Files
VoCat/internal/update/github.go
T
2026-08-09 14:43:34 +08:00

102 lines
3.2 KiB
Go

package update
import (
"context"
"encoding/json"
"fmt"
"io"
"net/http"
"strings"
)
// Release mirrors the subset of the GitHub releases API response that the
// self-updater consumes.
type Release struct {
TagName string `json:"tag_name"`
Name string `json:"name"`
Body string `json:"body"`
Assets []Asset `json:"assets"`
}
// Asset is a single downloadable artifact attached to a release.
type Asset struct {
Name string `json:"name"`
BrowserDownloadURL string `json:"browser_download_url"`
Size int64 `json:"size"`
}
const githubAPI = "https://api.github.com"
// LatestRelease fetches the newest published release for repo (form
// "owner/name"). A non-empty token is sent as a Bearer header, which is
// required for private repositories and lifts the unauthenticated rate limit.
func LatestRelease(ctx context.Context, repo, token string) (*Release, error) {
repo = strings.TrimSpace(repo)
if repo == "" {
return nil, fmt.Errorf("update: repository not configured (set --repo or VOCAT_REPO)")
}
if strings.Count(repo, "/") != 1 {
return nil, fmt.Errorf("update: invalid repository %q (expected owner/name)", repo)
}
req, err := http.NewRequestWithContext(ctx, http.MethodGet, githubAPI+"/repos/"+repo+"/releases/latest", nil)
if err != nil {
return nil, err
}
req.Header.Set("Accept", "application/vnd.github+json")
if token != "" {
req.Header.Set("Authorization", "Bearer "+token)
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
return nil, fmt.Errorf("update: fetch latest release: %w", err)
}
defer resp.Body.Close()
if resp.StatusCode == http.StatusForbidden {
// The releases API returns 403 (not 404) when rate-limited.
body, _ := io.ReadAll(io.LimitReader(resp.Body, 512))
return nil, fmt.Errorf("update: GitHub API rejected the request (likely rate-limited): %s", strings.TrimSpace(string(body)))
}
if resp.StatusCode == http.StatusNotFound {
return nil, fmt.Errorf("update: no published release found for %s", repo)
}
if resp.StatusCode != http.StatusOK {
return nil, fmt.Errorf("update: GitHub API returned %s", resp.Status)
}
var release Release
if err := json.NewDecoder(resp.Body).Decode(&release); err != nil {
return nil, fmt.Errorf("update: decode release JSON: %w", err)
}
return &release, nil
}
// downloadAsset streams a release asset into dst, honoring the request context.
// The token is applied for consistency with the API call (GitHub release assets
// redirect to a pre-signed S3 URL; the token is dropped on redirect, which is
// the expected public-CDN flow).
func downloadAsset(ctx context.Context, url, token string, dst io.Writer) error {
req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
if err != nil {
return err
}
req.Header.Set("Accept", "application/octet-stream")
if token != "" {
req.Header.Set("Authorization", "Bearer "+token)
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
return fmt.Errorf("update: download asset: %w", err)
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return fmt.Errorf("update: asset download returned %s", resp.Status)
}
if _, err := io.Copy(dst, resp.Body); err != nil {
return fmt.Errorf("update: read asset body: %w", err)
}
return nil
}