overflow: auto;overflow-wrap: normal;word-break: normal;">

微信公眾號：嵌入式開發(fā)圈
關注可了解更多的教程。問題或建議，請公眾號留言;
如果你覺得本文對你有幫助，歡迎贊賞

 1/*
 2?*?The?recovery?tool?communicates?with?the?main?system?through?/cache?files.
 3?*???/cache/recovery/command?-?INPUT?-?command?line?for?tool,?one?arg?per?line
 4?*???/cache/recovery/log?-?OUTPUT?-?combined?log?file?from?recovery?run(s)
 5?*???/cache/recovery/intent?-?OUTPUT?-?intent?that?was?passed?in
 6?*
 7?*?The?arguments?which?may?be?supplied?in?the?recovery.command?file:
 8?*???--send_intent=anystring?-?write?the?text?out?to?recovery.intent
 9?*???--update_package=path?-?verify?install?an?OTA?package?file
10?*???--wipe_data?-?erase?user?data?(and?cache),?then?reboot
11?*???--wipe_cache?-?wipe?cache?(but?not?user?data),?then?reboot
12?*???--set_encrypted_filesystem=on|off?-?enables?/?diasables?encrypted?fs
13?*???--just_exit?-?do?nothing;?exit?and?reboot
14?*
15?*?After?completing,?we?remove?/cache/recovery/command?and?reboot.
16?*?Arguments?may?also?be?supplied?in?the?bootloader?control?block?(BCB).
17?*?These?important?scenarios?must?be?safely?restartable?at?any?point:
18?*
19?*?FACTORY?RESET
20?*?1.?user?selects?"factory?reset"
21?*?2.?main?system?writes?"--wipe_data"?to?/cache/recovery/command
22?*?3.?main?system?reboots?into?recovery
23?*?4.?get_args()?writes?BCB?with?"boot-recovery"?and?"--wipe_data"
24?*????--?after?this,?rebooting?will?restart?the?erase?--
25?*?5.?erase_volume()?reformats?/data
26?*?6.?erase_volume()?reformats?/cache
27?*?7.?finish_recovery()?erases?BCB
28?*????--?after?this,?rebooting?will?restart?the?main?system?--
29?*?8.?main()?calls?reboot()?to?boot?main?system
30?*
31?*?OTA?INSTALL
32?*?1.?main?system?downloads?OTA?package?to?/cache/some-filename.zip
33?*?2.?main?system?writes?"--update_package=/cache/some-filename.zip"
34?*?3.?main?system?reboots?into?recovery
35?*?4.?get_args()?writes?BCB?with?"boot-recovery"?and?"--update_package=..."
36?*????--?after?this,?rebooting?will?attempt?to?reinstall?the?update?--
37?*?5.?install_package()?attempts?to?install?the?update
38?*????NOTE:?the?package?install?must?itself?be?restartable?from?any?point
39?*?6.?finish_recovery()?erases?BCB
40?*????--?after?this,?rebooting?will?(try?to)?restart?the?main?system?--
41?*?7.?**?if?install?failed?**
42?*????7a.?prompt_and_wait()?shows?an?error?icon?and?waits?for?the?user
43?*????7b;?the?user?reboots?(pulling?the?battery,?etc)?into?the?main?system
44?*?8.?main()?calls?maybe_install_firmware_update()
45?*????**?if?the?update?contained?radio/hboot?firmware?**:
46?*????8a.?m_i_f_u()?writes?BCB?with?"boot-recovery"?and?"--wipe_cache"
47?*????????--?after?this,?rebooting?will?reformat?cache?&?restart?main?system?--
48?*????8b.?m_i_f_u()?writes?firmware?image?into?raw?cache?partition
49?*????8c.?m_i_f_u()?writes?BCB?with?"update-radio/hboot"?and?"--wipe_cache"
50?*????????--?after?this,?rebooting?will?attempt?to?reinstall?firmware?--
51?*????8d.?bootloader?tries?to?flash?firmware
52?*????8e.?bootloader?writes?BCB?with?"boot-recovery"?(keeping?"--wipe_cache")
53?*????????--?after?this,?rebooting?will?reformat?cache?&?restart?main?system?--
54?*????8f.?erase_volume()?reformats?/cache
55?*????8g.?finish_recovery()?erases?BCB
56?*????????--?after?this,?rebooting?will?(try?to)?restart?the?main?system?--
57?*?9.?main()?calls?reboot()?to?boot?main?system
58?*/

1*?The?arguments?which?may?be?supplied?in?the?recovery.command?file:
2?*???--send_intent=anystring?-?write?the?text?out?to?recovery.intent
3?*???--update_package=path?-?verify?install?an?OTA?package?file
4?*???--wipe_data?-?erase?user?data?(and?cache),?then?reboot
5?*???--wipe_cache?-?wipe?cache?(but?not?user?data),?then?reboot
6?*???--set_encrypted_filesystem=on|off?-?enables?/?diasables?encrypted?fs
7?*???--just_exit?-?do?nothing;?exit?and?reboot

1--update_package=path(對應的OTA更新的路徑)

1--update_package=/mnt/external_sd/xxx.zip

1//重定向標準輸出和標準出錯到/tmp/recovery.log?這個文件里
2//static?const?char?*TEMPORARY_LOG_FILE?=?"/tmp/recovery.log";
3redirect_stdio(TEMPORARY_LOG_FILE);

1static?void?redirect_stdio(const?char*?filename)?{
2????//?If?these?fail,?there's?not?really?anywhere?to?complain...
3????freopen(filename,?"a",?stdout);?setbuf(stdout,?NULL);
4????freopen(filename,?"a",?stderr);?setbuf(stderr,?NULL);
5}?

 1????//?If?this?binary?is?started?with?the?single?argument?"--adbd",
 2????//?instead?of?being?the?normal?recovery?binary,?it?turns?into?kind
 3????//?of?a?stripped-down?version?of?adbd?that?only?supports?the
 4????//?'sideload'?command.??Note?this?must?be?a?real?argument,?not
 5????//?anything?in?the?command?file?or?bootloader?control?block;?the
 6????//?only?way?recovery?should?be?run?with?this?argument?is?when?it
 7????//?starts?a?copy?of?itself?from?the?apply_from_adb()?function.
 8????if?(argc?==?2?&&?strcmp(argv[1],?"--adbd")?==?0)?{
 9????????adb_main();
10????????return?0;
11????}

1????printf("Starting?recovery?(pid?%d)?on?%s",?getpid(),?ctime(&start));
2????//裝載recovery的分區(qū)表recovery.fstab
3????load_volume_table();
4????//在recovery中掛載/cache/recovery/last_log這個文件
5????//#define?LAST_LOG_FILE?"/cache/recovery/last_log"
6????ensure_path_mounted(LAST_LOG_FILE);
7????rotate_last_logs(KEEP_LOG_COUNT);

1/dev/block/by-name/boot?????????/boot?????????emmc?????defaults????????????????????????????????????????????????????????????????defaults
2/dev/block/by-name/recovery?????/recovery?????emmc?????defaults????????????????????????????????????????????????????????????????defaults
3/dev/block/by-name/splashscreen?/splashscreen?emmc?????defaults????????????????????????????????????????????????????????????????defaults
4/dev/block/by-name/fastboot?????/fastboot?????emmc?????defaults????????????????????????????????????????????????????????????????defaults
5/dev/block/by-name/misc?????????/misc?????????emmc?????defaults????????????????????????????????????????????????????????????????defaults
6/dev/block/by-name/system???????/system???????ext4?????ro,noatime??????????????????????????????????????????????????????????????wait
7/dev/block/by-name/cache????????/cache????????ext4?????nosuid,nodev,noatime,barrier=1,data=ordered?????????????????????????????wait,check
8/dev/block/by-name/userdata?????/data?????????ext4?????nosuid,nodev,noatime,discard,barrier=1,data=ordered,noauto_da_alloc?????wait,check
9/dev/block/by-name/factory??????/factory??????ext4?????nosuid,nodev,noatime,barrier=1,data=ordered?????????????????????????????wait

 1void?load_volume_table()
 2{
 3????int?i;
 4????int?ret;
 5????//讀recovery.fstab?這個分區(qū)表
 6????fstab?=?fs_mgr_read_fstab("/etc/recovery.fstab");
 7????if?(!fstab)?{
 8????????LOGE("failed?to?read?/etc/recovery.fstab\n");
 9????????return;
10????}
11????//將對應的信息加入到一條鏈表中
12????ret?=?fs_mgr_add_entry(fstab,?"/tmp",?"ramdisk",?"ramdisk");
13????//如果load到的分區(qū)表為空，后面做釋放操作
14????if?(ret?0?)?{
15????????LOGE("failed?to?add?/tmp?entry?to?fstab\n");
16????????fs_mgr_free_fstab(fstab);
17????????fstab?=?NULL;
18????????return;
19????}
20
21????printf("recovery?filesystem?table\n");
22????printf("=========================\n");
23????//到這一步，打印分區(qū)表信息，這類信息在
24????//recovery啟動的時候的log可以看到
25????//分別是以下
26????//編號|???掛載節(jié)點|??文件系統(tǒng)類型|??塊設備|???長度
27????for?(i?=?0;?i?num_entries;?++i)?{
28????????Volume*?v?=?&fstab->recs[i];
29????????printf("??%d?%s?%s?%s?%lld\n",?i,?v->mount_point,?v->fs_type,
30???????????????v->blk_device,?v->length);
31????}
32????printf("\n");
33}

 1//獲取參數(shù)
 2????//這個參數(shù)也可能是從/cache/recovery/command文件中得到相應的命令
 3????//也就是可以往command這個文件寫入對應的格式的命令即可
 4????get_args(&argc,?&argv);
 5
 6????const?char?*send_intent?=?NULL;
 7????const?char?*update_package?=?NULL;
 8????int?wipe_data?=?0,?wipe_cache?=?0,?show_text?=?0;
 9????bool?just_exit?=?false;
10????bool?shutdown_after?=?false;
11
12????int?arg;
13????//參數(shù)有擦除分區(qū)，OTA更新等
14????while?((arg?=?getopt_long(argc,?argv,?"",?OPTIONS,?NULL))?!=?-1)?{
15????????switch?(arg)?{
16????????case?'s':?send_intent?=?optarg;?break;
17????????case?'u':?update_package?=?optarg;?break;
18????????case?'w':?wipe_data?=?wipe_cache?=?1;?break;
19????????case?'c':?wipe_cache?=?1;?break;
20????????case?'t':?show_text?=?1;?break;
21????????case?'x':?just_exit?=?true;?break;
22????????case?'l':?locale?=?optarg;?break;
23????????case?'g':?{
24????????????if?(stage?==?NULL?||?*stage?==?'\0')?{
25????????????????char?buffer[20]?=?"1/";
26????????????????strncat(buffer,?optarg,?sizeof(buffer)-3);
27????????????????stage?=?strdup(buffer);
28????????????}
29????????????break;
30????????}
31????????case?'p':?shutdown_after?=?true;?break;
32????????case?'r':?reason?=?optarg;?break;
33????????case?'?':
34????????????LOGE("Invalid?command?argument\n");
35????????????continue;
36????????}
37????}

 1//設置語言
 2????if?(locale?==?NULL)?{
 3????????load_locale_from_cache();
 4????}
 5????printf("locale?is?[%s]\n",?locale);
 6????printf("stage?is?[%s]\n",?stage);
 7????printf("reason?is?[%s]\n",?reason);
 8????//創(chuàng)建設備
 9????Device*?device?=?make_device();
10????//獲取UI
11????ui?=?device->GetUI();
12????//設置當前的UI
13????gCurrentUI?=?ui;
14????//設置UI的語言信息
15????ui->SetLocale(locale);
16????//UI初始化
17????ui->Init();
18
19????int?st_cur,?st_max;
20????if?(stage?!=?NULL?&&?sscanf(stage,?"%d/%d",?&st_cur,?&st_max)?==?2)?{
21????????ui->SetStage(st_cur,?st_max);
22????}
23????//設置recovery的背景圖
24????ui->SetBackground(RecoveryUI::NONE);
25????//設置界面上是否能夠顯示字符，使能ui->print函數(shù)開關
26????if?(show_text)?ui->ShowText(true);
27????//設置selinux權限，一般我會把selinux?給disabled
28????struct?selinux_opt?seopts[]?=?{
29??????{?SELABEL_OPT_PATH,?"/file_contexts"?}
30????};
31
32????sehandle?=?selabel_open(SELABEL_CTX_FILE,?seopts,?1);
33
34????if?(!sehandle)?{
35????????ui->Print("Warning:?No?file_contexts\n");
36????}
37????//虛函數(shù)，沒有做什么流程
38????device->StartRecovery();
39
40????printf("Command:");
41????for?(arg?=?0;?arg?42????????printf("?\"%s\"",?argv[arg]);
43????}
44????printf("\n");?

 1//如果update_package(也就是要升級的OTA包)不為空的情況下
 2????//這里要對升級包的路徑做一下路徑轉換，這里可以自由定制自己升級包的路徑
 3????if?(update_package)?{
 4????????//?For?backwards?compatibility?on?the?cache?partition?only,?if
 5????????//?we're?given?an?old?'root'?path?"CACHE:foo",?change?it?to
 6????????//?"/cache/foo".
 7
 8????//這里就是做轉換的方法
 9????//先比較傳進來的recovery參數(shù)的前6個byte是否是CACHE
 10????//如果是將其路徑轉化為/cache/CACHE:?......
 11????????if?(strncmp(update_package,?"CACHE:",?6)?==?0)?{
 12????????????int?len?=?strlen(update_package)?+?10;
 13????????????char*?modified_path?=?(char*)malloc(len);
 14????????????strlcpy(modified_path,?"/cache/",?len);
 15????????????strlcat(modified_path,?update_package+6,?len);
 16????????????printf("(replacing?path?\"%s\"?with?\"%s\")\n",
 17???????????????????update_package,?modified_path);
 18????????????//這個update_package就是轉換后的路徑
 19????????????update_package?=?modified_path;
 20????????}
 21????}
 22????printf("\n");
 23????property_list(print_property,?NULL);
 24????//獲取屬性，這里應該是從一個文件中找到ro.build.display.id
 25????//獲取recovery的版本信息
 26????property_get("ro.build.display.id",?recovery_version,?"");
 27????printf("\n");
 28
 29????//定義一個安裝成功的標志位INSTALL_SUCCESS??---->?其實是個枚舉，值為0
 30????int?status?=?INSTALL_SUCCESS;
 31????//判斷轉換后的OTA升級包的路徑是否不為空，如果不為空
 32????//執(zhí)行install_package?函數(shù)進行升級
 33????if?(update_package?!=?NULL)?{
 34????????status?=?install_package(update_package,?&wipe_cache,?TEMPORARY_INSTALL_FILE,?true);
 35????????//判斷是否升級成功
 36????????if?(status?==?INSTALL_SUCCESS?&&?wipe_cache)?{
 37????????????//擦除這個路徑，相當于刪除了這個路徑下的OTA升級包
 38????????????if?(erase_volume("/cache"))?{
 39????????????????LOGE("Cache?wipe?(requested?by?package)?failed.");
 40????????????}
 41????????}
 42????????//如果安裝不成功
 43????????if?(status?!=?INSTALL_SUCCESS)?{
 44????????????ui->Print("Installation?aborted.\n");
 45
 46????????????//?If?this?is?an?eng?or?userdebug?build,?then?automatically
 47????????????//?turn?the?text?display?on?if?the?script?fails?so?the?error
 48????????????//?message?is?visible.
 49????????????char?buffer[PROPERTY_VALUE_MAX+1];
 50????????????property_get("ro.build.fingerprint",?buffer,?"");
 51????????????if?(strstr(buffer,?":userdebug/")?||?strstr(buffer,?":eng/"))?{
 52????????????????ui->ShowText(true);
 53????????????}
 54????????}
 55????}
 56????//如果跑的是格式化數(shù)據(jù)區(qū)，那么就走這個流程
 57????else?if?(wipe_data)?{
 58????????if?(device->WipeData())?status?=?INSTALL_ERROR;
 59????????//格式化/data分區(qū)
 60????????if?(erase_volume("/data"))?status?=?INSTALL_ERROR;
 61????????if?(wipe_cache?&&?erase_volume("/cache"))?status?=?INSTALL_ERROR;
 62????????if?(erase_persistent_partition()?==?-1?)?status?=?INSTALL_ERROR;
 63????????if?(status?!=?INSTALL_SUCCESS)?ui->Print("Data?wipe?failed.\n");
 64????}?
 65????//格式化cache分區(qū)
 66????else?if?(wipe_cache)?{
 67????????if?(wipe_cache?&&?erase_volume("/cache"))?status?=?INSTALL_ERROR;
 68????????if?(status?!=?INSTALL_SUCCESS)?ui->Print("Cache?wipe?failed.\n");
 69????}?
 70????else?if?(!just_exit)?{
 71????????status?=?INSTALL_NONE;??//?No?command?specified
 72????????ui->SetBackground(RecoveryUI::NO_COMMAND);
 73????}
 74????//如果安裝失敗或者。。。
 75????if?(status?==?INSTALL_ERROR?||?status?==?INSTALL_CORRUPT)?{
 76????????copy_logs();
 77????????//顯示錯誤的LOGO
 78????????ui->SetBackground(RecoveryUI::ERROR);
 79????}
 80????Device::BuiltinAction?after?=?shutdown_after???Device::SHUTDOWN?:?Device::REBOOT;
 81????if?(status?!=?INSTALL_SUCCESS?||?ui->IsTextVisible())?{
 82????????Device::BuiltinAction?temp?=?prompt_and_wait(device,?status);
 83????????if?(temp?!=?Device::NO_ACTION)?after?=?temp;
 84????}
 85
 86????//?Save?logs?and?clean?up?before?rebooting?or?shutting?down.
 87????//完成recovery升級
 88????finish_recovery(send_intent);
 89
 90????switch?(after)?{
 91????????case?Device::SHUTDOWN:
 92????????????ui->Print("Shutting?down...\n");
 93????????????property_set(ANDROID_RB_PROPERTY,?"shutdown,");
 94????????????break;
 95
 96????????case?Device::REBOOT_BOOTLOADER:
 97????????????ui->Print("Rebooting?to?bootloader...\n");
 98????????????property_set(ANDROID_RB_PROPERTY,?"reboot,bootloader");
 99????????????break;
100
101????????default:
102????????????ui->Print("Rebooting...\n");
103????????????property_set(ANDROID_RB_PROPERTY,?"reboot,");
104????????????break;
105????}
106????sleep(5);?//?should?reboot?before?this?finishes
107????return?EXIT_SUCCESS;

 1//安裝更新包
 2int
 3install_package(const?char*?path,?int*?wipe_cache,?const?char*?install_file,
 4????????????????bool?needs_mount)
 5{
 6????FILE*?install_log?=?fopen_path(install_file,?"w");
 7????if?(install_log)?{
 8????????fputs(path,?install_log);
 9????????fputc('\n',?install_log);
10????}?else?{
11????????LOGE("failed?to?open?last_install:?%s\n",?strerror(errno));
12????}
13????int?result;
14????//設置安裝掛載對應的節(jié)點
15????//這一步是關鍵
16????if?(setup_install_mounts()?!=?0)?{
17????????LOGE("failed?to?set?up?expected?mounts?for?install;?aborting\n");
18????????result?=?INSTALL_ERROR;
19????}?else?{
20????????//到這里才是真正的去安裝OTA包
21????????result?=?really_install_package(path,?wipe_cache,?needs_mount);
22????}
23????//如果返回結果為0，那么安裝就成功了
24????if?(install_log)?{
25????????fputc(result?==?INSTALL_SUCCESS???'1'?:?'0',?install_log);
26????????fputc('\n',?install_log);
27????????fclose(install_log);
28????}
29????return?result;
30}

 1//設置安裝掛載的節(jié)點
 2int?setup_install_mounts()?{
 3????if?(fstab?==?NULL)?{
 4????????LOGE("can't?set?up?install?mounts:?no?fstab?loaded\n");
 5????????return?-1;
 6????}
 7????for?(int?i?=?0;?i?num_entries;?++i)?{
 8????????Volume*?v?=?fstab->recs?+?i;
 9????//如果判斷掛載的路徑是/tmp?或者/cache
10????//那么就掛載對應的節(jié)點，而其它的節(jié)點都不會去掛載
11????????if?(strcmp(v->mount_point,?"/tmp")?==?0?||
12????????????strcmp(v->mount_point,?"/cache")?==?0)?{
13????????????if?(ensure_path_mounted(v->mount_point)?!=?0)?{
14????????????????LOGE("failed?to?mount?%s\n",?v->mount_point);
15????????????????return?-1;
16????????????}
17
18????????}
19????????//如果不是/tmp或者/cache這兩個節(jié)點，則默認就會卸載所有的掛載節(jié)點
20????????else?{
21????????????//卸載所有的掛載節(jié)點
22????????????if?(ensure_path_unmounted(v->mount_point)?!=?0)?{
23????????????????LOGE("failed?to?unmount?%s\n",?v->mount_point);
24????????????????return?-1;
25????????????}
26????????}
27????}
28????return?0;
29}?

 1static?int
 2really_install_package(const?char?*path,?int*?wipe_cache,?bool?needs_mount)
 3{
 4????//設置更新時的背景
 5????ui->SetBackground(RecoveryUI::INSTALLING_UPDATE);
 6????ui->Print("Finding?update?package...\n");
 7????//?Give?verification?half?the?progress?bar...
 8????//設置進度條的類型
 9????ui->SetProgressType(RecoveryUI::DETERMINATE);
10????//顯示進度條
11????ui->ShowProgress(VERIFICATION_PROGRESS_FRACTION,?VERIFICATION_PROGRESS_TIME);
12????LOGI("Update?location:?%s\n",?path);
13????//在屏幕上打印?Opening?update?package..
14????//?Map?the?update?package?into?memory.
15????ui->Print("Opening?update?package...\n");
16????//patch是OTA的路徑,need_mount參數(shù)表示是否需要掛載，1掛載，0，不掛載
17????if?(path?&&?needs_mount)?{
18????????if?(path[0]?==?'@')?{
19????????????ensure_path_mounted(path+1);
20????????}?else?{
21????????????//掛載OTA升級包的路徑------>?一般是執(zhí)行這個流程
22????????????ensure_path_mounted(path);
23????????}
24????}
25
26????MemMapping?map;
27????if?(sysMapFile(path,?&map)?!=?0)?{
28????????LOGE("failed?to?map?file\n");
29????????return?INSTALL_CORRUPT;
30????}
31
32????int?numKeys;
33????//獲取校驗公鑰文件
34????Certificate*?loadedKeys?=?load_keys(PUBLIC_KEYS_FILE,?&numKeys);
35????if?(loadedKeys?==?NULL)?{
36????????LOGE("Failed?to?load?keys\n");
37????????return?INSTALL_CORRUPT;
38????}
39????LOGI("%d?key(s)?loaded?from?%s\n",?numKeys,?PUBLIC_KEYS_FILE);
40
41????ui->Print("Verifying?update?package...\n");
42
43????int?err;
44????//校驗文件
45????err?=?verify_file(map.addr,?map.length,?loadedKeys,?numKeys);
46????free(loadedKeys);
47????LOGI("verify_file?returned?%d\n",?err);
48????//如果校驗不成功
49????if?(err?!=?VERIFY_SUCCESS)?{
50????????//打印簽名失敗
51????????LOGE("signature?verification?failed\n");
52????????sysReleaseMap(&map);
53????????return?INSTALL_CORRUPT;
54????}
55
56????/*?Try?to?open?the?package.
57?????*/
58????//嘗試去打開ota壓縮包
59????ZipArchive?zip;
60????err?=?mzOpenZipArchive(map.addr,?map.length,?&zip);
61????if?(err?!=?0)?{
62????????LOGE("Can't?open?%s\n(%s)\n",?path,?err?!=?-1???strerror(err)?:?"bad");
63????????sysReleaseMap(&map);
64????????return?INSTALL_CORRUPT;
65????}
66
67????/*?Verify?and?install?the?contents?of?the?package.
68?????*/
69????//開始安裝升級包
70????ui->Print("Installing?update...\n");
71????ui->SetEnableReboot(false);
72????int?result?=?try_update_binary(path,?&zip,?wipe_cache);
73????//安裝成功后自動重啟
74????ui->SetEnableReboot(true);
75????ui->Print("\n");
76
77????sysReleaseMap(&map);
78????//返回結果
79????return?result;
80}