Buffering streams

When a stream is unbuffered, bytes are passed through to the system immediately. Otherwise, bytes may be accumulated and transmitted as a block. When a stream is fully buffered, bytes are transmitted as a block when the buffer is filled. When a stream is line buffered, bytes are transmitted as a block when a newline byte is encountered. Furthermore, bytes transmitted as a block when a buffer is filled, when input is requested on an unbuffered stream, or when input is requested on a line-buffered stream that requires the transmission of bytes. Support for these characteristics can be initiated and affected via setbuf() and setvbuf().