概要：
此部分为全包升级主要实现过程，涉及到ota_from_target_files 文件，这个也是制作全包和差分包的主要工具，接下来我们就着重分析怎么利用这个工具制作full_ota_package的。主要流程：
源码分析：
上节中Makefile中otapackage目标最后的cmd为：
$(hide) MTK_SECURITY_SW_SUPPORT=$(MTK_SECURITY_SW_SUPPORT)MKBOOTIMG=$(MKBOOTIMG) \
./build/tools/releasetools/ota_from_target_files-v \
--block \
-p $(HOST_OUT) \
-k $(KEY_CERT_PAIR) \
$(if $(OEM_OTA_CONFIG), -o$(OEM_OTA_CONFIG)) \
$(BUILT_TARGET_FILES_PACKAGE) $@所以跳到ota_from_target_files python文件中，接下来我们先看一下这个文件的作用，usage以及cmd所带的参数的意义。
"""
Given a target-files zipfile, produces an OTA package that installs
that build. An incremental OTA is produced if -i is given, otherwise
a full OTA is produced.
Usage: ota_from_target_files [flags] input_target_files output_ota_package
--board_config <file>
Deprecated.
-k (--package_key) <key> Key to use to sign the package (default is
the value of default_system_dev_certificate from the input
target-files's META/misc_info.txt, or
"build/target/product/security/testkey" if that value is not
specified).
For incremental OTAs, the default value is based on the source
target-file, not the target build.
-i (--incremental_from) <file>
Generate an incremental OTA using the given target-files zip as
the starting build.
-v (--verify)
Remount and verify the checksums of the files written to the
system and vendor (if used) partitions. Incremental builds only.
-o (--oem_settings) <file>
Use the file to specify the expected OEM-specific properties
on the OEM partition of the intended device.
-w (--wipe_user_data)
Generate an OTA package that will wipe the user data partition
when installed.
-n (--no_prereq)
Omit the timestamp prereq check normally included at the top of
the build scripts (used for developer OTA packages which
legitimately need to go back and forth).
-e (--extra_script) <file>
Insert the contents of file at the end of the update script.
-r (--preloader) <file>
Specify 'preloader.img' to upgrade.
-l (--logo) <file>
Specify 'logo.img' to upgrade.
-u (--uboot) <file>
Specify 'uboot.img/lk.img' to upgrade.
-a (--aslr_mode) <on|off>
Specify whether to turn on ASLR for the package (on by default).
-2 (--two_step)
Generate a 'two-step' OTA package, where recovery is updated
first, so that any changes made to the system partition are done
using the new recovery (new kernel, etc.).
--block
Generate a block-based OTA if possible. Will fall back to a
file-based OTA if the target_files is older and doesn't support
block-based OTAs.
-b (--binary) <file>
Use the given binary as the update-binary in the output package,
instead of the binary in the build's target_files. Use for
development only.
-t (--worker_threads) <int>
Specifies the number of worker-threads that will be used when
generating patches for incremental updates (defaults to 3).
-f (--special_factory_reset)
After upgrade, it will execute special factory reset.
-z (--trustonic) <file>
Specify 'mobicore.bin' to upgrade.
"""文件的作用如英文描述：给出一个target_file的zip包生成一个ota包，如果带–i 参数则生成差分包，否则生成full_ota_package
Usage: ota_from_target_files [flags] input_target_filesoutput_ota_package
–board_config
Deprecated.-k :指定sign package使用的key
-i : 制作差分包，后面跟差分包基础包
-v：verify功能
-o：指定oem厂商信息
-w：清楚data区
-n：是否检查时间戳信息，以便确定向前或者向后升级
-e：指定额外的升级脚本
-r：是否升级preloader分区
-l：是否升级logo分区
-u：是否升级uboot分区
-a：是否打开ASLR
-2：生成一个two-step ota包
–block：生成一个block_base的ota包
-b：指定一个update-binary存放到ota包中
-t：指定线程数
-f：指定是否恢复出厂设置
-z：指定mobicore.bin
从此处开始执行，然后跳到main函数中
if __name__ == '__main__':
try:
common.CloseInheritedPipes()
main(sys.argv[1:])
except common.ExternalError, e:
print
print " ERROR: %s" % (e,)
print
sys.exit(1)
finally:
common.Cleanup()下面这一段代码主要作用是解析命令行参数，除了上面已经分析的参数外，另外加上了
Common.ParseOptions()接口中的参数列表，如下：
for o, a in opts:
if o in ("-h", "--help"):
Usage(docstring)
sys.exit()
elif o in ("-v", "--verbose"):
OPTIONS.verbose = True
elif o in ("-p", "--path"):
OPTIONS.search_path = a
elif o in ("--signapk_path",):
OPTIONS.signapk_path = a
elif o in ("--extra_signapk_args",):
OPTIONS.extra_signapk_args = shlex.split(a)
elif o in ("--java_path",):
OPTIONS.java_path = a
elif o in ("--java_args",):
OPTIONS.java_args = a
elif o in ("--public_key_suffix",):
OPTIONS.public_key_suffix = a
elif o in ("--private_key_suffix",):
OPTIONS.private_key_suffix = a
elif o in ("-s", "--device_specific"):
OPTIONS.device_specific = a
elif o in ("-x", "--extra"):
key, value = a.split("=", 1)
OPTIONS.extras[key] = value
else:
if extra_option_handler is None or notextra_option_handler(o, a):
assert False, "unknown option \"%s\""% (o,)由之前Makefile的cmd来看：
./build/tools/releasetools/ota_from_target_files-v \
--block \
-p $(HOST_OUT) \
-k $(KEY_CERT_PAIR) \
$(if $(OEM_OTA_CONFIG), -o$(OEM_OTA_CONFIG)) \
$(BUILT_TARGET_FILES_PACKAGE) $@此段代码执行结束后：
OPTIONS.block_based = True
OPTIONS.verbose = True（此处注意：-v代表verbose；–verify代表verify）
OPTIONS.search_path= $(HOST_OUT) /* xxx/out/host/linux-x86 */
OPTIONS.package_key = $(KEY_CERT_PAIR)
args = [‘xxx-target_files-eng.xx.zip’,’xxx-ota-eng.xx.zip’]//前者是obj下的压缩包，后者是最终的ota包。
如有疑惑，请自行参考getopt解析命令行参数模块代码
def main(argv):
def option_handler(o, a):
if o == "--board_config":
pass # deprecated
elif o in ("-k", "--package_key"):
OPTIONS.package_key = a
elif o in ("-i", "--incremental_from"):
OPTIONS.incremental_source = a
elif o in ("-w", "--wipe_user_data"):
OPTIONS.wipe_user_data = True
elif o in ("-n", "--no_prereq"):
OPTIONS.omit_prereq = True
elif o in ("-o", "--oem_settings"):
OPTIONS.oem_source = a
elif o in ("-e", "--extra_script"):
OPTIONS.extra_script = a
elif o in ("-a", "--aslr_mode"):
if a in ("on", "On", "true", "True", "yes", "Yes"):
OPTIONS.aslr_mode = True
else:
OPTIONS.aslr_mode = False
elif o in ("-t", "--worker_threads"):
if a.isdigit():
OPTIONS.worker_threads = int(a)
else:
raise ValueError("Cannot parse value %r for option %r - only "
"integers are allowed." % (a, o))
elif o in ("-f", "--special_factory_reset"):
OPTIONS.special_factory_reset = True
elif o in ("-x", "--tee"):
OPTIONS.tee = a
elif o in ("-z", "--trustonic"):
OPTIONS.trustonic = a
elif o in ("-2", "--two_step"):
OPTIONS.two_step = True
elif o in ("-r", "--preloader"):
OPTIONS.preloader = a
elif o in ("-l", "--logo"):
OPTIONS.logo = a
elif o in ("-u", "--uboot"):
OPTIONS.uboot = a
elif o in ("-f", "--special_factory_reset"):
OPTIONS.special_factory_reset = True
elif o in ("-g", "--ubifs"):
OPTIONS.ubifs = True
elif o == "--no_signing":
OPTIONS.no_signing = True
elif o in ("--verify"):
OPTIONS.verify = True
elif o == "--block":
OPTIONS.block_based = True
elif o in ("-b", "--binary"):
OPTIONS.updater_binary = a
elif o in ("--no_fallback_to_full",):
OPTIONS.fallback_to_full = False
else:
return False
return True
args = common.ParseOptions(argv, __doc__,
extra_opts="b:k:i:d:wfgne:r:l:u:x:z:t:a:2o:",
extra_long_opts=["board_config=",
"package_key=",
"incremental_from=",
"wipe_user_data",
"special_factory_reset",
"ubifs",
"tee=",
"trustonic=",
"no_prereq",
"extra_script=",
"preloader=",
"logo=",
"uboot=",
"worker_threads=",
"aslr_mode=",
"two_step",
"no_signing",
"block",
"binary=",
"oem_settings=",
"verify",
"no_fallback_to_full",
],
extra_option_handler=option_handler)
if os.getenv("MTK_SECURITY_SW_SUPPORT", "no")=="no":
OPTIONS.mtk_sec_boot_sig_tail = False
if len(args) != 2:
common.Usage(__doc__)
sys.exit(1)/*此处为false*/
if OPTIONS.extra_script is not None:
OPTIONS.extra_script = open(OPTIONS.extra_script).read()解压输入压缩包到一个中间文件夹，并把目录赋给OPTIONS.input_tem,同时创建一个输入压缩包的ZipFile（zipfile.py中）实例：input_zip
print "unzipping target target-files..."
OPTIONS.input_tmp, input_zip = common.UnzipTemp(args[0])把输入压缩包的解压目录赋给OPTIONS.target_tmp。
通过input_zip读取压缩包中的META/misc_info.txt文件，以及RECOVERY/RAMDISK/etc/recovery.fstab，SYSTEM/build.prop等文件，并把文件内容并转换成字典形式OPTIONS.info_dict，建立字典代码如下：
def LoadDictionaryFromLines(lines):
d = {}
for line in lines:
line = line.strip()
if not line or line.startswith("#"):continue
if "=" in line:
name, value = line.split("=", 1)
d[name] = value
return dOPTIONS.target_tmp = OPTIONS.input_tmp
OPTIONS.info_dict = common.LoadInfoDict(input_zip)如果OPTIONS.info_dict中存在key selinux_fc,则key对应键值为：tmpxxx/BOOT/RAMDISK/file_contexts
如果冗余模式为真，则打印字典内容，此处为真。
# If this image was originally labelled with SELinux contexts, make sure we
# also apply the labels in our new image. During building, the "file_contexts"
# is in the out/ directory tree, but for repacking from target-files.zip it's
# in the root directory of the ramdisk.
if "selinux_fc" in OPTIONS.info_dict:
OPTIONS.info_dict["selinux_fc"] = os.path.join(OPTIONS.input_tmp, "BOOT", "RAMDISK",
"file_contexts")
if OPTIONS.verbose:
print "--- target info ---"
common.DumpInfoDict(OPTIONS.info_dict)如果调用者利用-s/–device_specific指定了device-specific extension路径，则使用它
否者使用META/releasetools.py如果此文件存在target_files压缩包中
如果以上都没有，则通过查找字典中的key：‘tool_extension’，来作为device_specific
#If the caller explicitly specified the device-specific extensions
# path via -s/--device_specific, use that. Otherwise, use
# META/releasetools.py if it is present inthe target target_files.
# Otherwise, take the path of the file from 'tool_extensions' in the
# info dict and look for that in the localfilesystem, relative to
# the current directory.
ifOPTIONS.device_specific is None:
from_input =os.path.join(OPTIONS.input_tmp, "META", "releasetools.py")
ifos.path.exists(from_input):
print"(using device-specific extensions from target_files)"
OPTIONS.device_specific = from_input
else:
OPTIONS.device_specific = OPTIONS.info_dict.get("tool_extensions",None)
ifOPTIONS.device_specific is not None:
OPTIONS.device_specific =os.path.abspath(OPTIONS.device_specific)S1：此处OPTIONS.mtk_sec_boot_sig_tail为真，读取boot.sig ,recovery.sig内容
while True:
if OPTIONS.mtk_sec_boot_sig_tail:
#After WriteIncrementalOTAPackage, input_zip seems scramble, so read *.sig at first
boot_sig = input_zip.read("META/boot.sig")
recovery_sig = input_zip.read("META/recovery.sig")此处为false，所以走else语句：
创建一个temp_zip_file临时文件夹的_TemporaryFileWrapper实例
然后创建一个zipfile实例output_zip，以temp_zip_file为入参。其实就是对1中的临时文件进行一个zipfile实例化，最后可以利用zipfile中的属性方法对这个文件进行操作
if OPTIONS.no_signing:
if os.path.exists(args[1]): os.unlink(args[1])
output_zip = zipfile.ZipFile(args[1], "w", compression=zipfile.ZIP_DEFLATED)
else:
temp_zip_file = tempfile.NamedTemporaryFile()
output_zip = zipfile.ZipFile(temp_zip_file, "w",
compression=zipfile.ZIP_DEFLATED)判断是否带-i参数，有则进行差分包制作，无则进行全包制作. 此处没有, 所以走if语句为真，然后跳到WriteFullOTAPackage(input_zip,output_zip)中执行，可参考后文详细分析
if OPTIONS.incremental_source is None:
WriteFullOTAPackage(input_zip,output_zip)
ifOPTIONS.package_key is None:
OPTIONS.package_key =OPTIONS.info_dict.get(
"default_system_dev_certificate",
"build/target/product/security/testkey")
ifnot OPTIONS.mtk_sec_boot_sig_tail:
break
else:
print"unzipping source target-files..."
OPTIONS.source_tmp, source_zip =common.UnzipTemp(OPTIONS.incremental_source)
OPTIONS.target_info_dict =OPTIONS.info_dict
OPTIONS.source_info_dict =common.LoadInfoDict(source_zip)
if"selinux_fc" in OPTIONS.source_info_dict:
OPTIONS.source_info_dict["selinux_fc"] =os.path.join(OPTIONS.source_tmp, "BOOT", "RAMDISK",
"file_contexts")
ifOPTIONS.package_key is None:
OPTIONS.package_key = OPTIONS.source_info_dict.get(
"default_system_dev_certificate",
"build/target/product/security/testkey")
ifOPTIONS.verbose:
print"--- source info ---"
common.DumpInfoDict(OPTIONS.source_info_dict)
try:
WriteIncrementalOTAPackage(input_zip,source_zip, output_zip)
ifnot OPTIONS.mtk_sec_boot_sig_tail:
break
exceptValueError:
ifnot OPTIONS.fallback_to_full: raise
print"--- failed to build incremental; falling back to full ---"
OPTIONS.incremental_source = None
output_zip.close()接下来调到全包升级主要接口
WriteFullOTAPackage(input_zip, output_zip)def WriteFullOTAPackage(input_zip, output_zip):
# TODO: how to determine this? We don't know what version it will
# be installed on top of. For now, we expect the API just won't
# change very often.a1:创建一个脚本实例，这个脚本将来会被写入临时升级包中：/META-INF/com/google/android/updater-script
script = edify_generator.EdifyGenerator(3, OPTIONS.info_dict)/*获取oem参数，没有这个key*/
oem_props = OPTIONS.info_dict.get("oem_fingerprint_properties")
/*获取recovery_mount_options key所对应的value*/
recovery_mount_options = OPTIONS.info_dict.get("recovery_mount_options")
/*目前没有涉及oem信息，下面几行忽略*/
oem_dict = None
if oem_props is not None and len(oem_props) > 0:
if OPTIONS.oem_source is None:
raise common.ExternalError("OEM source required for this build")
script.Mount("/oem", recovery_mount_options)
oem_dict = common.LoadDictionaryFromLines(open(OPTIONS.oem_source).readlines())M1：得到metadata字典，供最后一步使用：
post-build:alps/full_(PROJECT_NAME):5.1/LMY47D/1501228112:eng/test-keys
post-timestamp: 1501228303
pre-device: $(PROJECT_NAME)
metadata = {"post-build": CalculateFingerprint(
oem_props, oem_dict, OPTIONS.info_dict),
"pre-device": GetOemProperty("ro.product.device", oem_props, oem_dict,
OPTIONS.info_dict),
"post-timestamp": GetBuildProp("ro.build.date.utc",
OPTIONS.info_dict),
}
device_specific = common.DeviceSpecificParams(
input_zip=input_zip,
input_version=OPTIONS.info_dict["recovery_api_version"],
output_zip=output_zip,
script=script,
input_tmp=OPTIONS.input_tmp,
metadata=metadata,
info_dict=OPTIONS.info_dict)/判断是否有recovery path：target_files_zip.getinfo("SYSTEM/recovery-from-boot.p")，为真*/
has_recovery_patch = HasRecoveryPatch(input_zip)
/*是否支持block，生成ota包时有带–block参数，所以此处为真*/
block_based = OPTIONS.block_based and has_recovery_patch
/*不执行*/
if not OPTIONS.omit_prereq:
ts = GetBuildProp("ro.build.date.utc", OPTIONS.info_dict)
ts_text = GetBuildProp("ro.build.date", OPTIONS.info_dict)
script.AssertOlderBuild(ts, ts_text)升级脚本中添加：getprop(“ro.product.device”) ==“p92s_hd” || abort(“This package is for “p92s_hd"devices; this is a “” + getprop(“ro.product.device”) +””.");
AppendAssertions(script, OPTIONS.info_dict, oem_dict)
device_specific.FullOTA_Assertions()此处为false，不执行
if OPTIONS.two_step:
if not OPTIONS.info_dict.get("multistage_support", None):
assert False, "two-step packages not supported by this build"
fs = OPTIONS.info_dict["fstab"]["/misc"]
assert fs.fs_type.upper() == "EMMC", \
"two-step packages only supported on devices with EMMC /misc partitions"
bcb_dev = {"bcb_dev": fs.device}
common.ZipWriteStr(output_zip, "recovery.img", recovery_img.data)
if OPTIONS.info_dict.get("mtk_header_support", None):
recovery_bthdr_img = common.GetBootableImage("recovery_bthdr.img", "recovery_bthdr.img",
OPTIONS.input_tmp, "RECOVERY")
common.ZipWriteStr(output_zip, "recovery_bthdr.img", recovery_bthdr_img.data)
script.AppendExtra("""
if get_stage("%(bcb_dev)s") == "2/3" then
""" % bcb_dev)
script.WriteRawImage("/recovery", "recovery.img")
script.AppendExtra("""
set_stage("%(bcb_dev)s", "3/3");
reboot_now("%(bcb_dev)s", "recovery");
else if get_stage("%(bcb_dev)s") == "3/3" then
""" % bcb_dev)
device_specific.FullOTA_InstallBegin()system_progress = 0.75
if OPTIONS.wipe_user_data:
system_progress -= 0.1
if HasVendorPartition(input_zip):
system_progress -= 0.1
if HasCustomPartition(input_zip):
system_progress -= 0.1
/*把file_contexts写入升级包中*/
if "selinux_fc" in OPTIONS.info_dict:
WritePolicyConfig(OPTIONS.info_dict["selinux_fc"], output_zip)
/*得到recovery_mount_optionskey所对应的value*/
recovery_mount_options = OPTIONS.info_dict.get("recovery_mount_options")
/*设置system分区对应的config文件为：META/filesystem_config.txt,留着后续使用*/
system_items = ItemSet("system", "META/filesystem_config.txt")
/*在升级脚本中添加语句：show_progress(0.750000, 0);*/
script.ShowProgress(system_progress, 0)此处为真，然后执行下面任务：
先从input_tem(原始包解压后的中间文件夹)中得到system.img对system.img进行resetFileMap,具体不用深究在中间文件中生成：system.transfer.list; system.new.dat ; system.patch.dat最后再把这三个文件system.transfer.list; system.new.dat ; system.patch.dat写入到OTA包中，并添加script语句：ui_print(“Patching system imageunconditionally…”);
block_image_update(“system”,package_extract_file(“system.transfer.list”),“system.new.dat”, “system.patch.dat”);
以上涉及到另外两个python文件：common.py ; blockimgdiff.py
if block_based:
# Full OTA is done as an "incremental" against an empty source
# image. This has the effect of writing new data from the package
# to the entire partition, but lets us reuse the updater code that
# writes incrementals to do it.
system_tgt = GetImage("system", OPTIONS.input_tmp, OPTIONS.info_dict)
system_tgt.ResetFileMap()
system_diff = common.BlockDifference("system", system_tgt, src=None)
system_diff.WriteScript(script, output_zip)
else:
if OPTIONS.ubifs:
cust_dir1 = GetBuildProp("ro.product.device", OPTIONS.info_dict)
system_path = os.path.join("out/target/product",cust_dir1,"android.fixup.img")
if os.path.exists(system_path):
system_img = open(system_path).read()
common.ZipWriteStr(output_zip, "system.img", system_img)
script.WriteRawImageUbifs("system", "system.img")
script.Mount("/system", recovery_mount_options)
if not has_recovery_patch:
script.UnpackPackageDir("recovery", "/system")
symlinks = CopyPartitionFiles(system_items, input_zip, output_zip)
else:
script.FormatPartition("/system")
script.Mount("/system", recovery_mount_options)
if not has_recovery_patch:
script.UnpackPackageDir("recovery", "/system")
script.UnpackPackageDir("system", "/system")
symlinks = CopyPartitionFiles(system_items, input_zip, output_zip)
script.MakeSymlinks(symlinks)
try:
custom_size = OPTIONS.info_dict["custom_size"]
except:
custom_size = None
if custom_size is not None:
if (custom_size > 0) and (HasCustomPartition(input_zip) == True):
custom_items = ItemSet("custom", "META/custom_filesystem_config.txt")
if block_based:
custom_tgt = GetImage("custom", OPTIONS.input_tmp, OPTIONS.info_dict)
custom_tgt.ResetFileMap()
custom_diff = common.BlockDifference("custom", custom_tgt)
custom_diff.WriteScript(script, output_zip)
else:
script.FormatPartition("/custom")
script.Mount("/custom")
script.UnpackPackageDir("custom", "/custom")
symlinks = CopyPartitionFiles(custom_items, input_zip, output_zip)
script.MakeSymlinks(symlinks)
custom_items.GetMetadata(input_zip)
custom_items.Get("custom").SetPermissions(script)B1:从输入文件中获得boot.img(已存在)，然后返回一个FILE class的实例，name：为镜像名；data：镜像的二进制内容，如下：common.py
class File(object):
def init(self,name, data):
self.name = name
self.data = data
self.size = len(data)
self.sha1 = sha1(data).hexdigest()@classmethod
def FromLocalFile(cls,name, diskname):
f = open(diskname, "rb")data = f.read()
f.close()
return File(name, data)
….这个boot_img实例在后续会使用
boot_img = common.GetBootableImage("boot.img", "boot.img",
OPTIONS.input_tmp, "BOOT")
if not block_based:
def output_sink(fn, data):
common.ZipWriteStr(output_zip, "recovery/" + fn, data)
system_items.Get("system/" + fn, dir=False)
common.MakeRecoveryPatch(OPTIONS.input_tmp, output_sink,
recovery_img, boot_img)
system_items.GetMetadata(input_zip)
system_items.Get("system").SetPermissions(script)
if HasVendorPartition(input_zip):
vendor_items = ItemSet("vendor", "META/vendor_filesystem_config.txt")
script.ShowProgress(0.1, 0)
if block_based:
vendor_tgt = GetImage("vendor", OPTIONS.input_tmp, OPTIONS.info_dict)
vendor_tgt.ResetFileMap()
vendor_diff = common.BlockDifference("vendor", vendor_tgt)
vendor_diff.WriteScript(script, output_zip)
else:
script.FormatPartition("/vendor")
script.Mount("/vendor", recovery_mount_options)
script.UnpackPackageDir("vendor", "/vendor")
symlinks = CopyPartitionFiles(vendor_items, input_zip, output_zip)
script.MakeSymlinks(symlinks)
vendor_items.GetMetadata(input_zip)
vendor_items.Get("vendor").SetPermissions(script)
if HasCustomPartition(input_zip):
custom_items = ItemSet("custom", "META/custom_filesystem_config.txt")
script.ShowProgress(0.1, 0)
if block_based:
custom_tgt = GetImage("custom", OPTIONS.input_tmp, OPTIONS.info_dict)
custom_tgt.ResetFileMap()
custom_diff = common.BlockDifference("custom", custom_tgt)
custom_diff.WriteScript(script, output_zip)
else:
script.FormatPartition("/custom")
script.Mount("/custom")
script.UnpackPackageDir("custom", "/custom")
symlinks = CopyPartitionFiles(custom_items, input_zip, output_zip)
script.MakeSymlinks(symlinks)
custom_items.GetMetadata(input_zip)
custom_items.Get("custom").SetPermissions(script)check boot.img镜像的大小，是否超过max_size,此处用到B1中boot_img class中的data
2.把boot_img.data内容写入到输出压缩包中，参考zipfile.py , tempfile.py
- 同时写入script脚本：
show_progress(0.050000,5);
assert(package_extract_file(“boot.img”,"/tmp/boot.img"),
write_raw_image("/tmp/boot.img", "bootimg"),delete("/tmp/boot.img"));
common.CheckSize(boot_img.data, "boot.img", OPTIONS.info_dict)
common.ZipWriteStr(output_zip, "boot.img", boot_img.data)
script.ShowProgress(0.05, 5)
script.WriteRawImage("/boot", "boot.img")下面几行主要是：获得SEC_VER.txt的路径，并把它写入输出的压缩包中
[SEC OTA] config : vendor/mediatek/proprietary/custom/$(PROJECT_NAME)/security/recovery/SEC_VER.txt
# security version
print "[SEC OTA] Adding security version (WriteFullOTAPackage)"
cust_dir = GetBuildProp("ro.product.model", OPTIONS.info_dict)
cust_dir_base = GetBuildProp("ro.product.device", OPTIONS.info_dict)
print "[SEC OTA] cust directory : ", cust_dir_base
sec_ver_path = os.path.join("vendor/mediatek/proprietary/custom",cust_dir_base,"security/recovery/SEC_VER.txt")
print "[SEC OTA] security config : ", sec_ver_path
if os.path.exists(sec_ver_path):
sec_ver = open(sec_ver_path).read()
common.ZipWriteStr(output_zip, "SEC_VER.txt", sec_ver)判断是否有：out/target/product/device/bror/p92s_hd/signed_bin/sig_info/boot.img.sig
如果有，写入输出压缩包中；没有则不需操作
boot_sec_sig_ext_path = os.path.join("out/target/product",cust_dir,"signed_bin/sig_info/boot.img.sig")
if not os.path.exists(boot_sec_sig_ext_path):
cust_dir = GetBuildProp("ro.product.name", OPTIONS.info_dict)
boot_sec_sig_ext_path = os.path.join("out/target/product",cust_dir,"signed_bin/sig_info/boot.img.sig")
if not os.path.exists(boot_sec_sig_ext_path):
cust_dir = GetBuildProp("ro.mediatek.project.path", OPTIONS.info_dict)
boot_sec_sig_ext_path = os.path.join("out/target/product",cust_dir,"signed_bin/sig_info/boot.img.sig")
print "[SEC OTA] security boot sig_ext : ", boot_sec_sig_ext_path
if os.path.exists(boot_sec_sig_ext_path):
boot_sec_sig_ext = open(boot_sec_sig_ext_path).read()
common.ZipWriteStr(output_zip, "boot.img.sig", boot_sec_sig_ext)在output_zip中写入type.txt文件，内容为1.（全包为1，差分包为0）
#wschen start
common.ZipWriteStr(output_zip, "type.txt", "1")把ota_scatter.txt写入output_zip中，命名为scatter.txt
cust_dir =GetBuildProp("ro.product.model", OPTIONS.info_dict)
scatter_path =os.path.join("out/target/product",cust_dir,"ota_scatter.txt")
if not os.path.exists(scatter_path):
cust_dir = GetBuildProp("ro.product.device",OPTIONS.info_dict)
scatter_path =os.path.join("out/target/product",cust_dir,"ota_scatter.txt")
if not os.path.exists(scatter_path):
cust_dir = GetBuildProp("ro.product.name", OPTIONS.info_dict)
cust_dir = cust_dir.split('full_')[-1]
scatter_path =os.path.join("out/target/product",cust_dir,"ota_scatter.txt")
if not os.path.exists(scatter_path):
cust_dir = GetBuildProp("ro.mediatek.project.path",OPTIONS.info_dict)
cust_dir = cust_dir.split('/')[-1]
scatter_path = os.path.join("out/target/product",cust_dir,"ota_scatter.txt")
ota_scatter = open(scatter_path).read()
common.ZipWriteStr(output_zip,"scatter.txt", ota_scatter)下面这几步是判断是否进行preloader，logo，uboot，tee等分区进行升级，如不需要，则忽略
# if OPTIONS.preloader is not None or OPTIONS.uboot is not None or OPTIONS.logo is not None:
# script.AppendExtra('assert(run_program(\"/system/bin/dd\", \"if=/dev/zero\", \"of=/proc/driver/mtd_writeable\", \"bs=3\", \"count=1\"));')
if OPTIONS.logo is not None:
logo_img = open(OPTIONS.logo).read()
common.ZipWriteStr(output_zip, "logo.img", logo_img)
script.WriteRawImage2("logo", "logo.img")
if OPTIONS.preloader is not None:
preloader_img = open(OPTIONS.preloader).read()
common.ZipWriteStr(output_zip, "preloader.img", preloader_img)
script.WriteRawImage2("preloader", "preloader.img")
if OPTIONS.uboot is not None:
uboot_img = open(OPTIONS.uboot).read()
common.ZipWriteStr(output_zip, "uboot.img", uboot_img)
script.WriteRawImage2("uboot", "uboot.img")
#tonykuo start
if OPTIONS.tee is not None:
tee_img = open(OPTIONS.tee).read()
common.ZipWriteStr(output_zip, "tee.img", tee_img)
script.WriteRawImage2("tee1", "tee.img")
#tonykuo end
#koshi start
if OPTIONS.trustonic is not None:
trustonic_img = open(OPTIONS.trustonic).read()
common.ZipWriteStr(output_zip, "mobicore.bin", trustonic_img)
script.WriteRawImage2("tee1", "mobicore.bin")
#koshi end添加script语句：show_progress(0.200000, 10);
并声明WriteFull_ota制作结束
script.ShowProgress(0.2, 10)
device_specific.FullOTA_InstallEnd()如果存在额外脚本，则把脚本内容填入升级script中，此处为None
if OPTIONS.extra_script is not None:
script.AppendExtra(OPTIONS.extra_script)升级脚本中添加unmount所有mount_point语句，如下：
def UnmountAll(self):
for p insorted(self.mounts):
self.script.append(‘unmount("%s");’% (p,))
self.mounts = set()
但由于sef.mounts在全包升级中为空集合，所以此处没有添加unmount语句到脚本中
script.UnmountAll()制作ota包命令行中是否带有"-f","–special_factory_reset"参数，没有则不执行下面语句，此处为False
#wschen
if OPTIONS.special_factory_reset:
script.AppendExtra('special_factory_reset();')制作ota包命令行中是否带有"-w", "–wipe_user_data"参数，没有则不执行下面语句：
清楚data分区。此处为False
if OPTIONS.wipe_user_data:
script.ShowProgress(0.1, 10)
script.FormatPartition("/data")添加升级脚本语句：
self.script.append((‘apply_sig(package_extract_file("%(sigfile_name)s"),"%(partion_name)s");’)
% {'sigfile_name':sigfile_name,'partion_name':partion_name})==>apply_sig(package_extract_file(“sig/boot.sig”),“bootimg”);
if OPTIONS.mtk_sec_boot_sig_tail:
script.ApplySig("sig/boot.sig", "bootimg")制作ota包命令行中是否带有"-2", "–two_step"参数，没有则不执行下面语句：
清楚data分区。此处为False
if OPTIONS.two_step:
script.AppendExtra("""
set_stage("%(bcb_dev)s", "");
""" % bcb_dev)
script.AppendExtra("else\n")
script.WriteRawImage("/boot", "recovery.img")
script.AppendExtra("""
set_stage("%(bcb_dev)s", "2/3");
reboot_now("%(bcb_dev)s", "");
endif;
endif;
""" % bcb_dev)此处尤为重要，主要做两件事情：
将升级脚本语句script序列写入到升级包中："META-INF/com/google/android/updater-script"将升级工具（可执行文件）写入升级包中："META-INF/com/google/android/update-binary"代码如下：请参考edify_generator.py:
defAddToZip(self, input_zip, output_zip, input_path=None):
“”"Write the accumulated script to the output_zipfile. input_zip
isused as the source for the ‘updater’ binary needed to run
script. If input_path is not None, it will be used asa local
pathfor the binary instead of input_zip."""
self.UnmountAll()
common.ZipWriteStr(output_zip,“META-INF/com/google/android/updater-script”,
"\n".join(self.script) + "\n")/此处为序列之间加入‘\n’，所以最终的文件中都是一行一行的呈现出来/
ifinput_path is None:
data= input_zip.read(“OTA/bin/updater”)
else:
data= open(input_path, “rb”).read()
common.ZipWriteStr(output_zip,“META-INF/com/google/android/update-binary”,
data,perms=0755)
script.AddToZip(input_zip, output_zip, input_path=OPTIONS.updater_binary)把上文M1处内容中的字典格式转换成‘%s=%s’格式，并写入到升级包中：
“META-INF/com/android/metadata”
如下文code：调用
defWriteMetadata(metadata, output_zip):
common.ZipWriteStr(output_zip,“META-INF/com/android/metadata”,
"".join(["%s=%s\n" % kv
for kv insorted(metadata.iteritems())]))最终文件内容如下：
post-build=alps/full_p92s_hd/p92s_hd:5.1/LMY47D/1501228112:eng/test-keys
post-timestamp=1501228303
pre-device=p92s_hd
WriteMetadata(metadata, output_zip)至此，writeFullOTAPackage函数运行完毕
接下来再继续跳到main函数剩余部分接着执行
if OPTIONS.incremental_source is None:
WriteFullOTAPackage(input_zip, output_zip)
if OPTIONS.package_key is None:
OPTIONS.package_key = OPTIONS.info_dict.get(
"default_system_dev_certificate",
"build/target/product/security/testkey")
if not OPTIONS.mtk_sec_boot_sig_tail:
break
else:
print "unzipping source target-files..."
OPTIONS.source_tmp, source_zip = common.UnzipTemp(OPTIONS.incremental_source)
OPTIONS.target_info_dict = OPTIONS.info_dict
OPTIONS.source_info_dict = common.LoadInfoDict(source_zip)
if "selinux_fc" in OPTIONS.source_info_dict:
OPTIONS.source_info_dict["selinux_fc"] = os.path.join(OPTIONS.source_tmp, "BOOT", "RAMDISK",
"file_contexts")
if OPTIONS.package_key is None:
OPTIONS.package_key = OPTIONS.source_info_dict.get(
"default_system_dev_certificate",
"build/target/product/security/testkey")
if OPTIONS.verbose:
print "--- source info ---"
common.DumpInfoDict(OPTIONS.source_info_dict)
try:
WriteIncrementalOTAPackage(input_zip, source_zip, output_zip)
if not OPTIONS.mtk_sec_boot_sig_tail:
break
except ValueError:
if not OPTIONS.fallback_to_full: raise
print "--- failed to build incremental; falling back to full ---"
OPTIONS.incremental_source = None
output_zip.close()此处为真，接下来在临时升级文件包中写入sig/boot.sig; sig/recovery.sig文件
其中源data（boot_sig,recovery_sig）为上文S1步骤中的内容
if OPTIONS.mtk_sec_boot_sig_tail:
common.ZipWriteStr(output_zip, "sig/boot.sig", boot_sig)
common.ZipWriteStr(output_zip, "sig/recovery.sig", recovery_sig)
break;
output_zip.close()对中间升级文件包进行前签名，生成最终的升级包
1.running: openssl pkcs8 -inbuild/target/product/security/testkey.pk8 -inform DER -nocrypt
2.running: java -Xmx2048m -jarout/host/linux-x86/framework/signapk.jar -wbuild/target/product/security/testkey.x509.pembuild/target/product/security/testkey.pk8 /tmp/tmpBXjz5Z out/target/product/xxxx/xxxx-ota-eng.wan.zip
最终生成升级包
第2步中会调用build/tools/signapk/signapk.java文件，生成META-INF/MANIFEST.MF,META-INF/CERT.RSA,META-INF/CERT.SF,
META-INF/com/android/otacert文件
if not OPTIONS.no_signing:
SignOutput(temp_zip_file.name, args[1])
temp_zip_file.close()
print "done."最终压缩包中的文件列表如下：
着重看下META-INF/com/google/android下的两个升级文件：
Update-binary：升级工具，可执行文件
Updater-script:升级脚本，由制作升级包的过程中一步一步生成的，其内容如下：
文章参考：
Android OTA升级（二）之ota_from_target_files文件分析