Freezer: fix exception when parsing /proc/locks (bbe06e7b) · Commits · e / os / android_frameworks_base

core/java/android/os/Process.java

+0 −42

Original line number	Diff line number	Diff line
		@@ -34,12 +34,9 @@ import dalvik.system.VMRuntime;

		import libcore.io.IoUtils;

		import java.io.BufferedReader;
		import java.io.FileDescriptor;
		import java.io.FileReader;
		import java.io.IOException;
		import java.util.Map;
		import java.util.StringTokenizer;
		import java.util.concurrent.TimeoutException;

		/**
		@@ -1472,43 +1469,4 @@ public class Process {
		}

		private static native int nativePidFdOpen(int pid, int flags) throws ErrnoException;

		/**
		* Checks if a process corresponding to a specific pid owns any file locks.
		* @param pid The process ID for which we want to know the existence of file locks.
		* @return true If the process holds any file locks, false otherwise.
		* @throws IOException if /proc/locks can't be accessed.
		*
		* @hide
		*/
		public static boolean hasFileLocks(int pid) throws Exception {
		BufferedReader br = null;

		try {
		br = new BufferedReader(new FileReader("/proc/locks"));
		String line;

		while ((line = br.readLine()) != null) {
		StringTokenizer st = new StringTokenizer(line);

		for (int i = 0; i < 5 && st.hasMoreTokens(); i++) {
		String str = st.nextToken();
		try {
		if (i == 4 && Integer.parseInt(str) == pid) {
		return true;
		}
		} catch (NumberFormatException nfe) {
		throw new Exception("Exception parsing /proc/locks at \" "
		+ line + " \", token #" + i);
		}
		}
		}

		return false;
		} finally {
		if (br != null) {
		br.close();
		}
		}
		}
		}

core/java/com/android/internal/os/ProcLocksReader.java

0 → 100644

+89 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2021 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.internal.os;

		import com.android.internal.util.ProcFileReader;

		import libcore.io.IoUtils;

		import java.io.FileInputStream;
		import java.io.IOException;

		/**
		* Reads and parses {@code locks} files in the {@code proc} filesystem.
		* A typical example of /proc/locks
		*
		* 1: POSIX ADVISORY READ 18403 fd:09:9070 1073741826 1073742335
		* 2: POSIX ADVISORY WRITE 18292 fd:09:34062 0 EOF
		* 2: -> POSIX ADVISORY WRITE 18291 fd:09:34062 0 EOF
		* 2: -> POSIX ADVISORY WRITE 18293 fd:09:34062 0 EOF
		* 3: POSIX ADVISORY READ 3888 fd:09:13992 128 128
		* 4: POSIX ADVISORY READ 3888 fd:09:14230 1073741826 1073742335
		*/
		public class ProcLocksReader {
		private final String mPath;

		public ProcLocksReader() {
		mPath = "/proc/locks";
		}

		public ProcLocksReader(String path) {
		mPath = path;
		}

		/**
		* Checks if a process corresponding to a specific pid owns any file locks.
		* @param pid The process ID for which we want to know the existence of file locks.
		* @return true If the process holds any file locks, false otherwise.
		* @throws IOException if /proc/locks can't be accessed.
		*/
		public boolean hasFileLocks(int pid) throws Exception {
		ProcFileReader reader = null;
		long last = -1;
		long id; // ordinal position of the lock in the list
		int owner; // the PID of the process that owns the lock

		try {
		reader = new ProcFileReader(new FileInputStream(mPath));

		while (reader.hasMoreData()) {
		id = reader.nextLong(true); // lock id
		if (id == last) {
		reader.finishLine(); // blocked lock
		continue;
		}

		reader.nextIgnored(); // lock type: POSIX?
		reader.nextIgnored(); // lock type: MANDATORY?
		reader.nextIgnored(); // lock type: RW?

		owner = reader.nextInt(); // pid
		if (owner == pid) {
		return true;
		}
		reader.finishLine();
		last = id;
		}
		} catch (IOException e) {
		// TODO: let ProcFileReader log the failed line
		throw new Exception("Exception parsing /proc/locks");
		} finally {
		IoUtils.closeQuietly(reader);
		}
		return false;
		}
		}

core/java/com/android/internal/util/ProcFileReader.java

+37 −6

Original line number	Diff line number	Diff line
		@@ -28,8 +28,8 @@ import java.nio.charset.StandardCharsets;
		* requires each line boundary to be explicitly acknowledged using
		* {@link #finishLine()}. Assumes {@link StandardCharsets#US_ASCII} encoding.
		* <p>
		* Currently doesn't support formats based on {@code \0}, tabs, or repeated
		* delimiters.
		* Currently doesn't support formats based on {@code \0}, tabs.
		* Consecutive spaces are treated as a single delimiter.
		*/
		public class ProcFileReader implements Closeable {
		private final InputStream mStream;
		@@ -75,6 +75,11 @@ public class ProcFileReader implements Closeable {
		private void consumeBuf(int count) throws IOException {
		// TODO: consider moving to read pointer, but for now traceview says
		// these copies aren't a bottleneck.

		// skip all consecutive delimiters.
		while (count < mTail && mBuffer[count] == ' ') {
		count++;
		}
		System.arraycopy(mBuffer, count, mBuffer, 0, mTail - count);
		mTail -= count;
		if (mTail == 0) {
		@@ -159,11 +164,18 @@ public class ProcFileReader implements Closeable {
		* Parse and return next token as base-10 encoded {@code long}.
		*/
		public long nextLong() throws IOException {
		return nextLong(false);
		}

		/**
		* Parse and return next token as base-10 encoded {@code long}.
		*/
		public long nextLong(boolean stopAtInvalid) throws IOException {
		final int tokenIndex = nextTokenIndex();
		if (tokenIndex == -1) {
		throw new ProtocolException("Missing required long");
		} else {
		return parseAndConsumeLong(tokenIndex);
		return parseAndConsumeLong(tokenIndex, stopAtInvalid);
		}
		}

		@@ -176,7 +188,7 @@ public class ProcFileReader implements Closeable {
		if (tokenIndex == -1) {
		return def;
		} else {
		return parseAndConsumeLong(tokenIndex);
		return parseAndConsumeLong(tokenIndex, false);
		}
		}

		@@ -186,7 +198,10 @@ public class ProcFileReader implements Closeable {
		return s;
		}

		private long parseAndConsumeLong(int tokenIndex) throws IOException {
		/**
		* If stopAtInvalid is true, don't throw IOException but return whatever parsed so far.
		*/
		private long parseAndConsumeLong(int tokenIndex, boolean stopAtInvalid) throws IOException {
		final boolean negative = mBuffer[0] == '-';

		// TODO: refactor into something like IntegralToString
		@@ -194,8 +209,12 @@ public class ProcFileReader implements Closeable {
		for (int i = negative ? 1 : 0; i < tokenIndex; i++) {
		final int digit = mBuffer[i] - '0';
		if (digit < 0 \|\| digit > 9) {
		if (stopAtInvalid) {
		break;
		} else {
		throw invalidLong(tokenIndex);
		}
		}

		// always parse as negative number and apply sign later; this
		// correctly handles MIN_VALUE which is "larger" than MAX_VALUE.
		@@ -226,6 +245,18 @@ public class ProcFileReader implements Closeable {
		return (int) value;
		}

		/**
		* Bypass the next token.
		*/
		public void nextIgnored() throws IOException {
		final int tokenIndex = nextTokenIndex();
		if (tokenIndex == -1) {
		throw new ProtocolException("Missing required token");
		} else {
		consumeBuf(tokenIndex + 1);
		}
		}

		@Override
		public void close() throws IOException {
		mStream.close();

core/tests/coretests/src/com/android/internal/os/ProcLocksReaderTest.java

0 → 100644

+90 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2021 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.internal.os;

		import static org.junit.Assert.assertFalse;
		import static org.junit.Assert.assertTrue;

		import android.content.Context;
		import android.os.FileUtils;

		import androidx.test.InstrumentationRegistry;
		import androidx.test.filters.SmallTest;
		import androidx.test.runner.AndroidJUnit4;

		import org.junit.After;
		import org.junit.Before;
		import org.junit.Test;
		import org.junit.runner.RunWith;

		import java.io.File;
		import java.nio.file.Files;

		@SmallTest
		@RunWith(AndroidJUnit4.class)
		public class ProcLocksReaderTest {
		private File mProcDirectory;

		@Before
		public void setUp() {
		Context context = InstrumentationRegistry.getContext();
		mProcDirectory = context.getDir("proc", Context.MODE_PRIVATE);
		}

		@After
		public void tearDown() throws Exception {
		FileUtils.deleteContents(mProcDirectory);
		}

		@Test
		public void testRunSimpleLocks() throws Exception {
		String simpleLocks =
		"1: POSIX ADVISORY READ 18403 fd:09:9070 1073741826 1073742335\n" +
		"2: POSIX ADVISORY WRITE 18292 fd:09:34062 0 EOF\n";
		assertFalse(runHasFileLocks(simpleLocks, 18402));
		assertFalse(runHasFileLocks(simpleLocks, 18404));
		assertTrue(runHasFileLocks(simpleLocks, 18403));
		assertTrue(runHasFileLocks(simpleLocks, 18292));
		}

		@Test
		public void testRunBlockedLocks() throws Exception {
		String blockedLocks =
		"1: POSIX ADVISORY READ 18403 fd:09:9070 1073741826 1073742335\n" +
		"2: POSIX ADVISORY WRITE 18292 fd:09:34062 0 EOF\n" +
		"2: -> POSIX ADVISORY WRITE 18291 fd:09:34062 0 EOF\n" +
		"2: -> POSIX ADVISORY WRITE 18293 fd:09:34062 0 EOF\n" +
		"3: POSIX ADVISORY READ 3888 fd:09:13992 128 128\n" +
		"4: POSIX ADVISORY READ 3888 fd:09:14230 1073741826 1073742335\n";
		assertFalse(runHasFileLocks(blockedLocks, 18402));
		assertFalse(runHasFileLocks(blockedLocks, 18404));
		assertTrue(runHasFileLocks(blockedLocks, 18403));
		assertTrue(runHasFileLocks(blockedLocks, 18292));

		assertFalse(runHasFileLocks(blockedLocks, 18291));
		assertFalse(runHasFileLocks(blockedLocks, 18293));
		assertTrue(runHasFileLocks(blockedLocks, 3888));
		}

		private boolean runHasFileLocks(String fileContents, int pid) throws Exception {
		File tempFile = File.createTempFile("locks", null, mProcDirectory);
		Files.write(tempFile.toPath(), fileContents.getBytes());
		boolean result = new ProcLocksReader(tempFile.toString()).hasFileLocks(pid);
		Files.delete(tempFile.toPath());
		return result;
		}
		}

core/tests/utiltests/src/com/android/internal/util/ProcFileReaderTest.java

+40 −0

Original line number	Diff line number	Diff line
		@@ -166,6 +166,46 @@ public class ProcFileReaderTest extends AndroidTestCase {
		assertEquals(-1L, reader.nextOptionalLong(-1L));
		}

		public void testInvalidLongs() throws Exception {
		final ProcFileReader reader = buildReader("12: 34\n56 78@#\n");

		assertEquals(12L, reader.nextLong(true));
		assertEquals(34L, reader.nextLong(true));
		reader.finishLine();
		assertTrue(reader.hasMoreData());

		assertEquals(56L, reader.nextLong(true));
		assertEquals(78L, reader.nextLong(true));
		reader.finishLine();
		assertFalse(reader.hasMoreData());
		}

		public void testConsecutiveDelimiters() throws Exception {
		final ProcFileReader reader = buildReader("1 2 3 4 5\n");

		assertEquals(1L, reader.nextLong());
		assertEquals(2L, reader.nextLong());
		assertEquals(3L, reader.nextLong());
		assertEquals(4L, reader.nextLong());
		assertEquals(5L, reader.nextLong());
		reader.finishLine();
		assertFalse(reader.hasMoreData());
		}

		public void testIgnore() throws Exception {
		final ProcFileReader reader = buildReader("a b c\n");

		assertEquals("a", reader.nextString());
		assertTrue(reader.hasMoreData());

		reader.nextIgnored();
		assertTrue(reader.hasMoreData());

		assertEquals("c", reader.nextString());
		reader.finishLine();
		assertFalse(reader.hasMoreData());
		}

		private static ProcFileReader buildReader(String string) throws IOException {
		return buildReader(string, 2048);
		}