redshift: Add hooks for user actions on period switch

Hooks are executable scripts in ~/.config/redshift/hooks/ that
are run when a certain event happens. The first parameter to the
script indicates the event and further parameters may indicate
more details about the event.

The event "period-changed" is indicated when the period changes
("night", "daytime", "transition"). The second parameter is the old
period and the third is the new period. The event is signaled when
Redshift starts up with the old period set to "none".

1 files changed, 19 insertions, 0 deletions

diff --git a/src/redshift.c b/src/redshift.c
index 11b7f34..c1fc259 100644
--- a/src/redshift.c
+++ b/src/redshift.c
@@ -48,6 +48,7 @@
 #include "config-ini.h"
 #include "solar.h"
 #include "systemtime.h"
+#include "hooks.h"
 
 
 #define MIN(x,y)  ((x) < (y) ? (x) : (y))
@@ -1422,6 +1423,18 @@ main(int argc, char *argv[])
 			perror("sigaction");
 			exit(EXIT_FAILURE);
 		}
+
+		/* Ignore CHLD signal. This causes child processes
+		   (hooks) to be reaped automatically. */
+		sigact.sa_handler = SIG_IGN;
+		sigact.sa_mask = sigset;
+		sigact.sa_flags = 0;
+
+		r = sigaction(SIGCHLD, &sigact, NULL);
+		if (r < 0) {
+			perror("sigaction");
+			exit(EXIT_FAILURE);
+		}
 #endif /* HAVE_SIGNAL_H && ! __WIN32__ */
 
 		if (verbose) {
@@ -1517,6 +1530,12 @@ main(int argc, char *argv[])
 				print_period(period, transition);
 			}
 
+			/* Activate hooks if period changed */
+			if (period != prev_period) {
+				hooks_signal_period_change(prev_period,
+							   period);
+			}
+
 			/* Ongoing short transition */
 			if (short_trans_delta) {
 				/* Calculate alpha */