From 7328b3f891102f87312a21313906bd427eca252c Mon Sep 17 00:00:00 2001
From: Yuxuan Shui <yshuiv7@gmail.com>
Date: Mon, 11 Nov 2019 20:46:06 +0000
Subject: [PATCH] file_watch: only use inotify on linux

Fixes build on *BSD platforms.

Fixes #262, Closes #261

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
---
 src/file_watch.c | 25 ++++++++++++++++++++-----
 src/meson.build  |  8 ++++++++
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/src/file_watch.c b/src/file_watch.c
index f72659b..0bef173 100644
--- a/src/file_watch.c
+++ b/src/file_watch.c
@@ -1,6 +1,8 @@
 #include <errno.h>
 #include <string.h>
+#ifdef HAS_INOTIFY
 #include <sys/inotify.h>
+#endif
 
 #include <ev.h>
 #include <uthash.h>
@@ -26,9 +28,11 @@ struct file_watch_registry {
 
 static void file_watch_ev_cb(EV_P_ struct ev_io *w, int revent attr_unused) {
 	auto fwr = (struct file_watch_registry *)w;
-	struct inotify_event inotify_event;
 
 	while (true) {
+		int wd = -1;
+#ifdef HAS_INOTIFY
+		struct inotify_event inotify_event;
 		auto ret = read(w->fd, &inotify_event, sizeof(struct inotify_event));
 		if (ret < 0) {
 			if (errno != EAGAIN) {
@@ -37,9 +41,11 @@ static void file_watch_ev_cb(EV_P_ struct ev_io *w, int revent attr_unused) {
 			}
 			break;
 		}
+		wd = inotify_event.wd;
+#endif
 
 		struct watched_file *wf = NULL;
-		HASH_FIND_INT(fwr->reg, &inotify_event.wd, wf);
+		HASH_FIND_INT(fwr->reg, &wd, wf);
 		if (!wf) {
 			log_warn("Got notification for a file I didn't watch.");
 			continue;
@@ -50,11 +56,17 @@ static void file_watch_ev_cb(EV_P_ struct ev_io *w, int revent attr_unused) {
 
 void *file_watch_init(EV_P) {
 	log_debug("Starting watching for file changes");
-	int fd = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
+	int fd = -1;
+#ifdef HAS_INOTIFY
+	fd = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
 	if (fd < 0) {
 		log_error("inotify_init1 failed: %s", strerror(errno));
 		return NULL;
 	}
+#else
+	log_info("No file watching support found on the host system.");
+	return NULL;
+#endif
 	auto fwr = ccalloc(1, struct file_watch_registry);
 	ev_io_init(&fwr->w, file_watch_ev_cb, fd, EV_READ);
 	ev_io_start(EV_A_ & fwr->w);
@@ -80,12 +92,15 @@ void file_watch_destroy(EV_P_ void *_fwr) {
 bool file_watch_add(void *_fwr, const char *filename, file_watch_cb_t cb, void *ud) {
 	log_debug("Adding \"%s\" to watched files", filename);
 	auto fwr = (struct file_watch_registry *)_fwr;
-	int wd = inotify_add_watch(fwr->w.fd, filename,
-	                           IN_CLOSE_WRITE | IN_MOVE_SELF | IN_DELETE_SELF);
+	int wd = -1;
+#ifdef HAS_INOTIFY
+	wd = inotify_add_watch(fwr->w.fd, filename,
+	                       IN_CLOSE_WRITE | IN_MOVE_SELF | IN_DELETE_SELF);
 	if (wd < 0) {
 		log_error("Failed to watch file \"%s\": %s", filename, strerror(errno));
 		return false;
 	}
+#endif
 
 	auto w = ccalloc(1, struct watched_file);
 	w->wd = wd;
diff --git a/src/meson.build b/src/meson.build
index e2e0e05..05626f5 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -78,6 +78,14 @@ if get_option('unittest')
 	cflags += ['-DUNIT_TEST']
 endif
 
+host_system = host_machine.system()
+if host_system == 'linux'
+	cflags += ['-DHAS_INOTIFY']
+elif host_system == 'freebsd' or host_system == 'netbsd' or
+     host_system == 'dragonfly' or host_system == 'openbsd'
+	cflags += ['-DHAS_KQUEUE']
+endif
+
 subdir('backend')
 
 picom = executable('picom', srcs, c_args: cflags,