Android OTA 升级之一：编译升级包
作者： 宋立新
前言
OTA 升级是 Android 系统提供的标准软件升级方式。 它功能强大，提供了完全升级、增量升级模式，可以通过 SD 卡升级，也可以通过网络升级。
这里，我们先研究最简单的情况，通过 SD 卡进行完全升级。
如何执行升级就不多说了，网上有很多资料。（比如，介绍 HTC 手机如何升级）。我们感兴趣的是它是如何实现的，作为开发者，如何修改它以符合我们的定制化需求。
首先，我们研究一下 ota 升级包的编译过程。
Quick start
首先编译出 android, 然后执行：
make otapackage
即可获得： out/target/product/{product_name}/ {product_name} -ota-eng.{uid}.zip
将该文件改名为 update.zip 放到 T 卡根目录 , 即可开始 recovery 模式下的 OTA 升级。
编译过程研究
主要分两步，第一步， 会准备一个包，其中包含升级需要的内容 ( 原材料 ) ，比如， system 目录。
第二步，运行 python 脚本 ./build/tools/releasetools/ota_from_target_files ，以步骤一准备的 ZIP 包作为输入，最终生成需要的升级包。
步骤一
编译脚本如下 :
(From: build/core/Makefile)
- 1073 # Depending on the various images guarantees that the underlying
- 1074 # directories are up-to-date.
- 1075 $(BUILT_TARGET_FILES_PACKAGE): /
- 1076 $(INSTALLED_BOOTIMAGE_TARGET) /
- 1077 $(INSTALLED_RADIOIMAGE_TARGET) /
- 1078 $(INSTALLED_RECOVERYIMAGE_TARGET) /
- 1079 $(INSTALLED_FACTORYIMAGE_TARGET) /
- 1080 $(INSTALLED_SYSTEMIMAGE) /
- 1081 $(INSTALLED_USERDATAIMAGE_TARGET) /
- 1082 $(INSTALLED_SECROIMAGE_TARGET) /
- 1083 $(INSTALLED_ANDROID_INFO_TXT_TARGET) /
- 1084 $(built_ota_tools) /
- 1085 $(APKCERTS_FILE) /
- 1086 $(HOST_OUT_EXECUTABLES)/fs_config /
- 1087 | $(ACP)
- 1088 @echo "Package target files: $@"
- 1089 $(hide) rm -rf $@ $(zip_root)
- 1090 $(hide) mkdir -p $(dir $@) $(zip_root)
- 1091 @# Components of the recovery image
- 1092 $(hide) mkdir -p $(zip_root)/RECOVERY
- 1093 $(hide) $(call package_files-copy-root, /
- 1094 $(TARGET_RECOVERY_ROOT_OUT),$(zip_root)/RECOVERY/RAMDISK)
- 1095 ifdef INSTALLED_KERNEL_TARGET
- 1096 $(hide) $(ACP) $(INSTALLED_KERNEL_TARGET) $(zip_root)/RECOVERY/kernel
- 1097 $(hide) $(ACP) $(recovery_ramdisk) $(zip_root)/RECOVERY/ramdisk
- 1098 endif
- 1099 ifdef INSTALLED_2NDBOOTLOADER_TARGET
- 1100 $(hide) $(ACP) /
- 1101 $(INSTALLED_2NDBOOTLOADER_TARGET) $(zip_root)/RECOVERY/second
- 1102 endif
- 1103 ifdef BOARD_KERNEL_CMDLINE
- 1104 $(hide) echo "$(BOARD_KERNEL_CMDLINE)" > $(zip_root)/RECOVERY/cmdline
- 1105 endif
- 1106 ifdef BOARD_KERNEL_BASE
- 1107 $(hide) echo "$(BOARD_KERNEL_BASE)" > $(zip_root)/RECOVERY/ base
- 1108 endif
- 1109 @# Components of the factory image
- 1110 $(hide) mkdir -p $(zip_root)/FACTORY
- 1111 $(hide) $(call package_files-copy-root, /
- 1112 $(TARGET_FACTORY_ROOT_OUT),$(zip_root)/FACTORY/RAMDISK)
- 1113 ifdef INSTALLED_KERNEL_TARGET
- 1114 $(hide) $(ACP) $(INSTALLED_KERNEL_TARGET) $(zip_root)/FACTORY/kernel
- 1115 endif
- 1116 ifdef INSTALLED_2NDBOOTLOADER_TARGET
- 1117 $(hide) $(ACP) /
- 1118 $(INSTALLED_2NDBOOTLOADER_TARGET) $(zip_root)/FACTORY/second
- 1119 endif
- 1120 ifdef BOARD_KERNEL_CMDLINE
- 1121 $(hide) echo "$(BOARD_KERNEL_CMDLINE)" > $(zip_root)/FACTORY/cmdline
- 1122 endif
- 1123 ifdef BOARD_KERNEL_BASE
- 1124 $(hide) echo "$(BOARD_KERNEL_BASE)" > $(zip_root)/FACTORY/ base
- 1125 endif
- 1126 @# Components of the boot image
- 1127 $(hide) mkdir -p $(zip_root)/BOOT
- 1128 $(hide) $(call package_files-copy-root, /
- 1129 $(TARGET_ROOT_OUT),$(zip_root)/BOOT/RAMDISK)
- 1130 ifdef INSTALLED_KERNEL_TARGET
- 1131 $(hide) $(ACP) $(INSTALLED_KERNEL_TARGET) $(zip_root)/BOOT/kernel
- 1132 $(hide) $(ACP) $(INSTALLED_RAMDISK_TARGET) $(zip_root)/BOOT/ramdisk
- 1133 endif
- 1134 ifdef INSTALLED_2NDBOOTLOADER_TARGET
- 1135 $(hide) $(ACP) /
- 1136 $(INSTALLED_2NDBOOTLOADER_TARGET) $(zip_root)/BOOT/second
- 1137 endif
- 1138 ifdef BOARD_KERNEL_CMDLINE
- 1139 $(hide) echo "$(BOARD_KERNEL_CMDLINE)" > $(zip_root)/BOOT/cmdline
- 1140 endif
- 1141 ifdef BOARD_KERNEL_BASE
- 1142 $(hide) echo "$(BOARD_KERNEL_BASE)" > $(zip_root)/BOOT/ base
- 1143 endif
- 1144 $(hide) $(foreach t,$(INSTALLED_RADIOIMAGE_TARGET),/
- 1145 mkdir -p $(zip_root)/RADIO; /
- 1146 $(ACP) $(t) $(zip_root)/RADIO/$(notdir $(t));)
- 1147 @# Contents of the system image
- 1148 $(hide) $(call package_files-copy-root, /
- 1149 $(SYSTEMIMAGE_SOURCE_DIR),$(zip_root)/SYSTEM)
- 1150 @# Contents of the data image
- 1151 $(hide) $(call package_files-copy-root, /
- 1152 $(TARGET_OUT_DATA),$(zip_root)/DATA)
- 1153 @# Extra contents of the OTA package
- 1154 $(hide) mkdir -p $(zip_root)/OTA/bin
- 1155 $(hide) $(ACP) $(INSTALLED_ANDROID_INFO_TXT_TARGET) $(zip_root)/OTA/
- 1156 $(hide) $(ACP) $(PRIVATE_OTA_TOOLS) $(zip_root)/OTA/bin/
- 1157 @# Files that do not end up in any images, but are necessary to
- 1158 @# build them.
- 1159 $(hide) mkdir -p $(zip_root)/META
- 1160 $(hide) $(ACP) $(APKCERTS_FILE) $(zip_root)/META/apkcerts.txt
- 1161 $(hide) echo "$(PRODUCT_OTA_PUBLIC_KEYS)" > $(zip_root)/META/otakeys.txt
- 1162 $(hide) echo "$(PRIVATE_RECOVERY_API_VERSION)" > $(zip_root)/META/recovery-api-version.txt
- 1163 $(hide) echo "blocksize $(BOARD_FLASH_BLOCK_SIZE)" > $(zip_root)/META/imagesizes.txt
- 1164 $(hide) echo "boot $(call image-size-from-data-size,$(BOARD_BOOTIMAGE_PARTITION_SIZE))" >> $(zip_root)/META/imagesizes.txt
- 1165 $(hide) echo "recovery $(call image-size-from-data-size,$(BOARD_RECOVERYIMAGE_PARTITION_SIZE))" >> $(zip_root)/META/imagesizes.txt
- 1166 $(hide) echo "system $(call image-size-from-data-size,$(BOARD_SYSTEMIMAGE_PARTITION_SIZE))" >> $(zip_root)/META/imagesizes.txt
- 1167 $(hide) echo "secro $(call image-size-from-data-size,$(BOARD_SECROIMAGE_PARTITION_SIZE))" >> $(zip_root)/META/imagesizes.txt
- 1168 $(hide) echo "userdata $(call image-size-from-data-size,$(BOARD_USERDATAIMAGE_PARTITION_SIZE))" >> $(zip_root)/META/imagesizes.txt
- 1169 $(hide) echo "$(tool_extensions)" > $(zip_root)/META/tool-extensions.txt
- 1170 @# Zip everything up, preserving symlinks
- 1171 $(hide) (cd $(zip_root) && zip -qry ../$(notdir $@) .)
- 1172 @# Run fs_config on all the system files in the zip, and save the output
- 1173 $(hide) zipinfo -1 $@ | awk -F/ 'BEGIN { OFS="/" } /^SYSTEM/// {$$1 = "system"; print}' | $(HOST_OUT_EXECUTABLES)/fs_config > $(zip_root)/META/filesystem_config.txt
- 1174 $(hide) (cd $(zip_root) && zip -q ../$(notdir $@) META/filesystem_config.txt)
- 1073
- # Depending on the various images guarantees that the underlying
- 1074 # directories are up-to-date.
- 1075 $(BUILT_TARGET_FILES_PACKAGE): /
- 1076 $(INSTALLED_BOOTIMAGE_TARGET) /
- 1077 $(INSTALLED_RADIOIMAGE_TARGET) /
- 1078 $(INSTALLED_RECOVERYIMAGE_TARGET) /
- 1079 $(INSTALLED_FACTORYIMAGE_TARGET) /
- 1080 $(INSTALLED_SYSTEMIMAGE) /
- 1081 $(INSTALLED_USERDATAIMAGE_TARGET) /
- 1082 $(INSTALLED_SECROIMAGE_TARGET) /
- 1083 $(INSTALLED_ANDROID_INFO_TXT_TARGET) /
- 1084 $(built_ota_tools) /
- 1085 $(APKCERTS_FILE) /
- 1086 $(HOST_OUT_EXECUTABLES)/fs_config /
- 1087 | $(ACP)
- 1088 @echo "Package target files: $@"
- 1089 $(hide) rm -rf $@ $(zip_root)
- 1090 $(hide) mkdir -p $(dir $@) $(zip_root)
- 1091 @# Components of the recovery image
- 1092 $(hide) mkdir -p $(zip_root)/RECOVERY
- 1093 $(hide) $(call package_files-copy-root, /
- 1094
- $(TARGET_RECOVERY_ROOT_OUT),$(zip_root)/RECOVERY/RAMDISK)
- 1095 ifdef INSTALLED_KERNEL_TARGET
- 1096 $(hide) $(ACP) $(INSTALLED_KERNEL_TARGET)
- $(zip_root)/RECOVERY/kernel
- 1097 $(hide) $(ACP) $(recovery_ramdisk)
- $(zip_root)/RECOVERY/ramdisk
- 1098 endif
- 1099 ifdef INSTALLED_2NDBOOTLOADER_TARGET
- 1100 $(hide) $(ACP) /
- 1101 $(INSTALLED_2NDBOOTLOADER_TARGET)
- $(zip_root)/RECOVERY/second
- 1102 endif
- 1103 ifdef BOARD_KERNEL_CMDLINE
- 1104 $(hide) echo "$(BOARD_KERNEL_CMDLINE)" >
- $(zip_root)/RECOVERY/cmdline
- 1105 endif
- 1106 ifdef BOARD_KERNEL_BASE
- 1107 $(hide) echo "$(BOARD_KERNEL_BASE)" >
- $(zip_root)/RECOVERY/base
- 1108 endif
- 1109 @# Components of the factory image
- 1110 $(hide) mkdir -p $(zip_root)/FACTORY
- 1111 $(hide) $(call package_files-copy-root, /
- 1112
- $(TARGET_FACTORY_ROOT_OUT),$(zip_root)/FACTORY/RAMDISK)
- 1113 ifdef INSTALLED_KERNEL_TARGET
- 1114 $(hide) $(ACP) $(INSTALLED_KERNEL_TARGET)
- $(zip_root)/FACTORY/kernel
- 1115 endif
- 1116 ifdef INSTALLED_2NDBOOTLOADER_TARGET
- 1117 $(hide) $(ACP) /
- 1118 $(INSTALLED_2NDBOOTLOADER_TARGET)
- $(zip_root)/FACTORY/second
- 1119 endif
- 1120 ifdef BOARD_KERNEL_CMDLINE
- 1121 $(hide) echo "$(BOARD_KERNEL_CMDLINE)" >
- $(zip_root)/FACTORY/cmdline
- 1122 endif
- 1123 ifdef BOARD_KERNEL_BASE
- 1124 $(hide) echo "$(BOARD_KERNEL_BASE)" >
- $(zip_root)/FACTORY/base
- 1125 endif
- 1126 @# Components of the boot image
- 1127 $(hide) mkdir -p $(zip_root)/BOOT
- 1128 $(hide) $(call package_files-copy-root, /
- 1129 $(TARGET_ROOT_OUT),$(zip_root)/BOOT/RAMDISK)
- 1130 ifdef INSTALLED_KERNEL_TARGET
- 1131 $(hide) $(ACP) $(INSTALLED_KERNEL_TARGET)
- $(zip_root)/BOOT/kernel
- 1132 $(hide) $(ACP) $(INSTALLED_RAMDISK_TARGET)
- $(zip_root)/BOOT/ramdisk
- 1133 endif
- 1134 ifdef INSTALLED_2NDBOOTLOADER_TARGET
- 1135 $(hide) $(ACP) /
- 1136 $(INSTALLED_2NDBOOTLOADER_TARGET)
- $(zip_root)/BOOT/second
- 1137 endif
- 1138 ifdef BOARD_KERNEL_CMDLINE
- 1139 $(hide) echo "$(BOARD_KERNEL_CMDLINE)" >
- $(zip_root)/BOOT/cmdline
- 1140 endif
- 1141 ifdef BOARD_KERNEL_BASE
- 1142 $(hide) echo "$(BOARD_KERNEL_BASE)" >
- $(zip_root)/BOOT/base
- 1143 endif
- 1144 $(hide) $(foreach t,$(INSTALLED_RADIOIMAGE_TARGET),/
- 1145 mkdir -p $(zip_root)/RADIO; /
- 1146 $(ACP) $(t) $(zip_root)/RADIO/$(notdir $(t));)
- 1147 @# Contents of the system image
- 1148 $(hide) $(call package_files-copy-root, /
- 1149 $(SYSTEMIMAGE_SOURCE_DIR),$(zip_root)/SYSTEM)
- 1150 @# Contents of the data image
- 1151 $(hide) $(call package_files-copy-root, /
- 1152 $(TARGET_OUT_DATA),$(zip_root)/DATA)
- 1153 @# Extra contents of the OTA package
- 1154 $(hide) mkdir -p $(zip_root)/OTA/bin
- 1155 $(hide) $(ACP) $(INSTALLED_ANDROID_INFO_TXT_TARGET)
- $(zip_root)/OTA/
- 1156 $(hide) $(ACP) $(PRIVATE_OTA_TOOLS) $(zip_root)/OTA/bin/
- 1157 @# Files that do not end up in any images, but are
- necessary to
- 1158 @# build them.
- 1159 $(hide) mkdir -p $(zip_root)/META
- 1160 $(hide) $(ACP) $(APKCERTS_FILE)
- $(zip_root)/META/apkcerts.txt
- 1161 $(hide) echo "$(PRODUCT_OTA_PUBLIC_KEYS)" >
- $(zip_root)/META/otakeys.txt
- 1162 $(hide) echo "$(PRIVATE_RECOVERY_API_VERSION)" >
- $(zip_root)/META/recovery-api-version.txt
- 1163 $(hide) echo "blocksize $(BOARD_FLASH_BLOCK_SIZE)" >
- $(zip_root)/META/imagesizes.txt
- 1164 $(hide) echo "boot $(call
- image-size-from-data-size,$(BOARD_BOOTIMAGE_PARTITION_SIZE))" >>
- $(zip_root)/META/imagesizes.txt
- 1165 $(hide) echo "recovery $(call
- image-size-from-data-size,$(BOARD_RECOVERYIMAGE_PARTITION_SIZE))"
- >> $(zip_root)/META/imagesizes.txt
- 1166 $(hide) echo "system $(call
- image-size-from-data-size,$(BOARD_SYSTEMIMAGE_PARTITION_SIZE))" >>
- $(zip_root)/META/imagesizes.txt
- 1167 $(hide) echo "secro $(call
- image-size-from-data-size,$(BOARD_SECROIMAGE_PARTITION_SIZE))" >>
- $(zip_root)/META/imagesizes.txt
- 1168 $(hide) echo "userdata $(call
- image-size-from-data-size,$(BOARD_USERDATAIMAGE_PARTITION_SIZE))"
- >> $(zip_root)/META/imagesizes.txt
- 1169 $(hide) echo "$(tool_extensions)" >
- $(zip_root)/META/tool-extensions.txt
- 1170 @# Zip everything up, preserving symlinks
- 1171 $(hide) (cd $(zip_root) && zip -qry ../$(notdir $@)
- .)
- 1172 @# Run fs_config on all the system files in the zip, and
- save the output
- 1173 $(hide) zipinfo -1 $@ | awk -F/ 'BEGIN { OFS="/" }
- /^SYSTEM/// {$$1 = "system"; print}' | $(HOST_OUT_EXECUTABLES)/fs_config
- > $(zip_root)/META/filesystem_config.txt
- 1174 $(hide) (cd $(zip_root) && zip -q ../$(notdir $@)
- META/filesystem_config.txt)
可见往里面添加了很多内容。
L1089-1090 , 造一个目录。
L1091-1108 ，填充 RECOVERY 子目录的内容。用于生成recovery.img 。包括：kernel 的image, recovery 根文件系统的 image, recovery 根文件系统的内容：
RECOVERY$ tree -L 2
├── kernel
├── ramdisk
└── RAMDISK
├── advanced_meta_init.rc
├── data
├── default.prop
├── dev
├── etc
├── init
├── init.factory.rc
├── init.goldfish.rc
├── init.mt6516.rc
├── init.rc
├── meta_init.rc
├── proc
├── res
├── sbin
├── sys
├── system
└── tmp
L1109-1125, 填充 FACTORY 子目录的内容， 没有用到，包括：kernel 的image
L1126-1143, 填充 BOOT 子目录的内容，用于生成boot.img 。和 RECOVERY 目录类似，包括：kernel 的image, 根文件系统的image, 根文件系统的内容：
BOOT$ tree -L 2
.
├── kernel
├── ramdisk
└── RAMDISK
├── advanced_meta_init.rc
├── data
├── default.prop
├── dev
├── init
├── init.factory.rc
├── init.goldfish.rc
├── init.mt6516.rc
├── init.rc
├── meta_init.rc
├── proc
├── res -> /system/res
├── sbin
├── sys
└── system
L1144-1146, 填充 RADIO 子目录的内容， 没有用到。
L1147-1149, 填充 SYSTEM 子目录的内容。 这是升级的主要内容。
L1150-1152, 填充 DATA 子目录的内容。缺省没有用到。
L1153-1156, 填充 OTA/bin 子目录的内容, 这是OTA 升级自己使用的程序。后面会遇到。
OTA/bin$ tree
.
├── applypatch
├── applypatch_static
├── check_prereq
└── updater
L1159-1169, 填充 META 子目录的内容, 这里包含了OTA 脚本需要的一些附加信息。
L1170-1171, 将所有内容打包。供下一阶段使用。
L1173-1174, 生成 META/filesystem_config.txt 并将其加入到 zip 包中。该文件保存了 system 目录下各目录、文件的权限及owner.
$ head META/filesystem_config.txt
system 0 0 755
system/usr 0 0 755
system/usr/srec 0 0 755
system/usr/srec/config 0 0 755
system/usr/srec/config/en.us 0 0 755
system/usr/srec/config/en.us/grammars 0 0 755
system/usr/srec/config/en.us/grammars/phone_type_choice.g2g 0 0 644
system/usr/srec/config/en.us/grammars/VoiceDialer.g2g 0 0 644
system/usr/srec/config/en.us/grammars/boolean.g2g 0 0 644
system/usr/srec/config/en.us/g2p 0 0 755
这里，目录由 zipinfo –l 提供， 而权限则由 fs_config 设定。此程序的源码位于：build/tools/fs_config, 其中fs_config包含了一个头文件：
这个文件(system/core/include/private/android_filesystem_config.h ) 以hardcoding 的方式设定了 system 下各目录、文件的权限、属主。比如：
如果需要升级其它内容，比如 bootloader, 则可以在这里加入。
步骤二
编译脚本如下 :
(From: build/core/Makefile)
- 1186 name := $(TARGET_PRODUCT)
- 1187 ifeq ($(TARGET_BUILD_TYPE),debug)
- 1188 name := $(name)_debug
- 1189 endif
- 1190 name := $(name)-ota-$(FILE_NAME_TAG)
- 1191
- 1192 INTERNAL_OTA_PACKAGE_TARGET := $(PRODUCT_OUT)/$(name).zip
- 1193
- 1194 $(INTERNAL_OTA_PACKAGE_TARGET): KEY_CERT_PAIR := $(DEFAULT_KEY_CERT_PAIR)
- 1195
- 1196 ifeq ($(TARGET_OTA_SCRIPT_MODE),)
- 1197 # default to "auto"
- 1198 $(INTERNAL_OTA_PACKAGE_TARGET): scriptmode := auto
- 1199 else
- 1200 $(INTERNAL_OTA_PACKAGE_TARGET): scriptmode := $(TARGET_OTA_SCRIPT_MODE)
- 1201 endif
- 1202
- 1203 $(INTERNAL_OTA_PACKAGE_TARGET): $(BUILT_TARGET_FILES_PACKAGE) $(OTATOOLS)
- 1204 @echo "Package OTA: $@"
- 1205 $(hide) ./build/tools/releasetools/ota_from_target_files /
- 1206 -m $(scriptmode) /
- 1207 -p $(HOST_OUT) /
- 1208 -k $(KEY_CERT_PAIR) /
- 1209 $(BUILT_TARGET_FILES_PACKAGE) $@
- 1186 name := $(TARGET_PRODUCT)
- 1187 ifeq ($(TARGET_BUILD_TYPE),debug)
- 1188 name := $(name)_debug
- 1189 endif
- 1190 name := $(name)-ota-$(FILE_NAME_TAG)
- 1191
- 1192 INTERNAL_OTA_PACKAGE_TARGET := $(PRODUCT_OUT)/$(name).zip
- 1193
- 1194 $(INTERNAL_OTA_PACKAGE_TARGET): KEY_CERT_PAIR := $(DEFAULT_KEY_CERT_PAIR)
- 1195
- 1196 ifeq ($(TARGET_OTA_SCRIPT_MODE),)
- 1197 # default to "auto"
- 1198 $(INTERNAL_OTA_PACKAGE_TARGET): scriptmode := auto
- 1199 else
- 1200 $(INTERNAL_OTA_PACKAGE_TARGET): scriptmode := $(TARGET_OTA_SCRIPT_MODE)
- 1201 endif
- 1202
- 1203 $(INTERNAL_OTA_PACKAGE_TARGET): $(BUILT_TARGET_FILES_PACKAGE) $(OTATOOLS)
- 1204 @echo "Package OTA: $@"
- 1205 $(hide) ./build/tools/releasetools/ota_from_target_files /
- 1206 -m $(scriptmode) /
- 1207 -p $(HOST_OUT) /
- 1208 -k $(KEY_CERT_PAIR) /
- 1209 $(BUILT_TARGET_FILES_PACKAGE) $@
核心是一个python 脚本: ota_from_target_files, 它以前一步骤生成的ZIP 包作为输入，生成可用于OTA 升级的zip 包。 具体内容我们后文继续分析。
