/// <summary>
/// Sets the file position of the descriptor to the given offset
/// </summary>
/// <param name="descriptor">The descriptor</param>
/// <param name="offset">The offset</param>
/// <param name="whence">The direction</param>
/// <returns>The new offset from the beginning of the file in bytes</returns>
public static int Seek(int descriptor, int offset, FileWhence whence)
{
FileDescriptors descriptors = Tasking.CurrentTask.FileDescriptors;
Node node = descriptors.GetNode(descriptor);
if (node == null)
{
return(-(int)ErrorCode.EBADF);
}
uint currentOffset = descriptors.GetOffset(descriptor);
if (whence == FileWhence.SEEK_CUR)
{
currentOffset = (uint)(currentOffset + offset);
}
else if (whence == FileWhence.SEEK_SET)
{
if (offset < 0)
{
currentOffset = 0;
}
else
{
currentOffset = (uint)offset;
}
}
else if (whence == FileWhence.SEEK_END)
{
if (offset > 0)
{
currentOffset = node.Size;
}
else
{
currentOffset = (uint)(node.Size + offset);
}
}
else
{
return(-(int)ErrorCode.EINVAL);
}
descriptors.SetOffset(descriptor, currentOffset);
return((int)currentOffset);
}
/// <summary>
/// Write to a file descriptor
/// </summary>
/// <param name="descriptor">The descriptor ID</param>
/// <param name="buffer">The buffer</param>
/// <param name="size">The size</param>
/// <returns>The amount of bytes written</returns>
public static int Write(int descriptor, byte[] buffer, uint size)
{
FileDescriptors descriptors = Tasking.CurrentTask.FileDescriptors;
Node node = descriptors.GetNode(descriptor);
if (node == null)
{
return(-(int)ErrorCode.EBADF);
}
uint offset = descriptors.GetOffset(descriptor);
descriptors.SetOffset(descriptor, offset + size);
return((int)VFS.Write(node, offset, size, buffer));
}
/// <summary>
/// Read from a file descriptor
/// </summary>
/// <param name="descriptor">The descriptor ID</param>
/// <param name="buffer">The buffer</param>
/// <param name="size">The size</param>
/// <returns>The amount of bytes read</returns>
public static int Read(int descriptor, byte[] buffer, uint size)
{
FileDescriptors descriptors = Tasking.CurrentTask.FileDescriptors;
Node node = descriptors.GetNode(descriptor);
if (node == null)
{
return(-(int)ErrorCode.EBADF);
}
// Can't do read from a directory
if ((node.Flags & NodeFlags.DIRECTORY) == NodeFlags.DIRECTORY)
{
return(-(int)ErrorCode.EISDIR);
}
bool isNonBlocking = ((node.OpenFlags & O_NONBLOCK) == O_NONBLOCK);
// Wait until data is available if its blocking
if (!isNonBlocking)
{
while (VFS.GetSize(node) == 0)
{
Tasking.Yield();
}
}
// Non-blocking but no data available?
else
{
if (VFS.GetSize(node) == 0)
{
return(-(int)ErrorCode.EAGAIN);
}
}
uint offset = descriptors.GetOffset(descriptor);
uint readBytes = VFS.Read(node, offset, size, buffer);
descriptors.SetOffset(descriptor, offset + readBytes);
return((int)readBytes);
}
