RootShell: Simplify, synchronize, clean up
Signed-off-by: Samuel Holland <samuel@sholland.org>
This commit is contained in:
Samuel Holland
parent
662bc3894b
commit
52e8eef9ce
@ -1,8 +1,6 @@
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package com.wireguard.android.util;
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import android.content.Context;
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import android.system.ErrnoException;
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import android.system.OsConstants;
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import android.util.Log;
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import com.wireguard.android.Application.ApplicationContext;
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@ -10,16 +8,14 @@ import com.wireguard.android.Application.ApplicationScope;
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import com.wireguard.android.R;
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import java.io.BufferedReader;
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import java.io.BufferedWriter;
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import java.io.File;
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import java.io.FileNotFoundException;
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import java.io.IOException;
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import java.io.InputStreamReader;
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import java.io.OutputStreamWriter;
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import java.nio.charset.StandardCharsets;
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import java.util.Collection;
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import java.util.UUID;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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import javax.inject.Inject;
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@ -29,30 +25,29 @@ import javax.inject.Inject;
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@ApplicationScope
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public class RootShell {
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private static final Pattern ERRNO_EXTRACTOR = Pattern.compile("error=(\\d+)");
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private static final String SU = "su";
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private static final String TAG = "WireGuard/" + RootShell.class.getSimpleName();
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private final String exceptionMessage;
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private final String deviceNotRootedMessage;
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private final File localBinaryDir;
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private final File localTemporaryDir;
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private final String preamble;
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private Process process;
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private BufferedReader stderr;
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private BufferedWriter stdin;
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private OutputStreamWriter stdin;
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private BufferedReader stdout;
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@Inject
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public RootShell(@ApplicationContext final Context context) {
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final File binDir = new File(context.getCacheDir(), "bin");
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final File tmpDir = new File(context.getCacheDir(), "tmp");
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if (!(binDir.isDirectory() || binDir.mkdirs())
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|| !(tmpDir.isDirectory() || tmpDir.mkdirs()))
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throw new RuntimeException(new IOException("Cannot create binary dir/TMPDIR"));
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exceptionMessage = context.getString(R.string.error_root);
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preamble = String.format("export PATH=\"%s:$PATH\" TMPDIR='%s'; id;\n", binDir, tmpDir);
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deviceNotRootedMessage = context.getString(R.string.error_root);
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final File cacheDir = context.getCacheDir();
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localBinaryDir = new File(cacheDir, "bin");
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localTemporaryDir = new File(cacheDir, "tmp");
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preamble = String.format("export PATH=\"%s:$PATH\" TMPDIR='%s'; id -u\n",
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localBinaryDir, localTemporaryDir);
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}
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private static boolean isExecutable(final String name) {
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private static boolean isExecutableInPath(final String name) {
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final String path = System.getenv("PATH");
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if (path == null)
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return false;
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@ -62,61 +57,18 @@ public class RootShell {
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return false;
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}
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private void ensureRoot() throws ErrnoException, IOException, NoRootException {
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public boolean isRunning() {
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try {
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if (process != null) {
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process.exitValue();
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process = null;
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// Throws an exception if the process hasn't finished yet.
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synchronized (this) {
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if (process != null)
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process.exitValue();
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}
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} catch (IllegalThreadStateException e) {
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return;
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}
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if (!isExecutable("su"))
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throw new NoRootException(exceptionMessage);
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try {
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final ProcessBuilder builder = new ProcessBuilder();
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builder.environment().put("LANG", "C");
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builder.command("su");
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process = builder.start();
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stdin = new BufferedWriter(new OutputStreamWriter(process.getOutputStream(), StandardCharsets.UTF_8));
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stdout = new BufferedReader(new InputStreamReader(process.getInputStream(), StandardCharsets.UTF_8));
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stderr = new BufferedReader(new InputStreamReader(process.getErrorStream(), StandardCharsets.UTF_8));
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Log.d(TAG, "New root shell, sending preamble: " + preamble);
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stdin.write(preamble);
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stdin.flush();
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final String id = stdout.readLine();
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try {
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int errno = process.exitValue();
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String line;
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while ((line = stderr.readLine()) != null) {
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if (line.contains("Permission denied"))
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throw new NoRootException(exceptionMessage);
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}
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throw new ErrnoException("Unknown error when obtaining root access", errno);
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} catch (IllegalThreadStateException e) {
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// We're alive, so keep executing.
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}
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if (id == null || !id.contains("uid=0"))
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throw new NoRootException(exceptionMessage);
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} catch (Exception e) {
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Log.w(TAG, "Session failed with exception", e);
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process.destroy();
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process = null;
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final Matcher match = ERRNO_EXTRACTOR.matcher(e.toString());
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if (match.find()) {
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final int errno = Integer.valueOf(match.group(1));
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if (errno == OsConstants.EACCES)
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throw new NoRootException(exceptionMessage);
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else
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throw new ErrnoException("Unknown error when obtaining root access", errno);
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}
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throw e;
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} catch (final IllegalThreadStateException ignored) {
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// The existing process is still running.
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return true;
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}
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return false;
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}
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/**
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@ -125,78 +77,92 @@ public class RootShell {
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* @param output Lines read from stdout are appended to this list. Pass null if the
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* output from the shell is not important.
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* @param command Command to run as root.
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* @return The exit value of the last command run, or -1 if there was an internal error.
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* @return The exit value of the command.
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*/
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public synchronized int run(final Collection<String> output, final String command)
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throws ErrnoException, IOException, NoRootException {
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ensureRoot();
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StringBuilder builder = new StringBuilder();
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throws IOException, NoRootException {
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start();
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final String marker = UUID.randomUUID().toString();
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final String begin = marker + " begin";
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final String end = marker + " end";
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builder.append(String.format("echo '%s';", begin));
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builder.append(String.format("echo '%s' >&2;", begin));
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builder.append('(');
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builder.append(command);
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builder.append(");");
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builder.append("ret=$?;");
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builder.append(String.format("echo '%s' $ret;", end));
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builder.append(String.format("echo '%s' $ret >&2;", end));
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builder.append('\n');
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Log.v(TAG, "executing: " + command);
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stdin.write(builder.toString());
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final String script = '(' + command + "); ret=$?; echo " + marker + " $ret; "
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+ "echo " + marker + " $ret >&2\n";
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Log.v(TAG, "executing: " + script);
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stdin.write(script);
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stdin.flush();
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String line;
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boolean first = true;
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int errnoStdout = -1, errnoStderr = -2;
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int beginEnds = 0;
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int errnoStdout = Integer.MIN_VALUE;
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int errnoStderr = Integer.MAX_VALUE;
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while ((line = stdout.readLine()) != null) {
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if (first) {
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first = false;
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if (!line.startsWith(begin))
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throw new ErrnoException("Could not find begin marker", OsConstants.EBADMSG);
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++beginEnds;
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continue;
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}
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if (line.startsWith(end) && line.length() > end.length() + 1) {
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errnoStdout = Integer.valueOf(line.substring(end.length() + 1));
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++beginEnds;
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if (line.startsWith(marker) && line.length() > marker.length() + 1) {
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errnoStdout = Integer.valueOf(line.substring(marker.length() + 1));
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break;
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}
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if (output != null)
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output.add(line);
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Log.v(TAG, "stdout: " + line);
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}
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first = true;
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while ((line = stderr.readLine()) != null) {
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if (first) {
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first = false;
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if (!line.startsWith(begin))
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throw new ErrnoException("Could not find begin marker", OsConstants.EBADMSG);
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++beginEnds;
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continue;
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}
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if (line.startsWith(end) && line.length() > end.length() + 1) {
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errnoStderr = Integer.valueOf(line.substring(end.length() + 1));
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++beginEnds;
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if (line.startsWith(marker) && line.length() > marker.length() + 1) {
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errnoStderr = Integer.valueOf(line.substring(marker.length() + 1));
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break;
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}
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Log.v(TAG, "stderr: " + line);
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}
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if (errnoStderr != errnoStdout || beginEnds != 4)
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throw new ErrnoException("Incorrect errno reporting", OsConstants.EBADMSG);
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if (errnoStdout != errnoStderr)
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throw new IOException("Unable to read exit status");
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Log.v(TAG, "exit: " + errnoStdout);
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return errnoStdout;
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}
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public synchronized void start() throws IOException, NoRootException {
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if (isRunning())
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return;
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if (!localBinaryDir.isDirectory() && !localBinaryDir.mkdirs())
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throw new FileNotFoundException("Could not create local binary directory");
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if (!localTemporaryDir.isDirectory() && !localTemporaryDir.mkdirs())
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throw new FileNotFoundException("Could not create local temporary directory");
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if (!isExecutableInPath(SU))
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throw new NoRootException(deviceNotRootedMessage);
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final ProcessBuilder builder = new ProcessBuilder().command(SU);
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builder.environment().put("LC_ALL", "C");
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process = builder.start();
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stdin = new OutputStreamWriter(process.getOutputStream(), StandardCharsets.UTF_8);
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stdout = new BufferedReader(new InputStreamReader(process.getInputStream(),
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StandardCharsets.UTF_8));
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stderr = new BufferedReader(new InputStreamReader(process.getErrorStream(),
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StandardCharsets.UTF_8));
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stdin.write(preamble);
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stdin.flush();
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// Check that the shell started successfully.
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final String uid = stdout.readLine();
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if (!"0".equals(uid)) {
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Log.w(TAG, "Root check did not return correct UID: " + uid);
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throw new NoRootException(deviceNotRootedMessage);
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}
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if (!isRunning()) {
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String line;
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while ((line = stderr.readLine()) != null) {
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Log.w(TAG, "Root check returned an error: " + line);
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if (line.contains("Permission denied"))
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throw new NoRootException(deviceNotRootedMessage);
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}
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throw new IOException("Shell failed to start: " + process.exitValue());
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}
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}
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public void stop() throws IOException {
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synchronized (this) {
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if (process != null) {
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process.destroy();
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process = null;
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}
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}
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}
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public static class NoRootException extends Exception {
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public NoRootException(final String message, final Throwable cause) {
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super(message, cause);
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}
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public NoRootException(final String message) {
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super(message);
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}
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@ -1,7 +1,6 @@
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package com.wireguard.android.util;
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import android.content.Context;
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import android.system.ErrnoException;
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import android.system.OsConstants;
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import android.util.Log;
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@ -69,7 +68,7 @@ public final class ToolsInstaller {
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script.append("exit ").append(OsConstants.EALREADY).append(';');
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try {
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return rootShell.run(null, script.toString()) == OsConstants.EALREADY;
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} catch (final ErrnoException | IOException | NoRootException ignored) {
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} catch (final IOException | NoRootException ignored) {
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return false;
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}
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}
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@ -84,7 +83,7 @@ public final class ToolsInstaller {
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script.append("exit ").append(OsConstants.EALREADY).append(';');
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try {
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return rootShell.run(null, script.toString()) == OsConstants.EALREADY;
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} catch (final ErrnoException | IOException | NoRootException ignored) {
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} catch (final IOException | NoRootException ignored) {
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return false;
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}
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}
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@ -125,8 +124,6 @@ public final class ToolsInstaller {
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}
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try {
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return rootShell.run(null, script.toString());
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} catch (final ErrnoException e) {
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return e.errno;
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} catch (final IOException ignored) {
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return OsConstants.EXIT_FAILURE;
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} catch (final NoRootException ignored) {
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@ -143,8 +140,6 @@ public final class ToolsInstaller {
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}
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try {
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return rootShell.run(null, script.toString());
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} catch (final ErrnoException e) {
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return e.errno;
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} catch (final IOException ignored) {
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return OsConstants.EXIT_FAILURE;
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} catch (final NoRootException ignored) {
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