From f95038cb0393991e0bc6cc42560c008abf1dd318 Mon Sep 17 00:00:00 2001
From: Marco Fontani <MFONTANI@cpan.org>
Date: Thu, 16 May 2019 13:36:28 +0200
Subject: [PATCH] fix disable resetting color+temp continuously

To reproduce without this patch:

1. run `./src/redshift -v` in a terminal
2. in another terminal, `pkill -USR1 redshift`
   ... which ought to disable its processing altogether, once completed
   ... but doesn't :(
3. while it's disabled, manually set the brightness:
    `xrandr --output HDMI2 --brightness 0.5`
4. after a few seconds (default is 5secs between iterations), the
   brightness (and temp) jumps up again despite redshift being disabled

With this patch, instead - the resetting of colour and temperature is
done only once after the program's been disabled, and subsequent changes
of brightness or temperature etc. via a separate `xrandr` while the
program is disabled have the desired effect (i.e. they stick instead of
being reset by a "disabled" redshift program).

Once the program is re-enabled again (i.e. via another `pkill -USR1
redshift`), the program is again allowed to make changes to brightness
and temperature, as it ought to be able to.
---
 src/redshift.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/src/redshift.c b/src/redshift.c
index e0221d5e..a68a1c3e 100644
--- a/src/redshift.c
+++ b/src/redshift.c
@@ -662,6 +662,7 @@ run_continual_mode(const location_provider_t *provider,
 	int prev_disabled = 1;
 	int disabled = 0;
 	int location_available = 1;
+	int should_reset = 0;
 	while (1) {
 		/* Check to see if disable signal was caught */
 		if (disable && !done) {
@@ -685,6 +686,7 @@ run_continual_mode(const location_provider_t *provider,
 		if (verbose && disabled != prev_disabled) {
 			printf(_("Status: %s\n"), disabled ?
 			       _("Disabled") : _("Enabled"));
+			should_reset = 1;
 		}
 
 		prev_disabled = disabled;
@@ -724,7 +726,9 @@ run_continual_mode(const location_provider_t *provider,
 
 		if (disabled) {
 			period = PERIOD_NONE;
-			color_setting_reset(&target_interp);
+			if (should_reset) {
+				color_setting_reset(&target_interp);
+			}
 		}
 
 		if (done) {
@@ -797,18 +801,23 @@ run_continual_mode(const location_provider_t *provider,
 		}
 
 		/* Adjust temperature */
-		r = method->set_temperature(
-			method_state, &interp, preserve_gamma);
-		if (r < 0) {
-			fputs(_("Temperature adjustment failed.\n"),
-			      stderr);
-			return -1;
+		if (!disabled || should_reset) {
+			r = method->set_temperature(
+				method_state, &interp, preserve_gamma);
+			if (r < 0) {
+				fputs(_("Temperature adjustment failed.\n"),
+				      stderr);
+				return -1;
+			}
 		}
 
 		/* Save period and target color setting as previous */
 		prev_period = period;
 		prev_target_interp = target_interp;
 
+		/* All resets have been done now */
+		should_reset = 0;
+
 		/* Sleep length depends on whether a fade is ongoing. */
 		int delay = SLEEP_DURATION;
 		if (fade_length != 0) {