工具
1 mkbootfs
mkbootfs的源代码在system/core/cpio中。
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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。
使用方法：
signapk.jar -w
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
的各种实现)
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