从golang中的缓冲读取器读取特定数量的字节

Question

I am aware of the specific function in golang from the bufio package.

func (b *Reader) Peek(n int) ([]byte, error)

Peek returns the next n bytes without advancing the reader. The bytes stop being valid at the next read call. If Peek returns fewer than n bytes, it also returns an error explaining why the read is short. The error is ErrBufferFull if n is larger than b's buffer size.

I need to be able to read a specific number of bytes from a Reader that will advance the reader. Basically, identical to the function above, but it advances the reader. Does anybody know how to accomplish this?

Answer 1

Note that the bufio.Read method calls the underlying io.Read at most once, meaning that it can return n < len(p), without reaching EOF. If you want to read exactly len(p) bytes or fail with an error, you can use io.ReadFull like this:

n, err := io.ReadFull(reader, p)

This works even if the reader is buffered.