| 1 | package cdp |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "context" |
| 6 | "fmt" |
| 7 | "os" |
| 8 | "os/exec" |
| 9 | "path/filepath" |
| 10 | "runtime" |
| 11 | "strings" |
| 12 | "sync" |
| 13 | "time" |
| 14 | |
| 15 | "reasonix/internal/proc" |
| 16 | ) |
| 17 | |
| 18 | // activePortFile is where Chrome records the port it actually bound, which is |
| 19 | // the only reliable answer when the launcher asks for port 0. |
| 20 | const activePortFile = "DevToolsActivePort" |
| 21 | |
| 22 | // launched is one Chrome this package started and therefore must reap. |
| 23 | type launched struct { |
| 24 | cmd *exec.Cmd |
| 25 | handle uintptr |
| 26 | dir string |
| 27 | owned bool |
| 28 | |
| 29 | once sync.Once |
| 30 | } |
| 31 | |
| 32 | // baseArgs keeps a launched Chrome out of the user's profile and away from the |
| 33 | // background services that make a first run slow and chatty. |
| 34 | func baseArgs(userDataDir string, headless bool) []string { |
| 35 | args := []string{ |
| 36 | "--remote-debugging-port=0", |
| 37 | "--user-data-dir=" + userDataDir, |
| 38 | "--no-first-run", |
| 39 | "--no-default-browser-check", |
| 40 | "--disable-background-networking", |
| 41 | "--disable-backgrounding-occluded-windows", |
| 42 | "--disable-renderer-backgrounding", |
| 43 | "--disable-features=Translate,MediaRouter", |
| 44 | "--password-store=basic", |
| 45 | "--window-size=1280,900", |
| 46 | } |
| 47 | if runtime.GOOS == "darwin" { |
| 48 | args = append(args, "--use-mock-keychain") |
| 49 | } |
| 50 | if headless { |
| 51 | args = append(args, "--headless=new", "--hide-scrollbars") |
| 52 | } |
| 53 | return args |
| 54 | } |
| 55 | |
| 56 | // launchChrome starts a browser and returns it with its DevTools socket URL. |
| 57 | func launchChrome(ctx context.Context, opts Options) (*launched, string, error) { |
| 58 | bin, err := chromePath(opts.ChromePath) |
| 59 | if err != nil { |
| 60 | return nil, "", err |
| 61 | } |
| 62 | dir, owned, err := userDataDir(opts.UserDataDir) |
| 63 | if err != nil { |
| 64 | return nil, "", err |
| 65 | } |
| 66 | args := append(baseArgs(dir, opts.Headless), opts.ChromeArgs...) |
| 67 | cmd := proc.CommandContext(ctx, bin, append(args, "about:blank")...) |
| 68 | var errBuf bytes.Buffer |
| 69 | cmd.Stderr = &boundedWriter{buf: &errBuf, limit: 8 << 10} |
| 70 | handle, err := proc.StartTracked(cmd) |
| 71 | if err != nil { |
| 72 | cleanupDir(dir, owned) |
| 73 | return nil, "", fmt.Errorf("cdp: start %s: %w", bin, err) |
| 74 | } |
| 75 | l := &launched{cmd: cmd, handle: handle, dir: dir, owned: owned} |
| 76 | wsURL, err := readActivePort(ctx, dir, opts.LaunchTimeout) |
| 77 | if err != nil { |
| 78 | l.stop() |
| 79 | if detail := strings.TrimSpace(errBuf.String()); detail != "" { |
| 80 | return nil, "", fmt.Errorf("%w: %s", err, lastLine(detail)) |
| 81 | } |
| 82 | return nil, "", err |
| 83 | } |
| 84 | return l, wsURL, nil |
| 85 | } |
| 86 | |
| 87 | // stop kills the browser tree and drops a user-data directory this package |
| 88 | // created. A directory the caller supplied is left alone: it is their profile. |
| 89 | func (l *launched) stop() { |
| 90 | l.once.Do(func() { |
| 91 | proc.KillTracked(l.cmd, l.handle) |
| 92 | _ = l.cmd.Wait() |
| 93 | proc.FinishTracked(l.handle) |
| 94 | cleanupDir(l.dir, l.owned) |
| 95 | }) |
| 96 | } |
| 97 | |
| 98 | func cleanupDir(dir string, owned bool) { |
| 99 | if owned && dir != "" { |
| 100 | _ = os.RemoveAll(dir) |
| 101 | } |
| 102 | } |
| 103 | |
| 104 | func userDataDir(configured string) (string, bool, error) { |
| 105 | if dir := strings.TrimSpace(configured); dir != "" { |
| 106 | if err := os.MkdirAll(dir, 0o700); err != nil { |
| 107 | return "", false, fmt.Errorf("cdp: user data dir %s: %w", dir, err) |
| 108 | } |
| 109 | return dir, false, nil |
| 110 | } |
| 111 | dir, err := os.MkdirTemp("", "reasonix-chrome-") |
| 112 | if err != nil { |
| 113 | return "", false, fmt.Errorf("cdp: temporary user data dir: %w", err) |
| 114 | } |
| 115 | return dir, true, nil |
| 116 | } |
| 117 | |
| 118 | // readActivePort waits for Chrome to publish its bound port and socket path. |
| 119 | func readActivePort(ctx context.Context, dir string, timeout time.Duration) (string, error) { |
| 120 | if timeout <= 0 { |
| 121 | timeout = 30 * time.Second |
| 122 | } |
| 123 | deadline, cancel := context.WithTimeout(ctx, timeout) |
| 124 | defer cancel() |
| 125 | path := filepath.Join(dir, activePortFile) |
| 126 | for { |
| 127 | data, err := os.ReadFile(path) |
| 128 | if err == nil { |
| 129 | lines := strings.Split(strings.TrimSpace(string(data)), "\n") |
| 130 | if len(lines) >= 2 && strings.TrimSpace(lines[0]) != "" { |
| 131 | return fmt.Sprintf("ws://127.0.0.1:%s%s", strings.TrimSpace(lines[0]), strings.TrimSpace(lines[1])), nil |
| 132 | } |
| 133 | } |
| 134 | select { |
| 135 | case <-deadline.Done(): |
| 136 | return "", fmt.Errorf("cdp: browser did not write %s within %s", activePortFile, timeout) |
| 137 | case <-time.After(50 * time.Millisecond): |
| 138 | } |
| 139 | } |
| 140 | } |
| 141 | |
| 142 | // chromePath resolves the browser binary: the configured path first, then the |
| 143 | // usual install locations for Chrome, Chromium, and Chromium-based Edge. |
| 144 | func chromePath(configured string) (string, error) { |
| 145 | if p := strings.TrimSpace(configured); p != "" { |
| 146 | if _, err := os.Stat(p); err != nil { |
| 147 | return "", fmt.Errorf("cdp: chrome_path %s: %w", p, err) |
| 148 | } |
| 149 | return p, nil |
| 150 | } |
| 151 | for _, env := range []string{"REASONIX_CHROME", "CHROME_PATH"} { |
| 152 | if p := strings.TrimSpace(os.Getenv(env)); p != "" { |
| 153 | if _, err := os.Stat(p); err == nil { |
| 154 | return p, nil |
| 155 | } |
| 156 | } |
| 157 | } |
| 158 | for _, candidate := range chromeCandidates() { |
| 159 | if candidate == "" { |
| 160 | continue |
| 161 | } |
| 162 | if strings.ContainsRune(candidate, os.PathSeparator) { |
| 163 | if info, err := os.Stat(candidate); err == nil && !info.IsDir() { |
| 164 | return candidate, nil |
| 165 | } |
| 166 | continue |
| 167 | } |
| 168 | if p, err := exec.LookPath(candidate); err == nil { |
| 169 | return p, nil |
| 170 | } |
| 171 | } |
| 172 | return "", fmt.Errorf("cdp: no Chrome, Chromium, or Edge binary found; set browser.chrome_path or REASONIX_CHROME") |
| 173 | } |
| 174 | |
| 175 | func chromeCandidates() []string { |
| 176 | switch runtime.GOOS { |
| 177 | case "darwin": |
| 178 | home, _ := os.UserHomeDir() |
| 179 | return []string{ |
| 180 | "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome", |
| 181 | filepath.Join(home, "Applications/Google Chrome.app/Contents/MacOS/Google Chrome"), |
| 182 | "/Applications/Chromium.app/Contents/MacOS/Chromium", |
| 183 | "/Applications/Microsoft Edge.app/Contents/MacOS/Microsoft Edge", |
| 184 | } |
| 185 | case "windows": |
| 186 | var out []string |
| 187 | for _, env := range []string{"ProgramFiles", "ProgramFiles(x86)", "LocalAppData"} { |
| 188 | root := os.Getenv(env) |
| 189 | if root == "" { |
| 190 | continue |
| 191 | } |
| 192 | out = append(out, |
| 193 | filepath.Join(root, `Google\Chrome\Application\chrome.exe`), |
| 194 | filepath.Join(root, `Microsoft\Edge\Application\msedge.exe`)) |
| 195 | } |
| 196 | return out |
| 197 | default: |
| 198 | return []string{"google-chrome", "google-chrome-stable", "chromium", "chromium-browser", "microsoft-edge"} |
| 199 | } |
| 200 | } |
| 201 | |
| 202 | // boundedWriter keeps only the first limit bytes of a child's stderr so a |
| 203 | // noisy browser cannot grow the parent's memory. |
| 204 | type boundedWriter struct { |
| 205 | buf *bytes.Buffer |
| 206 | limit int |
| 207 | } |
| 208 | |
| 209 | func (w *boundedWriter) Write(p []byte) (int, error) { |
| 210 | if room := w.limit - w.buf.Len(); room > 0 { |
| 211 | if len(p) < room { |
| 212 | room = len(p) |
| 213 | } |
| 214 | w.buf.Write(p[:room]) |
| 215 | } |
| 216 | return len(p), nil |
| 217 | } |
| 218 | |
| 219 | func lastLine(s string) string { |
| 220 | lines := strings.Split(strings.TrimSpace(s), "\n") |
| 221 | return strings.TrimSpace(lines[len(lines)-1]) |
| 222 | } |
| 223 |