示例#1
0
        /// <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);
        }