Move watchdogd out of init

We're moving past a world where static executables are needed,
including watchdogd, so treat this like any other executable and place
it in /system/bin.

Bug: 73660730
Test: watchdogd still runs
Change-Id: I1f7508fd55dce6e9ee72a6ab7a085011a76c0053
diff --git a/watchdogd/watchdogd.cpp b/watchdogd/watchdogd.cpp
new file mode 100644
index 0000000..5dc41e6
--- /dev/null
+++ b/watchdogd/watchdogd.cpp
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * 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 <errno.h>
+#include <fcntl.h>
+#include <linux/watchdog.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <android-base/logging.h>
+
+#define DEV_NAME "/dev/watchdog"
+
+int main(int argc, char** argv) {
+    android::base::InitLogging(argv, &android::base::KernelLogger);
+
+    int interval = 10;
+    if (argc >= 2) interval = atoi(argv[1]);
+
+    int margin = 10;
+    if (argc >= 3) margin = atoi(argv[2]);
+
+    LOG(INFO) << "watchdogd started (interval " << interval << ", margin " << margin << ")!";
+
+    int fd = open(DEV_NAME, O_RDWR | O_CLOEXEC);
+    if (fd == -1) {
+        PLOG(ERROR) << "Failed to open " << DEV_NAME;
+        return 1;
+    }
+
+    int timeout = interval + margin;
+    int ret = ioctl(fd, WDIOC_SETTIMEOUT, &timeout);
+    if (ret) {
+        PLOG(ERROR) << "Failed to set timeout to " << timeout;
+        ret = ioctl(fd, WDIOC_GETTIMEOUT, &timeout);
+        if (ret) {
+            PLOG(ERROR) << "Failed to get timeout";
+        } else {
+            if (timeout > margin) {
+                interval = timeout - margin;
+            } else {
+                interval = 1;
+            }
+            LOG(WARNING) << "Adjusted interval to timeout returned by driver: "
+                         << "timeout " << timeout << ", interval " << interval << ", margin "
+                         << margin;
+        }
+    }
+
+    while (true) {
+        write(fd, "", 1);
+        sleep(interval);
+    }
+}