Add pre-save and post-save hooks

This adds support for hooks which are executed before/after saving
calcurse data. Hooks can be placed under hooks/pre-save and
hooks/post-save in the data directory and need to be executable.

Potential use cases include:

* Automatically commit any changes to the data files using a VCS.
* Automatically sync with some sever component on data file changes.

Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

src/Makefile.am

@@ -20,6 +20,7 @@ calcurse_SOURCES = \
 	event.c \
 	getstring.c \
 	help.c \
+	hooks.c \
 	ical.c \
 	io.c \
 	keys.c \

src/calcurse.h

@@ -93,6 +93,7 @@
 #define DPID_PATH_NAME   ".daemon.pid"
 #define DLOG_PATH_NAME   "daemon.log"
 #define NOTES_DIR_NAME   "notes/"
+#define HOOKS_DIR_NAME   "hooks/"
 
 #define TODO_PATH        DIR_NAME TODO_PATH_NAME
 #define APTS_PATH        DIR_NAME APTS_PATH_NAME
@@ -102,6 +103,7 @@
 #define DLOG_PATH        DIR_NAME DLOG_PATH_NAME
 #define DPID_PATH        DIR_NAME DPID_PATH_NAME
 #define NOTES_DIR        DIR_NAME NOTES_DIR_NAME
+#define HOOKS_DIR        DIR_NAME HOOKS_DIR_NAME
 
 #define DEFAULT_EDITOR     "vi"
 #define DEFAULT_PAGER      "less"
@@ -779,6 +781,9 @@ int updatestring(WINDOW *, char **, int, int);
 /* help.c */
 int display_help(const char *);
 
+/* hooks.c */
+int run_hook(const char *);
+
 /* ical.c */
 void ical_import_data(FILE *, FILE *, unsigned *, unsigned *, unsigned *,
 		      unsigned *, unsigned *);
@@ -1111,6 +1116,7 @@ extern char path_notes[BUFSIZ];
 extern char path_cpid[BUFSIZ];
 extern char path_dpid[BUFSIZ];
 extern char path_dmon_log[BUFSIZ];
+extern char path_hooks[BUFSIZ];
 extern struct conf conf;
 extern struct pad apad;
 extern struct nbar nbar;

src/hooks.c

@@ -0,0 +1,63 @@
+/*
+ * Calcurse - text-based organizer
+ *
+ * Copyright (c) 2004-2016 calcurse Development Team <misc@calcurse.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *      - Redistributions of source code must retain the above
+ *        copyright notice, this list of conditions and the
+ *        following disclaimer.
+ *
+ *      - Redistributions in binary form must reproduce the above
+ *        copyright notice, this list of conditions and the
+ *        following disclaimer in the documentation and/or other
+ *        materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Send your feedback or comments to : misc@calcurse.org
+ * Calcurse home page : http://calcurse.org
+ *
+ */
+
+#include <stddef.h>
+
+#include "calcurse.h"
+
+int run_hook(const char *name)
+{
+	char *hook_path;
+	char const *arg[2];
+	int pid, ret = -127;
+
+	asprintf(&hook_path, "%s/%s", path_hooks, name);
+	arg[0] = hook_path;
+	arg[1] = NULL;
+
+	if (!io_file_exists(hook_path))
+		return 0;
+
+	wins_prepare_external();
+	if ((pid = shell_exec(NULL, NULL, *arg, arg))) {
+		ret = child_wait(NULL, NULL, pid);
+		if (ret)
+			press_any_key();
+	}
+	wins_unprepare_external();
+
+	return ret;
+}

src/io.c

@@ -239,6 +239,7 @@ void io_init(const char *cfile, const char *datadir)
 		snprintf(path_dpid, BUFSIZ, "%s/" DPID_PATH_NAME, home);
 		snprintf(path_dmon_log, BUFSIZ, "%s/" DLOG_PATH_NAME,
 			 home);
+		snprintf(path_hooks, BUFSIZ, "%s/" HOOKS_DIR_NAME, home);
 	} else {
 		home = getenv("HOME");
 		if (home == NULL) {
@@ -252,6 +253,7 @@ void io_init(const char *cfile, const char *datadir)
 		snprintf(path_dpid, BUFSIZ, "%s/" DPID_PATH, home);
 		snprintf(path_dmon_log, BUFSIZ, "%s/" DLOG_PATH, home);
 		snprintf(path_notes, BUFSIZ, "%s/" NOTES_DIR, home);
+		snprintf(path_hooks, BUFSIZ, "%s/" HOOKS_DIR, home);
 	}
 
 	if (cfile == NULL) {
@@ -391,6 +393,7 @@ void io_save_cal(enum save_display display)
 	if (read_only)
 		return;
 
+	run_hook("pre-save");
 	pthread_mutex_lock(&io_save_mutex);
 
 	show_bar = 0;
@@ -428,6 +431,7 @@ void io_save_cal(enum save_display display)
 	}
 
 	pthread_mutex_unlock(&io_save_mutex);
+	run_hook("post-save");
 }
 
 static void io_load_error(const char *filename, unsigned line,

src/vars.c

@@ -111,6 +111,7 @@ char path_keys[] = "";
 char path_cpid[] = "";
 char path_dpid[] = "";
 char path_dmon_log[] = "";
+char path_hooks[] = "";
 
 /* Variable to store global configuration. */
 struct conf conf;