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package com.wireguard.android.backends;
import android.content.Context;
import android.util.Log;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.nio.charset.StandardCharsets;
import java.util.List;
import java.util.regex.Pattern;
import java.util.regex.Matcher;
/**
* Helper class for running commands as root.
*/
class RootShell {
/**
* Setup commands that are run at the beginning of each root shell. The trap command ensures
* access to the return value of the last command, since su itself always exits with 0.
*/
private static final String SETUP_TEMPLATE = "export TMPDIR=%s\ntrap 'echo $?' EXIT\n";
private static final String TAG = "RootShell";
private static final Pattern ERRNO_EXTRACTOR = Pattern.compile("error=(\\d+)");
private final byte[] setupCommands;
private final String shell;
RootShell(final Context context) {
this(context, "su");
}
RootShell(final Context context, final String shell) {
final String tmpdir = context.getCacheDir().getPath();
setupCommands = String.format(SETUP_TEMPLATE, tmpdir).getBytes(StandardCharsets.UTF_8);
this.shell = shell;
}
/**
* Run a series of commands in a root shell. These commands are all sent to the same shell
* process, so they can be considered a shell script.
*
* @param output Lines read from stdout and stderr are appended to this list. Pass null if the
* output from the shell is not important.
* @param commands One or more commands to run as root (each element is a separate line).
* @return The exit value of the last command run, or -1 if there was an internal error.
*/
int run(final List<String> output, final String... commands) {
if (commands.length < 1)
throw new IndexOutOfBoundsException("At least one command must be supplied");
int exitValue = -1;
try {
final ProcessBuilder builder = new ProcessBuilder().redirectErrorStream(true);
final Process process = builder.command(shell).start();
final OutputStream stdin = process.getOutputStream();
stdin.write(setupCommands);
for (final String command : commands)
stdin.write(command.concat("\n").getBytes(StandardCharsets.UTF_8));
stdin.close();
Log.d(TAG, "Sent " + commands.length + " command(s), now reading output");
final InputStream stdout = process.getInputStream();
final BufferedReader stdoutReader =
new BufferedReader(new InputStreamReader(stdout, StandardCharsets.UTF_8));
String line;
String lastLine = null;
while ((line = stdoutReader.readLine()) != null) {
Log.v(TAG, line);
lastLine = line;
if (output != null)
output.add(line);
}
process.waitFor();
process.destroy();
if (lastLine != null) {
// Remove the exit value line from the output
if (output != null)
output.remove(output.size() - 1);
exitValue = Integer.parseInt(lastLine);
}
Log.d(TAG, "Session completed with exit value " + exitValue);
} catch (IOException | InterruptedException | NumberFormatException e) {
Log.w(TAG, "Session failed with exception", e);
final Matcher match = ERRNO_EXTRACTOR.matcher(e.toString());
if (match.find())
exitValue = Integer.valueOf(match.group(1));
}
return exitValue;
}
}
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