From 159754c1cd7d2a86d5ba37746f8baeaf06e34123 Mon Sep 17 00:00:00 2001
From: Jon Lund Steffensen <jonlst@gmail.com>
Date: Fri, 30 May 2014 00:16:35 +0200
Subject: 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".
---
 src/hooks.c | 113 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 src/hooks.c

(limited to 'src/hooks.c')

diff --git a/src/hooks.c b/src/hooks.c
new file mode 100644
index 0000000..d051c4b
--- /dev/null
+++ b/src/hooks.c
@@ -0,0 +1,113 @@
+/* hooks.c -- Hooks triggered by events
+   This file is part of Redshift.
+
+   Redshift is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   Redshift is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with Redshift.  If not, see <http://www.gnu.org/licenses/>.
+
+   Copyright (c) 2014  Jon Lund Steffensen <jonlst@gmail.com>
+*/
+
+#include <stdlib.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <errno.h>
+#ifndef _WIN32
+# include <pwd.h>
+#endif
+
+#include "hooks.h"
+#include "redshift.h"
+
+#define MAX_HOOK_PATH  4096
+
+
+/* Names of periods supplied to scripts. */
+static const char *period_names[] = {
+	"none",
+	"daytime",
+	"night",
+	"transition"
+};
+
+
+/* Try to open the directory containing hooks. HP is a string
+   of MAX_HOOK_PATH length that will be filled with the path
+   of the returned directory. */
+static DIR *
+open_hooks_dir(char *hp)
+{
+	char *env;
+
+	if ((env = getenv("XDG_CONFIG_HOME")) != NULL &&
+	    env[0] != '\0') {
+		snprintf(hp, MAX_HOOK_PATH, "%s/redshift/hooks", env);
+		return opendir(hp);
+	}
+
+	if ((env = getenv("HOME")) != NULL &&
+	    env[0] != '\0') {
+		snprintf(hp, MAX_HOOK_PATH, "%s/.config/redshift/hooks", env);
+		return opendir(hp);
+	}
+
+#ifndef _WIN32
+	struct passwd *pwd = getpwuid(getuid());
+	snprintf(hp, MAX_HOOK_PATH, "%s/.config/redshift/hooks", pwd->pw_dir);
+	return opendir(hp);
+#else
+	return NULL;
+#endif
+}
+
+/* Run hooks with a signal that the period changed. */
+void
+hooks_signal_period_change(period_t prev_period, period_t period)
+{
+	char hooksdir_path[MAX_HOOK_PATH];
+	DIR *hooks_dir = open_hooks_dir(hooksdir_path);
+	if (hooks_dir == NULL) return;
+
+	struct dirent* ent;
+	while ((ent = readdir(hooks_dir)) != NULL) {
+		/* Skip hidden and special files (., ..) */
+		if (ent->d_name[0] == '\0' || ent->d_name[0] == '.') continue;
+
+		char *hook_name = ent->d_name;
+		char hook_path[MAX_HOOK_PATH];
+		snprintf(hook_path, sizeof(hook_path), "%s/%s",
+			 hooksdir_path, hook_name);
+
+#ifndef _WIN32
+		/* Fork and exec the hook. We close stdout
+		   so the hook cannot interfere with the normal
+		   output. */
+		pid_t pid = fork();
+		if (pid == (pid_t)-1) {
+			perror("fork");
+			continue;
+		} else if (pid == 0) { /* Child */
+			close(STDOUT_FILENO);
+
+			int r = execl(hook_path, hook_name,
+				      "period-changed",
+				      period_names[prev_period],
+				      period_names[period], NULL);
+			if (r < 0 && errno != EACCES) perror("execl");
+
+			/* Only reached on error */
+			_exit(EXIT_FAILURE);
+		}
+#endif
+	}
+}
-- 
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