Use Go 1.13 error wrapping

Migrate from github.com/pkg/errors to fmt.Errorf wrapping with %w.

child.go

@@ -4,8 +4,6 @@ import (
 	"encoding/gob"
 	"fmt"
 	"os"
-
-	"github.com/pkg/errors"
 )
 
 type child struct {
@@ -22,14 +20,14 @@ func startChild(env *env, passedFiles map[fileName]*file) (*child, error) {
 	// readyW is passed to the child, readyR stays with the parent
 	readyR, readyW, err := os.Pipe()
 	if err != nil {
-		return nil, errors.Wrap(err, "pipe failed")
+		return nil, fmt.Errorf("pipe failed: %s", err)
 	}
 
 	namesR, namesW, err := os.Pipe()
 	if err != nil {
 		readyR.Close()
 		readyW.Close()
-		return nil, errors.Wrap(err, "pipe failed")
+		return nil, fmt.Errorf("pipe failed: %s", err)
 	}
 
 	// Copy passed fds and append the notification pipe
@@ -53,7 +51,7 @@ func startChild(env *env, passedFiles map[fileName]*file) (*child, error) {
 		readyW.Close()
 		namesR.Close()
 		namesW.Close()
-		return nil, errors.Wrapf(err, "can't start process %s", os.Args[0])
+		return nil, fmt.Errorf("can't start process %s: %s", os.Args[0], err)
 	}
 
 	exited := make(chan struct{})

dup_fd.go

@@ -3,15 +3,14 @@
 package tableflip
 
 import (
+	"fmt"
 	"syscall"
-
-	"github.com/pkg/errors"
 )
 
 func dupFd(fd uintptr, name fileName) (*file, error) {
 	dupfd, _, errno := syscall.Syscall(syscall.SYS_FCNTL, fd, syscall.F_DUPFD_CLOEXEC, 0)
 	if errno != 0 {
-		return nil, errors.Wrap(errno, "can't dup fd using fcntl")
+		return nil, fmt.Errorf("can't dup fd using fcntl: %s", errno)
 	}
 
 	return newFile(dupfd, name), nil

fds.go

@@ -1,14 +1,13 @@
 package tableflip
 
 import (
+	"fmt"
 	"net"
 	"os"
 	"runtime"
 	"strings"
 	"sync"
 	"syscall"
-
-	"github.com/pkg/errors"
 )
 
 // Listener can be shared between processes.
@@ -94,12 +93,12 @@ func (f *Fds) Listen(network, addr string) (net.Listener, error) {
 
 	ln, err = net.Listen(network, addr)
 	if err != nil {
-		return nil, errors.Wrap(err, "can't create new listener")
+		return nil, fmt.Errorf("can't create new listener: %s", err)
 	}
 
 	if _, ok := ln.(Listener); !ok {
 		ln.Close()
-		return nil, errors.Errorf("%T doesn't implement tableflip.Listener", ln)
+		return nil, fmt.Errorf("%T doesn't implement tableflip.Listener", ln)
 	}
 
 	err = f.addListenerLocked(network, addr, ln.(Listener))
@@ -130,7 +129,7 @@ func (f *Fds) listenerLocked(network, addr string) (net.Listener, error) {
 
 	ln, err := net.FileListener(file.File)
 	if err != nil {
-		return nil, errors.Wrapf(err, "can't inherit listener %s %s", network, addr)
+		return nil, fmt.Errorf("can't inherit listener %s %s: %s", network, addr, err)
 	}
 
 	delete(f.inherited, key)
@@ -176,7 +175,7 @@ func (f *Fds) Conn(network, addr string) (net.Conn, error) {
 
 	conn, err := net.FileConn(file.File)
 	if err != nil {
-		return nil, errors.Wrapf(err, "can't inherit connection %s %s", network, addr)
+		return nil, fmt.Errorf("can't inherit connection %s %s: %s", network, addr, err)
 	}
 
 	delete(f.inherited, key)
@@ -198,7 +197,7 @@ func (f *Fds) addConnLocked(kind, network, addr string, conn syscall.Conn) error
 	key := fileName{kind, network, addr}
 	file, err := dupConn(conn, key)
 	if err != nil {
-		return errors.Wrapf(err, "can't dup %s (%s %s)", kind, network, addr)
+		return fmt.Errorf("can't dup %s (%s %s): %s", kind, network, addr, err)
 	}
 
 	delete(f.inherited, key)
@@ -336,7 +335,7 @@ func dupConn(conn syscall.Conn, name fileName) (*file, error) {
 		dup, duperr = dupFd(fd, name)
 	})
 	if err != nil {
-		return nil, errors.Wrap(err, "can't access fd")
+		return nil, fmt.Errorf("can't access fd: %s", err)
 	}
 	return dup, duperr
 }

go.mod

@@ -1,5 +1,3 @@
 module github.com/cloudflare/tableflip
 
 go 1.13
-
-require github.com/pkg/errors v0.9.1

go.sum

@@ -1,2 +0,0 @@
-github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
-github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=

parent.go

@@ -2,11 +2,11 @@ package tableflip
 
 import (
 	"encoding/gob"
+	"errors"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
-
-	"github.com/pkg/errors"
 )
 
 const (
@@ -31,7 +31,7 @@ func newParent(env *env) (*parent, map[fileName]*file, error) {
 	var names [][]string
 	dec := gob.NewDecoder(rd)
 	if err := dec.Decode(&names); err != nil {
-		return nil, nil, errors.Wrap(err, "can't decode names from parent process")
+		return nil, nil, fmt.Errorf("can't decode names from parent process: %s", err)
 	}
 
 	files := make(map[fileName]*file)
@@ -58,7 +58,7 @@ func newParent(env *env) (*parent, map[fileName]*file, error) {
 		if n != 0 {
 			err = errors.New("unexpected data from parent process")
 		} else if err != nil {
-			err = errors.Wrap(err, "unexpected error while waiting for parent to exit")
+			err = fmt.Errorf("unexpected error while waiting for parent to exit: %s", err)
 		}
 		result <- err
 		close(exited)
@@ -74,7 +74,7 @@ func newParent(env *env) (*parent, map[fileName]*file, error) {
 func (ps *parent) sendReady() error {
 	defer ps.wr.Close()
 	if _, err := ps.wr.Write([]byte{notifyReady}); err != nil {
-		return errors.Wrap(err, "can't notify parent process")
+		return fmt.Errorf("can't notify parent process: %s", err)
 	}
 	return nil
 }

upgrader.go

@@ -2,15 +2,15 @@ package tableflip
 
 import (
 	"context"
+	"errors"
+	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
 	"strconv"
 	"sync"
 	"time"
-
-	"github.com/pkg/errors"
 )
 
 // DefaultUpgradeTimeout is the duration before the Upgrader kills the new process if no
@@ -52,13 +52,13 @@ var ErrNotSupported = errors.New("tableflip: platform does not support graceful
 
 // New creates a new Upgrader. Files are passed from the parent and may be empty.
 //
-// Only the first call to this function will succeed.
+// Only the first call to this function will succeed. May return ErrNotSupported.
 func New(opts Options) (upg *Upgrader, err error) {
 	stdEnvMu.Lock()
 	defer stdEnvMu.Unlock()
 
 	if !isSupportedOS() {
-		return nil, ErrNotSupported
+		return nil, fmt.Errorf("%w", ErrNotSupported)
 	}
 
 	if stdEnvUpgrader != nil {
@@ -116,7 +116,7 @@ func (u *Upgrader) Ready() error {
 
 	if u.opts.PIDFile != "" {
 		if err := writePIDFile(u.opts.PIDFile); err != nil {
-			return errors.Wrap(err, "tableflip: can't write PID file")
+			return fmt.Errorf("tableflip: can't write PID file: %s", err)
 		}
 	}
 
@@ -244,7 +244,7 @@ func (u *Upgrader) run() {
 func (u *Upgrader) doUpgrade() (*os.File, error) {
 	child, err := startChild(u.env, u.Fds.copy())
 	if err != nil {
-		return nil, errors.Wrap(err, "can't start child")
+		return nil, fmt.Errorf("can't start child: %s", err)
 	}
 
 	readyTimeout := time.After(u.opts.UpgradeTimeout)
@@ -255,17 +255,17 @@ func (u *Upgrader) doUpgrade() (*os.File, error) {
 
 		case err := <-child.result:
 			if err == nil {
-				return nil, errors.Errorf("child %s exited", child)
+				return nil, fmt.Errorf("child %s exited", child)
 			}
-			return nil, errors.Wrapf(err, "child %s exited", child)
+			return nil, fmt.Errorf("child %s exited: %s", child, err)
 
 		case <-u.stopC:
 			child.Kill()
 			return nil, errors.New("terminating")
 
 		case <-readyTimeout:
 			child.Kill()
-			return nil, errors.Errorf("new child %s timed out", child)
+			return nil, fmt.Errorf("new child %s timed out", child)
 
 		case file := <-child.ready:
 			return file, nil