chore: io/ioutil has been deprecated

rpc/dataconn/frameconn/frameconn.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net"
 	"sync"
 	"syscall"
@@ -354,7 +353,7 @@ func (c *Conn) Shutdown(deadline time.Time) error {
 	// TODO DoS mitigation by reading limited number of bytes
 	// see discussion above why this is non-trivial
 	defer prometheus.NewTimer(prom.ShutdownDrainSeconds).ObserveDuration()
-	n, _ := io.Copy(ioutil.Discard, c.nc)
+	n, _ := io.Copy(io.Discard, c.nc)
 	prom.ShutdownDrainBytesRead.Observe(float64(n))
 
 	return closeWire("close")

rpc/dataconn/timeoutconn/internal/wireevaluator/wireevaluator.go

@@ -5,7 +5,6 @@ import (
 	"context"
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path"
 
@@ -47,7 +46,7 @@ func main() {
 	flag.StringVar(&args.testCase, "testcase", "", "")
 	flag.Parse()
 
-	bytes, err := ioutil.ReadFile(args.configPath)
+	bytes, err := os.ReadFile(args.configPath)
 	noerror(err)
 	err = yaml.UnmarshalStrict(bytes, &conf)
 	noerror(err)

rpc/dataconn/timeoutconn/internal/wireevaluator/wireevaluator_closewrite.go

@@ -3,7 +3,6 @@ package main
 import (
 	"bytes"
 	"io"
-	"io/ioutil"
 	"log"
 
 	"github.com/zrepl/zrepl/transport"
@@ -83,7 +82,7 @@ func (CloseWrite) receiver(wire transport.Wire) {
 	// consume half the test data, then detect an error, send it and CloseWrite
 
 	r := io.LimitReader(wire, int64(5*len(closeWriteTestSendData)/3))
-	_, err := io.Copy(ioutil.Discard, r)
+	_, err := io.Copy(io.Discard, r)
 	noerror(err)
 
 	var errBuf bytes.Buffer
@@ -95,7 +94,7 @@ func (CloseWrite) receiver(wire transport.Wire) {
 	noerror(err)
 
 	// drain wire, as documented in transport.Wire, this is the only way we know the client closed the conn
-	_, err = io.Copy(ioutil.Discard, wire)
+	_, err = io.Copy(io.Discard, wire)
 	if err != nil {
 		// io.Copy masks io.EOF to nil, and we expect io.EOF from the client's Close() call
 		log.Panicf("unexpected error returned from reading conn: %s", err)