在 su 进程中读取命令输出

Question

首先我将介绍我的情况。 我需要在我的 android 应用程序中执行“su”命令，它运行良好。然后我需要执行“ls”命令并读取输出。我通过从“su”进程中获取输出流并将我的命令写入其中来做到这一点。

问题来了。如何读取“ls”进程的输出？我所拥有的只是“su” Process 对象。从中获取输入流什么也没有，因为“su”不写任何东西。但是“ls”可以，我不知道如何访问它的输出消息。

我搜索了很多网站，但没有找到任何解决方案。也许有人会帮助我:)

问候

Answer 1

好的，我找到了解决方案。它应该是这样的：

Process p = Runtime.getRuntime().exec(new String[]{"su", "-c", "system/bin/sh"});
DataOutputStream stdin = new DataOutputStream(p.getOutputStream());
//from here all commands are executed with su permissions
stdin.writeBytes("ls /data\n"); // \n executes the command
InputStream stdout = p.getInputStream();
byte[] buffer = new byte[BUFF_LEN];
int read;
String out = new String();
//read method will wait forever if there is nothing in the stream
//so we need to read it in another way than while((read=stdout.read(buffer))>0)
while(true){
    read = stdout.read(buffer);
    out += new String(buffer, 0, read);
    if(read<BUFF_LEN){
        //we have read everything
        break;
    }
}
//do something with the output

希望对某人有所帮助

Answer 2

public String ls () {
    Class<?> execClass = Class.forName("android.os.Exec");
    Method createSubprocess = execClass.getMethod("createSubprocess", String.class, String.class, String.class, int[].class);
    int[] pid = new int[1];
    FileDescriptor fd = (FileDescriptor)createSubprocess.invoke(null, "/system/bin/ls", "/", null, pid);

    BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(fd)));
    String output = "";
    try {
        String line;
        while ((line = reader.readLine()) != null) {
            output += line + "\n";
        }
    }
    catch (IOException e) {}
    return output;
}

检查这里提到的这段代码：

How to run terminal command in Android application?

---

try {
// Executes the command.
Process process = Runtime.getRuntime().exec("/system/bin/ls /sdcard");

// Reads stdout.
// NOTE: You can write to stdin of the command using
//       process.getOutputStream().
BufferedReader reader = new BufferedReader(
        new InputStreamReader(process.getInputStream()));
int read;
char[] buffer = new char[4096];
StringBuffer output = new StringBuffer();
while ((read = reader.read(buffer)) > 0) {
    output.append(buffer, 0, read);
}
reader.close();

// Waits for the command to finish.
process.waitFor();

return output.toString();
} catch (IOException e) {
throw new RuntimeException(e);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}

---

参考文献

this code GScript

Answer 3

我针对以下问题修改了@glodos 接受的答案：

1. 流已关闭，否则 exec 进程将永远挂起，在打开的流上。如果你在shell中执行ps（即adb shell） 多次执行后，您将看到几个 su 进程 活。需要正确终止它们。
2. 添加了waitFor() 以确保进程终止。
3. 添加了对read=-1 的处理，现在可以执行带有空stdout 的命令。以前他们在new String(buffer, 0, read) 上崩溃了

4. 使用StringBuffer 更有效地处理字符串。

   private String execCommand(String cmd) throws IOException, InterruptedException {
       Process p = Runtime.getRuntime().exec(new String[]{"su", "-c", "system/bin/sh"});
       DataOutputStream stdout = new DataOutputStream(p.getOutputStream());
   
       stdout.writeBytes(cmd);
       stdout.writeByte('\n');
       stdout.flush();
       stdout.close();
   
       BufferedReader stdin = new BufferedReader(new InputStreamReader(p.getInputStream()));
       char[] buffer = new char[1024];
       int read;
       StringBuffer out = new StringBuffer();
   
       while((read = stdin.read(buffer)) > 0) {
           out.append(buffer, 0, read);
       }
       stdin.close();
       p.waitFor();
       return out.toString();
   }
   

一些学分归@Sherif elKhatib ))