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Add support for delta encoding to patch PCKs

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This commit is contained in:
Mikael Hermansson
2025-10-24 16:10:45 +02:00
parent 9dd6c4dbac
commit 0cc88f34da
17 changed files with 851 additions and 92 deletions
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110
core/io/delta_encoding.cpp Normal file
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/**************************************************************************/
/* delta_encoding.cpp */
/**************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/**************************************************************************/
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/**************************************************************************/
#include "delta_encoding.h"
#include <zstd.h>
#define ERR_FAIL_ZSTD_V_MSG(m_result, m_retval, m_msg) \
ERR_FAIL_COND_V_MSG(ZSTD_isError(m_result), m_retval, vformat("%s Zstandard reported error code %d: \"%s\".", m_msg, ZSTD_getErrorCode(m_result), ZSTD_getErrorString(ZSTD_getErrorCode(m_result))))
struct ZstdCompressionContext {
ZSTD_CCtx *context = ZSTD_createCCtx();
~ZstdCompressionContext() { ZSTD_freeCCtx(context); }
operator ZSTD_CCtx *() { return context; }
};
struct ZstdDecompressionContext {
ZSTD_DCtx *context = ZSTD_createDCtx();
~ZstdDecompressionContext() { ZSTD_freeDCtx(context); }
operator ZSTD_DCtx *() { return context; }
};
static constexpr uint8_t DELTA_MAGIC[4] = { 'G', 'D', 'D', 'L' };
static constexpr uint8_t DELTA_VERSION_NUMBER = 1;
static constexpr size_t DELTA_HEADER_SIZE = 5;
Error DeltaEncoding::encode_delta(Span<uint8_t> p_old_data, Span<uint8_t> p_new_data, Vector<uint8_t> &r_delta, int p_compression_level) {
size_t zstd_result = ZSTD_compressBound(p_new_data.size());
ERR_FAIL_ZSTD_V_MSG(zstd_result, FAILED, "Failed to encode delta. Calculating compression bounds failed.");
r_delta.reserve_exact(DELTA_HEADER_SIZE + zstd_result);
r_delta.resize(DELTA_HEADER_SIZE + zstd_result);
memcpy(r_delta.ptrw(), DELTA_MAGIC, 4);
r_delta.write[4] = DELTA_VERSION_NUMBER;
ZstdCompressionContext zstd_context;
ZSTD_parameters zstd_params = ZSTD_getParams(p_compression_level, p_new_data.size(), p_old_data.size());
zstd_params.fParams.contentSizeFlag = 1;
zstd_params.fParams.checksumFlag = 1;
zstd_result = ZSTD_CCtx_setParams(zstd_context, zstd_params);
ERR_FAIL_ZSTD_V_MSG(zstd_result, FAILED, "Failed to encode delta. Setting compression parameters failed.");
zstd_result = ZSTD_CCtx_refPrefix(zstd_context, p_old_data.ptr(), p_old_data.size());
ERR_FAIL_ZSTD_V_MSG(zstd_result, FAILED, "Failed to encode delta. Setting prefix dictionary failed.");
zstd_result = ZSTD_compress2(zstd_context, r_delta.ptrw() + DELTA_HEADER_SIZE, r_delta.size() - DELTA_HEADER_SIZE, p_new_data.ptr(), p_new_data.size());
ERR_FAIL_ZSTD_V_MSG(zstd_result, FAILED, "Failed to encode delta. Compression failed.");
r_delta.resize(DELTA_HEADER_SIZE + zstd_result);
return OK;
}
Error DeltaEncoding::decode_delta(Span<uint8_t> p_old_data, Span<uint8_t> p_delta, Vector<uint8_t> &r_new_data) {
ERR_FAIL_COND_V_MSG(p_delta.size() < DELTA_HEADER_SIZE, ERR_INVALID_DATA, vformat("Failed to decode delta. File size (%d) is too small.", p_delta.size()));
uint8_t magic[4];
memcpy(magic, p_delta.ptr(), sizeof(magic));
uint8_t version = p_delta[4];
ERR_FAIL_COND_V_MSG(memcmp(magic, DELTA_MAGIC, 4) != 0, ERR_FILE_CORRUPT, "Failed to decode delta. Header is invalid.");
ERR_FAIL_COND_V_MSG(version != DELTA_VERSION_NUMBER, ERR_FILE_UNRECOGNIZED, vformat("Failed to decode delta. Expected version %d but found %d.", DELTA_VERSION_NUMBER, version));
size_t zstd_result = ZSTD_findDecompressedSize(p_delta.ptr() + DELTA_HEADER_SIZE, p_delta.size() - DELTA_HEADER_SIZE);
ERR_FAIL_ZSTD_V_MSG(zstd_result, FAILED, "Failed to decode delta. Unable to find decompressed size.");
r_new_data.reserve_exact(zstd_result);
r_new_data.resize(zstd_result);
ZstdDecompressionContext zstd_context;
zstd_result = ZSTD_DCtx_refPrefix(zstd_context, p_old_data.ptr(), p_old_data.size());
ERR_FAIL_ZSTD_V_MSG(zstd_result, FAILED, "Failed to decode delta. Setting prefix dictionary failed.");
zstd_result = ZSTD_decompressDCtx(zstd_context, r_new_data.ptrw(), r_new_data.size(), p_delta.ptr() + DELTA_HEADER_SIZE, p_delta.size() - DELTA_HEADER_SIZE);
ERR_FAIL_ZSTD_V_MSG(zstd_result, FAILED, "Failed to decode delta. Decompression failed.");
ERR_FAIL_COND_V(zstd_result != (size_t)r_new_data.size(), ERR_FILE_CORRUPT);
return OK;
}