perf TUI: Don't ignore job control

In its infinite wisdom, by default, SLang sets susp undef, and this can
only be un-done by calling SLtty_set_suspend_state(true).  After every
SLang_init_tty().

Additionally, no provisions are made for maintaining the teletype
attributes across suspend/continue (outside of curses emulation
mode(?!), which provides full support, naturally), so we need to save
and restore the flags ourselves, as well as reset the text colours when
going under.  We need to also re-draw the screen, and raising SIGWINCH,
shockingly, Just Works.

The correct solution would be to Not Use SLang, but as a stop-gap,
this makes TUI 'perf report' usable.
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: yaowenbin <yaowenbin1@huawei.com>
Link: https://lore.kernel.org/r/0354dcae23a8713f75f4fed609e0caec3c6e3cd5.1672174189.git.nabijaczleweli@nabijaczleweli.xyzSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/browsers/annotate.c

@@ -938,6 +938,7 @@ int hist_entry__tui_annotate(struct hist_entry *he, struct evsel *evsel,
 	/* reset abort key so that it can get Ctrl-C as a key */
 	SLang_reset_tty();
 	SLang_init_tty(0, 0, 0);
+	SLtty_set_suspend_state(true);
 
 	return map_symbol__tui_annotate(&he->ms, evsel, hbt);
 }

tools/perf/ui/browsers/hists.c

@@ -3000,6 +3000,7 @@ static int evsel__hists_browse(struct evsel *evsel, int nr_events, const char *h
 	/* reset abort key so that it can get Ctrl-C as a key */
 	SLang_reset_tty();
 	SLang_init_tty(0, 0, 0);
+	SLtty_set_suspend_state(true);
 
 	if (min_pcnt)
 		browser->min_pcnt = min_pcnt;
@@ -3667,6 +3668,7 @@ int block_hists_tui_browse(struct block_hist *bh, struct evsel *evsel,
 	/* reset abort key so that it can get Ctrl-C as a key */
 	SLang_reset_tty();
 	SLang_init_tty(0, 0, 0);
+	SLtty_set_suspend_state(true);
 
 	memset(&action, 0, sizeof(action));
 

tools/perf/ui/browsers/scripts.c

@@ -166,6 +166,7 @@ void run_script(char *cmd)
 	printf("\033[c\033[H\033[J");
 	fflush(stdout);
 	SLang_init_tty(0, 0, 0);
+	SLtty_set_suspend_state(true);
 	SLsmg_refresh();
 }
 

tools/perf/ui/tui/setup.c

@@ -2,12 +2,14 @@
 #include <signal.h>
 #include <stdbool.h>
 #include <stdlib.h>
+#include <termios.h>
 #include <unistd.h>
 #include <linux/kernel.h>
 #ifdef HAVE_BACKTRACE_SUPPORT
 #include <execinfo.h>
 #endif
 
+#include "../../util/color.h"
 #include "../../util/debug.h"
 #include "../browser.h"
 #include "../helpline.h"
@@ -121,6 +123,23 @@ static void ui__signal(int sig)
 	exit(0);
 }
 
+static void ui__sigcont(int sig)
+{
+	static struct termios tty;
+
+	if (sig == SIGTSTP) {
+		while (tcgetattr(SLang_TT_Read_FD, &tty) == -1 && errno == EINTR)
+			;
+		while (write(SLang_TT_Read_FD, PERF_COLOR_RESET, sizeof(PERF_COLOR_RESET) - 1) == -1 && errno == EINTR)
+			;
+		raise(SIGSTOP);
+	} else {
+		while (tcsetattr(SLang_TT_Read_FD, TCSADRAIN, &tty) == -1 && errno == EINTR)
+			;
+		raise(SIGWINCH);
+	}
+}
+
 int ui__init(void)
 {
 	int err;
@@ -135,6 +154,7 @@ int ui__init(void)
 	err = SLang_init_tty(-1, 0, 0);
 	if (err < 0)
 		goto out;
+	SLtty_set_suspend_state(true);
 
 	err = SLkp_init();
 	if (err < 0) {
@@ -149,6 +169,8 @@ int ui__init(void)
 	signal(SIGINT, ui__signal);
 	signal(SIGQUIT, ui__signal);
 	signal(SIGTERM, ui__signal);
+	signal(SIGTSTP, ui__sigcont);
+	signal(SIGCONT, ui__sigcont);
 
 	perf_error__register(&perf_tui_eops);