/// <summary>
/// Search for ZIP 'End of central directory record' near the end of file.
/// Returns offset of 'PK' signature or -1 if no signature was found.
/// </summary>
internal unsafe long SearchForSignature(ArcView file, byte[] signature)
{
if (signature.Length < 4)
{
throw new ArgumentException("Invalid ZIP file signature", "signature");
}
uint tail_size = (uint)Math.Min(file.MaxOffset, 0x10016L);
if (tail_size < 0x16)
{
return(-1);
}
var start_offset = file.MaxOffset - tail_size;
using (var view = file.CreateViewAccessor(start_offset, tail_size))
using (var pointer = new ViewPointer(view, start_offset))
{
byte *ptr_end = pointer.Value;
byte *ptr = ptr_end + tail_size - 0x16;
for (; ptr >= ptr_end; --ptr)
{
if (signature[3] == ptr[3] && signature[2] == ptr[2] &&
signature[1] == ptr[1] && signature[0] == ptr[0])
{
return(start_offset + (ptr - ptr_end));
}
}
return(-1);
}
}
byte[] DecryptIndex(ArcView idx)
{
int idx_size = (int)idx.MaxOffset - 4;
byte[] output = new byte[idx_size];
using (var view = idx.CreateViewAccessor(0, (uint)idx.MaxOffset))
unsafe
{
var rng = new CRuntimeRandomGenerator();
rng.SRand(view.ReadInt32(idx_size));
byte *ptr = view.GetPointer(0);
try
{
for (int i = 0; i < idx_size; ++i)
{
output[i] = (byte)(ptr[i] ^ IndexKey[rng.Rand() % IndexKey.Length]);
}
return(output);
}
finally
{
view.SafeMemoryMappedViewHandle.ReleasePointer();
}
}
}
/// <summary>
/// Search for ZIP 'End of central directory record' near the end of file.
/// Returns offset of 'PK' signature or -1 if no signature was found.
/// </summary>
private unsafe long SearchForSignature(ArcView file)
{
uint tail_size = (uint)Math.Min(file.MaxOffset, 0x10016L);
if (tail_size < 0x16)
{
return(-1);
}
var start_offset = file.MaxOffset - tail_size;
using (var view = file.CreateViewAccessor(start_offset, tail_size))
{
byte *ptr_end = view.GetPointer(start_offset);
byte *ptr = ptr_end + tail_size - 0x16;
try {
for (; ptr >= ptr_end; --ptr)
{
if (6 == ptr[3] && 5 == ptr[2] && 'K' == ptr[1] && 'P' == ptr[0])
{
return(start_offset + (ptr - ptr_end));
}
}
return(-1);
} finally {
view.SafeMemoryMappedViewHandle.ReleasePointer();
}
}
}
byte[] DecryptIndex(ArcView idx)
{
int idx_size = (int)idx.MaxOffset-4;
byte[] output = new byte[idx_size];
using (var view = idx.CreateViewAccessor (0, (uint)idx.MaxOffset))
unsafe
{
m_rng.SRand (view.ReadInt32 (idx_size));
byte* ptr = view.GetPointer (0);
try
{
for (int i = 0; i < idx_size; ++i)
{
output[i] = (byte)(ptr[i] ^ IndexKey[m_rng.Rand() % IndexKey.Length]);
}
return output;
}
finally
{
view.SafeMemoryMappedViewHandle.ReleasePointer();
}
}
}
private long SkipExeHeader(ArcView file)
{
long offset = 0x10;
long pe_offset = file.View.ReadUInt32(0x3c);
if (pe_offset < file.MaxOffset && 0x4550 == file.View.ReadUInt32(pe_offset)) // 'PE'
{
int opt_header = file.View.ReadUInt16(pe_offset + 0x14); // SizeOfOptionalHeader
offset = file.View.ReadUInt32(pe_offset + 0x54); // SizeOfHeaders
long section_table = pe_offset + opt_header + 0x18;
int count = file.View.ReadUInt16(pe_offset + 6); // NumberOfSections
if (section_table + 0x28 * count < file.MaxOffset)
{
for (int i = 0; i < count; ++i)
{
uint size = file.View.ReadUInt32(section_table + 0x10);
uint addr = file.View.ReadUInt32(section_table + 0x14);
if (file.View.AsciiEqual(section_table, ".rsrc\0"))
{
// look within EXE resource section
offset = addr;
break;
}
section_table += 0x28;
if (0 != size)
{
offset = Math.Max((long)addr + size, offset);
}
}
}
}
unsafe
{
while (offset < file.MaxOffset)
{
uint page_size = (uint)Math.Min(0x10000L, file.MaxOffset - offset);
if (page_size < 0x20)
{
break;
}
using (var view = file.CreateViewAccessor(offset, page_size))
{
byte *page_begin = view.GetPointer(offset);
byte *page_end = page_begin + page_size - 0x10;
try {
for (byte *ptr = page_begin; ptr != page_end; ++ptr)
{
// TODO: search every byte only when inside resource section,
// otherwise stick to paragraph boundary.
int i = 0;
while (ptr[i] == s_xp3_header[i])
{
if (++i == s_xp3_header.Length)
{
// check whether index offset is non-zero
if (0 == *(uint *)(ptr + i))
{
break;
}
return(offset + (ptr - page_begin));
}
}
}
}
finally {
view.SafeMemoryMappedViewHandle.ReleasePointer();
}
}
offset += page_size - 0x10;
}
}
return(0);
}