Add kanshictl utility.

It can talk to kanshi via the varlink interface. The only command
currently supported is to reload the config.

Co-authored-by: Érico Nogueira <erico.erc@gmail.com>

ctl.c

@@ -0,0 +1,90 @@
+#define _POSIX_C_SOURCE 200809L
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/param.h>
+#include <varlink.h>
+
+#include "ipc.h"
+
+static void usage(const char *progname) {
+	fprintf(stderr, "Usage: %s [command]\n"
+			"Accepted commands:\n"
+			"  reload - reload the config file\n",
+			progname);
+}
+
+static long reload_callback(VarlinkConnection *connection, const char *error,
+		VarlinkObject *parameters, uint64_t flags, void *userdata) {
+	return varlink_connection_close(connection);
+}
+
+static int set_blocking(int fd) {
+	int flags = fcntl(fd, F_GETFL);
+	if (flags == -1) {
+		fprintf(stderr, "fnctl F_GETFL failed: %s\n", strerror(errno));
+		return -1;
+	}
+	flags &= ~O_NONBLOCK;
+	if (fcntl(fd, F_SETFL, flags) == -1) {
+		fprintf(stderr, "fnctl F_SETFL failed: %s\n", strerror(errno));
+		return -1;
+	}
+	return 0;
+}
+
+int wait_for_event(VarlinkConnection *connection) {
+	int fd = varlink_connection_get_fd(connection);
+	if (set_blocking(fd) != 0) {
+		return -1;
+	}
+
+	while (!varlink_connection_is_closed(connection)) {
+		uint32_t events = varlink_connection_get_events(connection);
+		long result = varlink_connection_process_events(connection, events);
+		if (result != 0) {
+			fprintf(stderr, "varlink_connection_process_events failed: %s\n",
+					varlink_error_string(-result));
+			return -1;
+		}
+	}
+	return 0;
+}
+
+int main(int argc, char *argv[]) {
+	if (argc < 2) {
+		usage(argv[0]);
+		return EXIT_FAILURE;
+	}
+	if (strcmp(argv[1], "-h") == 0 || strcmp(argv[1], "--help") == 0) {
+		usage(argv[0]);
+		return EXIT_SUCCESS;
+	}
+
+	VarlinkConnection *connection;
+	char address[PATH_MAX];
+	if (get_ipc_address(address, sizeof(address)) < 0) {
+		return EXIT_FAILURE;
+	}
+	if (varlink_connection_new(&connection, address) != 0) {
+		fprintf(stderr, "Couldn't connect to kanshi at %s.\n"
+				"Is the kanshi daemon running?\n", address);
+		return EXIT_FAILURE;
+	}
+	if (strcmp(argv[1], "reload") == 0) {
+		long result = varlink_connection_call(connection,
+				"fr.emersion.kanshi.Reload", NULL, 0, reload_callback, NULL);
+		if (result != 0) {
+			fprintf(stderr, "varlink_connection_call failed: %s\n",
+					varlink_error_string(-result));
+			return EXIT_FAILURE;
+		}
+		return wait_for_event(connection);
+	}
+	fprintf(stderr, "invalid command: %s\n", argv[1]);
+	usage(argv[0]);
+	return EXIT_FAILURE;
+}

kanshi.1.scd

@@ -43,4 +43,4 @@ https://github.com/emersion/kanshi.
 
 # SEE ALSO
 
-*kanshi*(5)
+*kanshi*(5) *kanshictl*(1)

kanshictl.1.scd

@@ -0,0 +1,28 @@
+kanshictl(1)
+
+# NAME
+
+kanshictl - control the kanshi daemon remotely
+
+# SYNOPSIS
+
+*kanshictl* [options...] [command]
+
+# OPTIONS
+
+*-h, --help*
+	Show help message and quit.
+
+# COMMANDS
+
+reload - reload the config file
+
+# AUTHORS
+
+Maintained by Simon Ser <contact@emersion.fr>, who is assisted by other
+open-source contributors. For more information about kanshi development, see
+https://github.com/emersion/kanshi.
+
+# SEE ALSO
+
+*kanshi*(1)

meson.build

@@ -69,6 +69,19 @@ executable(
 	install: true,
 )
 
+if varlink.found()
+	executable(
+			meson.project_name() + 'ctl',
+			files(
+				'ctl.c',
+				'ipc-addr.c',
+			),
+			include_directories: include_directories('include'),
+			dependencies: [varlink],
+			install: true,
+	)
+endif
+
 scdoc = dependency(
 	'scdoc',
 	version: '>=1.9.2',
@@ -83,6 +96,9 @@ if scdoc.found()
 		'kanshi.1.scd',
 		'kanshi.5.scd',
 	]
+	if varlink.found()
+		man_files += 'kanshictl.1.scd'
+	endif
 	foreach filename : man_files
 		topic = filename.split('.')[-3].split('/')[-1]
 		section = filename.split('.')[-2]