restic/internal/selfupdate/github.go

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package selfupdate
import (
"context"
"encoding/json"
"fmt"
"io"
"net/http"
"strings"
"time"
"github.com/pkg/errors"
)
// Release collects data about a single release on GitHub.
type Release struct {
Name string `json:"name"`
TagName string `json:"tag_name"`
Draft bool `json:"draft"`
PreRelease bool `json:"prerelease"`
PublishedAt time.Time `json:"published_at"`
Assets []Asset `json:"assets"`
Version string `json:"-"` // set manually in the code
}
// Asset is a file uploaded and attached to a release.
type Asset struct {
ID int `json:"id"`
Name string `json:"name"`
URL string `json:"url"`
}
func (r Release) String() string {
return fmt.Sprintf("%v %v, %d assets",
r.TagName,
r.PublishedAt.Local().Format("2006-01-02 15:04:05"),
len(r.Assets))
}
const githubAPITimeout = 30 * time.Second
// githubError is returned by the GitHub API, e.g. for rate-limiting.
type githubError struct {
Message string
}
// GitHubLatestRelease uses the GitHub API to get information about the latest
// release of a repository.
func GitHubLatestRelease(ctx context.Context, owner, repo string) (Release, error) {
ctx, cancel := context.WithTimeout(ctx, githubAPITimeout)
defer cancel()
url := fmt.Sprintf("https://api.github.com/repos/%s/%s/releases/latest", owner, repo)
req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
if err != nil {
return Release{}, err
}
// pin API version 3
req.Header.Set("Accept", "application/vnd.github.v3+json")
res, err := http.DefaultClient.Do(req)
if err != nil {
return Release{}, err
}
if res.StatusCode != http.StatusOK {
content := res.Header.Get("Content-Type")
if strings.Contains(content, "application/json") {
// try to decode error message
var msg githubError
jerr := json.NewDecoder(res.Body).Decode(&msg)
if jerr == nil {
return Release{}, fmt.Errorf("unexpected status %v (%v) returned, message:\n %v", res.StatusCode, res.Status, msg.Message)
}
}
_ = res.Body.Close()
return Release{}, fmt.Errorf("unexpected status %v (%v) returned", res.StatusCode, res.Status)
}
buf, err := io.ReadAll(res.Body)
if err != nil {
_ = res.Body.Close()
return Release{}, err
}
err = res.Body.Close()
if err != nil {
return Release{}, err
}
var release Release
err = json.Unmarshal(buf, &release)
if err != nil {
return Release{}, err
}
if release.TagName == "" {
return Release{}, errors.New("tag name for latest release is empty")
}
if !strings.HasPrefix(release.TagName, "v") {
return Release{}, errors.Errorf("tag name %q is invalid, does not start with 'v'", release.TagName)
}
release.Version = release.TagName[1:]
return release, nil
}
func getGithubData(ctx context.Context, url string) ([]byte, error) {
req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
if err != nil {
return nil, err
}
// request binary data
req.Header.Set("Accept", "application/octet-stream")
res, err := http.DefaultClient.Do(req)
if err != nil {
return nil, err
}
if res.StatusCode != http.StatusOK {
return nil, fmt.Errorf("unexpected status %v (%v) returned", res.StatusCode, res.Status)
}
buf, err := io.ReadAll(res.Body)
if err != nil {
_ = res.Body.Close()
return nil, err
}
err = res.Body.Close()
if err != nil {
return nil, err
}
return buf, nil
}
func getGithubDataFile(ctx context.Context, assets []Asset, suffix string, printf func(string, ...interface{})) (filename string, data []byte, err error) {
var url string
for _, a := range assets {
if strings.HasSuffix(a.Name, suffix) {
url = a.URL
filename = a.Name
break
}
}
if url == "" {
return "", nil, fmt.Errorf("unable to find file with suffix %v", suffix)
}
printf("download %v\n", filename)
data, err = getGithubData(ctx, url)
if err != nil {
return "", nil, err
}
return filename, data, nil
}