Refactor

Signed-off-by: Mattias Andrée <m@maandree.se>

21 files changed, 619 insertions, 416 deletions

diff --git a/src/Makefile b/src/Makefile
index 36bf18b..693638c 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -4,7 +4,7 @@ CONFIGFILE = config.mk
 include $(CONFIGFILE)
 
 
-PACKAGE_STRING = $(PACKAGE) 1.13
+VERSION_STRING = redshift-ng 1.13
 
 
 OBJ =\
@@ -28,7 +28,7 @@ OBJ =\
 
 CPPFLAGS_STRINGS =\
 	-D'PACKAGE="$(PACKAGE)"'\
-	-D'PACKAGE_STRING="$(PACKAGE_STRING)"'\
+	-D'VERSION_STRING="$(VERSION_STRING)"'\
 	-D'LOCALEDIR="$(LOCALEDIR)"'
 
 
diff --git a/src/colour.c b/src/colour.c
index 0138980..88acf64 100644
--- a/src/colour.c
+++ b/src/colour.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -43,11 +44,6 @@ colour_setting_diff_is_major(const struct colour_setting *a, const struct colour
 }
 
 
-#if defined(__GNUC__)
-# pragma GCC diagnostic ignored "-Wfloat-equal"
-#endif
-
-
 #define X(SUFFIX, TYPE, MAX, DEPTH)\
 	/**
 	 * Fill a gamma ramp
@@ -65,7 +61,7 @@ colour_setting_diff_is_major(const struct colour_setting *a, const struct colour
 		size_t i;\
 		double v;\
 		brightness /= (size - 1U);\
-		if (gamma == 1.0) {\
+		if (exact_eq(gamma, 1.0)) {\
 			brightness *= (MAX);\
 			for (i = 0; i < size; i++)\
 				ramp[i] = (TYPE)(i * brightness);\
diff --git a/src/common.h b/src/common.h
index e3cc37b..d9a7c3a 100644
--- a/src/common.h
+++ b/src/common.h
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -51,7 +52,9 @@
 #ifdef WINDOWS
 # include <windows.h>
 # define localtime_r(T, TM) localtime_s((TM), (T))
+# define pause()  millisleep(100U)
 #else
+# include <poll.h>
 # include <pwd.h>
 # include <time.h>
 #endif
@@ -84,8 +87,13 @@
 
 #if defined(__clang__)
 # pragma clang diagnostic ignored "-Wunsafe-buffer-usage" /* broken in clang 19.1.7 */
+# pragma clang diagnostic ignored "-Wdisabled-macro-expansion" /* warns about system headers (also a stupid warning) */
+# pragma clang diagnostic ignored "-Wassign-enum" /* warns about bit field enums */
+# pragma clang diagnostic ignored "-Wpadded" /* only relevant for library headers */
+# pragma clang diagnostic ignored "-Wcomma" /* comma is useful in loop conditions */
 #elif defined(__GNUC__)
-# pragma GCC diagnostic ignored "-Wunsuffixed-float-constants"
+# pragma GCC diagnostic ignored "-Wunsuffixed-float-constants" /* stupid warning */
+# pragma GCC diagnostic ignored "-Wpadded" /* only relevant for library headers */
 #endif
 
 
@@ -126,6 +134,11 @@
  */
 #define BETWEEN(LO, X, UP)  ((LO) < (X) && (X) < (UP))
 
+/**
+ * Quiet not-a-number `double`
+ */
+#define FNAN ((double)NAN) /* because clang warns when implicitly promoted to double */
+
 
 /**
  * Symbol used to delimit paths in environment
@@ -598,8 +611,8 @@ struct settings {
 		struct setting_f brightness;
 		struct setting_f3 gamma;
 	} day, night;
-	struct setting_i preserve_gamma; /* Whether to preserve gamma ramps if supported by gamma method. */
-	struct setting_i use_fade; /* Whether to fade between large skips in colour temperature. */
+	struct setting_i preserve_gamma;
+	struct setting_i use_fade; /* Whether to fade between large skips in colour temperature */
 
 	struct setting_f elevation_high; /* TODO no cmdline option */
 	struct setting_f elevation_low; /* TODO no cmdline option */
@@ -608,14 +621,14 @@ struct settings {
 		struct setting_time end;
 	} dawn, dusk; /* TODO no cmdline option */
 
-	/* Selected gamma method. */
+	/* Selected gamma method */
 	const struct gamma_method *method;
-	/* Arguments for gamma method. */
+	/* Arguments for gamma method */
 	char *method_args;
 
-	/* Selected location provider. */
+	/* Selected location provider */
 	const struct location_provider *provider;
-	/* Arguments for location provider. */
+	/* Arguments for location provider */
 	char *provider_args;
 };
 
@@ -636,6 +649,12 @@ struct gamma_method {
 	int autostart;
 
 	/**
+	 * 1 if the method automatically resets the adjustments when disconnected,
+	 * 0 otherwise
+	 */
+	int autoreset;
+
+	/**
 	 * Create an initialised state object
 	 * 
 	 * @param   state_out  Output parameter for the state object
@@ -703,13 +722,15 @@ struct gamma_method {
  *
  * @param  NAME:const char *  Value for `.name`
  * @param  AUTOSTART:int      Value for `.autostart`
+ * @param  AUTORESET:int      Value for `.autoreset`
  * @param  PREFIX:identifier  The text, sans terminal underscore (_), prefixed to the
  *                            names of each function implementing the adjustment method
  */
-#define GAMMA_METHOD_INIT(NAME, AUTOSTART, PREFIX)\
+#define GAMMA_METHOD_INIT(NAME, AUTOSTART, AUTORESET, PREFIX)\
 	{\
 		.name = (NAME),\
 		.autostart = (AUTOSTART),\
+		.autoreset = (AUTORESET),\
 		.create = &PREFIX##_create,\
 		.set_option = &PREFIX##_set_option,\
 		.print_help = &PREFIX##_print_help,\
@@ -857,14 +878,26 @@ extern struct colour_setting night_settings;
 extern union scheme scheme;
 
 /**
- * Whether the application is in verbose mode
+ * The mode the application is running in
  */
-extern int verbose;
+extern enum program_mode mode;
 
 /**
- * The mode the application is running in
+ * Whether initially applied adjustments (assumed
+ * to be colour calibration) shall remain applied
  */
-extern enum program_mode mode;
+extern int preserve_gamma;
+
+/**
+ * Whether smooth transitions shall be applied when
+ * a large change in colour settings occurs
+ */
+extern int use_fade;
+
+/**
+ * Whether the application is in verbose mode
+ */
+extern int verbose;
 
 
 /* colour.c */
@@ -963,13 +996,44 @@ void load_settings(struct settings *settings, int argc, char *argv[]);
 
 /* gamma.c */
 
+/**
+ * Get and configure adjustment method
+ * 
+ * @param  settings          The loaded application settings, will be updated
+ *                           to point `settings->method` to the adjustment method
+ * @param  method_state_out  Output parameter for the state of the adjustment method
+ * 
+ * The function will print an error message and exit the
+ * process if no adjustment method is available
+ */
 void acquire_adjustment_method(struct settings *settings, GAMMA_STATE **method_state_out);
 
 
 /* location.c */
 
-int get_location(const struct location_provider *provider, LOCATION_STATE *state, int timeout, struct location *loc);
+/**
+ * Get the current location from the location provider
+ *
+ * @param   provider      The location provider functions
+ * @param   state         The location provider state
+ * @param   timeout       The number of milliseconds to wait, -1 for indefinitely
+ * @param   location_out  Output parameter for the location, in GPS coordinates
+ * @return                1 if `*location_out` was updated,
+ *                        0 if the timeout was reached,
+ *                        -1 on error
+ */
+int get_location(const struct location_provider *provider, LOCATION_STATE *state, int timeout, struct location *location_out);
 
+/**
+ * Get and configure location provider
+ * 
+ * @param  settings            The loaded application settings, will be updated
+ *                             to point `settings->provider` to the location provider
+ * @param  location_state_out  Output parameter for the state of the location provider
+ * 
+ * The function will print an error message and exit the
+ * process if no location provider is available
+ */
 void acquire_location_provider(struct settings *settings, LOCATION_STATE **location_state_out);
 
 /**
@@ -1064,55 +1128,58 @@ DIR *try_path_opendir(const struct env_path *path_spec, const char **path_out, c
 
 #ifndef WINDOWS
 /**
- * Create a pipe(7) where both ends have `O_CLOEXEC` and,
- * if available for pipes, `O_DIRECT`, applied, the read-end
- * will also have `O_NONBLOCK` applied
+ * Create a pipe(7) where both ends have `O_CLOEXEC`,
+ * the read-end will also have `O_NONBLOCK` applied
  * 
  * @param   pipefds  Output parameter for the pipe's file descriptors:
  *                   0) reading file descriptor, and
  *                   1) writing file descriptor
- * @return           0 on success, -1 on failure
  */
-int pipe_rdnonblock(int pipefds[2]);
+void pipe_rdnonblock(int pipefds[2]);
 #endif
 
 
 extern const struct gamma_method dummy_gamma_method;
-
 #ifdef ENABLE_COOPGAMMA
 extern const struct gamma_method coopgamma_gamma_method;
 #endif
-
 #ifdef ENABLE_RANDR
 extern const struct gamma_method randr_gamma_method;
 #endif
-
 #ifdef ENABLE_VIDMODE
 extern const struct gamma_method vidmode_gamma_method;
 #endif
-
 #ifdef ENABLE_DRM
 extern const struct gamma_method drm_gamma_method;
 #endif
-
 #ifdef ENABLE_QUARTZ
 extern const struct gamma_method quartz_gamma_method;
 #endif
-
 #ifdef ENABLE_W32GDI
 extern const struct gamma_method w32gdi_gamma_method;
 #endif
 
-
 extern const struct location_provider manual_location_provider;
-
 #ifdef ENABLE_GEOCLUE2
 extern const struct location_provider geoclue2_location_provider;
 #endif
-
 #ifdef ENABLE_CORELOCATION
 extern const struct location_provider corelocation_location_provider;
 #endif
 
 
+#if defined(__GNUC__)
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wfloat-equal"
+#endif
+static inline int
+exact_eq(double a, double b)
+{
+	return a == b;
+}
+#if defined(__GNUC__)
+# pragma GCC diagnostic pop
+#endif
+
+
 #endif
diff --git a/src/config-ini.c b/src/config-ini.c
index 1a78903..015668f 100644
--- a/src/config-ini.c
+++ b/src/config-ini.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -27,7 +28,7 @@ static const struct env_path paths[] = {
 	{0, "XDG_CONFIG_HOME", "/redshift-ng/redshift.conf"},
 	{0, "XDG_CONFIG_HOME", "/redshift/redshift.conf"},
 	{0, "XDG_CONFIG_HOME", "/redshift.conf"},
-#ifdef WINDOWS
+#if defined(WINDOWS)
 	{0, "localappdata", "/redshift-ng/redshift.conf"},
 	{0, "localappdata", "/redshift/redshift.conf"},
 	{0, "localappdata", "/redshift.conf"},
@@ -43,9 +44,11 @@ static const struct env_path paths[] = {
 	{1, "XDG_CONFIG_DIRS", "/redshift-ng/redshift.conf"},
 	{1, "XDG_CONFIG_DIRS", "/redshift/redshift.conf"},
 	{1, "XDG_CONFIG_DIRS", "/redshift.conf"},
+#if !defined(WINDOWS)
 	{0, "", "/etc/redshift-ng/redshift.conf"},
 	{0, "", "/etc/redshift/redshift.conf"},
 	{0, "", "/etc/redshift.conf"}
+#endif
 };
 
 
@@ -95,7 +98,7 @@ config_ini_init(struct config_ini_state *state, const char *path)
 	char *line = NULL, *s, *p, *value, *end, *pathbuf;
 	char *next_line = NULL, *name;
 	size_t size = 0;
-	ssize_t len;
+	ssize_t len = 0; /* initialised to silence false warning from clang */
 	FILE *f;
 
 	state->sections = NULL;
diff --git a/src/config.c b/src/config.c
index 1613770..5762a9c 100644
--- a/src/config.c
+++ b/src/config.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -21,13 +22,15 @@
 
 /* TODO missing translation */
 USAGE("[-b day:night] [-c file] [-g r:g:b] [-l latitude:longitude | -l provider[:options]]"
-      " [-m method[:options]] [-o | -O temperature | -t day:night | -x] [-pPrv] | -hV");
+      " [-m method[:options]] [-o | -O temperature | -t day:night | -x] [-pPrv] | -h | -V");
 
 
 struct colour_setting day_settings;
 struct colour_setting night_settings;
 union scheme scheme = {.type = SOLAR_SCHEME};
 enum program_mode mode = PROGRAM_MODE_CONTINUAL;
+int preserve_gamma;
+int use_fade;
 int verbose = 0;
 
 
@@ -266,7 +269,7 @@ set_temperature(char *str, struct setting_lu *day, struct setting_lu *night, con
 	}
 
 	errno = 0;
-	for (i = 0, j = 0; i < ELEMSOF(settings); i++, j += settings[i] ? 1 : 0) {
+	for (i = 0, j = 0; i < ELEMSOF(settings); j += settings[i++] ? 1 : 0) {
 		if (!settings[i] || !strs[j] || settings[i]->source > source)
 			continue;
 		if (settings[i]->source & SETTING_CONFIGFILE) {
@@ -311,7 +314,7 @@ set_brightness(char *str, struct setting_f *day, struct setting_f *night, const
 	}
 
 	errno = 0;
-	for (i = 0, j = 0; i < ELEMSOF(settings); i++, j += settings[i] ? 1 : 0) {
+	for (i = 0, j = 0; i < ELEMSOF(settings); j += settings[i++] ? 1 : 0) {
 		if (!settings[i] || !strs[j] || settings[i]->source > source)
 			continue;
 		if (settings[i]->source & SETTING_CONFIGFILE) {
@@ -356,7 +359,7 @@ set_gamma(char *str, struct setting_f3 *day, struct setting_f3 *night, const cha
 	}
 
 	errno = 0;
-	for (i = 0, j = 0; i < ELEMSOF(settings); i++, j += settings[i] ? 3 : 0) {
+	for (i = 0, j = 0; i < ELEMSOF(settings); j += settings[i++] ? 3 : 0) {
 		if (!settings[i] || !strs[j] || settings[i]->source > source)
 			continue;
 		if (settings[i]->source & SETTING_CONFIGFILE) {
@@ -445,7 +448,7 @@ set_transition_time(char *str, struct setting_time *start, struct setting_time *
 	if (!get_strings(str, ELEMSOF(strs), strs, '-'))
 		return 0;
 
-	for (i = 0; i < ELEMSOF(settings); i++) {
+	for (i = 0; i < (int)ELEMSOF(settings); i++) {
 		if (!strs[i] || settings[i]->source > source)
 			continue;
 		if (settings[i]->source & SETTING_CONFIGFILE) {
@@ -703,9 +706,8 @@ load_from_cmdline(struct settings *settings, int argc, char *argv[])
 		break;
 
 	case 'V':
-		printf("%s\n", PACKAGE_STRING);
+		printf("%s\n", VERSION_STRING);
 		exit(0);
-		break;
 
 	case 'x':
 		mode = PROGRAM_MODE_RESET;
@@ -815,6 +817,10 @@ load_settings(struct settings *settings, int argc, char *argv[])
 	int i, j, n;
 	time_t duration;
 
+	/* Clear unused bit so they do not interfere with comparsion */
+	memset(&day_settings, 0, sizeof(day_settings));
+	memset(&night_settings, 0, sizeof(night_settings));
+
 	/* Load settings; some validation takes place */
 	load_defaults(settings);
 	load_from_cmdline(settings, argc, argv);
@@ -824,8 +830,8 @@ load_settings(struct settings *settings, int argc, char *argv[])
 			load_from_config_ini(settings, setting->name, setting->value);
 
 	/* Further validate settings */
-	n =  !settings->dawn.start.source + !settings->dawn.end.source;
-	n += !settings->dusk.start.source + !settings->dusk.end.source;
+	n =  !!settings->dawn.start.source + !!settings->dawn.end.source;
+	n += !!settings->dusk.start.source + !!settings->dusk.end.source;
 	if (n) {
 		scheme.type = CLOCK_SCHEME;
 		if (n != 4)
@@ -852,22 +858,6 @@ load_settings(struct settings *settings, int argc, char *argv[])
 	if (settings->elevation_high.value < settings->elevation_low.value)
 		eprintf(_("High transition elevation cannot be lower than the low transition elevation."));
 
-	/* If the effects are the same throughout the day, do not use a transition scheme */
-#if defined(__GNUC__)
-# pragma GCC diagnostic push
-# pragma GCC diagnostic ignored "-Wfloat-equal"
-#endif
-	if (settings->day.temperature.value == settings->night.temperature.value &&
-	    settings->day.brightness.value == settings->night.brightness.value &&
-	    settings->day.gamma.value[0] == settings->night.gamma.value[0] &&
-	    settings->day.gamma.value[1] == settings->night.gamma.value[1] &&
-	    settings->day.gamma.value[2] == settings->night.gamma.value[2]) {
-		scheme.type = STATIC_SCHEME;
-	}
-#if defined(__GNUC__)
-# pragma GCC diagnostic pop
-#endif
-
 	/* If reseting effects, use neutral colour settings (static scheme) and do not preserve gamma */
 	if (mode == PROGRAM_MODE_RESET) {
 		scheme.type = STATIC_SCHEME;
@@ -878,6 +868,8 @@ load_settings(struct settings *settings, int argc, char *argv[])
 	}
 
 	/* Publish loaded settings */
+	preserve_gamma = settings->preserve_gamma.value;
+	use_fade = settings->use_fade.value;
 	day_settings.temperature = settings->day.temperature.value;
 	day_settings.brightness = settings->day.brightness.value;
 	day_settings.gamma[0] = settings->day.gamma.value[0];
@@ -888,7 +880,10 @@ load_settings(struct settings *settings, int argc, char *argv[])
 	night_settings.gamma[0] = settings->night.gamma.value[0];
 	night_settings.gamma[1] = settings->night.gamma.value[1];
 	night_settings.gamma[2] = settings->night.gamma.value[2];
-	if (scheme.type == SOLAR_SCHEME) {
+	if (!memcmp(&day_settings, &night_settings, sizeof(day_settings))) {
+		/* If the effects are the same throughout the day, do not use a transition scheme */
+		scheme.type = STATIC_SCHEME;
+	} else if (scheme.type == SOLAR_SCHEME) {
 		scheme.elevation.high = settings->elevation_high.value;
 		scheme.elevation.low = settings->elevation_low.value;
 		scheme.elevation.range = scheme.elevation.high - scheme.elevation.low;
diff --git a/src/gamma-coopgamma.c b/src/gamma-coopgamma.c
index a4e08ef..fab083b 100644
--- a/src/gamma-coopgamma.c
+++ b/src/gamma-coopgamma.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -20,18 +21,24 @@
 
 #include <libcoopgamma.h>
 
+#if defined(__clang__)
+# pragma clang diagnostic ignored "-Wkeyword-macro"
+#endif
+
 
 struct coopgamma_output_id {
 	char *edid;
 	size_t index;
 };
 
+
 struct coopgamma_crtc_state {
 	libcoopgamma_filter_t filter;
 	libcoopgamma_ramps_t plain_ramps;
 	size_t rampsize;
 };
 
+
 struct gamma_state {
 	libcoopgamma_context_t ctx;
 	struct coopgamma_crtc_state *crtcs;
@@ -49,6 +56,7 @@ struct gamma_state {
 
 struct signal_blockage {int dummy;};
 
+
 static int
 unblocked_signal(int signo, struct signal_blockage *prev)
 {
@@ -145,6 +153,7 @@ coopgamma_create(struct gamma_state **state_out)
 	return 0;
 }
 
+
 static int
 coopgamma_start(struct gamma_state *state)
 {
@@ -242,12 +251,12 @@ coopgamma_start(struct gamma_state *state)
 		crtc->filter.priority = state->priority;
 		crtc->filter.crtc = state->outputs[i].edid;
 		crtc->filter.lifespan = lifespan;
-#if defined(__GNUC__)
+#if defined(__GNUC__) && !defined(__clang__)
 # pragma GCC diagnostic push
 # pragma GCC diagnostic ignored "-Wdiscarded-qualifiers"
 #endif
 		crtc->filter.class = PACKAGE "::redshift::standard";
-#if defined(__GNUC__)
+#if defined(__GNUC__) && !defined(__clang__)
 # pragma GCC diagnostic pop
 #endif
 
@@ -276,14 +285,15 @@ coopgamma_start(struct gamma_state *state)
 		LIST_RAMPS_STOP_VALUE_TYPES(X, ;);
 #undef X
 		default:
-			if (info.depth > 0)
-				fprintf(stderr, _("output `%s' uses an unsupported depth "
-						  "for its gamma ramps: %i bits, skipping\n"),
-					outputs[i], info.depth);
-			else
-				fprintf(stderr, _("output `%s' uses an unrecognised depth, "
-						  "for its gamma ramps, with the code %i, "
-						  "skipping\n"), outputs[i], info.depth);
+			if (info.depth > 0) {
+				weprintf(_("output `%s' uses an unsupported depth "
+				           "for its gamma ramps: %i bits, skipping\n"),
+				         outputs[i], info.depth);
+			} else {
+				weprintf(_("output `%s' uses an unrecognised depth, "
+				           "for its gamma ramps, with the code %i, "
+				           "skipping\n"), outputs[i], info.depth);
+			}
 			continue;
 		}
 		crtc->rampsize *= info.red_size + info.green_size + info.blue_size;
@@ -347,6 +357,7 @@ coopgamma_start(struct gamma_state *state)
 	return 0;
 }
 
+
 static void
 coopgamma_free(struct gamma_state *state)
 {
@@ -374,14 +385,14 @@ coopgamma_free(struct gamma_state *state)
 	state->outputs = NULL;
 }
 
+
 static void
 coopgamma_print_help(FILE *f)
 {
 	fputs(_("Adjust gamma ramps with coopgamma.\n"), f);
 	fputs("\n", f);
 
-	/* TRANSLATORS: coopgamma help output
-	   left column must not be translated */
+	/* TRANSLATORS: coopgamma help output left column must not be translated */
 	fputs(_("  edid=EDID      \tEDID of monitor to apply adjustments to, enter "
 		"`list' to list available monitors\n"
 		"  crtc=N         \tIndex of CRTC to apply adjustments to\n"
@@ -394,6 +405,7 @@ coopgamma_print_help(FILE *f)
 	fputs("\n", f);
 }
 
+
 static int
 coopgamma_set_option(struct gamma_state *state, const char *key, const char *value)
 {
@@ -416,8 +428,7 @@ coopgamma_set_option(struct gamma_state *state, const char *key, const char *val
 			return -1;
 		}
 		if (!strcasecmp(value, "list")) {
-			/* TRANSLATORS: coopgamma help output
-			   the word "coopgamma" must not be translated */
+			/* TRANSLATORS: coopgamma help output the word "coopgamma" must not be translated */
 			printf(_("Available adjustment methods for coopgamma:\n"));
 			for (i = 0; state->methods[i]; i++)
 				printf("  %s\n", state->methods[i]);
@@ -454,13 +465,14 @@ coopgamma_set_option(struct gamma_state *state, const char *key, const char *val
 		}
 		state->n_outputs++;
 	} else {
-		fprintf(stderr, _("Unknown method parameter: `%s'."), key);
+		weprintf(_("Unknown method parameter: `%s'."), key);
 		return -1;
 	}
 
 	return 0;
 }
 
+
 static void
 coopgamma_restore(struct gamma_state *state)
 {
@@ -472,6 +484,7 @@ coopgamma_restore(struct gamma_state *state)
 		state->crtcs[i].filter.lifespan = LIBCOOPGAMMA_UNTIL_DEATH;
 }
 
+
 static int
 coopgamma_apply(struct gamma_state *state, const struct colour_setting *setting, int perserve)
 {
@@ -517,4 +530,4 @@ coopgamma_apply(struct gamma_state *state, const struct colour_setting *setting,
 }
 
 
-const struct gamma_method coopgamma_gamma_method = GAMMA_METHOD_INIT("coopgamma", 1, coopgamma);
+const struct gamma_method coopgamma_gamma_method = GAMMA_METHOD_INIT("coopgamma", 1, 0, coopgamma);
diff --git a/src/gamma-drm.c b/src/gamma-drm.c
index 03454ae..2de0261 100644
--- a/src/gamma-drm.c
+++ b/src/gamma-drm.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -35,6 +36,7 @@ struct drm_crtc_state {
 	uint16_t *b_gamma;
 };
 
+
 struct gamma_state {
 	int card_num;
 	int crtc_num;
@@ -57,12 +59,12 @@ drm_create(struct gamma_state **state_out)
 	return 0;
 }
 
+
 static int
 drm_start(struct gamma_state *state)
 {
 	/* Acquire access to a graphics card. */
-	long maxlen = strlen(DRM_DIR_NAME) + strlen(DRM_DEV_NAME) + 10;
-	char pathname[maxlen];
+	char pathname[STRLEN(DRM_DIR_NAME"") + STRLEN(DRM_DEV_NAME"") + 3U * sizeof(int) + 2U];
 	int crtc_count;
 	struct drm_crtc_state *crtcs;
 
@@ -169,6 +171,7 @@ drm_start(struct gamma_state *state)
 	return 0;
 }
 
+
 static void
 drm_restore(struct gamma_state *state)
 {
@@ -182,6 +185,7 @@ drm_restore(struct gamma_state *state)
 	}
 }
 
+
 static void
 drm_free(struct gamma_state *state)
 {
@@ -207,6 +211,7 @@ drm_free(struct gamma_state *state)
 	free(state);
 }
 
+
 static void
 drm_print_help(FILE *f)
 {
@@ -220,6 +225,7 @@ drm_print_help(FILE *f)
 	fputs("\n", f);
 }
 
+
 static int
 drm_set_option(struct gamma_state *state, const char *key, const char *value)
 {
@@ -239,6 +245,7 @@ drm_set_option(struct gamma_state *state, const char *key, const char *value)
 	return 0;
 }
 
+
 static int
 drm_apply(struct gamma_state *state, const struct colour_setting *setting, int preserve)
 {
@@ -283,4 +290,4 @@ drm_apply(struct gamma_state *state, const struct colour_setting *setting, int p
 }
 
 
-const struct gamma_method drm_gamma_method = GAMMA_METHOD_INIT("drm", 0, drm);
+const struct gamma_method drm_gamma_method = GAMMA_METHOD_INIT("drm", 0, 0, drm);
diff --git a/src/gamma-dummy.c b/src/gamma-dummy.c
index 1751bbd..7074cd9 100644
--- a/src/gamma-dummy.c
+++ b/src/gamma-dummy.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -26,6 +27,7 @@ dummy_create(struct gamma_state **state_out)
 	return 0;
 }
 
+
 static int
 dummy_start(struct gamma_state *state)
 {
@@ -34,18 +36,21 @@ dummy_start(struct gamma_state *state)
 	return 0;
 }
 
+
 static void
 dummy_restore(struct gamma_state *state)
 {
 	(void) state;
 }
 
+
 static void
 dummy_free(struct gamma_state *state)
 {
 	(void) state;
 }
 
+
 static void
 dummy_print_help(FILE *f)
 {
@@ -53,6 +58,7 @@ dummy_print_help(FILE *f)
 	fputs("\n", f);
 }
 
+
 static int
 dummy_set_option(struct gamma_state *state, const char *key, const char *value)
 {
@@ -62,6 +68,7 @@ dummy_set_option(struct gamma_state *state, const char *key, const char *value)
 	return -1;
 }
 
+
 static int
 dummy_apply(struct gamma_state *state, const struct colour_setting *setting, int preserve)
 {
@@ -72,4 +79,4 @@ dummy_apply(struct gamma_state *state, const struct colour_setting *setting, int
 }
 
 
-const struct gamma_method dummy_gamma_method = GAMMA_METHOD_INIT("dummy", 0, dummy);
+const struct gamma_method dummy_gamma_method = GAMMA_METHOD_INIT("dummy", 0, 0, dummy);
diff --git a/src/gamma-quartz.c b/src/gamma-quartz.c
index d323d33..c05e72d 100644
--- a/src/gamma-quartz.c
+++ b/src/gamma-quartz.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -27,6 +28,7 @@ struct quartz_display_state {
 	float *saved_ramps;
 };
 
+
 struct gamma_state {
 	struct quartz_display_state *displays;
 	uint32_t display_count;
@@ -41,6 +43,7 @@ quartz_create(struct gamma_state **state_out)
 	return 0;
 }
 
+
 static int
 quartz_start(struct gamma_state *state)
 {
@@ -106,12 +109,14 @@ quartz_start(struct gamma_state *state)
 	return 0;
 }
 
+
 static void
 quartz_restore(struct gamma_state *state)
 {
 	CGDisplayRestoreColorSyncSettings();
 }
 
+
 static void
 quartz_free(struct gamma_state *state)
 {
@@ -123,6 +128,7 @@ quartz_free(struct gamma_state *state)
 	free(state);
 }
 
+
 static void
 quartz_print_help(FILE *f)
 {
@@ -130,6 +136,7 @@ quartz_print_help(FILE *f)
 	fputs("\n", f);
 }
 
+
 static int
 quartz_set_option(struct gamma_state *state, const char *key, const char *value)
 {
@@ -143,6 +150,7 @@ quartz_set_option(struct gamma_state *state, const char *key, const char *value)
 	return 0;
 }
 
+
 static void
 quartz_apply_for_display(struct gamma_state *state, int display_index, const colour_setting_t *setting, int preserve)
 {
@@ -183,16 +191,15 @@ quartz_apply_for_display(struct gamma_state *state, int display_index, const col
 	free(gamma_ramps);
 }
 
+
 static int
 quartz_apply(struct gamma_state *state, const colour_setting_t *setting, int preserve)
 {
 	uint32_t i;
-
 	for (i = 0; i < state->display_count; i++)
 		quartz_apply_for_display(state, i, setting, preserve);
-
 	return 0;
 }
 
 
-const struct gamma_method quartz_gamma_method = GAMMA_METHOD_INIT("quartz", 1, quartz);
+const struct gamma_method quartz_gamma_method = GAMMA_METHOD_INIT("quartz", 1, 1, quartz);
diff --git a/src/gamma-randr.c b/src/gamma-randr.c
index 561a243..10ea277 100644
--- a/src/gamma-randr.c
+++ b/src/gamma-randr.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -35,6 +36,7 @@ struct randr_crtc_state {
 	uint16_t *saved_ramps;
 };
 
+
 struct gamma_state {
 	xcb_connection_t *conn;
 	xcb_screen_t *screen;
@@ -97,6 +99,7 @@ fail:
 	return -1;
 }
 
+
 static int
 randr_start(struct gamma_state *state)
 {
@@ -208,6 +211,7 @@ randr_start(struct gamma_state *state)
 	return 0;
 }
 
+
 static void
 randr_restore(struct gamma_state *state)
 {
@@ -237,6 +241,7 @@ randr_restore(struct gamma_state *state)
 	}
 }
 
+
 static void
 randr_free(struct gamma_state *state)
 {
@@ -254,6 +259,7 @@ randr_free(struct gamma_state *state)
 	free(state);
 }
 
+
 static void
 randr_print_help(FILE *f)
 {
@@ -269,6 +275,7 @@ randr_print_help(FILE *f)
 	fputs("\n", f);
 }
 
+
 static int
 randr_set_option(struct gamma_state *state, const char *key, const char *value)
 {
@@ -322,6 +329,7 @@ randr_set_option(struct gamma_state *state, const char *key, const char *value)
 	return 0;
 }
 
+
 static int
 randr_apply_for_crtc(struct gamma_state *state, int crtc_num, const struct colour_setting *setting, int preserve)
 {
@@ -381,6 +389,7 @@ randr_apply_for_crtc(struct gamma_state *state, int crtc_num, const struct colou
 	return 0;
 }
 
+
 static int
 randr_apply(struct gamma_state *state, const struct colour_setting *setting, int preserve)
 {
@@ -401,4 +410,4 @@ randr_apply(struct gamma_state *state, const struct colour_setting *setting, int
 }
 
 
-const struct gamma_method randr_gamma_method = GAMMA_METHOD_INIT("randr", 1, randr);
+const struct gamma_method randr_gamma_method = GAMMA_METHOD_INIT("randr", 1, 0, randr);
diff --git a/src/gamma-vidmode.c b/src/gamma-vidmode.c
index a855914..7c5321a 100644
--- a/src/gamma-vidmode.c
+++ b/src/gamma-vidmode.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -48,6 +49,7 @@ vidmode_create(struct gamma_state **state_out)
 	return 0;
 }
 
+
 static int
 vidmode_start(struct gamma_state *state)
 {
@@ -97,6 +99,7 @@ vidmode_start(struct gamma_state *state)
 	return 0;
 }
 
+
 static void
 vidmode_free(struct gamma_state *state)
 {
@@ -105,6 +108,7 @@ vidmode_free(struct gamma_state *state)
 	free(state);
 }
 
+
 static void
 vidmode_print_help(FILE *f)
 {
@@ -116,6 +120,7 @@ vidmode_print_help(FILE *f)
 	fputs("\n", f);
 }
 
+
 static int
 vidmode_set_option(struct gamma_state *state, const char *key, const char *value)
 {
@@ -131,6 +136,7 @@ vidmode_set_option(struct gamma_state *state, const char *key, const char *value
 	return 0;
 }
 
+
 static void
 vidmode_restore(struct gamma_state *state)
 {
@@ -146,6 +152,7 @@ vidmode_restore(struct gamma_state *state)
 		weprintf(_("X request failed: %s"), "XF86VidModeSetGammaRamp");
 }
 
+
 static int
 vidmode_apply(struct gamma_state *state, const struct colour_setting *setting, int preserve)
 {
@@ -189,4 +196,4 @@ vidmode_apply(struct gamma_state *state, const struct colour_setting *setting, i
 }
 
 
-const struct gamma_method vidmode_gamma_method = GAMMA_METHOD_INIT("vidmode", 1, vidmode);
+const struct gamma_method vidmode_gamma_method = GAMMA_METHOD_INIT("vidmode", 1, 0, vidmode);
diff --git a/src/gamma-w32gdi.c b/src/gamma-w32gdi.c
index 533365d..6912167 100644
--- a/src/gamma-w32gdi.c
+++ b/src/gamma-w32gdi.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -40,6 +41,7 @@ w32gdi_create(struct gamma_state **state_out)
 	return 0;
 }
 
+
 static int
 w32gdi_start(struct gamma_state *state)
 {
@@ -76,6 +78,7 @@ w32gdi_start(struct gamma_state *state)
 	return 0;
 }
 
+
 static void
 w32gdi_free(struct gamma_state *state)
 {
@@ -84,6 +87,7 @@ w32gdi_free(struct gamma_state *state)
 }
 
 
+
 static void
 w32gdi_print_help(FILE *f)
 {
@@ -91,6 +95,7 @@ w32gdi_print_help(FILE *f)
 	fputs("\n", f);
 }
 
+
 static int
 w32gdi_set_option(struct gamma_state *state, const char *key, const char *value)
 {
@@ -104,6 +109,7 @@ w32gdi_set_option(struct gamma_state *state, const char *key, const char *value)
 	return 0;
 }
 
+
 static void
 w32gdi_restore(struct gamma_state *state)
 {
@@ -132,6 +138,7 @@ done:
 	ReleaseDC(NULL, hDC);
 }
 
+
 static int
 w32gdi_apply(struct gamma_state *state, const colour_setting_t *setting, int preserve)
 {
@@ -191,4 +198,4 @@ done:
 }
 
 
-const struct gamma_method w32gdi_gamma_method = GAMMA_METHOD_INIT("winfdi", 1, w32gdi);
+const struct gamma_method w32gdi_gamma_method = GAMMA_METHOD_INIT("winfdi", 1, 0, w32gdi);
diff --git a/src/gamma.c b/src/gamma.c
index 628105b..5b64f8c 100644
--- a/src/gamma.c
+++ b/src/gamma.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -43,6 +44,15 @@ const struct gamma_method *gamma_methods[] = {
 };
 
 
+/**
+ * Attempt to start a specific adjustment method
+ * 
+ * @param   method     The adjustment method
+ * @param   state_out  Output parameter for the adjustment method state
+ * @param   config     Loaded information file
+ * @param   args       `NULL` or option part of the command line argument for the adjustment method
+ * @return             0 on success, -1 on failure
+ */
 static int
 try_start(const struct gamma_method *method, GAMMA_STATE **state_out, struct config_ini_state *config, char *args)
 {
diff --git a/src/hooks.c b/src/hooks.c
index aaddd4f..e3abf44 100644
--- a/src/hooks.c
+++ b/src/hooks.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -53,7 +54,7 @@ static size_t dirpathlen;
 static const struct env_path paths[] = {
 	{0, "XDG_CONFIG_HOME", "/redshift-ng/hooks"},
 	{0, "XDG_CONFIG_HOME", "/redshift/hooks"},
-#ifdef WINDOWS
+#if defined(WINDOWS)
 	{0, "localappdata", "/redshift-ng/hooks"},
 	{0, "localappdata", "/redshift/hooks"},
 #endif
@@ -63,8 +64,10 @@ static const struct env_path paths[] = {
 	{0, NULL, "/.config/redshift/hooks"},
 	{1, "XDG_CONFIG_DIRS", "/redshift-ng/hooks"},
 	{1, "XDG_CONFIG_DIRS", "/redshift/hooks"},
+#if !defined(WINDOWS)
 	{0, "", "/etc/redshift-ng/hooks"},
 	{0, "", "/etc/redshift/hooks"}
+#endif
 };
 
 
diff --git a/src/location-corelocation.m b/src/location-corelocation.m
index 9f45899..c53ed14 100644
--- a/src/location-corelocation.m
+++ b/src/location-corelocation.m
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -22,17 +23,53 @@
 #import <CoreLocation/CoreLocation.h>
 
 
+/**
+ * Location data
+ */
 struct location_data {
+	/**
+	 * The user's geographical location
+	 */
 	struct location location;
+
+	/**
+	 * Whether the location provider is available
+	 */
 	int available;
+
+	/**
+	 * Whether an unrecoverable error has occurred
+	 */
 	int error;
 };
 
+
 struct location_state {
+	/**
+	 * Slave thread, used to receive location updates
+	 */
 	NSThread *thread;
+
+	/**
+	 * Read-end of piped used to send location data
+	 * from the slave thread to the master thread
+	 */
 	int pipe_fd_read;
+
+	/**
+	 * Write-end of piped used to send location data
+	 * from the slave thread to the master thread
+	 */
 	int pipe_fd_write;
+
+	/**
+	 * Location data available from the slave thread
+	 */
 	struct location_data data;
+
+	/**
+	 * Location data sent to the master thread
+	 */
 	struct location_data saved_data;
 };
 
@@ -136,6 +173,7 @@ pipe_close_callback(CFFileDescriptorRef fdref, CFOptionFlags callBackTypes, void
 	@property (nonatomic) struct location_state *state;
 @end
 
+
 @implementation LocationThread;
 
 // Run loop for location provider thread.
@@ -177,6 +215,7 @@ corelocation_create(struct location_state **state_out)
 	return 0;
 }
 
+
 static int
 corelocation_start(struct location_state *state)
 {
@@ -192,11 +231,7 @@ corelocation_start(struct location_state *state)
 	state->data.location.lon = 0;
 	state->saved_data = state->data;
 
-	if (pipe_rdnonblock(pipefds)) {
-		weprintf(_("Failed to start CoreLocation provider!"));
-		return -1;
-	}
-
+	pipe_rdnonblock(pipefds);
 	state->pipe_fd_read = pipefds[0];
 	state->pipe_fd_write = pipefds[1];
 
@@ -210,6 +245,7 @@ corelocation_start(struct location_state *state)
 	return 0;
 }
 
+
 static void
 corelocation_free(struct location_state *state)
 {
@@ -218,6 +254,7 @@ corelocation_free(struct location_state *state)
 	free(state);
 }
 
+
 static void
 corelocation_print_help(FILE *f)
 {
@@ -225,6 +262,7 @@ corelocation_print_help(FILE *f)
 	fputs("\n", f);
 }
 
+
 static int
 corelocation_set_option(struct location_state *state, const char *key, const char *value)
 {
@@ -234,12 +272,14 @@ corelocation_set_option(struct location_state *state, const char *key, const cha
 	return -1;
 }
 
+
 static int
 corelocation_get_fd(struct location_state *state)
 {
 	return state->pipe_fd_read;
 }
 
+
 static int
 corelocation_fetch(struct location_state *state, struct location *location_out, int *available_out)
 {
diff --git a/src/location-geoclue2.c b/src/location-geoclue2.c
index 84ef6b4..69323c2 100644
--- a/src/location-geoclue2.c
+++ b/src/location-geoclue2.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -33,21 +34,62 @@
 # pragma clang diagnostic pop
 #endif
 
+
+/**
+ * D-Bus error indicating denial of access
+ */
 #define DBUS_ACCESS_ERROR  "org.freedesktop.DBus.Error.AccessDenied"
 
 
+/**
+ * Location data
+ */
 struct location_data {
+	/**
+	 * The user's geographical location
+	 */
 	struct location location;
+
+	/**
+	 * Whether the location provider is available
+	 */
 	int available;
+
+	/**
+	 * Whether an unrecoverable error has occurred
+	 */
 	int error;
 };
 
+
 struct location_state {
 	GMainLoop *loop;
+
+	/**
+	 * Slave thread, used to receive location updates
+	 */
 	GThread *thread;
+
+	/**
+	 * Read-end of piped used to send location data
+	 * from the slave thread to the master thread
+	 */
 	int pipe_fd_read;
+
+	/**
+	 * Write-end of piped used to send location data
+	 * from the slave thread to the master thread
+	 */
 	int pipe_fd_write;
+
+	/**
+	 * Location data available from the slave thread
+	 */
 	struct location_data data;
+
+	/**
+	 * Location data sent to the master thread
+	 */
 	struct location_data saved_data;
 };
 
@@ -64,12 +106,14 @@ print_denial_message(void)
 		"information.\n"));
 }
 
+
 static void
 send_data(struct location_state *state)
 {
 	while (write(state->pipe_fd_write, &state->data, sizeof(state->data)) == -1 && errno == EINTR);
 }
 
+
 /* Indicate an unrecoverable error during GeoClue2 communication */
 static void
 mark_error(struct location_state *state)
@@ -78,6 +122,7 @@ mark_error(struct location_state *state)
 	send_data(state);
 }
 
+
 /* Handle position change callbacks */
 static void
 geoclue_client_signal_cb(GDBusProxy *client, gchar *sender_name, gchar *signal_name, GVariant *parameters, gpointer user_data)
@@ -119,6 +164,7 @@ geoclue_client_signal_cb(GDBusProxy *client, gchar *sender_name, gchar *signal_n
 	send_data(state);
 }
 
+
 /* Callback when GeoClue name appears on the bus */
 static void
 on_name_appeared(GDBusConnection *conn, const gchar *name, const gchar *name_owner, gpointer user_data)
@@ -230,6 +276,7 @@ on_name_appeared(GDBusConnection *conn, const gchar *name, const gchar *name_own
 	g_variant_unref(ret_v);
 }
 
+
 /* Callback when GeoClue disappears from the bus */
 static void
 on_name_vanished(GDBusConnection *connection, const gchar *name, gpointer user_data)
@@ -243,6 +290,7 @@ on_name_vanished(GDBusConnection *connection, const gchar *name, gpointer user_d
 	send_data(state);
 }
 
+
 /* Callback when the pipe to the main thread is closed */
 static gboolean
 on_pipe_closed(GIOChannel *channel, GIOCondition condition, gpointer user_data)
@@ -294,6 +342,7 @@ run_geoclue2_loop(void *state_)
 	return NULL;
 }
 
+
 static int
 geoclue2_create(struct location_state **state_out)
 {
@@ -304,6 +353,7 @@ geoclue2_create(struct location_state **state_out)
 	return 0;
 }
 
+
 static int
 geoclue2_start(struct location_state *state)
 {
@@ -318,11 +368,7 @@ geoclue2_start(struct location_state *state)
 	state->data.location.longitude = 0;
 	state->saved_data = state->data;
 
-	if (pipe_rdnonblock(pipefds)) {
-		weprintf(_("Failed to start GeoClue2 provider!"));
-		return -1;
-	}
-
+	pipe_rdnonblock(pipefds);
 	state->pipe_fd_read = pipefds[0];
 	state->pipe_fd_write = pipefds[1];
 
@@ -333,6 +379,7 @@ geoclue2_start(struct location_state *state)
 	return 0;
 }
 
+
 static void
 geoclue2_free(struct location_state *state)
 {
@@ -346,6 +393,7 @@ geoclue2_free(struct location_state *state)
 	free(state);
 }
 
+
 static void
 geoclue2_print_help(FILE *f)
 {
@@ -353,6 +401,7 @@ geoclue2_print_help(FILE *f)
 	fputs("\n", f);
 }
 
+
 static int
 geoclue2_set_option(struct location_state *state, const char *key, const char *value)
 {
@@ -362,12 +411,14 @@ geoclue2_set_option(struct location_state *state, const char *key, const char *v
 	return -1;
 }
 
+
 static int
 geoclue2_get_fd(struct location_state *state)
 {
 	return state->pipe_fd_read;
 }
 
+
 static int
 geoclue2_fetch(struct location_state *state, struct location *location_out, int *available_out)
 {
diff --git a/src/location-manual.c b/src/location-manual.c
index a394f29..d1285f1 100644
--- a/src/location-manual.c
+++ b/src/location-manual.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -20,7 +21,10 @@
 
 
 struct location_state {
-	struct location loc;
+	/**
+	 * The specified location, any unspecified coordinate is set to NAN
+	 */
+	struct location location;
 };
 
 
@@ -28,34 +32,36 @@ static int
 manual_create(struct location_state **state_out)
 {
 	*state_out = emalloc(sizeof(**state_out));
-	(*state_out)->loc.latitude = NAN;
-	(*state_out)->loc.longitude = NAN;
+	(*state_out)->location.latitude = FNAN;
+	(*state_out)->location.longitude = FNAN;
 	return 0;
 }
 
+
 GCC_ONLY(__attribute__((__pure__)))
 static int
 manual_start(struct location_state *state)
 {
-	if (isnan(state->loc.latitude) || isnan(state->loc.longitude))
+	if (isnan(state->location.latitude) || isnan(state->location.longitude))
 		eprintf(_("Latitude and longitude must be set."));
 	return 0;
 }
 
+
 static void
 manual_free(struct location_state *state)
 {
 	free(state);
 }
 
+
 static void
 manual_print_help(FILE *f)
 {
 	fputs(_("Specify location manually.\n"), f);
 	fputs("\n", f);
 
-	/* TRANSLATORS: Manual location help output
-	   left column must not be translated */
+	/* TRANSLATORS: Manual location help output left column must not be translated */
 	fputs(_("  lat=N\t\tLatitude\n"
 		"  lon=N\t\tLongitude\n"), f);
 	fputs("\n", f);
@@ -64,10 +70,10 @@ manual_print_help(FILE *f)
 	fputs("\n", f);
 }
 
+
 static int
 manual_set_option(struct location_state *state, const char *key, const char *value)
 {
-	/* Parse float value */
 	char *end;
 	double v;
 
@@ -79,9 +85,9 @@ manual_set_option(struct location_state *state, const char *key, const char *val
 	}
 
 	if (!strcasecmp(key, "lat")) {
-		state->loc.latitude = v;
+		state->location.latitude = v;
 	} else if (!strcasecmp(key, "lon")) {
-		state->loc.longitude = v;
+		state->location.longitude = v;
 	} else {
 		weprintf(_("Unknown method parameter: `%s'."), key);
 		return -1;
@@ -90,6 +96,7 @@ manual_set_option(struct location_state *state, const char *key, const char *val
 	return 0;
 }
 
+
 static int
 manual_get_fd(struct location_state *state)
 {
@@ -97,10 +104,11 @@ manual_get_fd(struct location_state *state)
 	return -1;
 }
 
+
 static int
 manual_fetch(struct location_state *state, struct location *location_out, int *available_out)
 {
-	*location_out = state->loc;
+	*location_out = state->location;
 	*available_out = 1;
 	return 0;
 }
diff --git a/src/location.c b/src/location.c
index 60a1ca0..a70be8c 100644
--- a/src/location.c
+++ b/src/location.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -31,6 +32,34 @@ const struct location_provider *location_providers[] = {
 };
 
 
+/**
+ * Get the current monotonic time in milliseconds
+ * 
+ * @return  The number of milliseconds elapsed since some arbitrary fixed time
+ */
+static long long int
+get_monotonic_millis(void)
+{
+#if defined(WINDOWS)
+	return (long long int)GetTickCount64();
+#else
+	struct timespec now;
+	if (clock_gettime(CLOCK_MONOTONIC, &now))
+		eprintf("clock_gettime CLOCK_MONOTONIC:");
+	return (long long int)now.tv_sec * 1000LL + (long long int)now.tv_nsec / 1000000LL;
+#endif
+}
+
+
+/**
+ * Attempt to start a specific location provider
+ * 
+ * @param   provider   The location provider
+ * @param   state_out  Output parameter for the location provider state
+ * @param   config     Loaded information file
+ * @param   args       `NULL` or option part of the command line argument for the location provider
+ * @return             0 on success, -1 on failure
+ */
 static int
 try_start(const struct location_provider *provider, LOCATION_STATE **state_out, struct config_ini_state *config, char *args)
 {
@@ -65,7 +94,7 @@ try_start(const struct location_provider *provider, LOCATION_STATE **state_out,
 			 * without keys on the command line for convencience
 			 * and for backwards compatability. We add the proper
 			 * keys here before calling set_option(). */
-			if (!strcmp(provider->name, "manual") && i < ELEMSOF(manual_keys)) {
+			if (!strcmp(provider->name, "manual") && i < (int)ELEMSOF(manual_keys)) {
 				key = manual_keys[i];
 				value = args;
 			} else {
@@ -103,28 +132,15 @@ fail:
 }
 
 
-static long long int
-get_monotonic_millis(void)
-{
-#if defined(WINDOWS)
-	return (long long int)GetTickCount64();
-#else
-	struct timespec now;
-	if (clock_gettime(CLOCK_MONOTONIC, &now))
-		eprintf("clock_gettime CLOCK_MONOTONIC:");
-	return (long long int)now.tv_sec * 1000LL + (long long int)now.tv_nsec / 1000000LL;
-#endif
-}
-
-
-/* Wait for location to become available from provider.
-   Waits until timeout (milliseconds) has elapsed or forever if timeout
-   is -1. Writes location to loc. Returns -1 on error,
-   0 if timeout was reached, 1 if location became available. */
 int
-get_location(const struct location_provider *provider, LOCATION_STATE *state, int timeout, struct location *loc)
+get_location(const struct location_provider *provider, LOCATION_STATE *state, int timeout, struct location *location_out)
 {
-	int r, available;
+#ifdef WINDOWS /* we don't have poll on Windows, but neither do with have any dynamic location providers */
+	int available;
+	return provider->fetch(state, location_out, &available) < 0 ? -1 : available;
+
+#else
+	int r, available = 0;
 	struct pollfd pollfds[1];
 	long long int now = get_monotonic_millis();
 	long long int end = now + (long long int)timeout;
@@ -150,11 +166,12 @@ get_location(const struct location_provider *provider, LOCATION_STATE *state, in
 			}
 		}
 
-		if (provider->fetch(state, loc, &available) < 0)
+		if (provider->fetch(state, location_out, &available) < 0)
 			return -1;
 	} while (!available);
 
 	return 1;
+#endif
 }
 
 
diff --git a/src/redshift.c b/src/redshift.c
index 04c6c77..77cabb8 100644
--- a/src/redshift.c
+++ b/src/redshift.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -18,42 +19,54 @@
  */
 #include "common.h"
 
-/* poll.h is not available on Windows but there is no Windows location provider
- * using polling. On Windows, we just define some stubs to make things compile.
+
+/**
+ * The number of milliseconds to sleep normally between colour updates
  */
-#ifndef WINDOWS
-# include <poll.h>
-#else
-# define POLLIN 0
-struct pollfd {
-	int fd;
-	short events;
-	short revents;
-};
-int poll(struct pollfd *fds, int nfds, int timeout) { abort(); }
-#endif
+#define SLEEP_DURATION  5000U
 
+/**
+ * The number of milliseconds to sleep between each step during
+ * fade between large colour settings
+ */
+#define SLEEP_DURATION_SHORT  25U
 
-/* Duration of sleep between screen updates (milliseconds). */
-#define SLEEP_DURATION        5000
-#define SLEEP_DURATION_SHORT  100
+/**
+ * The fade time, for when making large changes in colour
+ * settings, divided by `SLEEP_DURATION_SHORT`
+ */
+#define FADE_LENGTH  160U
 
-/* Length of fade in numbers of short sleep durations. */
-#define FADE_LENGTH  40
 
+/**
+ * The user's current geographical location
+ */
+static struct location location;
 
-#if defined(__GNUC__)
-# pragma GCC diagnostic push
-# pragma GCC diagnostic ignored "-Wfloat-equal"
-#endif
-static int
-exact_eq(double a, double b)
-{
-	return a == b;
-}
-#if defined(__GNUC__)
-# pragma GCC diagnostic pop
-#endif
+/**
+ * Whether the location provider is available
+ */
+static int location_available;
+
+/**
+ * State of location provider, `NULL` if none
+ */
+static LOCATION_STATE *provider_state;
+
+/**
+ * Locaiton provider functions
+ */
+static const struct location_provider *provider;
+
+/**
+ * State of the gamma ramp adjustment method, `NULL` if none (print mode)
+ */
+static GAMMA_STATE *method_state;
+
+/**
+ * Gamma ramp adjustment functions
+ */
+static const struct gamma_method *method;
 
 
 /**
@@ -124,14 +137,12 @@ print_period(enum period period, double day_level)
  * Get the current period of day and the colour settings
  * applicable to the current time of the day
  * 
- * @param  location       Geographical user location
  * @param  colour_out     Output parameter for the colour settings
  * @param  period_out     Output parameter for the period of the day
  * @param  day_level_out  Output parameter for the dayness level
  */
 static void
-get_colour_settings(const struct location *location, struct colour_setting *colour_out,
-                    enum period *period_out, double *day_level_out)
+get_colour_settings(struct colour_setting *colour_out, enum period *period_out, double *day_level_out)
 {
 	time_t time_offset;
 	double t, elevation;
@@ -148,7 +159,7 @@ get_colour_settings(const struct location *location, struct colour_setting *colo
 		*day_level_out = fma(t, scheme.time.periods->diff_over_duration, scheme.time.periods->day_level);
 
 	} else if (scheme.type == SOLAR_SCHEME) {
-		if (libred_solar_elevation(location->latitude, location->longitude, &elevation))
+		if (libred_solar_elevation(location.latitude, location.longitude, &elevation))
 			eprintf("libred_solar_elevation:");
 		if (verbose) {
 			/* TRANSLATORS: Append degree symbol if possible. */
@@ -158,7 +169,7 @@ get_colour_settings(const struct location *location, struct colour_setting *colo
 
 	} else {
 		/* Static scheme, no dayness-level or peroid; day_settings == nigh_settings, use either */
-		*day_level_out = NAN;
+		*day_level_out = FNAN;
 		*period_out = PERIOD_NONE;
 		*colour_out = day_settings;
 		return;
@@ -200,201 +211,167 @@ ease_fade(double t)
 }
 
 
-/* Run continual mode loop
-   This is the main loop of the continual mode which keeps track of the
-   current time and continuously updates the screen to the appropriate
-   colour temperature. */
+#ifndef WINDOWS /* we don't have poll on Windows, but neither do with have any dynamic location providers  */
+/**
+ * Get the current location
+ * 
+ * The function will return once any of the following has occured:
+ * - the specified timeout duration has elapsed,
+ * - a location message has been received (could be location or error), or
+ * - a signal(7) was received
+ * 
+ * @param  timeout      The number of milliseconds to wait before
+ *                      returning without updating the location
+ * @param  location_fd  File descriptor to wait on to receive input event
+ */
 static void
-run_continual_mode(const struct location_provider *provider, LOCATION_STATE *location_state,
-                   const struct gamma_method *method, GAMMA_STATE *method_state, int use_fade,
-                   int preserve_gamma)
+pull_location(unsigned int timeout, int location_fd)
 {
-	int done = 0;
-	int prev_disabled = 1;
-	int disabled = 0;
-	int location_available = 1;
-	struct colour_setting fade_start_interp;
-	struct colour_setting prev_target_interp;
-	struct colour_setting interp;
-	struct location loc;
-
-	/* Short fade parameters */
-	int fade_length = 0;
-	int fade_time = 0;
-
-	/* Save previous parameters so we can avoid printing status updates if
-	 * the values did not change. */
-	enum period prev_period = PERIOD_NONE;
-
-	install_signal_handlers();
-
-	/* Previous target colour setting and current actual colour setting.
-	 * Actual colour setting takes into account the current colour fade. */
-	prev_target_interp = COLOUR_SETTING_NEUTRAL;
-
-	interp = COLOUR_SETTING_NEUTRAL;
-
-	loc = (struct location){NAN, NAN};
-	if (scheme.type == SOLAR_SCHEME) {
-		weprintf(_("Waiting for initial location to become available..."));
+	struct pollfd pollfds[1];
+	struct location new_location;
+	int r, new_available;
+
+	/* Await new location information */
+	pollfds[0].fd = location_fd;
+	pollfds[0].events = POLLIN;
+	r = poll(pollfds, 1, (int)timeout);
+	if (r < 0) {
+#ifndef WINDOWS
+		if (errno == EINTR)
+			return;
+#endif
+		weprintf("poll:");
+		eprintf(_("Unable to get location from provider."));
+	} else if (!r) {
+		return;
+	}
 
-		if (get_location(provider, location_state, -1, &loc) < 0)
-			eprintf(_("Unable to get location from provider."));
+	/* Get new location and availability information */
+	if (provider->fetch(provider_state, &new_location, &new_available) < 0)
+		eprintf(_("Unable to get location from provider."));
+	if (new_available < location_available) {
+		weprintf(_("Location is temporarily unavailable; using previous"
+			   " location until it becomes available..."));
+		location_available = 0;
+		return;
+	}
 
-		if (!location_is_valid(&loc))
+	/* Store and announce new location */
+	if (new_available > location_available ||
+	    !exact_eq(new_location.latitude, location.latitude) ||
+	    !exact_eq(new_location.longitude, location.longitude)) {
+		location_available = 1;
+		location = new_location;
+		print_location(&location);
+		if (!location_is_valid(&location))
 			eprintf(_("Invalid location returned from provider."));
-
-		print_location(&loc);
 	}
+}
+#endif
 
-	if (verbose) {
-		printf(_("Color temperature: %luK\n"), interp.temperature);
-		printf(_("Brightness: %.2f\n"), interp.brightness);
-	}
 
-	/* Continuously adjust colour temperature */
-	for (;;) {
-		enum period period;
-		double day_level;
-		struct colour_setting target_interp;
-		int delay, loc_fd;
+/**
+ * Loop for `PROGRAM_MODE_CONTINUAL`
+ */
+static void
+run_continual_mode(void)
+{
+	enum period period, prev_period = PERIOD_NONE;
+	double day_level = FNAN, prev_day_level = FNAN;
+	int disabled = 0, prev_disabled = !disabled;
+	int done = 0;
+	struct colour_setting colour;
+	struct colour_setting target_colour, prev_target_colour;
+	struct colour_setting fade_start_colour;
+	unsigned int fade_length = 0;
+	unsigned int fade_time = 0;
+	unsigned int delay;
+	double fade_progress, eased_fade_progress;
+#ifndef WINDOWS
+	int location_fd;
+#endif
 
-		/* Check to see if disable signal was caught */
+	prev_target_colour = COLOUR_SETTING_NEUTRAL;
+	colour = COLOUR_SETTING_NEUTRAL;
+
+	for (;;) {
+		/* Act on signals */
 		if (disable && !done) {
-			disabled = !disabled;
+			disabled ^= 1;
 			disable = 0;
 		}
-
-		/* Check to see if exit signal was caught */
 		if (exiting) {
-			if (done)
+			if (done) /* TODO also if already disabled (fade complete) */
 				break; /* On second signal stop the ongoing fade */
 			done = 1;
 			disabled = 1;
 			exiting = 0;
 		}
-
-		/* Print status change */
 		if (verbose && disabled != prev_disabled)
 			printf(_("Status: %s\n"), disabled ? _("Disabled") : _("Enabled"));
-
 		prev_disabled = disabled;
 
-		get_colour_settings(&loc, &target_interp, &period, &day_level);
-
+		/* Get dayness level and corresponding colour settings */
 		if (disabled) {
 			period = PERIOD_NONE;
-			target_interp = COLOUR_SETTING_NEUTRAL;
+			target_colour = COLOUR_SETTING_NEUTRAL;
+		} else {
+			get_colour_settings(&target_colour, &period, &day_level);
 		}
-
-		if (done)
-			period = PERIOD_NONE;
-
-		/* Print period if it changed during this update,
-		 * or if we are in the transition period. In transition we
-		 * print the progress, so we always print it in
-		 * that case. */
-		if (verbose && (period != prev_period || period == PERIOD_TRANSITION))
+		if (verbose && (period != prev_period || !exact_eq(day_level, prev_day_level)))
 			print_period(period, day_level);
-
-		/* Activate hooks if period changed */
 		if (period != prev_period)
 			run_period_change_hooks(prev_period, period);
+		prev_period = period;
+		prev_day_level = day_level;
+		if (verbose) {
+			if (prev_target_colour.temperature != target_colour.temperature)
+				printf(_("Color temperature: %luK\n"), target_colour.temperature);
+			if (!exact_eq(prev_target_colour.brightness, target_colour.brightness))
+				printf(_("Brightness: %.2f\n"), target_colour.brightness);
+			if (memcmp(prev_target_colour.gamma, target_colour.gamma, sizeof(target_colour.gamma))) {
+				printf(_("Gamma: %.3f, %.3f, %.3f\n"),
+				       target_colour.gamma[0], target_colour.gamma[1], target_colour.gamma[2]);
+			}
+		}
 
-		/* Start fade if the parameter differences are too big to apply instantly */
-		if (use_fade && colour_setting_diff_is_major(&target_interp, fade_length ? &prev_target_interp : &interp)) {
+		/* Fade if the parameter differences are too big to apply instantly */
+		if (use_fade && colour_setting_diff_is_major(&target_colour, fade_length ? &prev_target_colour : &colour)) {
 			fade_length = FADE_LENGTH;
 			fade_time = 0;
-			fade_start_interp = interp;
+			fade_start_colour = colour;
 		}
-
-		/* Handle ongoing fade */
-		if (fade_length != 0) {
-			double frac = ++fade_time / (double)fade_length;
-			double alpha = CLAMP(0.0, ease_fade(frac), 1.0);
-
-			interpolate_colour_settings(&fade_start_interp, &target_interp, alpha, &interp);
-
-			if (fade_time > fade_length) {
+		if (fade_length) {
+			fade_progress = ++fade_time / (double)fade_length;
+			eased_fade_progress = ease_fade(fade_progress);
+			interpolate_colour_settings(&fade_start_colour, &target_colour, eased_fade_progress, &colour);
+			if (fade_time == fade_length) {
 				fade_time = 0;
 				fade_length = 0;
 			}
 		} else {
-			interp = target_interp;
+			colour = target_colour;
 		}
+		prev_target_colour = target_colour;
 
 		/* Break loop when done and final fade is over */
 		if (done && fade_length == 0)
 			break;
 
-		if (verbose) {
-			if (prev_target_interp.temperature != target_interp.temperature)
-				printf(_("Color temperature: %luK\n"), target_interp.temperature);
-			if (!exact_eq(prev_target_interp.brightness, target_interp.brightness))
-				printf(_("Brightness: %.2f\n"), target_interp.brightness);
-		}
-
-		/* Adjust temperature */
-		if (method->apply(method_state, &interp, preserve_gamma) < 0)
+		/* Adjust temperature and sleep */
+		if (method->apply(method_state, &colour, preserve_gamma) < 0)
 			eprintf(_("Temperature adjustment failed."));
-
-		/* Save period and target colour setting as previous */
-		prev_period = period;
-		prev_target_interp = target_interp;
-
-		/* Sleep length depends on whether a fade is ongoing */
 		delay = fade_length ? SLEEP_DURATION_SHORT : SLEEP_DURATION;
-
-		/* Update location */
-		loc_fd = scheme.type == SOLAR_SCHEME ? provider->get_fd(location_state) : -1;
-
-		if (loc_fd >= 0) {
-			struct pollfd pollfds[1];
-			struct location new_loc;
-			int r, new_available;
-
-			/* Provider is dynamic */
-			pollfds[0].fd = loc_fd;
-			pollfds[0].events = POLLIN;
-			r = poll(pollfds, 1, delay);
-			if (r < 0) {
 #ifndef WINDOWS
-				if (errno == EINTR)
-					continue;
+		location_fd = scheme.type == SOLAR_SCHEME ? provider->get_fd(provider_state) : -1;
+		if (location_fd >= 0)
+			pull_location(delay, location_fd);
+		else
 #endif
-				weprintf("poll:");
-				eprintf(_("Unable to get location from provider."));
-			} else if (!r) {
-				continue;
-			}
-
-			/* Get new location and availability information */
-			if (provider->fetch(location_state, &new_loc, &new_available) < 0)
-				eprintf(_("Unable to get location from provider."));
-
-			if (!new_available && new_available != location_available) {
-				weprintf(_("Location is temporarily unavailable; using previous"
-				           " location until it becomes available..."));
-			}
-
-			if (new_available &&
-			    (!exact_eq(new_loc.latitude, loc.latitude) ||
-			     !exact_eq(new_loc.longitude, loc.longitude) ||
-			     new_available != location_available)) {
-				loc = new_loc;
-				print_location(&loc);
-			}
-
-			location_available = new_available;
-
-			if (!location_is_valid(&loc))
-				eprintf(_("Invalid location returned from provider."));
-		} else {
 			millisleep(delay);
-		}
+		/* SLEEP_DURATION_SHORT is short enough for remaining time after interruption to be ignored */
 	}
 
-	/* Restore saved gamma ramps */
 	method->restore(method_state);
 }
 
@@ -403,15 +380,13 @@ int
 main(int argc, char *argv[])
 {
 	struct settings settings;
-	GAMMA_STATE *method_state = NULL;
-	LOCATION_STATE *location_state = NULL;
-	struct location loc = {NAN, NAN};
 	double day_level;
 	enum period period;
 	struct colour_setting colour;
 
 	argv0 = argv[0];
 
+	/* Set up localisation */
 #ifdef ENABLE_NLS
 	setlocale(LC_CTYPE, "");
 	setlocale(LC_MESSAGES, "");
@@ -419,63 +394,68 @@ main(int argc, char *argv[])
 	textdomain(PACKAGE);
 #endif
 
+	/* Get configurations and configure */
 	load_settings(&settings, argc, argv);
-	if (scheme.type == SOLAR_SCHEME)
-		acquire_location_provider(&settings, &location_state);
-	if (mode != PROGRAM_MODE_PRINT)
+	if (scheme.type == SOLAR_SCHEME) {
+		acquire_location_provider(&settings, &provider_state);
+		provider = settings.provider;
+	}
+	if (mode != PROGRAM_MODE_PRINT) {
 		acquire_adjustment_method(&settings, &method_state);
+		method = settings.method;
+	}
 	config_ini_free(&settings.config);
 
-	switch (mode) {
-	case PROGRAM_MODE_ONE_SHOT:
-	case PROGRAM_MODE_PRINT:
-	case PROGRAM_MODE_RESET:
-		if (scheme.type == SOLAR_SCHEME) {
-			weprintf(_("Waiting for current location to become available..."));
-
-			if (get_location(settings.provider, location_state, -1, &loc) < 0)
-				eprintf(_("Unable to get location from provider."));
-
-			if (!location_is_valid(&loc))
-				exit(1);
+	/* Set up interprocess communication */
+	install_signal_handlers();
 
-			print_location(&loc);
-		}
+	/* Get location if required */
+	if (scheme.type == SOLAR_SCHEME) {
+		if (provider->get_fd(provider_state) >= 0)
+			weprintf(_("Waiting for current location to become available..."));
+		if (get_location(provider, provider_state, -1, &location) < 0)
+			eprintf(_("Unable to get location from provider."));
+		if (!location_is_valid(&location))
+			eprintf(_("Invalid location returned from provider."));
+		print_location(&location);
+		location_available = 1;
+	}
 
-		get_colour_settings(&loc, &colour, &period, &day_level);
+	/* Get and print colour to set or if continual mode the initial colour */
+	get_colour_settings(&colour, &period, &day_level); /* needed in contiual mode for `period` and `day_level` */
+	if (mode == PROGRAM_MODE_CONTINUAL)
+		colour = COLOUR_SETTING_NEUTRAL;
+	if (verbose || mode == PROGRAM_MODE_PRINT) {
+		if (scheme.type != STATIC_SCHEME)
+			print_period(period, day_level);
+		printf(_("Color temperature: %luK\n"), colour.temperature);
+		printf(_("Brightness: %.2f\n"), colour.brightness);
+		printf(_("Gamma: %.3f, %.3f, %.3f\n"), colour.gamma[0], colour.gamma[1], colour.gamma[2]);
+	}
 
-		if (verbose || mode == PROGRAM_MODE_PRINT) {
-			if (scheme.type != STATIC_SCHEME)
-				print_period(period, day_level);
-			printf(_("Color temperature: %luK\n"), colour.temperature);
-			printf(_("Brightness: %.2f\n"), colour.brightness);
-			if (mode == PROGRAM_MODE_PRINT)
-				break;
-		}
+	switch (mode) {
+	case PROGRAM_MODE_PRINT:
+		break;
 
-		if (settings.method->apply(method_state, &colour, settings.preserve_gamma.value) < 0)
+	case PROGRAM_MODE_ONE_SHOT:
+	case PROGRAM_MODE_RESET:
+		if (method->apply(method_state, &colour, preserve_gamma) < 0)
 			eprintf(_("Temperature adjustment failed."));
-
-#ifndef WINDOWS
-		/* In Quartz (OSX) the gamma adjustments will automatically revert when
-		 * the process exits. Therefore, we have to loop until Ctrl+C is received. */
-		if (!strcmp(settings.method->name, "quartz")) {
+		if (method->autoreset) {
 			weprintf(_("Press ctrl-c to stop..."));
 			while (!exiting)
 				pause();
 		}
-#endif
 		break;
 
 	case PROGRAM_MODE_CONTINUAL:
-		run_continual_mode(settings.provider, location_state, settings.method, method_state,
-		                   settings.use_fade.value, settings.preserve_gamma.value);
+		run_continual_mode();
 		break;
 	}
 
 	if (method_state)
-		settings.method->free(method_state);
-	if (location_state)
-		settings.provider->free(location_state);
+		method->free(method_state);
+	if (provider_state)
+		provider->free(provider_state);
 	return 0;
 }
diff --git a/src/signals.c b/src/signals.c
index ca88425..3487d23 100644
--- a/src/signals.c
+++ b/src/signals.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
diff --git a/src/util.c b/src/util.c
index a562fd2..0c1adc9 100644
--- a/src/util.c
+++ b/src/util.c
@@ -1,4 +1,5 @@
-/* redshift-ng - Automatically adjust display colour temperature according the Sun
+/*-
+ * redshift-ng - Automatically adjust display colour temperature according the Sun
  * 
  * Copyright (c) 2009-2018        Jon Lund Steffensen <jonlst@gmail.com>
  * Copyright (c) 2014-2016, 2025  Mattias Andrée <m@maandree.se>
@@ -188,43 +189,28 @@ try_path_opendir(const struct env_path *path_spec, const char **path_out, char *
 
 
 #ifndef WINDOWS
-int
+void
 pipe_rdnonblock(int pipefds[2])
 {
 	int i, flags;
 
-	/* Try to use pipe2(2) create O_CLOEXEC pipe, preferably with O_DIRECT */
+	/* Try to use pipe2(2) create O_CLOEXEC pipe */
 # if defined(__linux__) && !defined(MISSING_PIPE2)
-	if (!pipe2(pipefds, O_CLOEXEC | O_DIRECT)) {
+	if (!pipe2(pipefds, O_CLOEXEC))
 		goto apply_nonblock;
-	} else if (errno == EINVAL) {
-		if (!pipe2(pipefds, O_CLOEXEC)) {
-			goto apply_nonblock;
-		} else if (errno != ENOSYS) {
-			weprintf("pipe2 <buffer> O_CLOEXEC:");
-			return -1;
-		}
-	} else if (errno != ENOSYS) {
-		weprintf("pipe2 <buffer> O_CLOEXEC|O_DIRECT:");
-		return -1;
-	}
+	else if (errno != ENOSYS)
+		eprintf("pipe2 <buffer> O_CLOEXEC:");
 # endif
 
-	/* Fallback for when pipe2(2) is not available (also indicates O_DIRECT cannot be used) */
-	if (pipe(pipefds)) {
-		weprintf("pipe:");
-		return -1;
-	}
+	/* Fallback for when pipe2(2) is not available */
+	if (pipe(pipefds))
+		eprintf("pipe:");
 	for (i = 0; i < 2; i++) {
 		flags = fcntl(pipefds[i], F_GETFD);
-		if (flags == -1) {
-			weprintf("fcntl <pipe> F_GETFD:");
-			goto fail;
-		}
-		if (fcntl(pipefds[i], F_SETFD, flags | O_CLOEXEC)) {
-			weprintf("fcntl <pipe> F_SETFD +O_CLOEXEC:");
-			goto fail;
-		}
+		if (flags == -1)
+			eprintf("fcntl <pipe> F_GETFD:");
+		if (fcntl(pipefds[i], F_SETFD, flags | O_CLOEXEC))
+			eprintf("fcntl <pipe> F_SETFD +O_CLOEXEC:");
 	}
 
 	/* Make the read-end non-blocking */
@@ -232,20 +218,9 @@ pipe_rdnonblock(int pipefds[2])
 apply_nonblock:
 # endif
 	flags = fcntl(pipefds[0], F_GETFL);
-	if (flags == -1) {
-		weprintf("fcntl <pipe> F_GETFL:");
-		goto fail;
-	}
-	if (fcntl(pipefds[0], F_SETFL, flags | O_NONBLOCK)) {
-		weprintf("fcntl <pipe> F_SETFL +O_NONBLOCK:");
-		goto fail;
-	}
-
-	return 0;
-
-fail:
-	close(pipefds[0]);
-	close(pipefds[1]);
-	return -1;
+	if (flags == -1)
+		eprintf("fcntl <pipe> F_GETFL:");
+	if (fcntl(pipefds[0], F_SETFL, flags | O_NONBLOCK))
+		eprintf("fcntl <pipe> F_SETFL +O_NONBLOCK:");
 }
 #endif