/// <summary>
/// Attempts to write to the specified pipe.
/// </summary>
/// <remarks>
/// Note that this function is non-blocking. It will, however, block a system caller thread by simply not returning it from
/// the deferred system call.
/// </remarks>
/// <param name="PipeId">The Id of the pipe to write.</param>
/// <param name="Blocking">Whether the write should be blocking or non-blocking.</param>
/// <param name="CallerProcess">The process which made the call.</param>
/// <param name="CallerThread">The thread which made the call.</param>
/// <returns>See descriptions on <see cref="PipeManager.RWResults"/> values.</returns>
public static RWResults WritePipe(int PipeId, bool Blocking, Process CallerProcess, Thread CallerThread)
{
#if PIPES_TRACE
BasicConsole.WriteLine("WritePipe: Validating inputs");
#endif
// Validate inputs
// - Check pipe exists
Pipe pipe = GetPipe(PipeId);
if (pipe == null)
{
return(RWResults.Error);
}
#if PIPES_TRACE
BasicConsole.WriteLine("WritePipe: Checking caller allowed to write");
#endif
// Check the caller is allowed to access the pipe
if (!AllowedToWritePipe(pipe, CallerProcess.Id))
{
return(RWResults.Error);
}
#if PIPES_TRACE
BasicConsole.WriteLine("WritePipe: Getting out process");
#endif
// Get outpoint process
Process OutProcess = ProcessManager.GetProcessById(pipe.Outpoint.ProcessId);
if (OutProcess == null)
{
return(RWResults.Error);
}
#if PIPES_TRACE
BasicConsole.WriteLine("WritePipe: Getting in process");
#endif
// Get inpoint process
Process InProcess = ProcessManager.GetProcessById(pipe.Inpoint.ProcessId);
if (InProcess == null)
{
return(RWResults.Error);
}
#if PIPES_TRACE
BasicConsole.WriteLine("WritePipe: Adding caller to write queue");
#endif
ProcessManager.EnableKernelAccessToProcessMemory(CallerProcess);
// Add caller thread to the write queue
WritePipeRequest *Request = (WritePipeRequest *)CallerThread.Param1;
pipe.QueueToWrite(CallerThread.Id, Request->Length);
// Set up initial failure return value
CallerThread.Return1 = (uint)SystemCallResults.Fail;
ProcessManager.DisableKernelAccessToProcessMemory(CallerProcess);
#if PIPES_TRACE
BasicConsole.WriteLine("WritePipe: Processing pipe queue");
#endif
// Process the pipe queue
ProcessPipeQueue(pipe, OutProcess, InProcess);
bool Completed = !pipe.AreThreadsWaitingToWrite();
if (!Blocking)
{
if (!Completed)
{
uint temp;
bool removed = pipe.RemoveLastToWrite(out temp);
if (!removed || temp != CallerThread.Id)
{
BasicConsole.WriteLine("PipeManager: Error! Async write failed and then removing last from queue resulted in thread Id mismatch!");
}
ProcessManager.EnableKernelAccessToProcessMemory(CallerProcess);
CallerThread.Return1 = (uint)SystemCallResults.Fail;
ProcessManager.DisableKernelAccessToProcessMemory(CallerProcess);
CallerThread._Wake();
}
}
return(Completed ? RWResults.Complete : RWResults.Queued);
}