ioutil

Documentation

Overview

Package ioutil contains extensions and utilities for package io from the standard library.

Index

• func LimitReader(r io.Reader, n uint64) (limited io.Reader)
• type LimitError
  • func (err *LimitError) Error() (msg string)
• type TruncatedWriter
  • func NewTruncatedWriter(w io.Writer, limit uint) (tw *TruncatedWriter)
  • func (w *TruncatedWriter) Write(b []byte) (n int, err error)

Examples

• TruncatedWriter

Functions

func LimitReader

func LimitReader(r io.Reader, n uint64) (limited io.Reader)

LimitReader returns an io.Reader that reads up to n bytes. Once that limit is reached, [ErrLimit] is returned from limited.Read. limited.Read is not safe for concurrent use. n must be non-negative.

Types

type LimitError

type LimitError struct {
	// Limit is the limit that triggered the error.
	Limit uint64
}

LimitError is returned when the Limit is reached.

func (*LimitError) Error

func (err *LimitError) Error() (msg string)

Error implements the error interface for *LimitError.

type TruncatedWriter

type TruncatedWriter struct {
	// contains filtered or unexported fields
}

TruncatedWriter is an io.Writer that writes up to a certain limit of bytes to its underlying writer and then ignores the rest.

Example

package main

import (
	"bytes"
	"fmt"

	"github.com/AdguardTeam/golibs/ioutil"
)

func main() {
	data := []byte("hello")

	buf := &bytes.Buffer{}
	fmt.Println(ioutil.NewTruncatedWriter(buf, 1).Write(data))
	fmt.Println(buf)

	buf = &bytes.Buffer{}
	fmt.Println(ioutil.NewTruncatedWriter(buf, 2).Write(data))
	fmt.Println(buf)

	buf = &bytes.Buffer{}
	fmt.Println(ioutil.NewTruncatedWriter(buf, 10).Write(data))
	fmt.Println(buf)

}

Output:

5 <nil>
h
5 <nil>
he
5 <nil>
hello

func NewTruncatedWriter

func NewTruncatedWriter(w io.Writer, limit uint) (tw *TruncatedWriter)

NewTruncatedWriter returns a new truncated writer. It wraps the given writer w the way it writes up to the given limit and then ignores the rest.

func (*TruncatedWriter) Write

func (w *TruncatedWriter) Write(b []byte) (n int, err error)

Write implements the io.Writer interface for *TruncatedWriter. n is always len(b).