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Fixed unaligned memory access in FastNBT.

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This should fix #420.
This commit is contained in:
madmaxoft 2014-01-02 17:33:18 +01:00
parent bb0d43f70e
commit c510683d2a
3 changed files with 44 additions and 5 deletions
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30
src/StringUtils.cpp
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@ -764,3 +764,33 @@ AString Base64Decode(const AString & a_Base64String)
short GetBEShort(const char * a_Mem)
{
return (((short)a_Mem[0]) << 8) | a_Mem[1];
}
int GetBEInt(const char * a_Mem)
{
return (((int)a_Mem[0]) << 24) | (((int)a_Mem[1]) << 16) | (((int)a_Mem[2]) << 8) | a_Mem[3];
}
void SetBEInt(char * a_Mem, Int32 a_Value)
{
a_Mem[0] = a_Value >> 24;
a_Mem[1] = (a_Value >> 16) & 0xff;
a_Mem[2] = (a_Value >> 8) & 0xff;
a_Mem[3] = a_Value & 0xff;
}

9
src/StringUtils.h
View File

@ -81,6 +81,15 @@ extern AString ReplaceAllCharOccurrences(const AString & a_String, char a_From,
/// Decodes a Base64-encoded string into the raw data
extern AString Base64Decode(const AString & a_Base64String);
/// Reads two bytes from the specified memory location and interprets them as BigEndian short
extern short GetBEShort(const char * a_Mem);
/// Reads four bytes from the specified memory location and interprets them as BigEndian int
extern int GetBEInt(const char * a_Mem);
/// Writes four bytes to the specified memory location so that they interpret as BigEndian int
extern void SetBEInt(char * a_Mem, Int32 a_Value);
// If you have any other string helper functions, declare them here

10
src/WorldStorage/FastNBT.cpp
View File

@ -80,7 +80,7 @@ bool cParsedNBT::ReadString(int & a_StringStart, int & a_StringLen)
{
NEEDBYTES(2);
a_StringStart = m_Pos + 2;
a_StringLen = ntohs(*((short *)(m_Data + m_Pos)));
a_StringLen = GetBEShort(m_Data + m_Pos);
if (a_StringLen < 0)
{
// Invalid string length
@ -135,7 +135,7 @@ bool cParsedNBT::ReadList(eTagType a_ChildrenType)
// Read the count:
NEEDBYTES(4);
int Count = ntohl(*((int *)(m_Data + m_Pos)));
int Count = GetBEInt(m_Data + m_Pos);
m_Pos += 4;
if (Count < 0)
{
@ -197,7 +197,7 @@ bool cParsedNBT::ReadTag(void)
case TAG_ByteArray:
{
NEEDBYTES(4);
int len = ntohl(*((int *)(m_Data + m_Pos)));
int len = GetBEInt(m_Data + m_Pos);
m_Pos += 4;
if (len < 0)
{
@ -229,7 +229,7 @@ bool cParsedNBT::ReadTag(void)
case TAG_IntArray:
{
NEEDBYTES(4);
int len = ntohl(*((int *)(m_Data + m_Pos)));
int len = GetBEInt(m_Data + m_Pos);
m_Pos += 4;
if (len < 0)
{
@ -401,7 +401,7 @@ void cFastNBTWriter::EndList(void)
ASSERT(m_Stack[m_CurrentStack].m_Type == TAG_List);
// Update the list count:
*((int *)(m_Result.c_str() + m_Stack[m_CurrentStack].m_Pos)) = htonl(m_Stack[m_CurrentStack].m_Count);
SetBEInt((char *)(m_Result.c_str() + m_Stack[m_CurrentStack].m_Pos), m_Stack[m_CurrentStack].m_Count);
--m_CurrentStack;
}