package io

import (
	"errors"
	"io"
)

var ErrLimit = errors.New("read reached limit")

func ReadAllLimit(r io.Reader, limit int) ([]byte, error) {
	b := make([]byte, 0, 512)
	for {
		if len(b) == cap(b) {
			// Add more capacity (let append pick how much).
			b = append(b, 0)[:len(b)]
		}
		c := limit
		if c > cap(b) {
			c = cap(b)
		}
		n, err := r.Read(b[len(b):c])
		b = b[:len(b)+n]
		if err != nil {
			if err == io.EOF {
				err = nil
			}
			return b, err
		}
		if len(b) == limit {
			return b, ErrLimit
		}
	}
}