kernel-shark: Suppress "Root privileges are required" if already root

[Steven Rostedt <rostedt@goodmis.org>]

From: Steven Rostedt (VMware) <rostedt@goodmis.org>

If the tracefs directory is configured into the kernel, and
kshark-record  fails to find the tracing directory, it should test if
it already has root privileges (geteuid() returns zero), before posting
a message "Root privileges are required" as that can confuse users.

Reported-by: howaboutsynergy@pm.me
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
diff --git a/kernel-shark/src/KsCaptureDialog.cpp b/kernel-shark/src/KsCaptureDialog.cpp
index 2e6e8f9c..dbf73302 100644
--- a/kernel-shark/src/KsCaptureDialog.cpp
+++ b/kernel-shark/src/KsCaptureDialog.cpp
@@ -18,6 +18,12 @@
 #include "KsCmakeDef.hpp"
 #include "KsCaptureDialog.hpp"
 
+extern "C" {
+  // To get access to geteuid()
+  #include <unistd.h>
+  #include <sys/types.h>
+}
+
 static inline tep_handle *local_events()
 {
 	return tracecmd_local_events(tracecmd_get_tracing_dir());
@@ -65,7 +71,9 @@ KsCaptureControl::KsCaptureControl(QWidget *parent)
 
 		if (!_localTEP)
 			message += "Cannot find or mount tracing directory.\n";
-		if (!pluginList.count())
+
+		// geteuid() returns 0 if running as effective id of root
+		if (!pluginList.count() && geteuid())
 			message += "Root privileges are required.\n";
 
 		QLabel *errorLabel = new QLabel(message);