Android Recovery 源碼解析和界面定製

Android Recovery 源碼解析和界面定製

Recovery主要功能

深入瞭解recovery源碼前，先瀏覽下recovery能夠給我們提供哪些功能；

首先是我們熟悉的恢復工廠設置 –> wipe_data wipe_cache
刷升級包，可以通過sdcard升級，通常說的卡刷，有些還提供ADB sideload升級；
可以進行系統的系統的OTA升級，本質上同手動刷包一樣；

源碼路徑和主要原文件

在Android源碼環境中，recovery的源碼主要在bootable/recovery文件下，另外再device目錄下，會根據各個設備定製自己的接口以及UI界面，也就是文章後半部分分析的界面定製的內容；

在bootable/recovery目錄下，主要的源文件有：

LOCAL_SRC_FILES := \
    adb_install.cpp \
    asn1_decoder.cpp \
    bootloader.cpp \
    device.cpp \
    fuse_sdcard_provider.c \
    install.cpp \
    recovery.cpp \
    roots.cpp \
    screen_ui.cpp \
    ui.cpp \
    verifier.cpp \

該部分代碼在編譯後，會統一輸出到 out/recovery/root/目錄；

recovery.cpp

命令行參數

recovery最後是編譯成一個可執行的命令，放在recovery文件系統中的/sbin/recovery；所以我們可以在終端中直接運行該命令，具體的參數如下：

--send_intent=anystring - 傳遞給recovery的信息
--adbd -adb sideload升級
--update_package=path - 指定OTA升級包
--wipe_data - 清楚用戶數據並重啓
--wipe_cache - 清楚緩存並重啓
--set_encrypted_filesystem=on|off - 使能或者關閉文件系統加密
--just_exit - 退出並重啓

main 函數

從main入口函數分析recovery的主要源碼：

輸出重定向

    redirect_stdio(TEMPORARY_LOG_FILE);
    //redirect log to serial output
#ifdef LogToSerial
    freopen("/dev/ttyFIQ0", "a", stdout); setbuf(stdout, NULL);
    freopen("/dev/ttyFIQ0", "a", stderr); setbuf(stderr, NULL);
#endif

這部分代碼很容易理解，主要作用是輸出log到/tem/recovery.log文件中

執行adb sideload分支

    if (argc == 2 && strcmp(argv[1], "--adbd") == 0) {
        adb_main(0, DEFAULT_ADB_PORT);
        return 0;
    }

判斷命令行參數是否爲–adbd，並執行adb_main函數，這部分代碼在後續adb_install.cpp中分析；

填充fstab結構體

在main函數中調用 load_volume_table()，讀取/etc/recovery.emmc.fstab文件內容，並填充fstab結構體，但是並沒有執行掛載操作：
load_volume_table函數在roots.cpp文件中，也是很容易理解：

void load_volume_table()
{
    ...
    int emmcState = getEmmcState();//判斷是否爲emmc設備
    if(emmcState) {
        fstab = fs_mgr_read_fstab("/etc/recovery.emmc.fstab");
    }else {
        fstab = fs_mgr_read_fstab("/etc/recovery.fstab");
    }
    ...
    //讀取文件中每個條目內容，填充fstab結構體
    ret = fs_mgr_add_entry(fstab, "/tmp", "ramdisk", "ramdisk");
    ...
    //日誌打印fstable信息
    printf("recovery filesystem table\n");
    printf("=========================\n");
    for (i = 0; i < fstab->num_entries; ++i) {
        Volume* v = &fstab->recs[i];
        printf("  %d %s %s %s %lld\n", i, v->mount_point, v->fs_type,
               v->blk_device, v->length);
    }
    printf("\n");
}

讀取控制參數
recovery 和 bootloader 必須通過內存的一個特定分區，才能進行相互的通信，這個分區一般是/misc；
對應的信息數據結構體爲bootloader_message；
參照源碼中bootloader_message 的註釋

struct bootloader_message {
    char command[32];//bootloader 啓動時讀取改數據，決定是否進入recovery模式
    char status[32];//由bootloader進行更新，標識升級的結果；
    char recovery[768];//由Android系統進行寫入，recovery從中讀取信息；
    char stage[32];
    char reserved[224];
};

recovery 根據命令行參數，再從/misc分區中解析出對應的參數，進行後續的操作，具體的調用函數爲get_args(&argc, &argv);

static void
get_args(int *argc, char ***argv) {
    struct bootloader_message boot;//參數結構體
    memset(&boot, 0, sizeof(boot));
    get_bootloader_message(&boot);  // 具體的讀取信息的函數，可能爲空的情況
    stage = strndup(boot.stage, sizeof(boot.stage));
    ...

     // 如果上述情況爲空，則從/cache/recovery/command獲取參數，其中COMMAND_FILE=/cache/recovery/command
    if (*argc <= 1) {
        FILE *fp = fopen_path(COMMAND_FILE, "r");
        if (fp != NULL) {
            char *token;
            char *argv0 = (*argv)[0];
            *argv = (char **) malloc(sizeof(char *) * MAX_ARGS);
            (*argv)[0] = argv0;  // use the same program name

            char buf[MAX_ARG_LENGTH];
            for (*argc = 1; *argc < MAX_ARGS; ++*argc) {
                if (!fgets(buf, sizeof(buf), fp)) break;
                token = strtok(buf, "\r\n");
                if (token != NULL) {
                    (*argv)[*argc] = strdup(token);  // Strip newline.
                } else {
                    --*argc;
                }
            }

            check_and_fclose(fp, COMMAND_FILE);
            LOGI("Got arguments from %s\n", COMMAND_FILE);
        }
    }

    //把從/cache/recovery/command獲取參數重新寫回到/misc分區
    // --> write the arguments we have back into the bootloader control block
    // always boot into recovery after this (until finish_recovery() is called)
    strlcpy(boot.command, "boot-recovery", sizeof(boot.command));
    strlcpy(boot.recovery, "recovery\n", sizeof(boot.recovery));
    int i;
    for (i = 1; i < *argc; ++i) {
        strlcat(boot.recovery, (*argv)[i], sizeof(boot.recovery));
        strlcat(boot.recovery, "\n", sizeof(boot.recovery));
    }
    set_bootloader_message(&boot);
}

解析命令行參數

    while ((arg = getopt_long(argc, argv, "", OPTIONS, NULL)) != -1) {
        switch (arg) {
        case 'f': factory_mode = optarg; bFactoryMode = true; break;
        case 'i': send_intent = optarg; break;
        case 'u': update_package = optarg; break;
        case 'w': should_wipe_data = true; break;
        case 'k':  update_rkimage = optarg;break;
        case 'c': should_wipe_cache = true; break;
        case 't': show_text = true; break;
        case 's': sideload = true; break;
        case 'a': sideload = true; sideload_auto_reboot = true; break;
        case 'x': just_exit = true; break;
        case 'l': locale = optarg; break;
        case 'g': {
            if (stage == NULL || *stage == '\0') {
                char buffer[20] = "1/";
                strncat(buffer, optarg, sizeof(buffer)-3);
                stage = strdup(buffer);
            }
            break;
        }
        case 'f'+'w': //fw_update
            if((optarg)&&(!sdboot_update_package)){
            sdboot_update_package = strdup(optarg);
            }
            break;
        case 'd': //demo_copy
            if((optarg)&&(! demo_copy_path)){
                demo_copy_path = strdup(optarg);
            }
            break;
        case 'p': shutdown_after = true; break;
        case 'r': reason = optarg; break;
        case 'w'+'a': { should_wipe_all = should_wipe_data = should_wipe_cache = true;show_text = true;} break;
        case '?':
            LOGE("Invalid command argument\n");
            continue;
        }
    }

這部分代碼很簡單，就是通過getopt_long進行命令行參數的解析並賦值；

顯示界面和功能選項

接下來就是創建device，顯示對應UI界面和功能選項；

    Device* device = make_device();//可以自己實現一個設備
    ui = device->GetUI();
    gCurrentUI = ui;//賦值ui界面

    ui->SetLocale(locale);//獲取歸屬地信息
    ui->Init();//初始化，可以重載，在init中實現相應功能
    ui->SetStage(st_cur, st_max);
    ui->SetBackground(RecoveryUI::NONE);

進行分區掛載操作
ensure_path_mounted

int ensure_path_mounted(const char* path) {
    ...
    Volume* v = volume_for_path(path);//根據路徑名獲取分區信息
    ...
    int result;
    result = scan_mounted_volumes();

    const MountedVolume* mv =
        find_mounted_volume_by_mount_point(v->mount_point);//根據掛載點，獲取已掛載分區的信息，如果不爲空，說明已經成功掛載
    if (mv) {
        // volume is already mounted
        return 0;
    }

    result = mkdir(v->mount_point, 0755);  // 創建對應目錄，確保目錄存在，也有可能目錄已經存在
    if (result!=0)
    {
        printf("failed to create %s dir,err=%s!\n",v->mount_point,strerror(errno));
    }

    // 根據文件系統類型，執行mount操作
    if (strcmp(v->fs_type, "yaffs2") == 0) {
        // mount an MTD partition as a YAFFS2 filesystem.
        mtd_scan_partitions();
        const MtdPartition* partition;
        partition = mtd_find_partition_by_name(v->blk_device);
        if (partition == NULL) {
            LOGE("failed to find \"%s\" partition to mount at \"%s\"\n",
                 v->blk_device, v->mount_point);
            return -1;
        }
        return mtd_mount_partition(partition, v->mount_point, v->fs_type, 0);
    } else if (strcmp(v->fs_type, "ext4") == 0 ||
               strcmp(v->fs_type, "ext3") == 0) {
        result = mount(v->blk_device, v->mount_point, v->fs_type,
                       MS_NOATIME | MS_NODEV | MS_NODIRATIME, "");
        if (result == 0) return 0;

        LOGE("failed to mount %s %s (%s)\n", v->mount_point, v->blk_device, strerror(errno));
        return -1;
    } else if (strcmp(v->fs_type, "vfat") == 0) {
        result = mount(v->blk_device, v->mount_point, v->fs_type,
                       MS_NOATIME | MS_NODEV | MS_NODIRATIME, "shortname=mixed,utf8");
        if (result == 0) return 0;

        LOGW("trying mount %s to ntfs\n", v->blk_device);
        result = mount(v->blk_device, v->mount_point, "ntfs",
                           MS_NOATIME | MS_NODEV | MS_NODIRATIME, "");
        if (result == 0) return 0;

        char *sec_dev = v->fs_options;
        if(sec_dev != NULL) {
            char *temp = strchr(sec_dev, ',');
            if(temp) {
                temp[0] = '\0';
            }

            result = mount(sec_dev, v->mount_point, v->fs_type,
                                   MS_NOATIME | MS_NODEV | MS_NODIRATIME, "shortname=mixed,utf8");
            if (result == 0) return 0;

            LOGW("trying mount %s to ntfs\n", sec_dev);
            result = mount(sec_dev, v->mount_point, "ntfs",
                               MS_NOATIME | MS_NODEV | MS_NODIRATIME, "");
            if (result == 0) return 0;
        }

        LOGE("failed to mount %s (%s)\n", v->mount_point, strerror(errno));
        return -1;
    }else if (strcmp(v->fs_type, "ntfs") == 0) {
        LOGW("trying mount %s to ntfs\n", v->blk_device);
        result = mount(v->blk_device, v->mount_point, "ntfs",
                           MS_NOATIME | MS_NODEV | MS_NODIRATIME, "");
        if (result == 0) return 0;

        LOGE("failed to mount %s (%s)\n", v->mount_point, strerror(errno));
        return -1;
    }

    LOGE("unknown fs_type \"%s\" for %s\n", v->fs_type, v->mount_point);
    return -1;
}

界面定製

實現Recovery UI

在自己的設備目錄下：device/vendor/recovery/recovery_ui.cpp

#include <linux/input.h>
#include <sys/stat.h>
#include <errno.h>
#include <string.h>

#include "common.h"
#include "device.h"
#include "screen_ui.h"

實現頭部顯示和列表項

const char* HEADERS[] = { "Volume up/down to move highlight;",
                         "power button to select.",
                         "",
                         NULL };

const char* ITEMS[] ={ "reboot system now",
                       //"apply update from ADB",
                       "apply update from external storage",
                       "update rkimage from external storage",
                       "apply update from cache",
                       "wipe data/factory reset",
                       "wipe cache partition",
                       "recovery system from backup",
                       NULL };

實現ScreenRecoveryUI

class DeviceUI : public ScreenRecoveryUI {
  public:
    DeviceUI () :
        consecutive_power_keys(0) {
    }

    //實現自己的識別key類型的功能，可以爲不同的輸入設備適配recovery功能
    virtual KeyAction CheckKey(int key) {
        if (IsKeyPressed(KEY_POWER) && key == KEY_VOLUMEUP) {
            return TOGGLE;
        }
        if (key == KEY_POWER) {
            ++consecutive_power_keys;
            if (consecutive_power_keys >= 7) {
                return REBOOT;
            }
        } else {
            consecutive_power_keys = 0;
        }
        return ENQUEUE;
    }

  private:
    int consecutive_power_keys;
};

實現設備類

class MyDevice : public Device {
  public:
    RkDevice() :
        ui(new DeviceUI ) {
    }

    RecoveryUI* GetUI() { return ui; }

    int HandleMenuKey(int key_code, int visible) {
        if (visible) {
            switch (key_code) {
              case KEY_DOWN:
              case KEY_VOLUMEDOWN:
                return kHighlightDown;

              case KEY_UP:
              case KEY_VOLUMEUP:
                return kHighlightUp;

              case KEY_ENTER:
              case KEY_POWER:
                return kInvokeItem;
            }
        }

        return kNoAction;
    }

    BuiltinAction InvokeMenuItem(int menu_position) {
        switch (menu_position) {
          case 0: return REBOOT;
          //case 1: return APPLY_ADB_SIDELOAD;
          case 1: return APPLY_EXT;
          case 2: return APPLY_INT_RKIMG;
          case 3: return APPLY_CACHE;
          case 4: return WIPE_DATA;
          case 5: return WIPE_CACHE;
          case 6: return RECOVER_SYSTEM;
          default: return NO_ACTION;
        }
    }

    const char* const* GetMenuHeaders() { return HEADERS; }
    const char* const* GetMenuItems() { return ITEMS; }

  private:
    RecoveryUI* ui;
};

//創建自己實現的設備
Device* make_device() {
    return new MyDevice ;
}

添加編譯實現

主要是覆蓋TARGET_RECOVERY_UI_LIB，輸出到/out/…./recovery/root目錄下：

Android.mk

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)

LOCAL_MODULE_TAGS := eng
LOCAL_C_INCLUDES += bootable/recovery
LOCAL_SRC_FILES := recovery_ui.cpp

# should match TARGET_RECOVERY_UI_LIB set in BoardConfig.mk
LOCAL_MODULE := librecovery_ui_$(TARGET_PRODUCT)

include $(BUILD_STATIC_LIBRARY)

Android Recovery 源碼解析和界面定製

Android Recovery 源碼解析和界面定製

Recovery主要功能

源碼路徑和主要原文件

recovery.cpp

命令行參數

main 函數

界面定製

實現Recovery UI

實現頭部顯示和列表項

實現ScreenRecoveryUI

實現設備類

添加編譯實現

Pytorch使用optim模塊訓練線性迴歸模型

libgdx中彈框組件如何阻止事件穿透到下層組件

利用PyTorch Autograd自動求導訓練線性迴歸模型

pytorch基礎入門一: 訓練原始的線性模型

Python 中用matplotlib 畫出 numpy.random.beta分佈

Mac下配置sublime實現LaTeX

https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

linux以太網驅動總結