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Code Issues Releases Wiki Activity

append salt bytes inside encoded data chunk

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Ted John
2016-07-11 19:09:16 +01:00
parent cf59929eaa
commit 81a597ab0d
3 changed files with 63 additions and 35 deletions
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84
src/object/ObjectRepository.cpp
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@@ -487,47 +487,68 @@ private:
}
}
static void SaveObject(const utf8 * path, const rct_object_entry * entry, const void * data, size_t dataSize)
static void SaveObject(const utf8 * path,
const rct_object_entry * entry,
const void * data, size_t dataSize,
bool fixChecksum = true)
{
uint8 objectType = entry->flags & 0x0F;
// Encode data
sawyercoding_chunk_header chunkHeader;
chunkHeader.encoding = object_entry_group_encoding[objectType];
chunkHeader.length = dataSize;
uint8 * encodedDataBuffer = Memory::Allocate<uint8>(0x600000);
size_t encodedDataSize = sawyercoding_write_chunk_buffer(encodedDataBuffer, (uint8 *)data, chunkHeader);
void * extraBytes = nullptr;
size_t extraBytesCount = 0;
int realChecksum = object_calculate_checksum(entry, data, dataSize);
if (realChecksum != entry->checksum)
if (fixChecksum)
{
char objectName[9];
object_entry_get_name_fixed(objectName, sizeof(objectName), entry);
log_verbose("[%s] Incorrect checksum, adding salt bytes...", objectName);
// Calculate the value of extra bytes that can be appended to the data so that the
// data is then valid for the object's checksum
extraBytes = CalculateExtraBytesToFixChecksum(realChecksum, entry->checksum, &extraBytesCount);
#ifdef DEBUG
int realChecksum = object_calculate_checksum(entry, data, dataSize);
if (realChecksum != entry->checksum)
{
// Check that CalculateExtraBytesToFixChecksum did the job
char objectName[9];
object_entry_get_name_fixed(objectName, sizeof(objectName), entry);
log_verbose("[%s] Incorrect checksum, adding salt bytes...", objectName);
// Calculate the value of extra bytes that can be appended to the data so that the
// data is then valid for the object's checksum
size_t extraBytesCount = 0;
void * extraBytes = CalculateExtraBytesToFixChecksum(realChecksum, entry->checksum, &extraBytesCount);
// Create new data blob with appended bytes
size_t newDataSize = dataSize + extraBytesCount;
void * newData = Memory::Allocate<void>(newDataSize);
void * newDataSaltOffset = (void *)((uintptr_t)newData + dataSize);
Memory::Copy(newData, data, dataSize);
Memory::Copy(newDataSaltOffset, extraBytes, extraBytesCount);
int actualChecksum = object_calculate_checksum(entry, newData, newDataSize);
Guard::Assert(actualChecksum == realChecksum, "CalculateExtraBytesToFixChecksum failed to fix checksum.");
try
{
int newRealChecksum = object_calculate_checksum(entry, newData, newDataSize);
if (newRealChecksum != entry->checksum)
{
Guard::Fail("CalculateExtraBytesToFixChecksum failed to fix checksum.");
Memory::Free(newData);
// Save old data form
SaveObject(path, entry, data, dataSize, false);
}
else
{
// Save new data form
SaveObject(path, entry, newData, newDataSize, false);
}
Memory::Free(newData);
Memory::Free(extraBytes);
}
catch (Exception ex)
{
Memory::Free(newData);
Memory::Free(extraBytes);
throw;
}
return;
}
#endif
}
// Encode data
uint8 objectType = entry->flags & 0x0F;
sawyercoding_chunk_header chunkHeader;
chunkHeader.encoding = object_entry_group_encoding[objectType];
chunkHeader.length = dataSize;
uint8 * encodedDataBuffer = Memory::Allocate<uint8>(0x600000);
size_t encodedDataSize = sawyercoding_write_chunk_buffer(encodedDataBuffer, (uint8 *)data, chunkHeader);
// Save to file
try
{
@@ -535,17 +556,10 @@ private:
fs.Write(entry, sizeof(rct_object_entry));
fs.Write(encodedDataBuffer, encodedDataSize);
if (extraBytes != nullptr)
{
fs.Write(extraBytes, extraBytesCount);
}
Memory::Free(extraBytes);
Memory::Free(encodedDataBuffer);
}
catch (Exception ex)
{
Memory::Free(extraBytes);
Memory::Free(encodedDataBuffer);
throw;
}