Android 自定义shell命令

news2025/1/2 20:38:28

模拟触摸、按键等操作，直接在命令行输入对应命令即可。命令行如何识别并操作此命令，执行操作的是shell程序，还是java程序？是不是可以添加自定义的命令？

以下在Android13的代码中分析input命令

Android系统中使用了一款叫mksh的shell程序，用于交互式的命令解释器。

mksh

mksh是一款开源的命令解释器(shell)，aosp中的源码路径是external/mksh，编译后会在/system/bin下生成 "sh"可执行程序，init.rc中配置了开机启动这个二进制程序。当"sh"启动后，终端工具上就会出现我们常知的命令解释器，可以输入shell命令进行操作。

init.rc中定义了名为"console"的service，service对应的可执行程序是sh这个二进制，这个二进制程序由 exteranl/mksh/Android.bp定义。

service console /system/bin/sh
    class core
    console
    disabled
    user shell
    group shell log readproc
    seclabel u:r:shell:s0

src/main.c中定义一些指令

static const char *initcoms[] = {
        Ttypeset, Tdr, initvsn, NULL,
        Ttypeset, Tdx, "HOME", TPATH, TSHELL, NULL,
        Ttypeset, "-i10", "COLUMNS", "LINES", "SECONDS", "TMOUT", NULL,
        Talias,
        "integer=\\\\builtin typeset -i",
        "local=\\\\builtin typeset",
        /* not "alias -t --": hash -r needs to work */
        "hash=\\\\builtin alias -t",
        "type=\\\\builtin whence -v",
        "autoload=\\\\builtin typeset -fu",
        "functions=\\\\builtin typeset -f",
        "history=\\\\builtin fc -l",
        "nameref=\\\\builtin typeset -n",
        "nohup=nohup ",
        "r=\\\\builtin fc -e -",
        "login=\\\\builtin exec login",
        "ll=\\ls -all",
        NULL,
         /* this is what AT&T ksh seems to track, with the addition of emacs */
        Talias, "-tU",
        Tcat, "cc", "chmod", "cp", "date", "ed", "emacs", "grep", "ls",
        "make", "mv", "pr", "rm", "sed", Tsh, "vi", "who", NULL,
        NULL 
};

可在此处添加命令。如：ll=ls -all

cmd命令的入口在frameworks/native/cmds/cmd，在cmd.cpp的cmdMain方法中，根据命令获取对应service

int cmdMain(const std::vector<std::string_view>& argv, TextOutput& outputLog, TextOutput& errorLog, int in, int out, int err, RunMode runMode) {
    sp<ProcessState> proc = ProcessState::self();
    proc->startThreadPool();
    ......
    sp<IServiceManager> sm = defaultServiceManager();
    if (sm == nullptr) {
        ALOGW("Unable to get default service manager!");
        errorLog << "cmd: Unable to get default service manager!" << endl;
        return 20;
    }
    int argc = argv.size();
    if (argc == 0) {
        errorLog << "cmd: No service specified; use -l to list all running services. Use -w to start and wait for a service." << endl;
        return 20;
    }
    ......
    const auto cmd = argv[serviceIdx];
    Vector<String16> args;
    String16 serviceName = String16(cmd.data(), cmd.size());
    ......
    sp<IBinder> service;
    if(waitForService) {
        service = sm->waitForService(serviceName);
    } else {
        service = sm->checkService(serviceName);
    }
    ......
    status_t error = IBinder::shellCommand(service, in, out, err, args, cb, result);

首先获取ServiceManage，根据命令获取对应的service，sm->checkService(serviceName);

通过service执行命令IBinder::shellCommand(service, in, out, err, args, cb, result);

因此执行cmd命令的是Java程序，如果执行input命令，需要一个service，系统中InputManagerService处理cmd命令

    @Override
    public void onShellCommand(FileDescriptor in, FileDescriptor out, FileDescriptor err, 
            String[] args, ShellCallback callback, ResultReceiver resultReceiver) {
        new InputShellCommand().exec(this, in, out, err, args, callback, resultReceiver);
    }

最终InputShellCommand执行命令。

此时命令行还不能识别input命令。需要要添加命令入口

frameworks/base/cmds/input,