfs_object_t *m)
{
free(m);
}
static sqfs_object_t *meta_reader_copy(const sqfs_object_t *obj)
{
const sqfs_meta_reader_t *m = (const sqfs_meta_reader_t *)obj;
sqfs_meta_reader_t *copy = malloc(sizeof(*copy));
if (copy != NULL) {
memcpy(copy, m, sizeof(*m));
}
/* XXX: cmp and file aren't deep-copied because m
doesn't own them either. */
return (sqfs_object_t *)copy;
}
sqfs_meta_reader_t *sqfs_meta_reader_create(sqfs_file_t *file,
sqfs_compressor_t *cmp,
sqfs_u64 start, sqfs_u64 limit)
{
sqfs_meta_reader_t *m = calloc(1, sizeof(*m));
if (m == NULL)
return NULL;
((sqfs_object_t *)m)->copy = meta_reader_copy;
((sqfs_object_t *)m)->destroy = meta_reader_destroy;
m->start = start;
m->limit = limit;
m->file = file;
m->cmp = cmp;
return m;
}
int sqfs_meta_reader_seek(sqfs_meta_reader_t *m, sqfs_u64 block_start,
size_t offset)
{
bool compressed;
sqfs_u16 header;
sqfs_u32 size;
sqfs_s32 ret;
int err;
if (block_start < m->start || block_start >= m->limit)
return SQFS_ERROR_OUT_OF_BOUNDS;
if (block_start == m->block_offset) {
if (offset >= m->data_used)
return SQFS_ERROR_OUT_OF_BOUNDS;
m->offset = offset;
return 0;
}
err = m->file->read_at(m->file, block_start, &header, 2);
if (err)
return err;
header = le16toh(header);
compressed = (header & 0x8000) == 0;
size = header & 0x7FFF;
if (size > sizeof(m->data))
return SQFS_ERROR_CORRUPTED;
if ((block_start + 2 + size) > m->limit)
return SQFS_ERROR_OUT_OF_BOUNDS;
err = m->file->read_at(m->file, block_start + 2, m->data, size);
if (err)
return err;
if (compressed) {
ret = m->cmp->do_block(m->cmp, m->data, size,
m->scratch, sizeof(m->scratch));
if (ret < 0)
return ret;
memcpy(m->data, m->scratch, ret);
m->data_used = ret;
} else {
m->data_used = size;
}
if (offset >= m->data_used)
return SQFS_ERROR_OUT_OF_BOUNDS;
m->block_offset = block_start;
m->next_block = block_start + size + 2;
m->offset = offset;
return 0;
}
void sqfs_meta_reader_get_position(const sqfs_meta_reader_t *m,
sqfs_u64 *block_start, size_t *offset)
{
*block_start = m->block_offset;
*offset = m->offset;
}
int sqfs_meta_reader_read(sqfs_meta_reader_t *m, void *data, size_t size)
{
size_t diff;
int ret;
while (size != 0) {
diff = m->data_used - m->offset;
if (diff == 0) {
ret = sqfs_meta_reader_seek(m, m->next_block, 0);
if (ret)
return ret;
diff = m->data_used;
}
if (diff > size)
diff = size;
memcpy(data, m->data + m->offset, diff);
m->offset += diff;
data = (char *)data + diff;
size -= diff;
}
return 0;
}
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