/// <summary>
/// Checks the basic validity of the header, assuming the stream is at least the given size.
/// Returns false (and the out exception) on failure.
/// </summary>
public static bool TryValidate(ref ModelHeader header, long size, out Exception ex)
{
Contracts.Check(size >= 0);
try
{
Contracts.CheckDecode(header.Signature == SignatureValue, "Wrong file type");
Contracts.CheckDecode(header.VerReadable <= header.VerWritten, "Corrupt file header");
Contracts.CheckDecode(header.VerReadable <= VerWrittenCur, "File is too new");
Contracts.CheckDecode(header.VerWritten >= VerWeCanReadBack, "File is too old");
// Currently the model always comes immediately after the header.
Contracts.CheckDecode(header.FpModel == Size);
Contracts.CheckDecode(header.FpModel + header.CbModel >= header.FpModel);
if (header.FpStringTable == 0)
{
// No strings.
Contracts.CheckDecode(header.CbStringTable == 0);
Contracts.CheckDecode(header.FpStringChars == 0);
Contracts.CheckDecode(header.CbStringChars == 0);
if (header.VerWritten < VerAssemblyNameSupported || header.FpAssemblyName == 0)
{
Contracts.CheckDecode(header.FpTail == header.FpModel + header.CbModel);
}
}
else
{
// Currently the string table always comes immediately after the model block.
Contracts.CheckDecode(header.FpStringTable == header.FpModel + header.CbModel);
Contracts.CheckDecode(header.CbStringTable % sizeof(long) == 0);
Contracts.CheckDecode(header.CbStringTable / sizeof(long) < int.MaxValue);
Contracts.CheckDecode(header.FpStringTable + header.CbStringTable > header.FpStringTable);
Contracts.CheckDecode(header.FpStringChars == header.FpStringTable + header.CbStringTable);
Contracts.CheckDecode(header.CbStringChars % sizeof(char) == 0);
Contracts.CheckDecode(header.FpStringChars + header.CbStringChars >= header.FpStringChars);
if (header.VerWritten < VerAssemblyNameSupported || header.FpAssemblyName == 0)
{
Contracts.CheckDecode(header.FpTail == header.FpStringChars + header.CbStringChars);
}
}
if (header.VerWritten >= VerAssemblyNameSupported)
{
if (header.FpAssemblyName == 0)
{
Contracts.CheckDecode(header.CbAssemblyName == 0);
}
else
{
// the assembly name always immediately after the string table, if there is one
if (header.FpStringTable == 0)
{
Contracts.CheckDecode(header.FpAssemblyName == header.FpModel + header.CbModel);
}
else
{
Contracts.CheckDecode(header.FpAssemblyName == header.FpStringChars + header.CbStringChars);
}
Contracts.CheckDecode(header.CbAssemblyName % sizeof(char) == 0);
Contracts.CheckDecode(header.FpTail == header.FpAssemblyName + header.CbAssemblyName);
}
}
Contracts.CheckDecode(header.FpLim == header.FpTail + sizeof(ulong));
Contracts.CheckDecode(size == 0 || size >= header.FpLim);
ex = null;
return(true);
}
catch (Exception e)
{
ex = e;
return(false);
}
}
/// <summary>
/// Checks the validity of the header, reads the string table, etc.
/// </summary>
public static bool TryValidate(ref ModelHeader header, BinaryReader reader, long fpMin, out string[] strings, out string loaderAssemblyName, out Exception ex)
{
Contracts.CheckValue(reader, nameof(reader));
Contracts.Check(fpMin >= 0);
if (!TryValidate(ref header, reader.BaseStream.Length - fpMin, out ex))
{
strings = null;
loaderAssemblyName = null;
return(false);
}
try
{
long fpOrig = reader.FpCur();
StringBuilder sb = null;
if (header.FpStringTable == 0)
{
// No strings.
strings = null;
if (header.VerWritten < VerAssemblyNameSupported)
{
// Before VerAssemblyNameSupported, if there were no strings in the model,
// validation ended here. Specifically the FpTail checks below were skipped.
// There are earlier versions of models that don't have strings, and 'reader' is
// not at FpTail at this point.
// Preserve the previous behavior by returning early here.
loaderAssemblyName = null;
ex = null;
return(true);
}
}
else
{
reader.Seek(header.FpStringTable + fpMin);
Contracts.Assert(reader.FpCur() == header.FpStringTable + fpMin);
long cstr = header.CbStringTable / sizeof(long);
Contracts.Assert(cstr < int.MaxValue);
long[] offsets = reader.ReadLongArray((int)cstr);
Contracts.Assert(header.FpStringChars == reader.FpCur() - fpMin);
Contracts.CheckDecode(offsets[cstr - 1] == header.CbStringChars);
strings = new string[cstr];
long offset = 0;
sb = new StringBuilder();
for (int i = 0; i < offsets.Length; i++)
{
Contracts.CheckDecode(header.FpStringChars + offset == reader.FpCur() - fpMin);
long offsetPrev = offset;
offset = offsets[i];
Contracts.CheckDecode(offsetPrev <= offset & offset <= header.CbStringChars);
Contracts.CheckDecode(offset % sizeof(char) == 0);
long cch = (offset - offsetPrev) / sizeof(char);
Contracts.CheckDecode(cch < int.MaxValue);
sb.Clear();
for (long ich = 0; ich < cch; ich++)
{
sb.Append((char)reader.ReadUInt16());
}
strings[i] = sb.ToString();
}
Contracts.CheckDecode(offset == header.CbStringChars);
Contracts.CheckDecode(header.FpStringChars + header.CbStringChars == reader.FpCur() - fpMin);
}
if (header.VerWritten >= VerAssemblyNameSupported && header.FpAssemblyName != 0)
{
reader.Seek(header.FpAssemblyName + fpMin);
int assemblyNameLength = (int)header.CbAssemblyName / sizeof(char);
sb = sb != null?sb.Clear() : new StringBuilder(assemblyNameLength);
for (long ich = 0; ich < assemblyNameLength; ich++)
{
sb.Append((char)reader.ReadUInt16());
}
loaderAssemblyName = sb.ToString();
}
else
{
loaderAssemblyName = null;
}
Contracts.CheckDecode(header.FpTail == reader.FpCur() - fpMin);
ulong tail = reader.ReadUInt64();
Contracts.CheckDecode(tail == TailSignatureValue, "Corrupt model file tail");
ex = null;
reader.Seek(fpOrig);
return(true);
}
catch (Exception e)
{
strings = null;
loaderAssemblyName = null;
ex = e;
return(false);
}
}
/// <summary>
/// Finish reading. Checks that the current reader position is the end of the model blob.
/// Seeks to the end of the entire model file (after the tail).
/// </summary>
public static void EndRead(long fpMin, ref ModelHeader header, BinaryReader reader)
{
Contracts.CheckDecode(header.FpModel + header.CbModel == reader.FpCur() - fpMin);
reader.Seek(header.FpLim + fpMin);
}
