android settings命令

键字： android, settings, cmd

20180822 tjy

转载请注明出处

Android 中有一个可执行文件settings，可以使得调试变得方便。
查看settings的代码，会有其他额外发现。

文件位置

device-name:/system/bin # ls -l settingsls -l settings-rwxr-xr-x 1 root shell 35 2018-08-03 04:17 settingsdevice-name:/system/bin #

settings用法

device-name:/ # settingssettingsSettings provider (settings) commands:  help      Print this help text.  get [--user  | current] NAMESPACE KEY      Retrieve the current value of KEY.  put [--user  | current] NAMESPACE KEY VALUE [TAG] [default]      Change the contents of KEY to VALUE.      TAG to associate with the setting.      {default} to set as the default, case-insensitive only for global/secure namespace  delete NAMESPACE KEY      Delete the entry for KEY.  reset [--user  | current] NAMESPACE {PACKAGE_NAME | RESET_MODE}      Reset the global/secure table for a package with mode.      RESET_MODE is one of {untrusted_defaults, untrusted_clear, trusted_defaults}, case-insensitive  list NAMESPACE      Print all defined keys.      NAMESPACE is one of {system, secure, global}, case-insensitive

settings list命令

device-name:/ # settings list globalsettings list globaladb_enabled=1add_users_when_locked=0airplane_mode_on=0airplane_mode_radios=cell,bluetooth,wifi,nfc,wimaxairplane_mode_toggleable_radios=bluetooth,wifi,nfcassisted_gps_enabled=1att_wifi_call_enable=0audio_safe_volume_state=3auto_time=1auto_time_zone=1bluetooth_disabled_profiles=0bluetooth_on=0boot_count=5call_auto_retry=0captive_portal_mode=1car_dock_sound=/system/media/audio/ui/Dock.oggcar_undock_sound=/system/media/audio/ui/Undock.oggcdma_cell_broadcast_sms=1data_roaming0=1data_roaming=1default_install_location=0default_restrict_background_data=0desk_dock_sound=/system/media/audio/ui/Dock.oggdesk_undock_sound=/system/media/audio/ui/Undock.oggdevelopment_settings_enabled=1device_provisioned=1dock_audio_media_enabled=1dock_sounds_enabled=0dock_sounds_enabled_when_accessbility=0emergency_affordance_needed=0emergency_tone=0heads_up_notifications_enabled=1lock_sound=/system/media/audio/ui/Lock.ogglow_battery_sound=/system/media/audio/ui/LowBattery.ogglow_battery_sound_timeout=0mobile_data0=1mobile_data=1mobile_data_always_on=0mode_ringer=2netstats_enabled=1network_recommendations_enabled=0package_verifier_enable=1power_sounds_enabled=1preferred_network_mode=10set_install_location=0stay_on_while_plugged_in=0subscription_mode=0theater_mode_on=0trusted_sound=/system/media/audio/ui/Trusted.oggunlock_sound=/system/media/audio/ui/Unlock.oggusb_mass_storage_enabled=1verifier_verify_adb_installs=0volte_vt_enabled=1wfc_ims_enabled=0wfc_ims_mode=1wifi_display_on=0wifi_max_dhcp_retry_count=9wifi_networks_available_notification_on=1wifi_on=0wifi_scan_always_enabled=0wifi_sleep_policy=2wifi_wakeup_available=0wifi_wakeup_enabled=1wireless_charging_started_sound=/system/media/audio/ui/WirelessChargingStarted.ogg

settings put和get

device-name:/ # settings get global bluetooth_onsettings get global bluetooth_on0device-name:/ # settings put global bluetooth_on 1settings put global bluetooth_on 1device-name:/ #

代码位置在frameworks/base/cmds/settings/settings，打开这个文件，发现它是一个shell，调用了cmd命令，cmd命令又在哪里呢？

//from http://androidxref.com/8.1.0_r33/xref/frameworks/base/cmds/settings/settings#!/system/bin/shcmd settings "$@"

在frameworks/native/cmds/cmd/cmd.cpp中，代码如下。
cmd通过IServiceManager去实现操作。

通过看代码，cmd -l可以把service都列出来。
cmd settings是通过调用 service settings中的方法来完成的。

//from http://androidxref.com/8.1.0_r33/xref/frameworks/native/cmds/cmd/cmd.cppint main(int argc, char* const argv[]){    signal(SIGPIPE, SIG_IGN);    sp proc = ProcessState::self();    // setThreadPoolMaxThreadCount(0) actually tells the kernel it's    // not allowed to spawn any additional threads, but we still spawn    // a binder thread from userspace when we call startThreadPool().    // This is safe because we only have 2 callbacks, neither of which    // block.    // See b/36066697 for rationale    proc->setThreadPoolMaxThreadCount(0);    proc->startThreadPool();    sp sm = defaultServiceManager();    fflush(stdout);    if (sm == NULL) {        ALOGW("Unable to get default service manager!");        aerr << "cmd: Unable to get default service manager!" << endl;        return 20;    }    if (argc == 1) {        aerr << "cmd: No service specified; use -l to list all services" << endl;        return 20;    }    if ((argc == 2) && (strcmp(argv[1], "-l") == 0)) {        Vector services = sm->listServices();        services.sort(sort_func);        aout << "Currently running services:" << endl;        for (size_t i=0; i service = sm->checkService(services[i]);            if (service != NULL) {                aout << "  " << services[i] << endl;            }        }        return 0;    }    Vector args;    for (int i=2; i service = sm->checkService(cmd);    if (service == NULL) {        ALOGW("Can't find service %s", argv[1]);        aerr << "cmd: Can't find service: " << argv[1] << endl;        return 20;    }    sp cb = new MyShellCallback();    sp result = new MyResultReceiver();#if DEBUG    ALOGD("cmd: Invoking %s in=%d, out=%d, err=%d", argv[1], STDIN_FILENO, STDOUT_FILENO,            STDERR_FILENO);#endif    // TODO: block until a result is returned to MyResultReceiver.    status_t err = IBinder::shellCommand(service, STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO, args,            cb, result);    if (err < 0) {        const char* errstr;        switch (err) {            case BAD_TYPE: errstr = "Bad type"; break;            case FAILED_TRANSACTION: errstr = "Failed transaction"; break;            case FDS_NOT_ALLOWED: errstr = "File descriptors not allowed"; break;            case UNEXPECTED_NULL: errstr = "Unexpected null"; break;            default: errstr = strerror(-err); break;        }        ALOGW("Failure calling service %s: %s (%d)", argv[1], errstr, -err);        aout << "cmd: Failure calling service " << argv[1] << ": " << errstr << " ("                << (-err) << ")" << endl;        return err;    }    cb->mActive = false;    status_t res = result->waitForResult();#if DEBUG    ALOGD("result=%d", (int)res);#endif    return res;}

继续追一下IBinder::shellCommand代码，定义在frameworks/native/libs/binder/Binder.cpp。
后续补充Binder的逻辑。

//from http://androidxref.com/8.1.0_r33/xref/frameworks/native/libs/binder/Binder.cpp#65status_t IBinder::shellCommand(const sp& target, int in, int out, int err,    Vector& args, const sp& callback,    const sp& resultReceiver){    Parcel send;    Parcel reply;    send.writeFileDescriptor(in);    send.writeFileDescriptor(out);    send.writeFileDescriptor(err);    const size_t numArgs = args.size();    send.writeInt32(numArgs);    for (size_t i = 0; i < numArgs; i++) {        send.writeString16(args[i]);    }    send.writeStrongBinder(callback != NULL ? IInterface::asBinder(callback) : NULL);    send.writeStrongBinder(resultReceiver != NULL ? IInterface::asBinder(resultReceiver) : NULL);    return target->transact(SHELL_COMMAND_TRANSACTION, send, &reply);}

作者：tjy_2011
链接：https://www.jianshu.com/p/409bd28ce8b4
来源：简书
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。

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