[NETD-BPF#10] Add WaitForProgsLoaded.h

Move waitForProgsLoaded() from libbpf_android.h to a single header file.
A transitional commit of separating headers, utilities from bfploader.

Bug: 202086915
Test: build; flash; cd system/netd; atest
Change-Id: Ief1bcd09e973f952c29859a7a8fba92c8626e32d

libbpf_android/include/WaitForProgsLoaded.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ * Android BPF library - public API
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include <log/log.h>
+
+#include <android-base/properties.h>
+
+namespace android {
+namespace bpf {
+
+// Wait for bpfloader to load BPF programs.
+static inline void waitForProgsLoaded() {
+    // infinite loop until success with 5/10/20/40/60/60/60... delay
+    for (int delay = 5;; delay *= 2) {
+        if (delay > 60) delay = 60;
+        if (android::base::WaitForProperty("bpf.progs_loaded", "1", std::chrono::seconds(delay)))
+            return;
+        ALOGW("Waited %ds for bpf.progs_loaded, still waiting...", delay);
+    }
+}
+
+}  // namespace bpf
+}  // namespace android

libbpf_android/include/libbpf_android.h

@@ -19,9 +19,6 @@
 
 #include <libbpf.h>
 #include <linux/bpf.h>
-#include <log/log.h>
-
-#include <android-base/properties.h>
 
 namespace android {
 namespace bpf {
@@ -32,16 +29,5 @@ int loadProg(const char* elfPath, bool* isCritical, const char* prefix = "");
 // Exposed for testing
 unsigned int readSectionUint(const char* name, std::ifstream& elfFile, unsigned int defVal);
 
-// Wait for bpfloader to load BPF programs.
-static inline void waitForProgsLoaded() {
-    // infinite loop until success with 5/10/20/40/60/60/60... delay
-    for (int delay = 5;; delay *= 2) {
-        if (delay > 60) delay = 60;
-        if (android::base::WaitForProperty("bpf.progs_loaded", "1", std::chrono::seconds(delay)))
-            return;
-        ALOGW("Waited %ds for bpf.progs_loaded, still waiting...", delay);
-    }
-}
-
 }  // namespace bpf
 }  // namespace android