public static unsafe PK_header ReadHeader(byte[] bytes)
{
PK_header header = new PK_header {
data = new List <PK_field>()
};
fixed(byte *buffer = bytes)
{
byte *cursor = buffer;
header.tag = *(ushort *)cursor;
cursor += 2;
header.size = *(ushort *)cursor;
cursor += 2;
byte *startOfData = cursor;
header.crc32 = *(uint *)cursor;
cursor += 4;
while (cursor - startOfData < header.size)
{
var field = new PK_field();
field.tag = *(ushort *)cursor;
cursor += 2;
field.size = *(ushort *)cursor;
cursor += 2;
field.value = new byte[field.size];
Marshal.Copy((IntPtr)cursor, field.value, 0, field.size);
cursor += field.size;
header.data.Add(field);
}
}
return(header);
}
public static unsafe byte[] WriteHeader(PK_header header)
{
var bufferSize = 8; //initial fixed size of PK_header
var crc = new CRC32();
foreach (var field in header.data)
{
bufferSize += 4; //base field size
bufferSize += field.size;
}
var buffer = new byte[bufferSize];
fixed(byte *bufferPtr = buffer)
{
var cursor = bufferPtr;
*(ushort *)cursor = header.tag;
cursor += 2;
*(ushort *)cursor = header.size;
cursor += 2;
//skip past the crc, well fill it in later
int *crcPtr = (int *)cursor;
cursor += 4;
foreach (var field in header.data)
{
*(ushort *)cursor = field.tag;
cursor += 2;
*(ushort *)cursor = field.size;
cursor += 2;
Marshal.Copy(field.value, 0, (IntPtr)cursor, field.value.Length);
cursor += field.value.Length;
}
crc.SlurpBlock(buffer, 8, bufferSize - 8);
*crcPtr = crc.Crc32Result;
}
return(buffer);
}
public static byte[] MakeVMSExtraBlock(RecordTypes recordType, RecordLayouts layout, FileAttributes attributes,
ushort recordSize, uint fileSize, byte bucketSize, ushort maxRecordSize, ushort defaultExtend,
DateTime created,
DateTime modified, uint ownerId, FileProtection system, FileProtection owner, FileProtection group,
FileProtection world)
{
var headerResult = new PK_header
{
tag = VMSAttributeHeader, size = VMSAttributeSize, data = new List <PK_field>()
};
var evenFileSize = Math.DivRem(fileSize, 512, out var fileSizeRemainder) + 1;
FatDef fatDef = new FatDef
{
b_rtype = MakeRecordType(recordType, layout),
b_rattrib = (byte)attributes,
w_rsize = recordSize,
l_hiblk = (uint)(((evenFileSize + 1) << 16) | ((evenFileSize + 1) >> 16)),
l_efblk = (uint)((evenFileSize << 16) | (evenFileSize >> 16)),
w_ffbyte = (ushort)fileSizeRemainder,
b_bktsize = bucketSize,
b_vfcsize = (byte)(recordType == RecordTypes.C_VFC ? 2 : 0),
w_maxrec = maxRecordSize,
w_defext = defaultExtend,
w_gbc = 0
};
headerResult.data.Add(new PK_field {
size = 32, tag = 4, value = WriteFATDef(fatDef)
});
headerResult.data.Add(new PK_field {
size = 4, tag = 3, value = BitConverter.GetBytes((int)0)
});
headerResult.data.Add(new PK_field {
size = 8, tag = 17, value = ConvertToSmithsonianTime(created)
});
headerResult.data.Add(new PK_field {
size = 8, tag = 18, value = ConvertToSmithsonianTime(modified)
});
headerResult.data.Add(new PK_field {
size = 8, tag = 19, value = BitConverter.GetBytes((long)0)
});
headerResult.data.Add(new PK_field {
size = 8, tag = 20, value = BitConverter.GetBytes((long)0)
});
headerResult.data.Add(new PK_field {
size = 2, tag = 13, value = new byte[] { 1, 0 }
});
headerResult.data.Add(new PK_field {
size = 4, tag = 21, value = BitConverter.GetBytes(ownerId)
});
headerResult.data.Add(
new PK_field {
size = 2, tag = 22, value = MakeProtection(system, owner, group, world)
});
headerResult.data.Add(new PK_field {
size = 2, tag = 23, value = new byte[] { 0, 0 }
});
headerResult.data.Add(new PK_field {
size = 1, tag = 29, value = new byte[] { 0 }
});
return(WriteHeader(headerResult));
}