android ota 升级包制作分析 （5 工具）

工具

1 mkbootfs

mkbootfs的源代码在system/core/cpio中。

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? Cpio - 维基百科

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mkbootfs -f boot_filesystem_config.txt targetfiles/BOOT/RAMDISK | minigzip > ramdisk.img

2 mkbootimg

mkbootimg的源代码在system/core/mkbootimg中。

mkbootimg --kernel kernel --ramdisk ramdisk.img --output /tmp/boot.img

3 minigzip

minigzip的源代码在external/zlib中。

4 fs_config

源码位于：build/tools/fs_config。

其中的fs_config.c包含了system/core/include/private/android_filesystem_config.h，真正权限配置和fs_config的实现都在这个头文件中。

static const struct fs_path_config android_dirs[] = {

{ 00770, AID_SYSTEM, AID_CACHE, 0, "cache" },

{ 00771, AID_SYSTEM, AID_SYSTEM, 0, "data/app" },

{ 00771, AID_SYSTEM, AID_SYSTEM, 0, "data/app-private" },

{ 00771, AID_SYSTEM, AID_SYSTEM, 0, "data/dalvik-cache" },

{ 00771, AID_SYSTEM, AID_SYSTEM, 0, "data/data" },

{ 00771, AID_SHELL, AID_SHELL, 0, "data/local/tmp" },

{ 00771, AID_SHELL, AID_SHELL, 0, "data/local" },

{ 01771, AID_SYSTEM, AID_MISC, 0, "data/misc" },

{ 00770, AID_DHCP, AID_DHCP, 0, "data/misc/dhcp" },

{ 00775, AID_MEDIA_RW, AID_MEDIA_RW, 0, "data/media" },

{ 00775, AID_MEDIA_RW, AID_MEDIA_RW, 0, "data/media/Music" },

{ 00771, AID_SYSTEM, AID_SYSTEM, 0, "data" },

{ 00750, AID_ROOT, AID_SHELL, 0, "sbin" },

{ 00755, AID_ROOT, AID_SHELL, 0, "system/bin" },

{ 00755, AID_ROOT, AID_SHELL, 0, "system/vendor" },

{ 00755, AID_ROOT, AID_SHELL, 0, "system/xbin" },

{ 00755, AID_ROOT, AID_ROOT, 0, "system/etc/ppp" },

{ 00755, AID_ROOT, AID_SHELL, 0, "vendor" },

{ 00777, AID_ROOT, AID_ROOT, 0, "sdcard" },

{ 00755, AID_ROOT, AID_ROOT, 0, 0 },

};

static const struct fs_path_config android_files[] = {

{ 00440, AID_ROOT, AID_SHELL, 0, "system/etc/init.goldfish.rc" },

{ 00550, AID_ROOT, AID_SHELL, 0, "system/etc/init.goldfish.sh" },

{ 00440, AID_ROOT, AID_SHELL, 0, "system/etc/init.trout.rc" },

{ 00550, AID_ROOT, AID_SHELL, 0, "system/etc/init.ril" },

{ 00550, AID_ROOT, AID_SHELL, 0, "system/etc/init.testmenu" },

{ 00550, AID_DHCP, AID_SHELL, 0, "system/etc/dhcpcd/dhcpcd-run-hooks" },

{ 00444, AID_RADIO, AID_AUDIO, 0, "system/etc/AudioPara4.csv" },

{ 00555, AID_ROOT, AID_ROOT, 0, "system/etc/ppp/*" },

{ 00555, AID_ROOT, AID_ROOT, 0, "system/etc/rc.*" },

{ 00644, AID_SYSTEM, AID_SYSTEM, 0, "data/app/*" },

{ 00644, AID_MEDIA_RW, AID_MEDIA_RW, 0, "data/media/*" },

{ 00644, AID_SYSTEM, AID_SYSTEM, 0, "data/app-private/*" },

{ 00644, AID_APP, AID_APP, 0, "data/data/*" },

{ 00755, AID_ROOT, AID_ROOT, 0, "system/bin/ping" },

/* the following file is INTENTIONALLY set-gid and not set-uid.

* Do not change. */

{ 02750, AID_ROOT, AID_INET, 0, "system/bin/netcfg" },

/* the following five files are INTENTIONALLY set-uid, but they

* are NOT included on user builds. */

{ 06755, AID_ROOT, AID_ROOT, 0, "system/xbin/su" },

{ 06755, AID_ROOT, AID_ROOT, 0, "system/xbin/librank" },

{ 06755, AID_ROOT, AID_ROOT, 0, "system/xbin/procrank" },

{ 06755, AID_ROOT, AID_ROOT, 0, "system/xbin/procmem" },

{ 06755, AID_ROOT, AID_ROOT, 0, "system/xbin/tcpdump" },

{ 04770, AID_ROOT, AID_RADIO, 0, "system/bin/pppd-ril" },

/* the following files have enhanced capabilities and ARE included in user builds. */

{ 00750, AID_ROOT, AID_SHELL, (1 << CAP_SETUID) | (1 << CAP_SETGID), "system/bin/run-as" },

{ 00755, AID_ROOT, AID_SHELL, 0, "system/bin/*" },

{ 00755, AID_ROOT, AID_ROOT, 0, "system/lib/valgrind/*" },

{ 00755, AID_ROOT, AID_SHELL, 0, "system/xbin/*" },

{ 00755, AID_ROOT, AID_SHELL, 0, "system/xbin/*" },

{ 00755, AID_ROOT, AID_SHELL, 0, "system/vendor/bin/*" },

{ 00755, AID_ROOT, AID_SHELL, 0, "vendor/bin/*" },

{ 00750, AID_ROOT, AID_SHELL, 0, "sbin/*" },

{ 00755, AID_ROOT, AID_ROOT, 0, "bin/*" },

{ 00750, AID_ROOT, AID_SHELL, 0, "init*" },

{ 00750, AID_ROOT, AID_SHELL, 0, "charger*" },

{ 00750, AID_ROOT, AID_SHELL, 0, "sbin/fs_mgr" },

{ 00640, AID_ROOT, AID_SHELL, 0, "fstab.*" },

{ 00644, AID_ROOT, AID_ROOT, 0, 0 },

};

5 imgdiff

工具imgdiff的源码位于：recovery/applypatch。对应的应用补丁的工具为imgpatch。imgdiff用来处理*.gz，*.zip，*.apk，*.jar，*.img。

imgpatch以及下面的bspatch都存在于applypatch工具中。与官方的bspatch在输入输出以及错误处理上有一些不同。根据diff文件的开头几个字节可以判断应该使用哪个补丁工具。开头为“BSDIFF40”的用bspatch处理，开头为“IMGDIFF2”用imgpatch处理。

6 bsdiff

工具bsdiff的源码位于：external/bsdiff。对应的应用补丁的工具为bspatch。bsdiff能够更高效地处理可执行文件。

7 signapk

signapk的源码位于：build/tools/signapk。

? Android APK 签名比对

? signapk流程分析

使用方法：

signapk.jar -w <公钥> <私钥> <输入文件> <输出文件>

其中：-w表示对整个文件进行签名。

签名算法：

1. 程序遍历update.apk包中的所有文件(entry)，对非文件夹非签名文件的文件，逐个生成SHA1的数字签名信息，再用Base64进行编码。

2. 如果-w整包签，则将 证书.x509.pem 复制到 META-INF/com//otacert； 
并在manifest对象中增加META-INF/com/android/otacert的SHA1摘要

3. 之后将生成的签名写入MANIFEST.MF文件。

4. 对前一步生成的Manifest，使用SHA1-RSA算法，用私钥进行签名。

5. 在CERT.RSA文件中保存公钥、所采用的加密算法等信息。

签名后，apk（zip）文件中多了下列文件

META-INF/MANIFEST.MF

META-INF/CERT.SF

META-INF/CERT.RSA