318 lines
8.5 KiB
C++
318 lines
8.5 KiB
C++
/*************************************************************************/
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/* file_access_encrypted.cpp */
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/*************************************************************************/
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/* This file is part of: */
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/* GODOT ENGINE */
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/* https://godotengine.org */
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/*************************************************************************/
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/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md). */
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/* */
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/* Permission is hereby granted, free of charge, to any person obtaining */
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/* a copy of this software and associated documentation files (the */
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/* "Software"), to deal in the Software without restriction, including */
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/* without limitation the rights to use, copy, modify, merge, publish, */
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/* distribute, sublicense, and/or sell copies of the Software, and to */
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/* permit persons to whom the Software is furnished to do so, subject to */
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/* the following conditions: */
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/* */
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/* The above copyright notice and this permission notice shall be */
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/* included in all copies or substantial portions of the Software. */
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/* */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
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/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
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/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
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/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
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/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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/*************************************************************************/
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#include "file_access_encrypted.h"
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#include "core/crypto/crypto_core.h"
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#include "core/string/print_string.h"
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#include "core/variant/variant.h"
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#include <stdio.h>
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Error FileAccessEncrypted::open_and_parse(FileAccess *p_base, const Vector<uint8_t> &p_key, Mode p_mode, bool p_with_magic) {
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ERR_FAIL_COND_V_MSG(file != nullptr, ERR_ALREADY_IN_USE, "Can't open file while another file from path '" + file->get_path_absolute() + "' is open.");
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ERR_FAIL_COND_V(p_key.size() != 32, ERR_INVALID_PARAMETER);
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pos = 0;
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eofed = false;
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use_magic = p_with_magic;
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if (p_mode == MODE_WRITE_AES256) {
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data.clear();
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writing = true;
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file = p_base;
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key = p_key;
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} else if (p_mode == MODE_READ) {
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writing = false;
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key = p_key;
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if (use_magic) {
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uint32_t magic = p_base->get_32();
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ERR_FAIL_COND_V(magic != ENCRYPTED_HEADER_MAGIC, ERR_FILE_UNRECOGNIZED);
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}
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unsigned char md5d[16];
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p_base->get_buffer(md5d, 16);
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length = p_base->get_64();
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unsigned char iv[16];
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for (int i = 0; i < 16; i++) {
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iv[i] = p_base->get_8();
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}
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base = p_base->get_position();
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ERR_FAIL_COND_V(p_base->get_length() < base + length, ERR_FILE_CORRUPT);
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uint64_t ds = length;
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if (ds % 16) {
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ds += 16 - (ds % 16);
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}
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data.resize(ds);
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uint64_t blen = p_base->get_buffer(data.ptrw(), ds);
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ERR_FAIL_COND_V(blen != ds, ERR_FILE_CORRUPT);
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{
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CryptoCore::AESContext ctx;
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ctx.set_encode_key(key.ptrw(), 256); // Due to the nature of CFB, same key schedule is used for both encryption and decryption!
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ctx.decrypt_cfb(ds, iv, data.ptrw(), data.ptrw());
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}
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data.resize(length);
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unsigned char hash[16];
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ERR_FAIL_COND_V(CryptoCore::md5(data.ptr(), data.size(), hash) != OK, ERR_BUG);
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ERR_FAIL_COND_V_MSG(String::md5(hash) != String::md5(md5d), ERR_FILE_CORRUPT, "The MD5 sum of the decrypted file does not match the expected value. It could be that the file is corrupt, or that the provided decryption key is invalid.");
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file = p_base;
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}
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return OK;
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}
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Error FileAccessEncrypted::open_and_parse_password(FileAccess *p_base, const String &p_key, Mode p_mode) {
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String cs = p_key.md5_text();
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ERR_FAIL_COND_V(cs.length() != 32, ERR_INVALID_PARAMETER);
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Vector<uint8_t> key;
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key.resize(32);
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for (int i = 0; i < 32; i++) {
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key.write[i] = cs[i];
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}
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return open_and_parse(p_base, key, p_mode);
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}
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Error FileAccessEncrypted::_open(const String &p_path, int p_mode_flags) {
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return OK;
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}
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void FileAccessEncrypted::close() {
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if (!file) {
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return;
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}
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_release();
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file->close();
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memdelete(file);
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file = nullptr;
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}
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void FileAccessEncrypted::release() {
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if (!file) {
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return;
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}
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_release();
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file = nullptr;
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}
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void FileAccessEncrypted::_release() {
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if (writing) {
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Vector<uint8_t> compressed;
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uint64_t len = data.size();
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if (len % 16) {
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len += 16 - (len % 16);
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}
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unsigned char hash[16];
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ERR_FAIL_COND(CryptoCore::md5(data.ptr(), data.size(), hash) != OK); // Bug?
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compressed.resize(len);
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memset(compressed.ptrw(), 0, len);
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for (int i = 0; i < data.size(); i++) {
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compressed.write[i] = data[i];
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}
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CryptoCore::AESContext ctx;
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ctx.set_encode_key(key.ptrw(), 256);
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if (use_magic) {
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file->store_32(ENCRYPTED_HEADER_MAGIC);
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}
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file->store_buffer(hash, 16);
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file->store_64(data.size());
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unsigned char iv[16];
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for (int i = 0; i < 16; i++) {
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iv[i] = Math::rand() % 256;
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file->store_8(iv[i]);
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}
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ctx.encrypt_cfb(len, iv, compressed.ptrw(), compressed.ptrw());
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file->store_buffer(compressed.ptr(), compressed.size());
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data.clear();
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}
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}
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bool FileAccessEncrypted::is_open() const {
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return file != nullptr;
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}
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String FileAccessEncrypted::get_path() const {
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if (file) {
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return file->get_path();
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} else {
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return "";
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}
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}
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String FileAccessEncrypted::get_path_absolute() const {
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if (file) {
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return file->get_path_absolute();
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} else {
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return "";
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}
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}
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void FileAccessEncrypted::seek(uint64_t p_position) {
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if (p_position > get_length()) {
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p_position = get_length();
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}
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pos = p_position;
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eofed = false;
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}
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void FileAccessEncrypted::seek_end(int64_t p_position) {
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seek(get_length() + p_position);
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}
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uint64_t FileAccessEncrypted::get_position() const {
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return pos;
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}
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uint64_t FileAccessEncrypted::get_length() const {
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return data.size();
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}
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bool FileAccessEncrypted::eof_reached() const {
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return eofed;
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}
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uint8_t FileAccessEncrypted::get_8() const {
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ERR_FAIL_COND_V_MSG(writing, 0, "File has not been opened in read mode.");
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if (pos >= get_length()) {
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eofed = true;
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return 0;
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}
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uint8_t b = data[pos];
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pos++;
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return b;
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}
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uint64_t FileAccessEncrypted::get_buffer(uint8_t *p_dst, uint64_t p_length) const {
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ERR_FAIL_COND_V(!p_dst && p_length > 0, -1);
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ERR_FAIL_COND_V_MSG(writing, -1, "File has not been opened in read mode.");
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uint64_t to_copy = MIN(p_length, get_length() - pos);
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for (uint64_t i = 0; i < to_copy; i++) {
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p_dst[i] = data[pos++];
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}
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if (to_copy < p_length) {
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eofed = true;
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}
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return to_copy;
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}
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Error FileAccessEncrypted::get_error() const {
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return eofed ? ERR_FILE_EOF : OK;
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}
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void FileAccessEncrypted::store_buffer(const uint8_t *p_src, uint64_t p_length) {
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ERR_FAIL_COND_MSG(!writing, "File has not been opened in write mode.");
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if (pos < get_length()) {
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for (uint64_t i = 0; i < p_length; i++) {
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store_8(p_src[i]);
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}
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} else if (pos == get_length()) {
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data.resize(pos + p_length);
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for (uint64_t i = 0; i < p_length; i++) {
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data.write[pos + i] = p_src[i];
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}
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pos += p_length;
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}
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}
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void FileAccessEncrypted::flush() {
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ERR_FAIL_COND_MSG(!writing, "File has not been opened in write mode.");
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// encrypted files keep data in memory till close()
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}
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void FileAccessEncrypted::store_8(uint8_t p_dest) {
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ERR_FAIL_COND_MSG(!writing, "File has not been opened in write mode.");
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if (pos < get_length()) {
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data.write[pos] = p_dest;
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pos++;
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} else if (pos == get_length()) {
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data.push_back(p_dest);
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pos++;
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}
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}
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bool FileAccessEncrypted::file_exists(const String &p_name) {
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FileAccess *fa = FileAccess::open(p_name, FileAccess::READ);
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if (!fa) {
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return false;
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}
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memdelete(fa);
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return true;
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}
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uint64_t FileAccessEncrypted::_get_modified_time(const String &p_file) {
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return 0;
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}
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uint32_t FileAccessEncrypted::_get_unix_permissions(const String &p_file) {
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return 0;
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}
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Error FileAccessEncrypted::_set_unix_permissions(const String &p_file, uint32_t p_permissions) {
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ERR_PRINT("Setting UNIX permissions on encrypted files is not implemented yet.");
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return ERR_UNAVAILABLE;
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}
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FileAccessEncrypted::~FileAccessEncrypted() {
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if (file) {
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close();
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}
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}
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