Include error reason if trace disabling fails.

platform-tracing.c

@@ -41,21 +41,24 @@ platform_disable_tracing(int strict)
 	int disable_trace = PROC_TRACE_CTL_DISABLE;
 
 	if (procctl(P_PID, 0, PROC_TRACE_CTL, &disable_trace) && strict)
-		fatal("unable to make the process untraceable");
+		fatal("unable to make the process untraceable: %s",
+		    strerror(errno));
 #endif
 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
 	/* Disable ptrace on Linux without sgid bit */
 	if (prctl(PR_SET_DUMPABLE, 0) != 0 && strict)
-		fatal("unable to make the process undumpable");
+		fatal("unable to make the process undumpable: %s",
+		    strerror(errno));
 #endif
 #if defined(HAVE_SETPFLAGS) && defined(__PROC_PROTECT)
 	/* On Solaris, we should make this process untraceable */
 	if (setpflags(__PROC_PROTECT, 1) != 0 && strict)
-		fatal("unable to make the process untraceable");
+		fatal("unable to make the process untraceable: %s",
+		    strerror(errno));
 #endif
 #ifdef PT_DENY_ATTACH
 	/* Mac OS X */
 	if (ptrace(PT_DENY_ATTACH, 0, 0, 0) == -1 && strict)
-		fatal("unable to set PT_DENY_ATTACH");
+		fatal("unable to set PT_DENY_ATTACH: %s", strerror(errno));
 #endif
 }