ssh-copy-id
+ bgo mode delegates uploads to the internal bgo scp client, + which handles authentication itself. Install bgo and add it to your + PATH first — see the + setup guide. + Note: bgo cannot create remote directories, so screenshots are saved + flat into the remote home directory (the Remote path setting is ignored). +
bgo scp
PATH
scp +// 这样既不引入额外的 PTY 依赖, 又满足 bgo 的运行约束. +// - bgo scp 不会自动创建远程目录, 且 bgo ssh 无法执行远程命令 (会 panic), +// 所以无法像 Kerberos 那样先 `mkdir -p`. 故 bgo 模式只能把文件平铺上传 +// 到远端用户的 $HOME 根目录 (文件名内嵌时间戳保证唯一), 上层 service +// 负责生成扁平文件名. +// - bgo 自带鉴权, 不需要也不应传 GSSAPI / 密码 / 公钥相关的 ssh 选项. +package ssh + +import ( + "bytes" + "context" + "fmt" + "os" + "os/exec" + "path" + "path/filepath" + "strconv" + "strings" + "time" + + "github.com/mmmy/snapgo/internal/domain" +) + +// systemScriptPath is the absolute path to the macOS BSD `script` utility, +// which we use purely to allocate a PTY for bgo. Absolute path avoids PATH +// hijacking and the minimal PATH GUI apps inherit on macOS. +const systemScriptPath = "/usr/bin/script" + +// bgoSearchPaths lists the locations we probe for the bgo binary when it is +// not already resolvable via $PATH. GUI apps on macOS launch with a minimal +// PATH that usually omits ~/.local/bin and Homebrew dirs, so we look there +// explicitly rather than failing with a confusing "command not found". +func bgoSearchPaths() []string { + home, _ := os.UserHomeDir() + return []string{ + filepath.Join(home, ".local", "bin", "bgo"), + "/usr/local/bin/bgo", + "/opt/homebrew/bin/bgo", + "/opt/bin/bgo", + } +} + +// BgoUploader satisfies application.SSHUploader by shelling out to `bgo scp` +// under a PTY allocated via the system `script` utility. +type BgoUploader struct { + cfg domain.SSHConfig +} + +// NewBgoUploader returns an uploader that delegates to the bgo client. +func NewBgoUploader(cfg domain.SSHConfig) *BgoUploader { + return &BgoUploader{cfg: cfg} +} + +// resolveBgoBinary locates the bgo executable, first via $PATH and then via +// the well-known install locations. Returns a clear error pointing the user +// to the setup guide when bgo cannot be found. +func resolveBgoBinary() (string, error) { + if p, err := exec.LookPath("bgo"); err == nil { + return p, nil + } + for _, candidate := range bgoSearchPaths() { + if info, err := os.Stat(candidate); err == nil && !info.IsDir() { + return candidate, nil + } + } + return "", fmt.Errorf("bgo executable not found — install bgo and add it to PATH (see the setup guide)") +} + +// Upload writes data to a flat remote filename in the user's remote $HOME by +// staging it locally and invoking `bgo scp` once under a PTY. +// +// remoteRelPath is expected to be a flat filename (no directory components), +// because bgo cannot create remote directories. Any directory components are +// collapsed to the base name defensively. +func (u *BgoUploader) Upload(ctx context.Context, remoteRelPath string, data []byte, mode os.FileMode) error { + start := time.Now() + // Collapse to a flat filename: bgo scp cannot create remote directories. + name := path.Base(normaliseRemotePath(remoteRelPath)) + if name == "" || name == "." || name == "/" { + return fmt.Errorf("ssh(bgo): remote filename is empty") + } + + bgoBin, err := resolveBgoBinary() + if err != nil { + sshLog().Error("bgo uploader: binary not found", "err", err) + return err + } + + sshLog().Info("bgo uploader start", + "host", u.cfg.Host, "user", u.cfg.User, "port", u.cfg.Port, + "remote_file", name, "size", len(data), "bgo", bgoBin) + + // 1. Stage the payload to a local temp file for scp to read. + tmp, err := os.CreateTemp("", "snapgo-bgo-*.png") + if err != nil { + return fmt.Errorf("ssh(bgo): create temp: %w", err) + } + tmpPath := tmp.Name() + defer os.Remove(tmpPath) + if _, err := tmp.Write(data); err != nil { + _ = tmp.Close() + return fmt.Errorf("ssh(bgo): write temp: %w", err) + } + if err := tmp.Close(); err != nil { + return fmt.Errorf("ssh(bgo): close temp: %w", err) + } + if err := os.Chmod(tmpPath, mode.Perm()); err != nil { + sshLog().Debug("bgo uploader chmod temp failed", "err", err) + } + + // 2. bgo scp under a PTY (via `script`). + remoteTarget := fmt.Sprintf("%s@%s:%s", u.cfg.User, bracketHost(u.cfg.Host), name) + bgoArgs := u.bgoScpArgs(bgoBin, tmpPath, remoteTarget) + if err := u.runUnderPTY(ctx, bgoArgs); err != nil { + sshLog().Error("bgo uploader scp failed", + "remote_file", name, "elapsed", time.Since(start), "err", err) + return err + } + sshLog().Info("bgo uploader done", + "remote_file", name, "size", len(data), "total_elapsed", time.Since(start)) + return nil +} + +// bgoScpArgs builds the argument vector "bgo scp [-P port] ". +// bgo manages its own auth, so we pass no ssh -o options here. +func (u *BgoUploader) bgoScpArgs(bgoBin, src, dst string) []string { + args := []string{bgoBin, "scp"} + if u.cfg.Port > 0 && u.cfg.Port != 22 { + args = append(args, "-P", strconv.Itoa(u.cfg.Port)) + } + args = append(args, src, dst) + return args +} + +// runUnderPTY runs the given command vector under a PTY allocated by the +// system `script` utility, capturing combined output for diagnostics. +// +// macOS BSD script signature: `script -q command [args...]`. +// We discard the typescript by writing to /dev/null. +func (u *BgoUploader) runUnderPTY(ctx context.Context, cmdVec []string) error { + args := append([]string{"-q", "/dev/null"}, cmdVec...) + cmd := exec.CommandContext(ctx, systemScriptPath, args...) + var combined bytes.Buffer + cmd.Stdout = &combined + cmd.Stderr = &combined + sshLog().Debug("bgo exec", "args", strings.Join(args, " ")) + if err := cmd.Run(); err != nil { + msg := strings.TrimSpace(combined.String()) + if msg == "" { + msg = err.Error() + } + return fmt.Errorf("bgo scp failed: %s", msg) + } + return nil +} + +// bracketHost wraps a bare IPv6 literal in [] so the "user@host:path" target +// parses correctly (e.g. fdbd:dc03:8:379::130 → [fdbd:dc03:8:379::130]). +// IPv4 addresses and hostnames are returned unchanged. Already-bracketed +// inputs are left as-is. +func bracketHost(host string) string { + host = strings.TrimSpace(host) + if host == "" { + return host + } + if strings.HasPrefix(host, "[") { + return host + } + // An IPv6 literal contains multiple ':' separators; a hostname:port style + // is not expected here because the port lives in cfg.Port. + if strings.Count(host, ":") >= 2 { + return "[" + host + "]" + } + return host +} + +// TestBgoConnection verifies that the bgo binary is resolvable. A real +// transfer test is intentionally avoided: bgo requires a PTY and a live +// remote, and bgo ssh cannot run a harmless remote probe command (it panics). +// Confirming bgo is installed and on PATH is the most useful signal we can +// give without performing an actual upload. +func TestBgoConnection(ctx context.Context, cfg domain.SSHConfig) error { + sshLog().Info("bgo test connection start", "host", cfg.Host, "user", cfg.User) + bin, err := resolveBgoBinary() + if err != nil { + return err + } + sshLog().Info("bgo test connection ok", "bgo", bin) + return nil +}