Support for tmux >= 2.9, with window-size

util/tmux.go

@@ -7,45 +7,17 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
-	"regexp"
 	"strconv"
 	"strings"
 	"text/template"
 )
 
-const (
-	requiredVersion = 2.6 // see issue #
-)
-
 var (
-	tmuxVersionRegex = regexp.MustCompile(`tmux (\d+\.\d+)`)
-
 	//go:embed tmux.sh.gotmpl
 	scriptSource   string
 	scriptTemplate = template.Must(template.New("tmux_script").Parse(scriptSource))
 )
 
-// CheckTmuxVersion checks the version of tmux and returns an error if it's not supported
-func CheckTmuxVersion() error {
-	cmd := exec.Command("tmux", "-V")
-	output, err := cmd.CombinedOutput()
-	if err != nil {
-		return err
-	}
-	matches := tmuxVersionRegex.FindStringSubmatch(string(output))
-	if len(matches) <= 1 {
-		return errors.New("unexpected tmux version output")
-	}
-	version, err := strconv.ParseFloat(matches[1], 32)
-	if err != nil {
-		return err
-	}
-	if version < requiredVersion-0.01 { // floats are fun
-		return fmt.Errorf("tmux version too low: tmux %.1f required, but found tmux %.1f", requiredVersion, version)
-	}
-	return nil
-}
-
 // Tmux represents a very special tmux(1) setup, specifially used for REPLbot. It consists of
 // two tmux sessions:
 // - session "replbot_$id_frame": session with one window and three panes to allow us to resize the terminal of the
@@ -58,13 +30,14 @@ type Tmux struct {
 }
 
 type tmuxScriptParams struct {
-	MainID, FrameID  string
-	Width, Height    int
-	Env              map[string]string
-	Command          string
-	ConfigFile       string
-	CaptureFile      string
-	LaunchScriptFile string
+	MainID, FrameID    string
+	Width, Height      int
+	Env                map[string]string
+	Command            string
+	ConfigFile         string
+	CaptureFile        string
+	LaunchScriptFile   string
+	SupportsWindowSize bool
 }
 
 // NewTmux creates a new Tmux instance, but does not start the tmux
@@ -86,15 +59,16 @@ func (s *Tmux) Start(env map[string]string, command ...string) error {
 	}
 	defer script.Close()
 	params := &tmuxScriptParams{
-		MainID:           s.mainID(),
-		FrameID:          s.frameID(),
-		Width:            s.width,
-		Height:           s.height,
-		Env:              env,
-		Command:          QuoteCommand(command),
-		ConfigFile:       s.configFile(),
-		CaptureFile:      s.captureFile(),
-		LaunchScriptFile: s.launchScriptFile(),
+		MainID:             s.mainID(),
+		FrameID:            s.frameID(),
+		Width:              s.width,
+		Height:             s.height,
+		Env:                env,
+		Command:            QuoteCommand(command),
+		ConfigFile:         s.configFile(),
+		CaptureFile:        s.captureFile(),
+		LaunchScriptFile:   s.launchScriptFile(),
+		SupportsWindowSize: supportsTmuxWindowSize(),
 	}
 	if err := scriptTemplate.Execute(script, params); err != nil {
 		return err

util/tmux.sh.gotmpl

@@ -11,6 +11,7 @@ command="{{.Command}}"
 config_file="{{.ConfigFile}}"
 capture_file="{{.CaptureFile}}"
 launch_script_file="{{.LaunchScriptFile}}"
+supports_window_size="{{if .SupportsWindowSize}}true{{end}}"
 
 # Set up cleanup hooks
 cleanup_on_failure() {
@@ -43,6 +44,9 @@ tmux set-option -t "${main_id}" status off
 tmux set-option -t "${main_id}" prefix none
 tmux set-option -t "${main_id}" remain-on-exit
 tmux set-hook -t "${main_id}" pane-died "capture-pane -S- -E-; save-buffer '${capture_file}'; kill-pane"
+if [ -n "${supports_window_size}" ]; then
+  tmux set-option -t "${main_id}" window-size smallest # default is 'latest' as of tmux >= 2.9
+fi
 
 # Start frame tmux session attaches to main session, allows resizing window
 tmux -f "${config_file}" new-session -s "${frame_id}" -d -x 200 -y 80 sh -c "while true; do sleep 10; if ! tmux has-session -t '${main_id}'; then exit; fi; done"
@@ -51,6 +55,9 @@ tmux split-window -v -t "${frame_id}.0" sh -c "while true; do sleep 10; if ! tmu
 tmux split-window -h -t "${frame_id}.1" sh -c "unset TMUX; tmux attach -t '${main_id}'"
 tmux resize-pane -t "${frame_id}.2" -x "${window_width}" -y "${window_height}"
 tmux select-pane -t "${frame_id}.2"
+if [ -n "${supports_window_size}" ]; then
+  tmux set-option -t "${frame_id}" window-size smallest # default is 'latest' as of tmux >= 2.9
+fi
 
 # Clean exit
 rm -f "${config_file}" "${launch_script_file}"

util/tmux_util.go

@@ -0,0 +1,49 @@
+package util
+
+import (
+	_ "embed" // required by go:embed
+	"errors"
+	"fmt"
+	"os/exec"
+	"regexp"
+	"strconv"
+)
+
+const (
+	minimumTmuxVersion    = 2.6 // see issue #39
+	windowSizeTmuxVersion = 2.9 // see issue #44
+)
+
+var (
+	tmuxVersionRegex = regexp.MustCompile(`tmux (\d+\.\d+)`)
+)
+
+// CheckTmuxVersion checks the version of tmux and returns an error if it's not supported
+func CheckTmuxVersion() error {
+	return checkTmuxVersion(minimumTmuxVersion)
+}
+
+// supportsTmuxWindowSize checks if the "window-size" option is supported (tmux >= 2.9)
+func supportsTmuxWindowSize() bool {
+	return checkTmuxVersion(windowSizeTmuxVersion) == nil
+}
+
+func checkTmuxVersion(compareVersion float64) error {
+	cmd := exec.Command("tmux", "-V")
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		return err
+	}
+	matches := tmuxVersionRegex.FindStringSubmatch(string(output))
+	if len(matches) <= 1 {
+		return errors.New("unexpected tmux version output")
+	}
+	version, err := strconv.ParseFloat(matches[1], 32)
+	if err != nil {
+		return err
+	}
+	if version < compareVersion-0.01 { // floats are fun
+		return fmt.Errorf("tmux version too low: tmux %.1f required, but found tmux %.1f", compareVersion, version)
+	}
+	return nil
+}