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/* SPDX-License-Identifier: GPL-3.0-or-later */
/*
* data_reader.c
*
* Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
*/
#include "config.h"
#include "data_reader.h"
#include "highlevel.h"
#include "util.h"
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
struct data_reader_t {
sqfs_fragment_t *frag;
size_t num_fragments;
size_t current_frag_index;
size_t frag_used;
off_t current_block;
compressor_t *cmp;
size_t block_size;
int sqfsfd;
void *block;
void *scratch;
void *frag_block;
};
static ssize_t read_block(data_reader_t *data, off_t offset, uint32_t size,
void *dst)
{
bool compressed = SQFS_IS_BLOCK_COMPRESSED(size);
void *ptr = compressed ? data->scratch : dst;
ssize_t ret;
size = SQFS_ON_DISK_BLOCK_SIZE(size);
if (size > data->block_size)
goto fail_bs;
if (read_data_at("reading block", offset, data->sqfsfd, ptr, size))
return -1;
if (compressed) {
ret = data->cmp->do_block(data->cmp, data->scratch, size,
dst, data->block_size);
if (ret <= 0) {
fputs("extracting block failed\n", stderr);
return -1;
}
size = ret;
}
return size;
fail_bs:
fputs("found compressed block larger than block size\n", stderr);
return -1;
}
static int precache_data_block(data_reader_t *data, off_t location,
uint32_t size)
{
ssize_t ret;
if (data->current_block == location)
return 0;
ret = read_block(data, location, size, data->block);
if (ret < 0)
return -1;
if (size < data->block_size)
memset((char *)data->block + size, 0, data->block_size - size);
data->current_block = location;
return 0;
}
static int precache_fragment_block(data_reader_t *data, size_t idx)
{
ssize_t ret;
if (idx == data->current_frag_index)
return 0;
if (idx >= data->num_fragments) {
fputs("fragment index out of bounds\n", stderr);
return -1;
}
ret = read_block(data, data->frag[idx].start_offset,
data->frag[idx].size, data->frag_block);
if (ret < 0)
return -1;
data->current_frag_index = idx;
data->frag_used = ret;
return 0;
}
data_reader_t *data_reader_create(int fd, sqfs_super_t *super,
compressor_t *cmp)
{
data_reader_t *data = calloc(1, sizeof(*data) + 3 * super->block_size);
size_t i, size;
if (data == NULL) {
perror("creating data reader");
return data;
}
data->num_fragments = super->fragment_entry_count;
data->current_frag_index = super->fragment_entry_count;
data->block = (char *)data + sizeof(*data);
data->scratch = (char *)data->block + super->block_size;
data->frag_block = (char *)data->scratch + super->block_size;
data->current_block = -1;
data->sqfsfd = fd;
data->block_size = super->block_size;
data->cmp = cmp;
if (super->fragment_entry_count == 0 ||
(super->flags & SQFS_FLAG_NO_FRAGMENTS) != 0) {
return data;
}
if (super->fragment_table_start >= super->bytes_used) {
fputs("Fragment table start is past end of file\n", stderr);
free(data);
return NULL;
}
size = sizeof(data->frag[0]) * data->num_fragments;
data->frag = sqfs_read_table(fd, cmp, size,
super->fragment_table_start);
if (data->frag == NULL) {
free(data);
return NULL;
}
for (i = 0; i < data->num_fragments; ++i) {
data->frag[i].size = le32toh(data->frag[i].size);
data->frag[i].start_offset =
le64toh(data->frag[i].start_offset);
}
return data;
}
void data_reader_destroy(data_reader_t *data)
{
free(data->frag);
free(data);
}
int data_reader_dump_file(data_reader_t *data, file_info_t *fi, int outfd,
bool allow_sparse)
{
uint64_t filesz = fi->size;
size_t fragsz = fi->size % data->block_size;
size_t count = fi->size / data->block_size;
off_t off = fi->startblock;
size_t i, diff;
if (fragsz != 0 && !(fi->flags & FILE_FLAG_HAS_FRAGMENT)) {
fragsz = 0;
++count;
}
if (allow_sparse && ftruncate(outfd, filesz))
goto fail_sparse;
for (i = 0; i < count; ++i) {
diff = filesz > data->block_size ? data->block_size : filesz;
filesz -= diff;
if (SQFS_IS_SPARSE_BLOCK(fi->blocks[i].size)) {
if (allow_sparse) {
if (lseek(outfd, diff, SEEK_CUR) == (off_t)-1)
goto fail_sparse;
} else {
memset(data->block, 0, diff);
}
} else {
if (precache_data_block(data, off, fi->blocks[i].size))
return -1;
off += SQFS_ON_DISK_BLOCK_SIZE(fi->blocks[i].size);
}
if (write_data("writing uncompressed block",
outfd, data->block, diff)) {
return -1;
}
}
if (fragsz > 0) {
if (precache_fragment_block(data, fi->fragment))
return -1;
if (fi->fragment_offset >= data->frag_used)
goto fail_range;
if ((fi->fragment_offset + fragsz - 1) >= data->frag_used)
goto fail_range;
if (write_data("writing uncompressed fragment", outfd,
(char *)data->frag_block + fi->fragment_offset,
fragsz)) {
return -1;
}
}
return 0;
fail_range:
fputs("attempted to read past fragment block limits\n", stderr);
return -1;
fail_sparse:
perror("creating sparse output file");
return -1;
}
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