all: Drop ctxhttp

This package is no longer needed, since we can use the stdlib's
http.NewRequestWithContext.

backend/rclone already did, but it needed a different error check due to
a difference between net/http and ctxhttp.

Also, store the http.Client by value in the REST backend (changed to a
pointer when ctxhttp was introduced) and use errors.WithStack instead
of errors.Wrap where the message was no longer accurate. Errors from
http.NewRequestWithContext will start with "net/http" or "net/url", so
they're easy to identify.

internal/backend/rclone/backend.go

@@ -22,7 +22,6 @@ import (
 	"github.com/restic/restic/internal/backend/rest"
 	"github.com/restic/restic/internal/debug"
 	"github.com/restic/restic/internal/errors"
-	"golang.org/x/net/context/ctxhttp"
 	"golang.org/x/net/http2"
 )
 
@@ -216,7 +215,7 @@ func newBackend(cfg Config, lim limiter.Limiter) (*Backend, error) {
 	}()
 
 	// send an HTTP request to the base URL, see if the server is there
-	client := &http.Client{
+	client := http.Client{
 		Transport: debug.RoundTripper(tr),
 		Timeout:   cfg.Timeout,
 	}
@@ -231,7 +230,7 @@ func newBackend(cfg Config, lim limiter.Limiter) (*Backend, error) {
 	}
 	req.Header.Set("Accept", rest.ContentTypeV2)
 
-	res, err := ctxhttp.Do(ctx, client, req)
+	res, err := client.Do(req)
 	if err != nil {
 		// ignore subsequent errors
 		_ = bg()
@@ -240,7 +239,7 @@ func newBackend(cfg Config, lim limiter.Limiter) (*Backend, error) {
 		// wait for rclone to exit
 		wg.Wait()
 		// try to return the program exit code if communication with rclone has failed
-		if be.waitResult != nil && (err == context.Canceled || errors.Is(err, io.ErrUnexpectedEOF) || errors.Is(err, syscall.EPIPE)) {
+		if be.waitResult != nil && (errors.Is(err, context.Canceled) || errors.Is(err, io.ErrUnexpectedEOF) || errors.Is(err, syscall.EPIPE)) {
 			err = be.waitResult
 		}
 

internal/backend/rest/rest.go

@@ -14,8 +14,6 @@ import (
 	"strconv"
 	"strings"
 
-	"golang.org/x/net/context/ctxhttp"
-
 	"github.com/restic/restic/internal/backend"
 	"github.com/restic/restic/internal/backend/sema"
 	"github.com/restic/restic/internal/debug"
@@ -33,7 +31,7 @@ type Backend struct {
 	url         *url.URL
 	connections uint
 	sem         sema.Semaphore
-	client      *http.Client
+	client      http.Client
 	backend.Layout
 }
 
@@ -45,8 +43,6 @@ const (
 
 // Open opens the REST backend with the given config.
 func Open(cfg Config, rt http.RoundTripper) (*Backend, error) {
-	client := &http.Client{Transport: rt}
-
 	sem, err := sema.New(cfg.Connections)
 	if err != nil {
 		return nil, err
@@ -60,7 +56,7 @@ func Open(cfg Config, rt http.RoundTripper) (*Backend, error) {
 
 	be := &Backend{
 		url:         cfg.URL,
-		client:      client,
+		client:      http.Client{Transport: rt},
 		Layout:      &backend.RESTLayout{URL: url, Join: path.Join},
 		connections: cfg.Connections,
 		sem:         sem,
@@ -138,9 +134,10 @@ func (b *Backend) Save(ctx context.Context, h restic.Handle, rd restic.RewindRea
 	defer cancel()
 
 	// make sure that client.Post() cannot close the reader by wrapping it
-	req, err := http.NewRequest(http.MethodPost, b.Filename(h), ioutil.NopCloser(rd))
+	req, err := http.NewRequestWithContext(ctx,
+		http.MethodPost, b.Filename(h), ioutil.NopCloser(rd))
 	if err != nil {
-		return errors.Wrap(err, "NewRequest")
+		return errors.WithStack(err)
 	}
 	req.Header.Set("Content-Type", "application/octet-stream")
 	req.Header.Set("Accept", ContentTypeV2)
@@ -150,7 +147,7 @@ func (b *Backend) Save(ctx context.Context, h restic.Handle, rd restic.RewindRea
 	req.ContentLength = rd.Length()
 
 	b.sem.GetToken()
-	resp, err := ctxhttp.Do(ctx, b.client, req)
+	resp, err := b.client.Do(req)
 	b.sem.ReleaseToken()
 
 	var cerr error
@@ -160,7 +157,7 @@ func (b *Backend) Save(ctx context.Context, h restic.Handle, rd restic.RewindRea
 	}
 
 	if err != nil {
-		return errors.Wrap(err, "client.Post")
+		return errors.WithStack(err)
 	}
 
 	if resp.StatusCode != 200 {
@@ -269,9 +266,9 @@ func (b *Backend) openReader(ctx context.Context, h restic.Handle, length int, o
 		return nil, errors.Errorf("invalid length %d", length)
 	}
 
-	req, err := http.NewRequest("GET", b.Filename(h), nil)
+	req, err := http.NewRequestWithContext(ctx, "GET", b.Filename(h), nil)
 	if err != nil {
-		return nil, errors.Wrap(err, "http.NewRequest")
+		return nil, errors.WithStack(err)
 	}
 
 	byteRange := fmt.Sprintf("bytes=%d-", offset)
@@ -283,7 +280,7 @@ func (b *Backend) openReader(ctx context.Context, h restic.Handle, length int, o
 	debug.Log("Load(%v) send range %v", h, byteRange)
 
 	b.sem.GetToken()
-	resp, err := ctxhttp.Do(ctx, b.client, req)
+	resp, err := b.client.Do(req)
 	b.sem.ReleaseToken()
 
 	if err != nil {
@@ -321,17 +318,17 @@ func (b *Backend) Stat(ctx context.Context, h restic.Handle) (restic.FileInfo, e
 		return restic.FileInfo{}, backoff.Permanent(err)
 	}
 
-	req, err := http.NewRequest(http.MethodHead, b.Filename(h), nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodHead, b.Filename(h), nil)
 	if err != nil {
-		return restic.FileInfo{}, errors.Wrap(err, "NewRequest")
+		return restic.FileInfo{}, errors.WithStack(err)
 	}
 	req.Header.Set("Accept", ContentTypeV2)
 
 	b.sem.GetToken()
-	resp, err := ctxhttp.Do(ctx, b.client, req)
+	resp, err := b.client.Do(req)
 	b.sem.ReleaseToken()
 	if err != nil {
-		return restic.FileInfo{}, errors.Wrap(err, "client.Head")
+		return restic.FileInfo{}, errors.WithStack(err)
 	}
 
 	_, _ = io.Copy(ioutil.Discard, resp.Body)
@@ -376,14 +373,14 @@ func (b *Backend) Remove(ctx context.Context, h restic.Handle) error {
 		return backoff.Permanent(err)
 	}
 
-	req, err := http.NewRequest("DELETE", b.Filename(h), nil)
+	req, err := http.NewRequestWithContext(ctx, "DELETE", b.Filename(h), nil)
 	if err != nil {
-		return errors.Wrap(err, "http.NewRequest")
+		return errors.WithStack(err)
 	}
 	req.Header.Set("Accept", ContentTypeV2)
 
 	b.sem.GetToken()
-	resp, err := ctxhttp.Do(ctx, b.client, req)
+	resp, err := b.client.Do(req)
 	b.sem.ReleaseToken()
 
 	if err != nil {
@@ -415,14 +412,14 @@ func (b *Backend) List(ctx context.Context, t restic.FileType, fn func(restic.Fi
 		url += "/"
 	}
 
-	req, err := http.NewRequest(http.MethodGet, url, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
 	if err != nil {
-		return errors.Wrap(err, "NewRequest")
+		return errors.WithStack(err)
 	}
 	req.Header.Set("Accept", ContentTypeV2)
 
 	b.sem.GetToken()
-	resp, err := ctxhttp.Do(ctx, b.client, req)
+	resp, err := b.client.Do(req)
 	b.sem.ReleaseToken()
 
 	if err != nil {

internal/selfupdate/github.go

@@ -10,7 +10,6 @@ import (
 	"time"
 
 	"github.com/pkg/errors"
-	"golang.org/x/net/context/ctxhttp"
 )
 
 // Release collects data about a single release on GitHub.
@@ -53,7 +52,7 @@ func GitHubLatestRelease(ctx context.Context, owner, repo string) (Release, erro
 	defer cancel()
 
 	url := fmt.Sprintf("https://api.github.com/repos/%s/%s/releases/latest", owner, repo)
-	req, err := http.NewRequest(http.MethodGet, url, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
 	if err != nil {
 		return Release{}, err
 	}
@@ -61,7 +60,7 @@ func GitHubLatestRelease(ctx context.Context, owner, repo string) (Release, erro
 	// pin API version 3
 	req.Header.Set("Accept", "application/vnd.github.v3+json")
 
-	res, err := ctxhttp.Do(ctx, http.DefaultClient, req)
+	res, err := http.DefaultClient.Do(req)
 	if err != nil {
 		return Release{}, err
 	}
@@ -112,7 +111,7 @@ func GitHubLatestRelease(ctx context.Context, owner, repo string) (Release, erro
 }
 
 func getGithubData(ctx context.Context, url string) ([]byte, error) {
-	req, err := http.NewRequest(http.MethodGet, url, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
 	if err != nil {
 		return nil, err
 	}
@@ -120,7 +119,7 @@ func getGithubData(ctx context.Context, url string) ([]byte, error) {
 	// request binary data
 	req.Header.Set("Accept", "application/octet-stream")
 
-	res, err := ctxhttp.Do(ctx, http.DefaultClient, req)
+	res, err := http.DefaultClient.Do(req)
 	if err != nil {
 		return nil, err
 	}