Android-Recovery Mode(recover模式详解)-幸福软件公司-ChinaUnix博客

Android-Recovery Mode（recover模式详解）

1. Recovery Mode: factory default, firmware upgrade, patch upgrade and OTA upgrade.

2. Android boot mode:

1.bootloader mode (camera + power)

2.recovery mode (home + power)

3.normal boot

https://www.360docs.net/doc/d65856519.html,mand == 'boot-recovery' →启动recovery.img。recovery模式

https://www.360docs.net/doc/d65856519.html,mand == 'update-radio/hboot' →更新firmware（bootloader)

3.其他→启动boot.img

3.CACHE分区文件

Recovery 工具通过NAND cache分区上的三个文件和主系统打交道。主系统（包括恢复出厂设置和OTA升级）可以写入recovery所需的命令，读出recovery过程中的LOG和intent。

/cache/recovery/command：recovery命令，由主系统写入。所有命令如下：

--send_intent=anystring - write the text out to recovery.intent

--update_package=root:path - verify install an OTA package file

--wipe_data - erase user data (and cache), then reboot

--wipe_cache - wipe cache (but not user data), then reboot

/cache/recovery/log：recovery过程日志，由主系统读出

/cache/recovery/intent：recovery输出的intent

4.MISC partition:

Bootloader Control Block (BCB) 存放recovery bootloader message。结构如下：

struct bootloader_message {

char command[32];

char recovery[1024];

};

command format:

“boot-recovery”：标示recovery正在进行，或指示bootloader应该进入recovery mode “update-hboot/radio”：指示bootloader更新firmware

recovery内容

“recovery\n

\n

”

其中recovery command为CACHE:/recovery/command命令

两种Recovery Case

?FACTORY RESET（恢复出厂设置）

1.用户选择“恢复出厂设置”

2.设置系统将"--wipe_data"命令写入/cache/recovery/command

3.系统重启，并进入recover模式（/sbin/recovery）

4.get_args() 将"boot-recovery"和"--wipe_data"写入BCB

5.erase_root() 格式化（擦除）DATA分区

6.erase_root() 格式化（擦除）CACHE分区

7.finish_recovery() 擦除BCB

8.重启系统

?OTA INSTALL（OTA升级）

1.升级系统下载OTA包到/cache/some-filename.zip

2.升级系统写入recovery命令"--update_package=CACHE:some-filename.zip"

3.重启，并进入recovery模式

4.get_args() 将"boot-recovery" 和"--update_package=..." 写入BCB

5.install_package() 作升级

6.finish_recovery() 擦除BCB

7.** 如果安装包失败** prompt_and_wait() 等待用户操作，选择ALT+S或ALT+W 升级或恢复出厂设置

8.main() 调用maybe_install_firmware_update()

1.如果包里有hboot/radio的firmware则继续，否则返回

2.将"boot-recovery" 和"--wipe_cache" 写入BCB

3.将firmware image写入cache分区

4.将"update-radio/hboot" 和"--wipe_cache" 写入BCB

5.重启系统

6.bootloader自身更新firmware

7.bootloader 将"boot-recovery" 写入BCB

8.erase_root() 擦除CACHE分区

9.清除BCB

9.main() 调用reboot() 重启系统

Recovery模式流程

/init →init.rc →/sbin/recovery →

main():recovery.c

ui_init():ui.c ［UI initialize］

gr_init():minui/graphics.c ［set tty0 to graphic mode, open fb0]

ev_init():minui/events.c [open /dev/input/event*]

res_create_surface:minui/resource.c [create surfaces for all bitmaps used later, include icons, bmps]

create 2 threads: progress/input_thread [create progress show and input event handler thread]

get_args():recovery.c

get_bootloader_message():bootloader.c [read mtdblock0(misc partition) 2nd page for commandline]

check if nand misc partition has boot message. If yes, fill argc/argv.

If no, get arguments from /cache/recovery/command, and fill argc/argv.

set_bootloader_message():bootloader.c [set bootloader message back to mtdblock0]

Parser argv[] filled above

register_update_commands():commands.c [ register all commands with name and hook function ]

registerCommand():commands.c

Register command with name, hook, type, cookie.

Commands, e.g: assert, delete, copy_dir, symlink, write_raw_image.

registerFunction():commands.c

Register function with name, hook, cookie.

Function, e.g: get_mark, matches, getprop, file_contains

install_package():

translate_root_path():roots.c [ "SYSTEM:lib" and turns it into a string like "/system/lib", translate the updater.zip path ]

mzOpenZipArchive():zip.c [ open updater.zip file (uncompass) ]

handle_update_package():install.c

verify_jar_signature():verifier.c [ verify signature with keys.inc key; verify manifest and zip package archive ]

verifySignature() [ verify the signature file: CERT.sf/rsa. ]

digestEntry():verifier.c [ get SHA-1 digest of CERT.sf file ]

RSA_verify(public key:keys.inc, signature:CERT.rsa, CERT.sf's digest):libc/rsa.c [ Verify a 2048 bit RSA PKCS1.5 signature against an expected SHA-1 hash. Use public key to decrypt the CERT.rsa to get original SHA digest, then compare to digest of CERT.sf ]

verifyManifest() [ Get manifest SHA1-Digest from CERT.sf. Then do digest to MANIFEST.MF. Compare them ]

verifyArchive() [ verify all the files in update.zip with digest listed in MANIFEST.MF ]

find_update_script():install.c [ find META-INF/com/google/android/update-script updater script ]

handle_update_script():install.c [ read cmds from script file, and do parser, exec ]

parseAmendScript():amend.c [ call yyparse() to parse to command ]

exeCommandList():install.c

exeCommand():execute.c [ call command hook function ]

erase DATA/CACHE partition

prompt_and_wait():recovery.c [ wait for user input: 1) reboot 2) update.zip 3) wipe data ]

ui_key_xxx get ALT+x keys

1) do nothing

2) install_package('SDCARD:update.zip')

3) erase_root() →format_root_device() DATA/CACHE

may_install_firmware_update():firmware.c [ remember_firmware_update() is called by write_hboot/radio_image command, it stores the bootloader image to CACHE partition, and write update-hboot/radio command to MISC partition for bootloader message to let bootloader update itself after reboot ]

set_bootloader_message()

write_update_for_bootloader():bootloader.c [ write firmware image into CACHE partition with update_header, busyimage and failimage ]

finish_recovery():recovery.c [ clear the recovery command and prepare to boot a (hopefully working) system, copy our log file to cache as well (for the system to read), and record any intent we were asked to communicate back to the system. ]

reboot()

Recovery模式流程图

以下流程图绘制了系统从启动加载bootloader后的行为流程。