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qsvreader.cpp
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qsvreader.cpp
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#pragma once
#include <cstdio>
#include <cstdint>
#include <cstring>
#include <QFile>
#include <QDebug>
#include "qsvreader.h"
void decrypt_1(BYTE* buffer, DWORD size) {
static const BYTE dict[] = {0x62, 0x67, 0x70, 0x79};
for(DWORD i = 0; i < size; ++i) {
DWORD j = ~i & 0x3;
buffer[i] ^= dict[j];
}
}
void decrypt_2(BYTE* buffer, DWORD size) {
DWORD x = 0x62677079;
for(DWORD i = size - 1; i != 0; --i) {
x = (x << 1) | (x >> 31);
x ^= buffer[i];
}
for(DWORD i = 1; i < size; ++i) {
x ^= buffer[i] & 0xFF;
x = (x >> 1) | (x << 31);
DWORD j = x % i;
BYTE tmp = buffer[j];
buffer[j] = tmp ^ (BYTE)~buffer[i];
buffer[i] = tmp;
}
}
QsvUnpacker::QsvUnpacker(const QString& file_path) {
infile = nullptr;
errcode = 0;
version = 0;
nb_indices = 0;
qindices = nullptr;
infile = new QFile(file_path);
if(!infile->open(QIODevice::ReadOnly)) {
errcode = -1;
msg = "无法打开文件";
return;
}
QsvHeader qheader;
if(infile->read((char*)&qheader, sizeof(QsvHeader)) != sizeof(QsvHeader)) {
errcode = -2;
msg = "文件不完整";
return;
}
if(memcmp(qheader.signature, QSV_SIGNATURE, sizeof(QSV_SIGNATURE) - 1) != 0) {
errcode = -3;
msg = "无法识别的格式";
return;
}
version = qheader.version;
if(version != 1 && version != 2) {
errcode = -4;
msg = "无法识别的格式";
}
nb_indices = qheader.nb_indices;
if(nb_indices < 1 || nb_indices > 0xFFFF) {
errcode = -3;
msg = "无法识别的格式";
return;
}
int _index_flag_size = (nb_indices + 7) >> 3;
if(infile->skip(_index_flag_size) != _index_flag_size) {
errcode = -2;
msg = "文件不完整";
return;
}
qindices = new QsvIndex[nb_indices];
if(infile->read((char*)qindices, nb_indices * sizeof(QsvIndex)) != nb_indices * sizeof(QsvIndex)) {
errcode = -2;
msg = "文件不完整";
return;
}
for(int i = 0; i < nb_indices; ++i) {
QsvIndex* index = qindices + i;
if(version == 2) {
decrypt_2((BYTE*)(qindices + i), sizeof(QsvIndex));
}
if(index->segment_offset + index->segment_size > (QWORD)infile->size()
|| index->segment_size < QSV_SIZE_ENCRYPTED) {
errcode = -3;
msg = "无法识别的格式";
return;
}
}
}
QsvUnpacker::~QsvUnpacker() {
if(infile) {
infile->close();
delete infile;
}
if(qindices) {
delete[] qindices;
}
}
int QsvUnpacker::get_errcode() const {
return errcode;
}
const QString& QsvUnpacker::get_msg() const {
return msg;
}
int QsvUnpacker::get_nb_indices() const {
return nb_indices;
}
void QsvUnpacker::seek_to_segment(int idx) {
read_index = idx;
read_offset = 0;
infile->seek(qindices[read_index].segment_offset);
}
int QsvUnpacker::read_bytes(BYTE* buffer, int read_size) {
errcode = 0;
if((DWORD)(read_offset + read_size) > qindices[read_index].segment_size) {
read_size = qindices[read_index].segment_size - read_offset;
}
if(read_size == 0) {
return -1; // end of file
}
read_size = infile->read((char*)buffer, read_size);
if(read_size <= 0) {
errcode = -1;
msg = "文件不完整";
return -1;
}
if(read_offset == 0) {
if(version == 1) {
decrypt_1(buffer, QSV_SIZE_ENCRYPTED);
} else if(version == 2) {
decrypt_2(buffer, QSV_SIZE_ENCRYPTED);
}
}
read_offset += read_size;
processed_size += read_size;
return read_size;
}
void QsvUnpacker::init_progress() {
total_size = 0;
for(int i = 0; i < nb_indices; ++i) {
total_size += qindices[i].segment_size;
}
processed_size = 0;
}
float QsvUnpacker::get_progress() const {
return (float)processed_size / total_size;
}