Add BpfBitmap Class
Generic bitmap class for use with bpf programs. Internally
uses bpfMap with key/value.
Test: atest BpfBitmapTest
Change-Id: Ica912b080849b50614e30ee168992c9ada74068c
diff --git a/staticlibs/Android.bp b/staticlibs/Android.bp
index ef80170..a311eb5 100644
--- a/staticlibs/Android.bp
+++ b/staticlibs/Android.bp
@@ -110,6 +110,7 @@
java_library {
name: "net-utils-device-common-bpf",
srcs: [
+ "device/com/android/net/module/util/BpfBitmap.java",
"device/com/android/net/module/util/BpfMap.java",
"device/com/android/net/module/util/HexDump.java",
"device/com/android/net/module/util/IBpfMap.java",
diff --git a/staticlibs/device/com/android/net/module/util/BpfBitmap.java b/staticlibs/device/com/android/net/module/util/BpfBitmap.java
new file mode 100644
index 0000000..0c8bb37
--- /dev/null
+++ b/staticlibs/device/com/android/net/module/util/BpfBitmap.java
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+
+package com.android.net.module.util;
+
+import android.system.ErrnoException;
+
+import androidx.annotation.NonNull;
+
+ /**
+ *
+ * Generic bitmap class for use with BPF programs. Corresponds to a BpfMap
+ * array type with key->int and value->uint64_t defined in the bpf program.
+ *
+ */
+public class BpfBitmap {
+ private BpfMap<Struct.U32, Struct.S64> mBpfMap;
+
+ /**
+ * Create a BpfBitmap map wrapper with "path" of filesystem.
+ *
+ * @param path The path of the BPF map.
+ */
+ public BpfBitmap(@NonNull String path) throws ErrnoException {
+ mBpfMap = new BpfMap<Struct.U32, Struct.S64>(path, BpfMap.BPF_F_RDWR,
+ Struct.U32.class, Struct.S64.class);
+ }
+
+ /**
+ * Retrieves the value from BpfMap for the given key.
+ *
+ * @param key The key in the map corresponding to the value to return.
+ */
+ private long getBpfMapValue(Struct.U32 key) throws ErrnoException {
+ Struct.S64 curVal = mBpfMap.getValue(key);
+ if (curVal != null) {
+ return curVal.val;
+ } else {
+ return 0;
+ }
+ }
+
+ /**
+ * Retrieves the bit for the given index in the bitmap.
+ *
+ * @param index Position in bitmap.
+ */
+ public boolean get(int index) throws ErrnoException {
+ if (index < 0) return false;
+
+ Struct.U32 key = new Struct.U32(index >> 6);
+ return ((getBpfMapValue(key) >>> (index & 63)) & 1L) != 0;
+ }
+
+ /**
+ * Set the specified index in the bitmap.
+ *
+ * @param index Position to set in bitmap.
+ */
+ public void set(int index) throws ErrnoException {
+ set(index, true);
+ }
+
+ /**
+ * Unset the specified index in the bitmap.
+ *
+ * @param index Position to unset in bitmap.
+ */
+ public void unset(int index) throws ErrnoException {
+ set(index, false);
+ }
+
+ /**
+ * Change the specified index in the bitmap to set value.
+ *
+ * @param index Position to unset in bitmap.
+ * @param set Boolean indicating to set or unset index.
+ */
+ public void set(int index, boolean set) throws ErrnoException {
+ if (index < 0) throw new IllegalArgumentException("Index out of bounds.");
+
+ Struct.U32 key = new Struct.U32(index >> 6);
+ long mask = (1L << (index & 63));
+ long val = getBpfMapValue(key);
+ if (set) val |= mask; else val &= ~mask;
+ mBpfMap.updateEntry(key, new Struct.S64(val));
+ }
+
+ /**
+ * Clears the map. The map may already be empty.
+ *
+ * @throws ErrnoException if updating entry to 0 fails.
+ */
+ public void clear() throws ErrnoException {
+ mBpfMap.forEach((key, value) -> {
+ mBpfMap.updateEntry(key, new Struct.S64(0));
+ });
+ }
+
+ /**
+ * Checks if all bitmap values are 0.
+ */
+ public boolean isEmpty() throws ErrnoException {
+ Struct.U32 key = mBpfMap.getFirstKey();
+ while (key != null) {
+ if (getBpfMapValue(key) != 0) {
+ return false;
+ }
+ key = mBpfMap.getNextKey(key);
+ }
+ return true;
+ }
+}