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Merge "Gracefully handle integer overflows." am: a308f79353

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Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1316217

Change-Id: I779298886cfaef330b433fea6009860682df35bd
This commit is contained in:
Junyu Lai
2020-07-29 01:37:48 +00:00
committed by Automerger Merge Worker
parent 03e5841ec1 a308f79353
commit aeddf47458
4 changed files with 83 additions and 59 deletions
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36
core/java/android/net/NetworkStatsHistory.java
View File

@@ -26,6 +26,7 @@ import static android.net.NetworkStatsHistory.DataStreamUtils.writeVarLongArray;
import static android.net.NetworkStatsHistory.Entry.UNKNOWN; import static android.net.NetworkStatsHistory.Entry.UNKNOWN;
import static android.net.NetworkStatsHistory.ParcelUtils.readLongArray; import static android.net.NetworkStatsHistory.ParcelUtils.readLongArray;
import static android.net.NetworkStatsHistory.ParcelUtils.writeLongArray; import static android.net.NetworkStatsHistory.ParcelUtils.writeLongArray;
import static android.net.NetworkUtils.multiplySafeByRational;
import static android.text.format.DateUtils.SECOND_IN_MILLIS; import static android.text.format.DateUtils.SECOND_IN_MILLIS;
import static com.android.internal.util.ArrayUtils.total; import static com.android.internal.util.ArrayUtils.total;
@@ -364,11 +365,12 @@ public class NetworkStatsHistory implements Parcelable {
if (overlap <= 0) continue; if (overlap <= 0) continue;
// integer math each time is faster than floating point // integer math each time is faster than floating point
final long fracRxBytes = rxBytes * overlap / duration; final long fracRxBytes = multiplySafeByRational(rxBytes, overlap, duration);
final long fracRxPackets = rxPackets * overlap / duration; final long fracRxPackets = multiplySafeByRational(rxPackets, overlap, duration);
final long fracTxBytes = txBytes * overlap / duration; final long fracTxBytes = multiplySafeByRational(txBytes, overlap, duration);
final long fracTxPackets = txPackets * overlap / duration; final long fracTxPackets = multiplySafeByRational(txPackets, overlap, duration);
final long fracOperations = operations * overlap / duration; final long fracOperations = multiplySafeByRational(operations, overlap, duration);
addLong(activeTime, i, overlap); addLong(activeTime, i, overlap);
addLong(this.rxBytes, i, fracRxBytes); rxBytes -= fracRxBytes; addLong(this.rxBytes, i, fracRxBytes); rxBytes -= fracRxBytes;
@@ -568,12 +570,24 @@ public class NetworkStatsHistory implements Parcelable {
if (overlap <= 0) continue; if (overlap <= 0) continue;
// integer math each time is faster than floating point // integer math each time is faster than floating point
if (activeTime != null) entry.activeTime += activeTime[i] * overlap / bucketSpan; if (activeTime != null) {
if (rxBytes != null) entry.rxBytes += rxBytes[i] * overlap / bucketSpan; entry.activeTime += multiplySafeByRational(activeTime[i], overlap, bucketSpan);
if (rxPackets != null) entry.rxPackets += rxPackets[i] * overlap / bucketSpan; }
if (txBytes != null) entry.txBytes += txBytes[i] * overlap / bucketSpan; if (rxBytes != null) {
if (txPackets != null) entry.txPackets += txPackets[i] * overlap / bucketSpan; entry.rxBytes += multiplySafeByRational(rxBytes[i], overlap, bucketSpan);
if (operations != null) entry.operations += operations[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; return entry;
} }

31
core/java/android/net/NetworkUtils.java
View File

@@ -476,4 +476,35 @@ public class NetworkUtils {
return true; 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;
}
} }

46
services/core/java/com/android/server/net/NetworkStatsCollection.java
View File

@@ -28,6 +28,7 @@ import static android.net.NetworkStats.SET_DEFAULT;
import static android.net.NetworkStats.TAG_NONE; import static android.net.NetworkStats.TAG_NONE;
import static android.net.NetworkStats.UID_ALL; import static android.net.NetworkStats.UID_ALL;
import static android.net.TrafficStats.UID_REMOVED; import static android.net.TrafficStats.UID_REMOVED;
import static android.net.NetworkUtils.multiplySafeByRational;
import static android.text.format.DateUtils.WEEK_IN_MILLIS; import static android.text.format.DateUtils.WEEK_IN_MILLIS;
import static com.android.server.net.NetworkStatsService.TAG; 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) { public int[] getRelevantUids(@NetworkStatsAccess.Level int accessLevel) {
return getRelevantUids(accessLevel, Binder.getCallingUid()); return getRelevantUids(accessLevel, Binder.getCallingUid());
} }
@@ -311,11 +283,13 @@ public class NetworkStatsCollection implements FileRotator.Reader {
} }
final long rawBytes = entry.rxBytes + entry.txBytes; final long rawBytes = entry.rxBytes + entry.txBytes;
final long rawRxBytes = entry.rxBytes; final long rawRxBytes = entry.rxBytes == 0 ? 1 : entry.rxBytes;
final long rawTxBytes = entry.txBytes; final long rawTxBytes = entry.txBytes == 0 ? 1 : entry.txBytes;
final long targetBytes = augmentPlan.getDataUsageBytes(); 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 // Scale all matching buckets to reach anchor target
final long beforeTotal = combined.getTotalBytes(); final long beforeTotal = combined.getTotalBytes();
@@ -323,8 +297,10 @@ public class NetworkStatsCollection implements FileRotator.Reader {
combined.getValues(i, entry); combined.getValues(i, entry);
if (entry.bucketStart >= augmentStart if (entry.bucketStart >= augmentStart
&& entry.bucketStart + entry.bucketDuration <= augmentEnd) { && entry.bucketStart + entry.bucketDuration <= augmentEnd) {
entry.rxBytes = multiplySafe(targetRxBytes, entry.rxBytes, rawRxBytes); entry.rxBytes = multiplySafeByRational(
entry.txBytes = multiplySafe(targetTxBytes, entry.txBytes, rawTxBytes); targetRxBytes, entry.rxBytes, rawRxBytes);
entry.txBytes = multiplySafeByRational(
targetTxBytes, entry.txBytes, rawTxBytes);
// We purposefully clear out packet counters to indicate // We purposefully clear out packet counters to indicate
// that this data has been augmented. // that this data has been augmented.
entry.rxPackets = 0; entry.rxPackets = 0;

29
tests/net/java/com/android/server/net/NetworkStatsCollectionTest.java
View File

@@ -23,11 +23,12 @@ import static android.net.NetworkStats.TAG_NONE;
import static android.net.NetworkStats.UID_ALL; import static android.net.NetworkStats.UID_ALL;
import static android.net.NetworkStatsHistory.FIELD_ALL; import static android.net.NetworkStatsHistory.FIELD_ALL;
import static android.net.NetworkTemplate.buildTemplateMobileAll; import static android.net.NetworkTemplate.buildTemplateMobileAll;
import static android.net.NetworkUtils.multiplySafeByRational;
import static android.os.Process.myUid; import static android.os.Process.myUid;
import static android.text.format.DateUtils.HOUR_IN_MILLIS; import static android.text.format.DateUtils.HOUR_IN_MILLIS;
import static android.text.format.DateUtils.MINUTE_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.assertArrayEquals;
import static org.junit.Assert.assertEquals; import static org.junit.Assert.assertEquals;
@@ -505,23 +506,25 @@ public class NetworkStatsCollectionTest {
} }
@Test @Test
public void testMultiplySafe() { public void testMultiplySafeRational() {
assertEquals(25, multiplySafe(50, 1, 2)); assertEquals(25, multiplySafeByRational(50, 1, 2));
assertEquals(100, multiplySafe(50, 2, 1)); assertEquals(100, multiplySafeByRational(50, 2, 1));
assertEquals(-10, multiplySafe(30, -1, 3)); assertEquals(-10, multiplySafeByRational(30, -1, 3));
assertEquals(0, multiplySafe(30, 0, 3)); assertEquals(0, multiplySafeByRational(30, 0, 3));
assertEquals(10, multiplySafe(30, 1, 3)); assertEquals(10, multiplySafeByRational(30, 1, 3));
assertEquals(20, multiplySafe(30, 2, 3)); assertEquals(20, multiplySafeByRational(30, 2, 3));
assertEquals(30, multiplySafe(30, 3, 3)); assertEquals(30, multiplySafeByRational(30, 3, 3));
assertEquals(40, multiplySafe(30, 4, 3)); assertEquals(40, multiplySafeByRational(30, 4, 3));
assertEquals(100_000_000_000L, 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, 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, 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));
} }
/** /**