update docs and ascii banner

4 files changed, 29 insertions, 5 deletions

diff --git a/internal/flags/flags.go b/internal/flags/flags.go
index 9b1c3cf..5d00b74 100644
--- a/internal/flags/flags.go
+++ b/internal/flags/flags.go
@@ -42,6 +42,9 @@ type Config struct {
 	CollapsedFields  []string
 	CountField       string
 	GlobalFilter     globalfilter.Filter
+
+	// ShowVersion prints the banner plus version and exits without running.
+	ShowVersion bool
 }
 
 var (
@@ -177,6 +180,7 @@ func parse() error {
 	flag.BoolVar(&cfg.TestLiveFlames, "testliveflames", false, "Run TUI with continuously-updating synthetic flamegraph data for live keyboard-navigation testing")
 	flag.DurationVar(&cfg.LiveInterval, "live-interval", cfg.LiveInterval, "Synthetic live flamegraph refresh interval for --testliveflames")
 	flag.BoolVar(&cfg.TUIExportEnable, "tuiExport", cfg.TUIExportEnable, "Enable TUI CSV snapshot export files (separate from Parquet recording)")
+	flag.BoolVar(&cfg.ShowVersion, "version", false, "Print version banner and exit")
 	fields := flag.String("fields", "",
 		fmt.Sprintf("Comma separated list of fields to collapse, valid are: %v", validFields))
 	flag.StringVar(&cfg.CountField, "count", cfg.CountField,
diff --git a/internal/flags/version.go b/internal/flags/version.go
index 3db0b9f..583d19b 100644
--- a/internal/flags/version.go
+++ b/internal/flags/version.go
@@ -5,11 +5,14 @@ import "fmt"
 // Version is the current application version.
 const Version = "v0.0.1"
 
-const asciiBannerTemplate = ` ___   _____    ___ _     _
-|_ _| / / _ \  | _ (_)___| |_ 
- | | / / (_) | |   / / _ \  _|
-|___/_/ \___/  |_|_\_\___/\__| NG
-               %s`
+const asciiBannerTemplate = ` ██╗    ██╗  ██████╗     ██████╗  ██╗  ██████╗  ████████╗
+ ██║   ██╔╝ ██╔═══██╗    ██╔══██╗ ██║ ██╔═══██╗ ╚══██╔══╝
+ ██║  ██╔╝  ██║   ██║    ██████╔╝ ██║ ██║   ██║    ██║   
+ ██║ ██╔╝   ██║   ██║    ██╔══██╗ ██║ ██║   ██║    ██║   
+ ██║██╔╝    ╚██████╔╝    ██║  ██║ ██║ ╚██████╔╝    ██║   
+ ╚═╝╚═╝      ╚═════╝     ╚═╝  ╚═╝ ╚═╝  ╚═════╝     ╚═╝   
+       ⚡ Next-Generation BPF I/O Syscall Tracer ⚡
+                          %s`
 
 // PrintVersion prints the banner with the current version.
 func PrintVersion() {
diff --git a/internal/ior.go b/internal/ior.go
index e6e7233..63da223 100644
--- a/internal/ior.go
+++ b/internal/ior.go
@@ -57,6 +57,11 @@ func dispatchRun(cfg flags.Config) error {
 	if cfg.TestLiveFlames {
 		return runTUITestLiveFlamesFn(cfg, tuiTestLiveFlamesStarter(cfg))
 	}
+	// All remaining modes require tracing, which needs root. Fail fast here so
+	// the TUI never starts (and hangs) when we already know it cannot trace.
+	if getEUID() != 0 {
+		return errRootPrivilegesRequired
+	}
 	if isHeadlessParquetMode(cfg) {
 		return runParquetFn(cfg)
 	}
diff --git a/internal/ior_mode_test.go b/internal/ior_mode_test.go
index a7fcab1..ab0466d 100644
--- a/internal/ior_mode_test.go
+++ b/internal/ior_mode_test.go
@@ -95,13 +95,16 @@ func TestDispatchRunUsesTraceModeWhenRequested(t *testing.T) {
 	origRunTUI := runTUIFn
 	origRunTUITestFlames := runTUITestFlamesFn
 	origRunTUITestLiveFlames := runTUITestLiveFlamesFn
+	origGetEUID := getEUID
 	defer func() {
 		runTraceFn = origRunTrace
 		runParquetFn = origRunParquet
 		runTUIFn = origRunTUI
 		runTUITestFlamesFn = origRunTUITestFlames
 		runTUITestLiveFlamesFn = origRunTUITestLiveFlames
+		getEUID = origGetEUID
 	}()
+	getEUID = func() int { return 0 }
 
 	traceCalled := false
 	tuiCalled := false
@@ -144,13 +147,16 @@ func TestDispatchRunUsesHeadlessParquetModeWhenRequested(t *testing.T) {
 	origRunTUI := runTUIFn
 	origRunTUITestFlames := runTUITestFlamesFn
 	origRunTUITestLiveFlames := runTUITestLiveFlamesFn
+	origGetEUID := getEUID
 	defer func() {
 		runTraceFn = origRunTrace
 		runParquetFn = origRunParquet
 		runTUIFn = origRunTUI
 		runTUITestFlamesFn = origRunTUITestFlames
 		runTUITestLiveFlamesFn = origRunTUITestLiveFlames
+		getEUID = origGetEUID
 	}()
+	getEUID = func() int { return 0 }
 
 	traceCalled := false
 	parquetCalled := false
@@ -196,12 +202,15 @@ func TestDispatchRunUsesTUIWhenOnlyPprofEnabled(t *testing.T) {
 	origRunTUI := runTUIFn
 	origRunTUITestFlames := runTUITestFlamesFn
 	origRunTUITestLiveFlames := runTUITestLiveFlamesFn
+	origGetEUID := getEUID
 	defer func() {
 		runTraceFn = origRunTrace
 		runTUIFn = origRunTUI
 		runTUITestFlamesFn = origRunTUITestFlames
 		runTUITestLiveFlamesFn = origRunTUITestLiveFlames
+		getEUID = origGetEUID
 	}()
+	getEUID = func() int { return 0 }
 
 	traceCalled := false
 	tuiCalled := false
@@ -239,12 +248,15 @@ func TestDispatchRunUsesTUIStarterWhenNotPlain(t *testing.T) {
 	origRunTUI := runTUIFn
 	origRunTUITestFlames := runTUITestFlamesFn
 	origRunTUITestLiveFlames := runTUITestLiveFlamesFn
+	origGetEUID := getEUID
 	defer func() {
 		runTraceWithContextFn = origRunTraceWithContext
 		runTUIFn = origRunTUI
 		runTUITestFlamesFn = origRunTUITestFlames
 		runTUITestLiveFlamesFn = origRunTUITestLiveFlames
+		getEUID = origGetEUID
 	}()
+	getEUID = func() int { return 0 }
 
 	traceDone := make(chan struct{}, 1)
 	runTraceWithContextFn = func(_ context.Context, _ flags.Config, started chan<- struct{}, configure func(*eventLoop)) error {