private bool Sys_Read()
{
// get fd index
UInt64 fd_index = RBX;
if (fd_index >= (UInt64)FDCount)
{
Terminate(ErrorCode.OutOfBounds); return(false);
}
// get fd
IFileWrapper fd = FileDescriptors[fd_index];
if (fd == null)
{
Terminate(ErrorCode.FDNotInUse); return(false);
}
// make sure we can read from it
if (!fd.CanRead())
{
Terminate(ErrorCode.FilePermissions); return(false);
}
// make sure we're in bounds
if (RCX >= MemorySize || RDX >= MemorySize || RCX + RDX > MemorySize)
{
Terminate(ErrorCode.OutOfBounds); return(false);
}
// make sure we're not in the readonly segment
if (RCX < ReadonlyBarrier)
{
Terminate(ErrorCode.AccessViolation); return(false);
}
// read from the file
try
{
Int64 n = fd.Read(Memory, (int)RCX, (int)RDX);
// if we got nothing but it's interactive
if (n == 0 && fd.IsInteractive())
{
--RIP; // await further data by repeating the syscall
SuspendedRead = true; // suspend execution until there's more data
}
// otherwise success - return num chars read from file
else
{
RAX = (UInt64)n;
}
}
// errors are failures - return -1
catch (Exception) { RAX = ~(UInt64)0; }
return(true);
}