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RootShell: Use a lock object instead of sync methods

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This avoids exposing the synchronization implementation details
in the class's interface.

Signed-off-by: Samuel Holland <samuel@sholland.org>
This commit is contained in:
Samuel Holland 2018-01-16 05:47:10 -06:00
parent 75aeec035c
commit d56eda2fd6
1 changed files with 98 additions and 88 deletions
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186
app/src/main/java/com/wireguard/android/util/RootShell.java
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@ -31,6 +31,7 @@ public class RootShell {
private final String deviceNotRootedMessage;
private final File localBinaryDir;
private final File localTemporaryDir;
private final Object lock = new Object();
private final String preamble;
private Process process;
private BufferedReader stderr;
@ -57,16 +58,18 @@ public class RootShell {
return false;
}
public synchronized boolean isRunning() {
try {
// Throws an exception if the process hasn't finished yet.
if (process != null)
process.exitValue();
} catch (final IllegalThreadStateException ignored) {
// The existing process is still running.
return true;
private boolean isRunning() {
synchronized (lock) {
try {
// Throws an exception if the process hasn't finished yet.
if (process != null)
process.exitValue();
return false;
} catch (final IllegalThreadStateException ignored) {
// The existing process is still running.
return true;
}
}
return false;
}
/**
@ -77,101 +80,108 @@ public class RootShell {
* @param command Command to run as root.
* @return The exit value of the command.
*/
public synchronized int run(final Collection<String> output, final String command)
public int run(final Collection<String> output, final String command)
throws IOException, NoRootException {
start();
final String marker = UUID.randomUUID().toString();
final String script = "echo " + marker + "; echo " + marker + " >&2; (" + command +
"); ret=$?; echo " + marker + " $ret; echo " + marker + " $ret >&2\n";
Log.v(TAG, "executing: " + command);
stdin.write(script);
stdin.flush();
String line;
int errnoStdout = Integer.MIN_VALUE;
int errnoStderr = Integer.MAX_VALUE;
int markersSeen = 0;
while ((line = stdout.readLine()) != null) {
if (line.startsWith(marker)) {
++markersSeen;
if (line.length() > marker.length() + 1) {
errnoStdout = Integer.valueOf(line.substring(marker.length() + 1));
break;
synchronized (lock) {
/* Start inside synchronized block to prevent a concurrent call to stop(). */
start();
final String marker = UUID.randomUUID().toString();
final String script = "echo " + marker + "; echo " + marker + " >&2; (" + command +
"); ret=$?; echo " + marker + " $ret; echo " + marker + " $ret >&2\n";
Log.v(TAG, "executing: " + command);
stdin.write(script);
stdin.flush();
String line;
int errnoStdout = Integer.MIN_VALUE;
int errnoStderr = Integer.MAX_VALUE;
int markersSeen = 0;
while ((line = stdout.readLine()) != null) {
if (line.startsWith(marker)) {
++markersSeen;
if (line.length() > marker.length() + 1) {
errnoStdout = Integer.valueOf(line.substring(marker.length() + 1));
break;
}
} else if (markersSeen > 0) {
if (output != null)
output.add(line);
Log.v(TAG, "stdout: " + line);
}
} else if (markersSeen > 0) {
if (output != null)
output.add(line);
Log.v(TAG, "stdout: " + line);
}
}
while ((line = stderr.readLine()) != null) {
if (line.startsWith(marker)) {
++markersSeen;
if (line.length() > marker.length() + 1) {
errnoStderr = Integer.valueOf(line.substring(marker.length() + 1));
break;
while ((line = stderr.readLine()) != null) {
if (line.startsWith(marker)) {
++markersSeen;
if (line.length() > marker.length() + 1) {
errnoStderr = Integer.valueOf(line.substring(marker.length() + 1));
break;
}
} else if (markersSeen > 2) {
Log.v(TAG, "stderr: " + line);
}
} else if (markersSeen > 2) {
Log.v(TAG, "stderr: " + line);
}
if (markersSeen != 4)
throw new IOException("Expected 4 markers, received " + markersSeen);
if (errnoStdout != errnoStderr)
throw new IOException("Unable to read exit status");
Log.v(TAG, "exit: " + errnoStdout);
return errnoStdout;
}
if (markersSeen != 4)
throw new IOException("Expected 4 markers, received " + markersSeen);
if (errnoStdout != errnoStderr)
throw new IOException("Unable to read exit status");
Log.v(TAG, "exit: " + errnoStdout);
return errnoStdout;
}
public synchronized void start() throws IOException, NoRootException {
if (isRunning())
return;
if (!localBinaryDir.isDirectory() && !localBinaryDir.mkdirs())
throw new FileNotFoundException("Could not create local binary directory");
if (!localTemporaryDir.isDirectory() && !localTemporaryDir.mkdirs())
throw new FileNotFoundException("Could not create local temporary directory");
public void start() throws IOException, NoRootException {
if (!isExecutableInPath(SU))
throw new NoRootException(deviceNotRootedMessage);
try {
final ProcessBuilder builder = new ProcessBuilder().command(SU);
builder.environment().put("LC_ALL", "C");
synchronized (lock) {
if (isRunning())
return;
if (!localBinaryDir.isDirectory() && !localBinaryDir.mkdirs())
throw new FileNotFoundException("Could not create local binary directory");
if (!localTemporaryDir.isDirectory() && !localTemporaryDir.mkdirs())
throw new FileNotFoundException("Could not create local temporary directory");
try {
process = builder.start();
} catch (final IOException e) {
// A failure at this stage means the device isn't rooted.
throw new NoRootException(deviceNotRootedMessage, e);
}
stdin = new OutputStreamWriter(process.getOutputStream(), StandardCharsets.UTF_8);
stdout = new BufferedReader(new InputStreamReader(process.getInputStream(),
StandardCharsets.UTF_8));
stderr = new BufferedReader(new InputStreamReader(process.getErrorStream(),
StandardCharsets.UTF_8));
stdin.write(preamble);
stdin.flush();
// Check that the shell started successfully.
final String uid = stdout.readLine();
if (!"0".equals(uid)) {
Log.w(TAG, "Root check did not return correct UID: " + uid);
throw new NoRootException(deviceNotRootedMessage);
}
if (!isRunning()) {
String line;
while ((line = stderr.readLine()) != null) {
Log.w(TAG, "Root check returned an error: " + line);
if (line.contains("Permission denied"))
throw new NoRootException(deviceNotRootedMessage);
final ProcessBuilder builder = new ProcessBuilder().command(SU);
builder.environment().put("LC_ALL", "C");
try {
process = builder.start();
} catch (final IOException e) {
// A failure at this stage means the device isn't rooted.
throw new NoRootException(deviceNotRootedMessage, e);
}
throw new IOException("Shell failed to start: " + process.exitValue());
stdin = new OutputStreamWriter(process.getOutputStream(), StandardCharsets.UTF_8);
stdout = new BufferedReader(new InputStreamReader(process.getInputStream(),
StandardCharsets.UTF_8));
stderr = new BufferedReader(new InputStreamReader(process.getErrorStream(),
StandardCharsets.UTF_8));
stdin.write(preamble);
stdin.flush();
// Check that the shell started successfully.
final String uid = stdout.readLine();
if (!"0".equals(uid)) {
Log.w(TAG, "Root check did not return correct UID: " + uid);
throw new NoRootException(deviceNotRootedMessage);
}
if (!isRunning()) {
String line;
while ((line = stderr.readLine()) != null) {
Log.w(TAG, "Root check returned an error: " + line);
if (line.contains("Permission denied"))
throw new NoRootException(deviceNotRootedMessage);
}
throw new IOException("Shell failed to start: " + process.exitValue());
}
} catch (final IOException | NoRootException e) {
stop();
throw e;
}
} catch (final IOException | NoRootException e) {
stop();
throw e;
}
}
public synchronized void stop() throws IOException {
if (process != null) {
process.destroy();
process = null;
public void stop() {
synchronized (lock) {
if (process != null) {
process.destroy();
process = null;
}
}
}