[PATCH] perf tui: don't ignore job control

[Ahelenia Ziemiańska]

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. 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@xxxxxxxxxxxxxxxxxx>
---
 tools/perf/ui/browsers/annotate.c |  1 +
 tools/perf/ui/browsers/hists.c    |  2 ++
 tools/perf/ui/browsers/scripts.c  |  1 +
 tools/perf/ui/tui/setup.c         | 19 +++++++++++++++++++
 4 files changed, 23 insertions(+)

diff --git a/tools/perf/ui/browsers/annotate.c b/tools/perf/ui/browsers/annotate.c
index c03fa76c02ff..6a4ffbf66c7f 100644
--- a/tools/perf/ui/browsers/annotate.c
+++ b/tools/perf/ui/browsers/annotate.c
@@ -942,6 +942,7 @@ 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, opts);
 }
diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index b72ee6822222..2479e6d42e7c 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -3010,6 +3010,7 @@ 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;
@@ -3682,6 +3683,7 @@ 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));
 
diff --git a/tools/perf/ui/browsers/scripts.c b/tools/perf/ui/browsers/scripts.c
index 47d2c7a8cbe1..50d45054ed6c 100644
--- a/tools/perf/ui/browsers/scripts.c
+++ b/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();
 }
 
diff --git a/tools/perf/ui/tui/setup.c b/tools/perf/ui/tui/setup.c
index a3b8c397c24d..4211a161458a 100644
--- a/tools/perf/ui/tui/setup.c
+++ b/tools/perf/ui/tui/setup.c
@@ -2,6 +2,7 @@
 #include <signal.h>
 #include <stdbool.h>
 #include <stdlib.h>
+#include <termios.h>
 #include <unistd.h>
 #include <linux/kernel.h>
 #ifdef HAVE_BACKTRACE_SUPPORT
@@ -122,6 +123,21 @@ 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)
+			;
+		raise(SIGSTOP);
+	} else {
+		while (tcsetattr(SLang_TT_Read_FD, TCSADRAIN, &tty) == -1 && errno == EINTR)
+			;
+		raise(SIGWINCH);
+	}
+}
+
 int ui__init(void)
 {
 	int err;
@@ -136,6 +152,7 @@ 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) {
@@ -150,6 +167,8 @@ 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);
 
-- 
2.30.2

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