package jackpal.androidterm;
import android.annotation.TargetApi;
import android.os.*;
import android.support.annotation.NonNull;
import java.io.FileDescriptor;
import java.io.IOException;
import java.lang.reflect.Field;
import java.util.*;
/**
* Utility methods for creating and managing a subprocess. This class differs from
* {@link java.lang.ProcessBuilder} in that a pty is used to communicate with the subprocess.
* <p>
* Pseudo-terminals are a powerful Unix feature, that allows programs to interact with other programs
* they start in slightly more human-like way. For example, a pty owner can send ^C (aka SIGINT)
* to attached shell, even if said shell runs under a different user ID.
*/
public class TermExec {
// Warning: bump the library revision, when an incompatible change happens
static {
System.loadLibrary("jackpal-termexec2");
}
public static final String SERVICE_ACTION_V1 = "jackpal.androidterm.action.START_TERM.v1";
private static Field descriptorField;
private final List<String> command;
private final Map<String, String> environment;
public TermExec(@NonNull String... command) {
this(new ArrayList<>(Arrays.asList(command)));
}
public TermExec(@NonNull List<String> command) {
this.command = command;
this.environment = new Hashtable<>(System.getenv());
}
public @NonNull List<String> command() {
return command;
}
public @NonNull Map<String, String> environment() {
return environment;
}
public @NonNull TermExec command(@NonNull String... command) {
return command(new ArrayList<>(Arrays.asList(command)));
}
public @NonNull TermExec command(List<String> command) {
command.clear();
command.addAll(command);
return this;
}
/**
* Start the process and attach it to the pty, corresponding to given file descriptor.
* You have to obtain this file descriptor yourself by calling
* {@link android.os.ParcelFileDescriptor#open} on special terminal multiplexer
* device (located at /dev/ptmx).
* <p>
* Callers are responsible for closing the descriptor.
*
* @return the PID of the started process.
*/
public int start(@NonNull ParcelFileDescriptor ptmxFd) throws IOException {
if (Looper.getMainLooper() == Looper.myLooper())
throw new IllegalStateException("This method must not be called from the main thread!");
if (command.size() == 0)
throw new IllegalStateException("Empty command!");
final String cmd = command.remove(0);
final String[] cmdArray = command.toArray(new String[command.size()]);
final String[] envArray = new String[environment.size()];
int i = 0;
for (Map.Entry<String, String> entry : environment.entrySet()) {
envArray[i++] = entry.getKey() + "=" + entry.getValue();
}
return createSubprocess(ptmxFd, cmd, cmdArray, envArray);
}
/**
* Causes the calling thread to wait for the process associated with the
* receiver to finish executing.
*
* @return The exit value of the Process being waited on
*/
public static native int waitFor(int processId);
/**
* Send signal via the "kill" system call. Android {@link android.os.Process#sendSignal} does not
* allow negative numbers (denoting process groups) to be used.
*/
public static native void sendSignal(int processId, int signal);
static int createSubprocess(ParcelFileDescriptor masterFd, String cmd, String[] args, String[] envVars) throws IOException
{
final int integerFd;
if (Build.VERSION.SDK_INT >= 12)
integerFd = FdHelperHoneycomb.getFd(masterFd);
else {
try {
if (descriptorField == null) {
descriptorField = FileDescriptor.class.getDeclaredField("descriptor");
descriptorField.setAccessible(true);
}
integerFd = descriptorField.getInt(masterFd.getFileDescriptor());
} catch (Exception e) {
throw new IOException("Unable to obtain file descriptor on this OS version: " + e.getMessage());
}
}
return createSubprocessInternal(cmd, args, envVars, integerFd);
}
private static native int createSubprocessInternal(String cmd, String[] args, String[] envVars, int masterFd);
}
// prevents runtime errors on old API versions with ruthless verifier
@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1)
class FdHelperHoneycomb {
static int getFd(ParcelFileDescriptor descriptor) {
return descriptor.getFd();
}
}