Merge "Gracefully handle integer overflows." (a308f793) · Commits · e / os / android_frameworks_base

core/java/android/net/NetworkStatsHistory.java

+25 −11

Original line number	Diff line number	Diff line
		@@ -26,6 +26,7 @@ import static android.net.NetworkStatsHistory.DataStreamUtils.writeVarLongArray;
		import static android.net.NetworkStatsHistory.Entry.UNKNOWN;
		import static android.net.NetworkStatsHistory.ParcelUtils.readLongArray;
		import static android.net.NetworkStatsHistory.ParcelUtils.writeLongArray;
		import static android.net.NetworkUtils.multiplySafeByRational;
		import static android.text.format.DateUtils.SECOND_IN_MILLIS;

		import static com.android.internal.util.ArrayUtils.total;
		@@ -364,11 +365,12 @@ public class NetworkStatsHistory implements Parcelable {
		if (overlap <= 0) continue;

		// integer math each time is faster than floating point
		final long fracRxBytes = rxBytes * overlap / duration;
		final long fracRxPackets = rxPackets * overlap / duration;
		final long fracTxBytes = txBytes * overlap / duration;
		final long fracTxPackets = txPackets * overlap / duration;
		final long fracOperations = operations * overlap / duration;
		final long fracRxBytes = multiplySafeByRational(rxBytes, overlap, duration);
		final long fracRxPackets = multiplySafeByRational(rxPackets, overlap, duration);
		final long fracTxBytes = multiplySafeByRational(txBytes, overlap, duration);
		final long fracTxPackets = multiplySafeByRational(txPackets, overlap, duration);
		final long fracOperations = multiplySafeByRational(operations, overlap, duration);


		addLong(activeTime, i, overlap);
		addLong(this.rxBytes, i, fracRxBytes); rxBytes -= fracRxBytes;
		@@ -568,12 +570,24 @@ public class NetworkStatsHistory implements Parcelable {
		if (overlap <= 0) continue;

		// integer math each time is faster than floating point
		if (activeTime != null) entry.activeTime += activeTime[i] * overlap / bucketSpan;
		if (rxBytes != null) entry.rxBytes += rxBytes[i] * overlap / bucketSpan;
		if (rxPackets != null) entry.rxPackets += rxPackets[i] * overlap / bucketSpan;
		if (txBytes != null) entry.txBytes += txBytes[i] * overlap / bucketSpan;
		if (txPackets != null) entry.txPackets += txPackets[i] * overlap / bucketSpan;
		if (operations != null) entry.operations += operations[i] * overlap / bucketSpan;
		if (activeTime != null) {
		entry.activeTime += multiplySafeByRational(activeTime[i], overlap, bucketSpan);
		}
		if (rxBytes != null) {
		entry.rxBytes += multiplySafeByRational(rxBytes[i], overlap, bucketSpan);
		}
		if (rxPackets != null) {
		entry.rxPackets += multiplySafeByRational(rxPackets[i], overlap, bucketSpan);
		}
		if (txBytes != null) {
		entry.txBytes += multiplySafeByRational(txBytes[i], overlap, bucketSpan);
		}
		if (txPackets != null) {
		entry.txPackets += multiplySafeByRational(txPackets[i], overlap, bucketSpan);
		}
		if (operations != null) {
		entry.operations += multiplySafeByRational(operations[i], overlap, bucketSpan);
		}
		}
		return entry;
		}

core/java/android/net/NetworkUtils.java

+31 −0

Original line number	Diff line number	Diff line
		@@ -476,4 +476,35 @@ public class NetworkUtils {

		return true;
		}

		/**
		* Safely multiple a value by a rational.
		* <p>
		* Internally it uses integer-based math whenever possible, but switches
		* over to double-based math if values would overflow.
		* @hide
		*/
		public static long multiplySafeByRational(long value, long num, long den) {
		if (den == 0) {
		throw new ArithmeticException("Invalid Denominator");
		}
		long x = value;
		long y = num;

		// Logic shamelessly borrowed from Math.multiplyExact()
		long r = x * y;
		long ax = Math.abs(x);
		long ay = Math.abs(y);
		if (((ax \| ay) >>> 31 != 0)) {
		// Some bits greater than 2^31 that might cause overflow
		// Check the result using the divide operator
		// and check for the special case of Long.MIN_VALUE * -1
		if (((y != 0) && (r / y != x)) \|\|
		(x == Long.MIN_VALUE && y == -1)) {
		// Use double math to avoid overflowing
		return (long) (((double) num / den) * value);
		}
		}
		return r / den;
		}
		}

services/core/java/com/android/server/net/NetworkStatsCollection.java

+11 −35

Original line number	Diff line number	Diff line
		@@ -28,6 +28,7 @@ import static android.net.NetworkStats.SET_DEFAULT;
		import static android.net.NetworkStats.TAG_NONE;
		import static android.net.NetworkStats.UID_ALL;
		import static android.net.TrafficStats.UID_REMOVED;
		import static android.net.NetworkUtils.multiplySafeByRational;
		import static android.text.format.DateUtils.WEEK_IN_MILLIS;

		import static com.android.server.net.NetworkStatsService.TAG;
		@@ -185,35 +186,6 @@ public class NetworkStatsCollection implements FileRotator.Reader {
		}
		}

		/**
		* Safely multiple a value by a rational.
		* <p>
		* Internally it uses integer-based math whenever possible, but switches
		* over to double-based math if values would overflow.
		*/
		@VisibleForTesting
		public static long multiplySafe(long value, long num, long den) {
		if (den == 0) den = 1;
		long x = value;
		long y = num;

		// Logic shamelessly borrowed from Math.multiplyExact()
		long r = x * y;
		long ax = Math.abs(x);
		long ay = Math.abs(y);
		if (((ax \| ay) >>> 31 != 0)) {
		// Some bits greater than 2^31 that might cause overflow
		// Check the result using the divide operator
		// and check for the special case of Long.MIN_VALUE * -1
		if (((y != 0) && (r / y != x)) \|\|
		(x == Long.MIN_VALUE && y == -1)) {
		// Use double math to avoid overflowing
		return (long) (((double) num / den) * value);
		}
		}
		return r / den;
		}

		public int[] getRelevantUids(@NetworkStatsAccess.Level int accessLevel) {
		return getRelevantUids(accessLevel, Binder.getCallingUid());
		}
		@@ -311,11 +283,13 @@ public class NetworkStatsCollection implements FileRotator.Reader {
		}

		final long rawBytes = entry.rxBytes + entry.txBytes;
		final long rawRxBytes = entry.rxBytes;
		final long rawTxBytes = entry.txBytes;
		final long rawRxBytes = entry.rxBytes == 0 ? 1 : entry.rxBytes;
		final long rawTxBytes = entry.txBytes == 0 ? 1 : entry.txBytes;
		final long targetBytes = augmentPlan.getDataUsageBytes();
		final long targetRxBytes = multiplySafe(targetBytes, rawRxBytes, rawBytes);
		final long targetTxBytes = multiplySafe(targetBytes, rawTxBytes, rawBytes);

		final long targetRxBytes = multiplySafeByRational(targetBytes, rawRxBytes, rawBytes);
		final long targetTxBytes = multiplySafeByRational(targetBytes, rawTxBytes, rawBytes);


		// Scale all matching buckets to reach anchor target
		final long beforeTotal = combined.getTotalBytes();
		@@ -323,8 +297,10 @@ public class NetworkStatsCollection implements FileRotator.Reader {
		combined.getValues(i, entry);
		if (entry.bucketStart >= augmentStart
		&& entry.bucketStart + entry.bucketDuration <= augmentEnd) {
		entry.rxBytes = multiplySafe(targetRxBytes, entry.rxBytes, rawRxBytes);
		entry.txBytes = multiplySafe(targetTxBytes, entry.txBytes, rawTxBytes);
		entry.rxBytes = multiplySafeByRational(
		targetRxBytes, entry.rxBytes, rawRxBytes);
		entry.txBytes = multiplySafeByRational(
		targetTxBytes, entry.txBytes, rawTxBytes);
		// We purposefully clear out packet counters to indicate
		// that this data has been augmented.
		entry.rxPackets = 0;

tests/net/java/com/android/server/net/NetworkStatsCollectionTest.java

+16 −13

Original line number	Diff line number	Diff line
		@@ -23,11 +23,12 @@ import static android.net.NetworkStats.TAG_NONE;
		import static android.net.NetworkStats.UID_ALL;
		import static android.net.NetworkStatsHistory.FIELD_ALL;
		import static android.net.NetworkTemplate.buildTemplateMobileAll;
		import static android.net.NetworkUtils.multiplySafeByRational;
		import static android.os.Process.myUid;
		import static android.text.format.DateUtils.HOUR_IN_MILLIS;
		import static android.text.format.DateUtils.MINUTE_IN_MILLIS;

		import static com.android.server.net.NetworkStatsCollection.multiplySafe;
		import static com.android.testutils.MiscAssertsKt.assertThrows;

		import static org.junit.Assert.assertArrayEquals;
		import static org.junit.Assert.assertEquals;
		@@ -505,23 +506,25 @@ public class NetworkStatsCollectionTest {
		}

		@Test
		public void testMultiplySafe() {
		assertEquals(25, multiplySafe(50, 1, 2));
		assertEquals(100, multiplySafe(50, 2, 1));
		public void testMultiplySafeRational() {
		assertEquals(25, multiplySafeByRational(50, 1, 2));
		assertEquals(100, multiplySafeByRational(50, 2, 1));

		assertEquals(-10, multiplySafe(30, -1, 3));
		assertEquals(0, multiplySafe(30, 0, 3));
		assertEquals(10, multiplySafe(30, 1, 3));
		assertEquals(20, multiplySafe(30, 2, 3));
		assertEquals(30, multiplySafe(30, 3, 3));
		assertEquals(40, multiplySafe(30, 4, 3));
		assertEquals(-10, multiplySafeByRational(30, -1, 3));
		assertEquals(0, multiplySafeByRational(30, 0, 3));
		assertEquals(10, multiplySafeByRational(30, 1, 3));
		assertEquals(20, multiplySafeByRational(30, 2, 3));
		assertEquals(30, multiplySafeByRational(30, 3, 3));
		assertEquals(40, multiplySafeByRational(30, 4, 3));

		assertEquals(100_000_000_000L,
		multiplySafe(300_000_000_000L, 10_000_000_000L, 30_000_000_000L));
		multiplySafeByRational(300_000_000_000L, 10_000_000_000L, 30_000_000_000L));
		assertEquals(100_000_000_010L,
		multiplySafe(300_000_000_000L, 10_000_000_001L, 30_000_000_000L));
		multiplySafeByRational(300_000_000_000L, 10_000_000_001L, 30_000_000_000L));
		assertEquals(823_202_048L,
		multiplySafe(4_939_212_288L, 2_121_815_528L, 12_730_893_165L));
		multiplySafeByRational(4_939_212_288L, 2_121_815_528L, 12_730_893_165L));

		assertThrows(ArithmeticException.class, () -> multiplySafeByRational(30, 3, 0));
		}

		/**