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/* SPDX-License-Identifier: GPL-3.0-or-later */
#include "config.h"
#include "frag_reader.h"
#include "highlevel.h"
#include "util.h"
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
struct frag_reader_t {
sqfs_fragment_t *tbl;
size_t num_fragments;
int fd;
compressor_t *cmp;
size_t block_size;
size_t used;
size_t current_index;
uint8_t buffer[];
};
static int precache_block(frag_reader_t *f, size_t i)
{
bool compressed;
size_t size;
ssize_t ret;
if (i == f->current_index)
return 0;
compressed = (f->tbl[i].size & (1 << 24)) == 0;
size = f->tbl[i].size & ((1 << 24) - 1);
if (size > f->block_size) {
fputs("found fragment block larger than block size\n", stderr);
return -1;
}
if (read_data_at("reading fragment", f->tbl[i].start_offset,
f->fd, f->buffer, size)) {
return -1;
}
if (compressed) {
ret = f->cmp->do_block(f->cmp, f->buffer, size,
f->buffer + f->block_size, f->block_size);
if (ret <= 0) {
fputs("extracting fragment failed\n", stderr);
return -1;
}
size = ret;
memmove(f->buffer, f->buffer + f->block_size, ret);
}
f->current_index = i;
f->used = size;
return 0;
}
frag_reader_t *frag_reader_create(sqfs_super_t *super, int fd,
compressor_t *cmp)
{
sqfs_fragment_t *tbl = NULL;
frag_reader_t *f = NULL;
size_t i;
f = calloc(1, sizeof(*f) + super->block_size * 2);
if (f == NULL) {
perror("creating fragment table");
return NULL;
}
f->block_size = super->block_size;
f->num_fragments = super->fragment_entry_count;
f->current_index = f->num_fragments;
f->cmp = cmp;
f->fd = fd;
f->tbl = sqfs_read_table(fd, cmp, sizeof(tbl[0]) * f->num_fragments,
super->fragment_table_start);
if (f->tbl == NULL) {
free(f);
return NULL;
}
for (i = 0; i < f->num_fragments; ++i) {
tbl[i].start_offset = le64toh(tbl[i].start_offset);
tbl[i].size = le32toh(tbl[i].size);
}
return f;
}
void frag_reader_destroy(frag_reader_t *f)
{
free(f->tbl);
free(f);
}
int frag_reader_read(frag_reader_t *f, size_t index, size_t offset,
void *buffer, size_t size)
{
if (precache_block(f, index))
return -1;
if (offset >= f->used)
goto fail_range;
if (size == 0)
return 0;
if ((offset + size - 1) >= f->used)
goto fail_range;
memcpy(buffer, f->buffer + offset, size);
return 0;
fail_range:
fputs("attempted to read past fragment block limits\n", stderr);
return -1;
}
const sqfs_fragment_t *frag_reader_get_table(const frag_reader_t *f)
{
return f->tbl;
}
size_t frag_reader_get_fragment_count(const frag_reader_t *f)
{
return f->num_fragments;
}
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