fdev: Introduce fdev for file event handling

This is an effort to keep cutting dependency to systemd.

Change-Id: I9a0c032a1095e297c7f3ac5b67827fda3658b8d9
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

1 files changed, 158 insertions, 0 deletions

diff --git a/src/fdev.c b/src/fdev.c
new file mode 100644
index 00000000..5c31d31b
--- /dev/null
+++ b/src/fdev.c
@@ -0,0 +1,158 @@
+/*
+ * Copyright (C) 2018 "IoT.bzh"
+ * Author José Bollo <jose.bollo@iot.bzh>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+#define FDEV_PROVIDER
+#include "fdev.h"
+
+struct fdev
+{
+	int fd;
+	uint32_t events;
+	int repeat;
+	unsigned refcount;
+	struct fdev_itf *itf;
+	void *closure_itf;
+	void (*callback)(void*,uint32_t,struct fdev*);
+	void *closure_callback;
+};
+
+struct fdev *fdev_create(int fd)
+{
+	struct fdev *fdev;
+
+	fdev = calloc(1, sizeof *fdev);
+	if (!fdev)
+		errno = ENOMEM;
+	else {
+		fdev->fd = fd;
+		fdev->refcount = 3; /* set autoclose by default */
+		fdev->repeat = -1;
+	}
+	return fdev;
+}
+
+void fdev_set_itf(struct fdev *fdev, struct fdev_itf *itf, void *closure_itf)
+{
+	fdev->itf = itf;
+	fdev->closure_itf = closure_itf;
+}
+
+void fdev_dispatch(struct fdev *fdev, uint32_t events)
+{
+	if (fdev->repeat > 0 && !--fdev->repeat && fdev->itf)
+		fdev->itf->disable(fdev->closure_itf, fdev);
+	if (fdev->callback)
+		fdev->callback(fdev->closure_callback, events, fdev);
+}
+
+struct fdev *fdev_addref(struct fdev *fdev)
+{
+	if (fdev)
+		__atomic_add_fetch(&fdev->refcount, 2, __ATOMIC_RELAXED);
+	return fdev;
+}
+
+void fdev_unref(struct fdev *fdev)
+{
+	if (fdev && __atomic_sub_fetch(&fdev->refcount, 2, __ATOMIC_RELAXED) <= 1) {
+		if (fdev->itf) {
+			fdev->itf->disable(fdev->closure_itf, fdev);
+			fdev->itf->unref(fdev->closure_itf);
+		}
+		if (fdev->refcount)
+			close(fdev->fd);
+		free(fdev);
+	}
+}
+
+int fdev_fd(const struct fdev *fdev)
+{
+	return fdev->fd;
+}
+
+uint32_t fdev_events(const struct fdev *fdev)
+{
+	return fdev->events;
+}
+
+int fdev_repeat(const struct fdev *fdev)
+{
+	return fdev->repeat;
+}
+
+int fdev_autoclose(const struct fdev *fdev)
+{
+	return 1 & fdev->refcount;
+}
+
+static inline int is_active(struct fdev *fdev)
+{
+	return fdev->repeat && fdev->callback;
+}
+
+static inline void update_activity(struct fdev *fdev, int old_active)
+{
+	if (is_active(fdev)) {
+		if (!old_active)
+			fdev->itf->enable(fdev->closure_itf, fdev);
+	} else {
+		if (old_active)
+			fdev->itf->disable(fdev->closure_itf, fdev);
+	}
+}
+
+void fdev_set_callback(struct fdev *fdev, void (*callback)(void*,uint32_t,struct fdev*), void *closure)
+{
+	int oa;
+
+	oa = is_active(fdev);
+	fdev->callback = callback;
+	fdev->closure_callback = closure;
+	update_activity(fdev, oa);
+}
+
+void fdev_set_events(struct fdev *fdev, uint32_t events)
+{
+	if (events != fdev->events) {
+		fdev->events = events;
+		if (is_active(fdev))
+			fdev->itf->enable(fdev->closure_itf, fdev);
+	}
+}
+
+void fdev_set_repeat(struct fdev *fdev, int count)
+{
+	int oa;
+
+	oa = is_active(fdev);
+	fdev->repeat = count;
+	update_activity(fdev, oa);
+}
+
+void fdev_set_autoclose(struct fdev *fdev, int autoclose)
+{
+	if (autoclose)
+		fdev->refcount |= 1;
+	else
+		fdev->refcount &= -2;
+}
+