package com.termux.app;
import android.util.Log;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.reflect.Field;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
/**
* A background job launched by Termux.
*/
public final class BackgroundJob {
private static final String LOG_TAG = "termux-task";
final Process mProcess;
public BackgroundJob(String cwd, String fileToExecute, final String[] args, final TermuxService service) {
String[] env = buildEnvironment(false, cwd);
if (cwd == null) cwd = TermuxService.HOME_PATH;
final String[] progArray = setupProcessArgs(fileToExecute, args);
final String processDescription = Arrays.toString(progArray);
Process process;
try {
process = Runtime.getRuntime().exec(progArray, env, new File(cwd));
} catch (IOException e) {
mProcess = null;
// TODO: Visible error message?
Log.e(LOG_TAG, "Failed running background job: " + processDescription, e);
return;
}
mProcess = process;
final int pid = getPid(mProcess);
new Thread() {
@Override
public void run() {
Log.i(LOG_TAG, "[" + pid + "] starting: " + processDescription);
InputStream stdout = mProcess.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(stdout, StandardCharsets.UTF_8));
String line;
try {
// FIXME: Long lines.
while ((line = reader.readLine()) != null) {
Log.i(LOG_TAG, "[" + pid + "] stdout: " + line);
}
} catch (IOException e) {
Log.e(LOG_TAG, "Error reading output", e);
}
try {
int exitCode = mProcess.waitFor();
service.onBackgroundJobExited(BackgroundJob.this);
if (exitCode == 0) {
Log.i(LOG_TAG, "[" + pid + "] exited normally");
} else {
Log.w(LOG_TAG, "[" + pid + "] exited with code: " + exitCode);
}
} catch (InterruptedException e) {
// Ignore.
}
}
}.start();
new Thread() {
@Override
public void run() {
InputStream stderr = mProcess.getErrorStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(stderr, StandardCharsets.UTF_8));
String line;
try {
// FIXME: Long lines.
while ((line = reader.readLine()) != null) {
Log.i(LOG_TAG, "[" + pid + "] stderr: " + line);
}
} catch (IOException e) {
// Ignore.
}
}
};
}
public static String[] buildEnvironment(boolean failSafe, String cwd) {
new File(TermuxService.HOME_PATH).mkdirs();
if (cwd == null) cwd = TermuxService.HOME_PATH;
final String termEnv = "TERM=xterm-256color";
final String homeEnv = "HOME=" + TermuxService.HOME_PATH;
final String prefixEnv = "PREFIX=" + TermuxService.PREFIX_PATH;
final String androidRootEnv = "ANDROID_ROOT=" + System.getenv("ANDROID_ROOT");
final String androidDataEnv = "ANDROID_DATA=" + System.getenv("ANDROID_DATA");
// EXTERNAL_STORAGE is needed for /system/bin/am to work on at least
// Samsung S7 - see https://plus.google.com/110070148244138185604/posts/gp8Lk3aCGp3.
final String externalStorageEnv = "EXTERNAL_STORAGE=" + System.getenv("EXTERNAL_STORAGE");
if (failSafe) {
// Keep the default path so that system binaries can be used in the failsafe session.
final String pathEnv = "PATH=" + System.getenv("PATH");
return new String[]{termEnv, homeEnv, prefixEnv, androidRootEnv, androidDataEnv, pathEnv, externalStorageEnv};
} else {
final String ps1Env = "PS1=$ ";
final String ldEnv = "LD_LIBRARY_PATH=" + TermuxService.PREFIX_PATH + "/lib";
final String langEnv = "LANG=en_US.UTF-8";
final String pathEnv = "PATH=" + TermuxService.PREFIX_PATH + "/bin:" + TermuxService.PREFIX_PATH + "/bin/applets";
final String pwdEnv = "PWD=" + cwd;
final String tmpdirEnv = "TMPDIR=" + TermuxService.PREFIX_PATH + "/tmp";
return new String[]{termEnv, homeEnv, prefixEnv, ps1Env, ldEnv, langEnv, pathEnv, pwdEnv, androidRootEnv, androidDataEnv, externalStorageEnv, tmpdirEnv};
}
}
public static int getPid(Process p) {
try {
Field f = p.getClass().getDeclaredField("pid");
f.setAccessible(true);
try {
return f.getInt(p);
} finally {
f.setAccessible(false);
}
} catch (Throwable e) {
return -1;
}
}
static String[] setupProcessArgs(String fileToExecute, String[] args) {
// The file to execute may either be:
// - An elf file, in which we execute it directly.
// - A script file without shebang, which we execute with our standard shell $PREFIX/bin/sh instead of the
// system /system/bin/sh. The system shell may vary and may not work at all due to LD_LIBRARY_PATH.
// - A file with shebang, which we try to handle with e.g. /bin/foo -> $PREFIX/bin/foo.
String interpreter = null;
try {
File file = new File(fileToExecute);
try (FileInputStream in = new FileInputStream(file)) {
byte[] buffer = new byte[256];
int bytesRead = in.read(buffer);
if (bytesRead > 4) {
if (buffer[0] == 0x7F && buffer[1] == 'E' && buffer[2] == 'L' && buffer[3] == 'F') {
// Elf file, do nothing.
} else if (buffer[0] == '#' && buffer[1] == '!') {
// Try to parse shebang.
StringBuilder builder = new StringBuilder();
for (int i = 2; i < bytesRead; i++) {
char c = (char) buffer[i];
if (c == ' ' || c == '\n') {
if (builder.length() == 0) {
// Skip whitespace after shebang.
} else {
// End of shebang.
String executable = builder.toString();
if (executable.startsWith("/usr") || executable.startsWith("/bin")) {
String[] parts = executable.split("/");
String binary = parts[parts.length - 1];
interpreter = TermuxService.PREFIX_PATH + "/bin/" + binary;
}
break;
}
} else {
builder.append(c);
}
}
} else {
// No shebang and no ELF, use standard shell.
interpreter = TermuxService.PREFIX_PATH + "/bin/sh";
}
}
}
} catch (IOException e) {
// Ignore.
}
List<String> result = new ArrayList<>();
if (interpreter != null) result.add(interpreter);
result.add(fileToExecute);
if (args != null) Collections.addAll(result, args);
return result.toArray(new String[result.size()]);
}
}