rtla/timerlat: Use pretty formatting only on interactive tty

timerlat top does some background/font color formatting. While useful
on terminal, it breaks the output on other formats. For example, when
piping the output for pastebin tools, the format strings are printed
as characters. For instance:

  [2;37;40m                                     Timer Latency                                              [0;0;0m
    0 00:00:01   |          IRQ Timer Latency (us)        |         Thread Timer Latency (us)
  [2;30;47mCPU COUNT      |      cur       min       avg       max |      cur       min       avg       max[0;0;0m
    0 #1013      |        1         0         1        54 |        5         2         4        57
    1 #1013      |        3         0         1        10 |        6         2         4        15

To avoid this problem, do the formatting only if running on a tty,
and in !quiet mode.

Link: https://lkml.kernel.org/r/8288e1544ceab21557d5dda93a0f00339497c649.1713968967.git.bristot@kernel.org

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>

tools/tracing/rtla/src/timerlat_top.c

@@ -44,6 +44,7 @@ struct timerlat_top_params {
 	int			hk_cpus;
 	int			user_top;
 	int			user_workload;
+	int			pretty_output;
 	cpu_set_t		hk_cpu_set;
 	struct sched_attr	sched_param;
 	struct trace_events	*events;
@@ -179,19 +180,22 @@ timerlat_top_handler(struct trace_seq *s, struct tep_record *record,
 /*
  * timerlat_top_header - print the header of the tool output
  */
-static void timerlat_top_header(struct osnoise_tool *top)
+static void timerlat_top_header(struct timerlat_top_params *params, struct osnoise_tool *top)
 {
-	struct timerlat_top_params *params = top->params;
 	struct trace_seq *s = top->trace.seq;
 	char duration[26];
 
 	get_duration(top->start_time, duration, sizeof(duration));
 
-	trace_seq_printf(s, "\033[2;37;40m");
+	if (params->pretty_output)
+		trace_seq_printf(s, "\033[2;37;40m");
+
 	trace_seq_printf(s, "                                     Timer Latency                                              ");
 	if (params->user_top)
 		trace_seq_printf(s, "                                         ");
-	trace_seq_printf(s, "\033[0;0;0m");
+
+	if (params->pretty_output)
+		trace_seq_printf(s, "\033[0;0;0m");
 	trace_seq_printf(s, "\n");
 
 	trace_seq_printf(s, "%-6s   |          IRQ Timer Latency (%s)        |         Thread Timer Latency (%s)", duration,
@@ -204,11 +208,15 @@ static void timerlat_top_header(struct osnoise_tool *top)
 	}
 
 	trace_seq_printf(s, "\n");
-	trace_seq_printf(s, "\033[2;30;47m");
+	if (params->pretty_output)
+		trace_seq_printf(s, "\033[2;30;47m");
+
 	trace_seq_printf(s, "CPU COUNT      |      cur       min       avg       max |      cur       min       avg       max");
 	if (params->user_top)
 		trace_seq_printf(s, " |      cur       min       avg       max");
-	trace_seq_printf(s, "\033[0;0;0m");
+
+	if (params->pretty_output)
+		trace_seq_printf(s, "\033[0;0;0m");
 	trace_seq_printf(s, "\n");
 }
 
@@ -305,7 +313,7 @@ timerlat_print_stats(struct timerlat_top_params *params, struct osnoise_tool *to
 	if (!params->quiet)
 		clear_terminal(trace->seq);
 
-	timerlat_top_header(top);
+	timerlat_top_header(params, top);
 
 	for (i = 0; i < nr_cpus; i++) {
 		if (params->cpus && !CPU_ISSET(i, &params->monitored_cpus))
@@ -693,6 +701,9 @@ timerlat_top_apply_config(struct osnoise_tool *top, struct timerlat_top_params *
 		}
 	}
 
+	if (isatty(1) && !params->quiet)
+		params->pretty_output = 1;
+
 	return 0;
 
 out_err: