feat: add updater package for in-place self-update

internal/updater/apply.go

@@ -0,0 +1,208 @@
+package updater
+
+import (
+	"bufio"
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+
+	"github.com/mathismqn/godeez/internal/buildinfo"
+	"github.com/mathismqn/godeez/internal/fileutil"
+)
+
+var managedPrefixes = []string{
+	"/nix/store",
+	"/opt/homebrew",
+	"/usr/local/Cellar",
+	"/home/linuxbrew",
+	"/snap",
+	"/var/lib/flatpak",
+}
+
+func resolveTarget() (string, error) {
+	if buildinfo.IsDev() {
+		return "", fmt.Errorf("development build cannot self-update. Install a release from https://github.com/%s/%s/releases",
+			repoOwner, repoName)
+	}
+
+	exe, err := os.Executable()
+	if err != nil {
+		return "", fmt.Errorf("failed to locate the running binary: %w", err)
+	}
+
+	target := exe
+	if resolved, err := filepath.EvalSymlinks(exe); err == nil {
+		target = resolved
+	}
+
+	for _, prefix := range managedPrefixes {
+		if strings.HasPrefix(target, prefix) {
+			return "", fmt.Errorf("%s was installed by a package manager. Update it with that instead", target)
+		}
+	}
+
+	return target, nil
+}
+
+func CheckUpdatable() error {
+	_, err := resolveTarget()
+
+	return err
+}
+
+func checkWritable(dir string) error {
+	f, err := os.CreateTemp(dir, tmpPattern)
+	if err != nil {
+		hint := "Re-run with sudo"
+		if runtime.GOOS == "windows" {
+			hint = "Re-run from an elevated prompt"
+		}
+
+		return fmt.Errorf("cannot write to %s: %w. %s", dir, err, hint)
+	}
+
+	name := f.Name()
+	f.Close()
+	os.Remove(name)
+
+	return nil
+}
+
+func (u *Updater) Apply(ctx context.Context, release *Release) error {
+	target, err := resolveTarget()
+	if err != nil {
+		return err
+	}
+
+	dir := filepath.Dir(target)
+	if err := checkWritable(dir); err != nil {
+		return err
+	}
+
+	asset, err := release.assetForRuntime()
+	if err != nil {
+		return err
+	}
+
+	want, err := u.fetchChecksum(ctx, release, asset.Name)
+	if err != nil {
+		return err
+	}
+
+	u.step("Downloading %s", asset.Name)
+	tmp, sum, err := u.download(ctx, dir, asset)
+	if err != nil {
+		return err
+	}
+	defer fileutil.DeleteFile(tmp)
+
+	u.step("Verifying checksum")
+	if sum != want {
+		return fmt.Errorf("checksum mismatch for %s: expected %s, got %s", asset.Name, want, sum)
+	}
+
+	if err := os.Chmod(tmp, 0755); err != nil {
+		return err
+	}
+
+	u.step("Replacing %s", target)
+
+	return replaceBinary(target, tmp)
+}
+
+func (u *Updater) fetchChecksum(ctx context.Context, release *Release, assetName string) (string, error) {
+	asset, ok := release.asset(checksumsAsset)
+	if !ok {
+		return "", fmt.Errorf("release %s does not publish %s", release.TagName, checksumsAsset)
+	}
+
+	ctx, cancel := context.WithTimeout(ctx, apiTimeout)
+	defer cancel()
+
+	body, err := u.get(ctx, asset.URL, nil)
+	if err != nil {
+		return "", err
+	}
+	defer body.Close()
+
+	return parseChecksums(io.LimitReader(body, maxResponseSize), assetName)
+}
+
+func parseChecksums(r io.Reader, name string) (string, error) {
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		fields := strings.Fields(scanner.Text())
+		if len(fields) != 2 {
+			continue
+		}
+		if strings.TrimPrefix(fields[1], "*") == name {
+			return strings.ToLower(fields[0]), nil
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		return "", err
+	}
+
+	return "", fmt.Errorf("no checksum listed for %s", name)
+}
+
+func (u *Updater) download(ctx context.Context, dir string, asset Asset) (string, string, error) {
+	body, err := u.get(ctx, asset.URL, nil)
+	if err != nil {
+		return "", "", err
+	}
+	defer body.Close()
+
+	f, err := os.CreateTemp(dir, tmpPattern)
+	if err != nil {
+		return "", "", err
+	}
+	tmp := f.Name()
+
+	hash := sha256.New()
+	if _, err := io.Copy(io.MultiWriter(f, hash), body); err != nil {
+		f.Close()
+		fileutil.DeleteFile(tmp)
+
+		return "", "", fmt.Errorf("failed to download %s: %w", asset.Name, err)
+	}
+	if err := f.Close(); err != nil {
+		fileutil.DeleteFile(tmp)
+
+		return "", "", err
+	}
+
+	return tmp, hex.EncodeToString(hash.Sum(nil)), nil
+}
+
+func replaceBinary(target, tmp string) error {
+	if runtime.GOOS != "windows" {
+		return os.Rename(tmp, target)
+	}
+
+	old := target + ".old"
+	os.Remove(old)
+
+	if err := os.Rename(target, old); err != nil {
+		return fmt.Errorf("failed to move the current binary aside: %w", err)
+	}
+
+	if err := os.Rename(tmp, target); err != nil {
+		if rollbackErr := os.Rename(old, target); rollbackErr != nil {
+			return fmt.Errorf("failed to install the new binary: %w. The previous one could not be restored from %s: %v",
+				err, old, rollbackErr)
+		}
+
+		return fmt.Errorf("failed to install the new binary: %w", err)
+	}
+
+	os.Remove(old)
+
+	return nil
+}

internal/updater/check.go

@@ -0,0 +1,118 @@
+package updater
+
+import (
+	"context"
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/mathismqn/godeez/internal/buildinfo"
+	"github.com/mathismqn/godeez/internal/fileutil"
+)
+
+const noCheckEnv = "GODEEZ_NO_UPDATE_CHECK"
+
+const (
+	cacheTTL     = 24 * time.Hour
+	checkTimeout = 3 * time.Second
+)
+
+type cacheEntry struct {
+	CheckedAt     time.Time `json:"checked_at"`
+	LatestVersion string    `json:"latest_version"`
+}
+
+func cachePath() (string, error) {
+	dir, err := os.UserCacheDir()
+	if err != nil {
+		return "", err
+	}
+
+	return filepath.Join(dir, "godeez", "update.json"), nil
+}
+
+func readCache() (cacheEntry, bool) {
+	path, err := cachePath()
+	if err != nil {
+		return cacheEntry{}, false
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return cacheEntry{}, false
+	}
+
+	var entry cacheEntry
+	if err := json.Unmarshal(data, &entry); err != nil {
+		return cacheEntry{}, false
+	}
+	if entry.LatestVersion == "" || time.Since(entry.CheckedAt) > cacheTTL {
+		return cacheEntry{}, false
+	}
+
+	return entry, true
+}
+
+func writeCache(version string) error {
+	path, err := cachePath()
+	if err != nil {
+		return err
+	}
+	if err := fileutil.EnsureDir(filepath.Dir(path)); err != nil {
+		return err
+	}
+
+	data, err := json.Marshal(cacheEntry{CheckedAt: time.Now(), LatestVersion: version})
+	if err != nil {
+		return err
+	}
+
+	return os.WriteFile(path, data, 0644)
+}
+
+func check(ctx context.Context) (string, error) {
+	if entry, ok := readCache(); ok {
+		return newerThanCurrent(entry.LatestVersion), nil
+	}
+
+	release, err := New().Latest(ctx)
+	if err != nil {
+		return "", err
+	}
+
+	latest := release.Version()
+	_ = writeCache(latest)
+
+	return newerThanCurrent(latest), nil
+}
+
+func newerThanCurrent(latest string) string {
+	if IsNewer(buildinfo.Version(), latest) {
+		return latest
+	}
+
+	return ""
+}
+
+func StartCheck(ctx context.Context) <-chan string {
+	ch := make(chan string, 1)
+
+	if os.Getenv(noCheckEnv) != "" || buildinfo.IsDev() {
+		close(ch)
+		return ch
+	}
+
+	go func() {
+		defer close(ch)
+
+		ctx, cancel := context.WithTimeout(ctx, checkTimeout)
+		defer cancel()
+
+		if latest, err := check(ctx); err == nil && latest != "" {
+			ch <- latest
+		}
+	}()
+
+	return ch
+}

internal/updater/release.go

@@ -0,0 +1,82 @@
+package updater
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"runtime"
+)
+
+const (
+	repoOwner        = "mathismqn"
+	repoName         = "godeez"
+	latestReleaseURL = "https://api.github.com/repos/" + repoOwner + "/" + repoName + "/releases/latest"
+	checksumsAsset   = "checksums.txt"
+	maxResponseSize  = 1 << 20
+)
+
+var githubAPIHeaders = map[string]string{
+	"Accept":               "application/vnd.github+json",
+	"X-GitHub-Api-Version": "2022-11-28",
+}
+
+type Release struct {
+	TagName string  `json:"tag_name"`
+	Assets  []Asset `json:"assets"`
+}
+
+type Asset struct {
+	Name string `json:"name"`
+	URL  string `json:"browser_download_url"`
+}
+
+func (u *Updater) Latest(ctx context.Context) (*Release, error) {
+	ctx, cancel := context.WithTimeout(ctx, apiTimeout)
+	defer cancel()
+
+	body, err := u.get(ctx, latestReleaseURL, githubAPIHeaders)
+	if err != nil {
+		return nil, err
+	}
+	defer body.Close()
+
+	var release Release
+	if err := json.NewDecoder(io.LimitReader(body, maxResponseSize)).Decode(&release); err != nil {
+		return nil, fmt.Errorf("failed to decode release: %w", err)
+	}
+	if release.TagName == "" {
+		return nil, fmt.Errorf("release has no tag name")
+	}
+
+	return &release, nil
+}
+
+func (r *Release) Version() string {
+	return trimV(r.TagName)
+}
+
+func (r *Release) asset(name string) (Asset, bool) {
+	for _, a := range r.Assets {
+		if a.Name == name {
+			return a, true
+		}
+	}
+
+	return Asset{}, false
+}
+
+func (r *Release) assetForRuntime() (Asset, error) {
+	name := fmt.Sprintf("%s_%s_%s_%s", repoName, r.Version(), runtime.GOOS, runtime.GOARCH)
+	if runtime.GOOS == "windows" {
+		name += ".exe"
+	}
+
+	asset, ok := r.asset(name)
+	if !ok {
+		return Asset{}, fmt.Errorf("release %s has no binary for %s/%s (expected %s)",
+			r.TagName, runtime.GOOS, runtime.GOARCH, name)
+	}
+
+	return asset, nil
+}

internal/updater/updater.go

@@ -0,0 +1,55 @@
+package updater
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"github.com/mathismqn/godeez/internal/buildinfo"
+)
+
+const (
+	apiTimeout = 30 * time.Second
+	tmpPattern = ".godeez-update-*"
+)
+
+type Updater struct {
+	client *http.Client
+	Out    io.Writer
+}
+
+func New() *Updater {
+	return &Updater{
+		client: &http.Client{},
+		Out:    io.Discard,
+	}
+}
+
+func (u *Updater) step(format string, args ...any) {
+	fmt.Fprintf(u.Out, format+"...\n", args...)
+}
+
+func (u *Updater) get(ctx context.Context, url string, headers map[string]string) (io.ReadCloser, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("User-Agent", buildinfo.UserAgent())
+	for name, value := range headers {
+		req.Header.Set(name, value)
+	}
+
+	resp, err := u.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode != http.StatusOK {
+		resp.Body.Close()
+
+		return nil, fmt.Errorf("unexpected status code %d from %s", resp.StatusCode, url)
+	}
+
+	return resp.Body, nil
+}

internal/updater/version.go

@@ -0,0 +1,35 @@
+package updater
+
+import (
+	"strings"
+
+	"golang.org/x/mod/semver"
+)
+
+func trimV(v string) string {
+	return strings.TrimPrefix(strings.TrimSpace(v), "v")
+}
+
+func canonical(v string) string {
+	v = strings.TrimSpace(v)
+	if v == "" {
+		return ""
+	}
+	if !strings.HasPrefix(v, "v") {
+		v = "v" + v
+	}
+	if !semver.IsValid(v) {
+		return ""
+	}
+
+	return v
+}
+
+func IsNewer(current, latest string) bool {
+	c, l := canonical(current), canonical(latest)
+	if c == "" || l == "" {
+		return false
+	}
+
+	return semver.Compare(l, c) > 0
+}