Merge "Ensure that the BD's HID descriptor includes the BD usage page (0x41)." into main (7574da8c) · Commits · e / os / android_frameworks_base

services/accessibility/java/com/android/server/accessibility/BrailleDisplayConnection.java

+57 −3

Original line number	Diff line number	Diff line
		@@ -232,9 +232,63 @@ class BrailleDisplayConnection extends IBrailleDisplayConnection.Stub {
		}

		/** Returns true if this descriptor includes usages for the Braille display usage page 0x41. */
		private static boolean isBrailleDisplay(byte[] descriptor) {
		// TODO: b/316036493 - Check that descriptor includes 0x41 reports.
		return true;
		@VisibleForTesting
		static boolean isBrailleDisplay(byte[] descriptor) {
		boolean foundMatch = false;
		for (int i = 0; i < descriptor.length; i++) {
		// HID Spec "6.2.2.2 Short Items" defines that the report descriptor is a collection of
		// items: each item is a collection of bytes where the first byte defines info about
		// the type of item and the following 0, 1, 2, or 4 bytes are data bytes for that item.
		// All items in the HID descriptor are expected to be Short Items.
		final byte itemInfo = descriptor[i];
		if (!isHidItemShort(itemInfo)) {
		Slog.w(LOG_TAG, "Item " + itemInfo + " declares unsupported long type");
		return false;
		}
		final int dataSize = getHidItemDataSize(itemInfo);
		if (i + dataSize >= descriptor.length) {
		Slog.w(LOG_TAG, "Item " + itemInfo + " specifies size past the remaining bytes");
		return false;
		}
		// The item we're looking for (usage page declaration) should have size 1.
		if (dataSize == 1) {
		final byte itemData = descriptor[i + 1];
		if (isHidItemBrailleDisplayUsagePage(itemInfo, itemData)) {
		foundMatch = true;
		}
		}
		// Move to the next item by skipping past all data bytes in this item.
		i += dataSize;
		}
		return foundMatch;
		}

		private static boolean isHidItemShort(byte itemInfo) {
		// Info bits 7-4 describe the item type, and HID Spec "6.2.2.3 Long Items" says that long
		// items always have type bits 1111. Otherwise, the item is a short item.
		return (itemInfo & 0b1111_0000) != 0b1111_0000;
		}

		private static int getHidItemDataSize(byte itemInfo) {
		// HID Spec "6.2.2.2 Short Items" says that info bits 0-1 specify the optional data size:
		// 0, 1, 2, or 4 bytes.
		return switch (itemInfo & 0b0000_0011) {
		case 0b00 -> 0;
		case 0b01 -> 1;
		case 0b10 -> 2;
		default -> 4;
		};
		}

		private static boolean isHidItemBrailleDisplayUsagePage(byte itemInfo, byte itemData) {
		// From HID Spec "6.2.2.7 Global Items"
		final byte usagePageType = 0b0000_0100;
		// From HID Usage Tables version 1.2.
		final byte brailleDisplayUsagePage = 0x41;
		// HID Spec "6.2.2.2 Short Items" says item info bits 2-7 describe the type and
		// function of the item.
		final byte itemType = (byte) (itemInfo & 0b1111_1100);
		return itemType == usagePageType && itemData == brailleDisplayUsagePage;
		}

		/**

services/tests/servicestests/src/com/android/server/accessibility/BrailleDisplayConnectionTest.java

+235 −146

Original line number	Diff line number	Diff line
		@@ -17,6 +17,7 @@
		package com.android.server.accessibility;

		import static com.google.common.truth.Truth.assertThat;
		import static com.google.common.truth.Truth.assertWithMessage;

		import static org.junit.Assert.assertThrows;
		import static org.mockito.ArgumentMatchers.anyInt;
		@@ -33,17 +34,24 @@ import android.testing.DexmakerShareClassLoaderRule;

		import androidx.test.platform.app.InstrumentationRegistry;

		import com.android.internal.util.HexDump;

		import com.google.common.truth.Expect;

		import org.junit.Before;
		import org.junit.Rule;
		import org.junit.Test;
		import org.junit.experimental.runners.Enclosed;
		import org.junit.runner.RunWith;
		import org.junit.runners.Parameterized;
		import org.mockito.Mock;
		import org.mockito.Mockito;
		import org.mockito.MockitoAnnotations;

		import java.io.File;
		import java.nio.file.Path;
		import java.util.Arrays;
		import java.util.Collection;
		import java.util.List;

		/**
		@@ -51,7 +59,10 @@ import java.util.List;
		*
		* <p>Prefer adding new tests in CTS where possible.
		*/
		@RunWith(Enclosed.class)
		public class BrailleDisplayConnectionTest {

		public static class ScannerTest {
		private static final Path NULL_PATH = Path.of("/dev/null");

		private BrailleDisplayConnection mBrailleDisplayConnection;
		@@ -108,7 +119,8 @@ public class BrailleDisplayConnectionTest {
		int descriptorSize = 4;
		byte[] descriptor = {0xB, 0xE, 0xE, 0xF};
		when(mNativeInterface.getHidrawDescSize(anyInt())).thenReturn(descriptorSize);
		when(mNativeInterface.getHidrawDesc(anyInt(), eq(descriptorSize))).thenReturn(descriptor);
		when(mNativeInterface.getHidrawDesc(anyInt(), eq(descriptorSize))).thenReturn(
		descriptor);

		BrailleDisplayConnection.BrailleDisplayScanner scanner =
		mBrailleDisplayConnection.getDefaultNativeScanner(mNativeInterface);
		@@ -198,15 +210,18 @@ public class BrailleDisplayConnectionTest {
		Bundle bd1 = new Bundle(), bd2 = new Bundle();

		Path path1 = Path.of("/dev/path1"), path2 = Path.of("/dev/path2");
		bd1.putString(BrailleDisplayController.TEST_BRAILLE_DISPLAY_HIDRAW_PATH, path1.toString());
		bd2.putString(BrailleDisplayController.TEST_BRAILLE_DISPLAY_HIDRAW_PATH, path2.toString());
		bd1.putString(BrailleDisplayController.TEST_BRAILLE_DISPLAY_HIDRAW_PATH,
		path1.toString());
		bd2.putString(BrailleDisplayController.TEST_BRAILLE_DISPLAY_HIDRAW_PATH,
		path2.toString());
		byte[] desc1 = {0xB, 0xE}, desc2 = {0xE, 0xF};
		bd1.putByteArray(BrailleDisplayController.TEST_BRAILLE_DISPLAY_DESCRIPTOR, desc1);
		bd2.putByteArray(BrailleDisplayController.TEST_BRAILLE_DISPLAY_DESCRIPTOR, desc2);
		String uniq1 = "uniq1", uniq2 = "uniq2";
		bd1.putString(BrailleDisplayController.TEST_BRAILLE_DISPLAY_UNIQUE_ID, uniq1);
		bd2.putString(BrailleDisplayController.TEST_BRAILLE_DISPLAY_UNIQUE_ID, uniq2);
		int bus1 = BrailleDisplayConnection.BUS_USB, bus2 = BrailleDisplayConnection.BUS_BLUETOOTH;
		int bus1 = BrailleDisplayConnection.BUS_USB, bus2 =
		BrailleDisplayConnection.BUS_BLUETOOTH;
		bd1.putBoolean(BrailleDisplayController.TEST_BRAILLE_DISPLAY_BUS_BLUETOOTH,
		bus1 == BrailleDisplayConnection.BUS_BLUETOOTH);
		bd2.putBoolean(BrailleDisplayController.TEST_BRAILLE_DISPLAY_BUS_BLUETOOTH,
		@@ -232,3 +247,77 @@ public class BrailleDisplayConnectionTest {
		expect.that(scanner.getHidrawNodePaths(Path.of("/dev"))).isNull();
		}
		}

		@RunWith(Parameterized.class)
		public static class BrailleDisplayDescriptorTest {
		@Parameterized.Parameters(name = "{0}")
		public static Collection<Object[]> data() {
		return Arrays.asList(new Object[][]{
		{"match_BdPage", new byte[]{
		// Just one item, defines the BD page
		0x05, 0x41}},
		{"match_BdPageAfterAnotherPage", new byte[]{
		// One item defines another page
		0x05, 0x01,
		// Next item defines BD page
		0x05, 0x41}},
		{"match_BdPageAfterSizeZeroItem", new byte[]{
		// Size-zero item (last 2 bits are 00)
		0x00,
		// Next item defines BD page
		0x05, 0x41}},
		{"match_BdPageAfterSizeOneItem", new byte[]{
		// Size-one item (last 2 bits are 01)
		0x01, 0x7F,
		// Next item defines BD page
		0x05, 0x41}},
		{"match_BdPageAfterSizeTwoItem", new byte[]{
		// Size-two item (last 2 bits are 10)
		0x02, 0x7F, 0x7F,
		0x05, 0x41}},
		{"match_BdPageAfterSizeFourItem", new byte[]{
		// Size-four item (last 2 bits are 11)
		0x03, 0x7F, 0x7F, 0x7F, 0x7F,
		0x05, 0x41}},
		{"match_BdPageInBetweenOtherPages", new byte[]{
		// One item defines another page
		0x05, 0x01,
		// Next item defines BD page
		0x05, 0x41,
		// Next item defines another page
		0x05, 0x02}},
		{"fail_OtherPage", new byte[]{
		// Just one item, defines another page
		0x05, 0x01}},
		{"fail_BdPageBeforeMissingData", new byte[]{
		// This item defines BD page
		0x05, 0x41,
		// Next item specifies size-one item (last 2 bits are 01) but
		// that one data byte is missing; this descriptor is malformed.
		0x01}},
		{"fail_BdPageWithWrongDataSize", new byte[]{
		// This item defines a page with two-byte ID 0x41 0x7F, not 0x41.
		0x06, 0x41, 0x7F}},
		{"fail_LongItem", new byte[]{
		// Item has type bits 1111, indicating Long Item.
		(byte) 0xF0}},
		});
		}


		@Parameterized.Parameter(0)
		public String mTestName;
		@Parameterized.Parameter(1)
		public byte[] mDescriptor;

		@Test
		public void isBrailleDisplay() {
		final boolean expectedMatch = mTestName.startsWith("match_");
		assertWithMessage(
		"Expected isBrailleDisplay==" + expectedMatch
		+ " for descriptor " + HexDump.toHexString(mDescriptor))
		.that(BrailleDisplayConnection.isBrailleDisplay(mDescriptor))
		.isEqualTo(expectedMatch);
		}
		}
		}