Android.bp

Android.bp相关知识

1.简介

早期的Android系统都是采⽤Android.mk的配置来编译源码，从Android 7.0开始引⼊Android.bp。很明显Android.bp的出现就是为了替换掉Android.mk。
再来说⼀说跟着Android版本相应的发展演变过程:

Android 7.0引⼊ninja和kati
Android 8.0使⽤Android.bp来替换Android.mk，引⼊Soong
Android 9.0强制使⽤Android.bp

转换关系图如下：

通过Kati将Android.mk转换成ninja格式的⽂件，通过Blueprint+ Soong将Android.bp转换成ninja格式的⽂件，通过androidmk将Android.mk转换成Android.bp，但针对没有分⽀、循环等流程控制的Android.mk才有效。这⾥涉及到Ninja, kati, Soong, bp概念，接下来分别简单介绍⼀下。

1-1.Ninja

ninja是⼀个编译框架，会根据相应的ninja格式的配置⽂件进⾏编译，但是ninja⽂件⼀般不会⼿动修改，⽽是通过将Android.bp⽂件转换成ninja格⽂件来编译。

1-2.Android.bp

Android.bp的出现就是为了替换Android.mk⽂件。bp跟mk⽂件不同，它是纯粹的配置，没有分⽀、循环等流程控制，不能做算数逻辑运算。如果需要控制逻辑，那么只能通过Go语⾔编写。

1-3.Soong

Soong类似于之前的Makefile编译系统的核⼼，负责提供Android.bp语义解析，并将之转换成Ninja⽂件。Soong还会编译⽣成⼀个androidmk命令，⽤于将Android.mk⽂件转换为Android.bp⽂件，不过这个转换功能仅限于没有分⽀、循环等流程控制的Android.mk才有效。

1-4.Blueprint

Blueprint是⽣成、解析Android.bp的⼯具，是Soong的⼀部分。Soong负责Android编译⽽设计的⼯具，⽽Blueprint只是解析⽂件格式，Soong解析内容的具体含义。Blueprint和Soong都是由Golang写的项⽬，从Android 7.0，prebuilts/go/⽬录下新增Golang所需的运⾏环境，在编译时使⽤。

1-5. Kati

kati是专为Android开发的⼀个基于Golang和C++的⼯具，主要功能是把Android中的Android.mk⽂件转换成Ninja⽂件。代码路径是build/kati/，编译后的产物是ckati。

2.Android.bp语法

Android.bp是⼀种纯粹的配置⽂件，设计简单，没有条件判断或控制流语句，采⽤在Go语⾔编写控制逻辑。Android.bp⽂件记录着模块信息，每⼀个模块以模块类型开始，后⾯跟着⼀组模块的属性，以名值对(name:value)表示，每个模块都必须有⼀个 name属性。

cc_library_shared {
name: "libbluetooth_jni",
srcs: [
    //编译成动态库，类似于Android.mk中的BUILD_SHARED_LIBRARY
    //编译出的模块的名称，类似于Android.mk中的LOCAL_MODULE
    //源⽂件，类似于Android.mk中的LOCAL_SRC_FILES
    "com_android_bluetooth_btservice_AdapterService.cpp",
    "com_android_bluetooth_hfp.cpp",
    "com_android_bluetooth_hfpclient.cpp",
    "com_android_bluetooth_a2dp.cpp",
    "com_android_bluetooth_a2dp_sink.cpp",
    "com_android_bluetooth_avrcp.cpp",
    "com_android_bluetooth_avrcp_controller.cpp",
    "com_android_bluetooth_hid.cpp",
    "com_android_bluetooth_hidd.cpp",
    "com_android_bluetooth_hdp.cpp",
    "com_android_bluetooth_pan.cpp",
    "com_android_bluetooth_gatt.cpp",
    "com_android_bluetooth_sdp.cpp",
    ],
include_dirs: [
    //⽤户指定的头⽂件查找路径，类似于Android.mk中的LOCAL_C_INCLUDES
    "libnativehelper/include/nativehelper",
    "system/bt/types",
    ],
shared_libs: [
    LOCAL_SHARED_LIBRARIES
    "libandroid_runtime",
    "libchrome",
    "libnativehelper",
    "libcutils",
    "libutils",
    "liblog",
    "libhardware",
    ],
//编译所依赖的动态库，类似于Android.mk中的static_libs: [
//编译所依赖的静态库，类似于Android.mk中的
LOCAL_STATIC_LIBRARIES
    "libbluetooth-types",
    ],
cflags: [
    ///编译flag,类似于Android.mk中的LOCAL_CFLAGS
    "-Wall",
    "-Wextra",
    "-Wno-unused-parameter",
    ],
}

2-1.模块

从前⾯的列⼦可以看出定义⼀个模块从模块的类型开始，模块有不同的类型，如前⾯例⼦中的cc_library_shared，当然类型还有很多种，譬如cc_binary android_app cc_library_static等等。模块包含⼀些属性格式为“property-name:property-value”，其中name属性必须指定，其属性值必须是全局唯⼀的。其中默认模块可⽤于在多个模块中重复相同的属性

cc_defaults {//
    //默认模块名称
    name: "default_module",
    shared_libs: ["libz"],
    stl: "none",
}
cc_binary {
    name: "test1",
    defaults: ["default_module"],
    //引⽤默认模块名称
    srcs: ["src/test/test.c"],
}

srcs 属性以字符串列表的形式指定⽤于编译模块的源⽂件。您可以使⽤模块引⽤语法 “:” 来引⽤⽣成源⽂件的其他
模块的输出，如 genrule 或 filegroup：

~/ssd/qcom_64/msm8953-9$ cd frameworks/base/core/java/
~/ssd/qcom_64/msm8953-9/frameworks/base/core/java$ vi Android.bp
filegroup {
    name: "IKeyAttestationApplicationIdProvider.aidl",
    srcs: ["android/security/keymaster/IKeyAttestationApplicationIdProvider.aidl"],
}
filegroup {
    name: "IDropBoxManagerService.aidl",
    srcs: ["com/android/internal/os/IDropBoxManagerService.aidl"],
    ~/ssd/qcom_64/msm8953-9/frameworks/base/core$ cd ..
    ~/ssd/qcom_64/msm8953-9/frameworks/base$ vi libs/services/Android.bp
    cc_library_shared {name: "libservices",
srcs: [
    ":IDropBoxManagerService.aidl",
    "src/os/DropBoxManager.cpp",
    "src/os/StatsDimensionsValue.cpp",
    "src/os/StatsLogEventWrapper.cpp",
],
shared_libs: [
    "libbinder",
    "liblog",
    "libcutils",
    "libutils",
],

2-2.类型

具体⽀持以下⼏种类型：

Bool(true or false)
Integers(int)
Strings("string")
Listsof strings (["string1", "string2"])
Maps({key1: "value1", key2: ["value2"]})

2-3.注释

我们知道Android.mk中可以进⾏注释，当然Android.bp⾥⾯也可以，Android.mk中使⽤"#"然后添加注释，Android.bp使⽤单⾏注释//和多⾏注释/* */两种⽅式。

2-4.变量

变量范围限定为声明它们的⽂件的其余部分，可以使⽤ “=” 号赋值，但是不能使⽤ “：=” 赋值。变量是不可变的，但有⼀个例外，它们可以附上+= 赋值，但仅在变量被引⽤之前。下⾯我们看⼀下正确使⽤变量的列⼦：

gzip_srcs = ["src/minigzip.c"],
    cc_binary {
    name: "gzip",
    srcs: gzip_srcs,
    shared_libs: ["libz"],
    stl: "none",
}

2-5.操作符

String类型、字符串列表类型和Map类型⽀持操作符“+”。

2-6.⽀持模块类型

Android.bp可以⽀持android_app、cc_binary、cc_binary_host等多种类型，具体定义在Android源码的
android-11/build/soong/androidmk/androidmk/android.go 可以查看，具体如下：

var moduleTypes = map[string]string{
    "BUILD_SHARED_LIBRARY": "cc_library_shared",
    "BUILD_STATIC_LIBRARY": "cc_library_static",
    "BUILD_HOST_SHARED_LIBRARY": "cc_library_host_shared",
    "BUILD_HOST_STATIC_LIBRARY": "cc_library_host_static",
    "BUILD_HEADER_LIBRARY": "cc_library_headers",
    "BUILD_EXECUTABLE": "cc_binary",
    "BUILD_HOST_EXECUTABLE": "cc_binary_host",
    "BUILD_NATIVE_TEST": "cc_test",
    "BUILD_HOST_NATIVE_TEST": "cc_test_host",
    "BUILD_NATIVE_BENCHMARK": "cc_benchmark",
    "BUILD_HOST_NATIVE_BENCHMARK": "cc_benchmark_host",
    "BUILD_JAVA_LIBRARY":
    "java_library_installable", // will be rewritten
    to java_library by bpfix
    "BUILD_STATIC_JAVA_LIBRARY": "java_library",
    "BUILD_HOST_JAVA_LIBRARY": "java_library_host",
    "BUILD_HOST_DALVIK_JAVA_LIBRARY": "java_library_host_dalvik",
    "BUILD_PACKAGE":
    "BUILD_CTS_EXECUTABLE":
    "android_app",
    "cc_binary",
    // will be further
    massaged by bpfix depending on the output path
    "BUILD_CTS_SUPPORT_PACKAGE":
    "cts_support_package", // will be rewritten to
    "cts_package", // will be rewritten to
    android_test by bpfix
    "BUILD_CTS_PACKAGE":
    android_test by bpfix
    "BUILD_CTS_TARGET_JAVA_LIBRARY": "cts_target_java_library", // will be rewritten to
    java_library by bpfix
    "BUILD_CTS_HOST_JAVA_LIBRARY":
    "cts_host_java_library",
    java_library_host by bpfix
}

2-7.⽀持预编译类型

Android.bp可以⽀持多种预编译类型，具体定义在Android源码的 android-11/build/soong/androidmk/androidmk/android.go

可以查看，如下图所示：

var prebuiltTypes = map[string]string{
    "SHARED_LIBRARIES": "cc_prebuilt_library_shared",
    "STATIC_LIBRARIES": "cc_prebuilt_library_static",
    "EXECUTABLES": "cc_prebuilt_binary",
    "JAVA_LIBRARIES": "java_import",
    "APPS": "android_app_import",
    "ETC": "prebuilt_etc",
}

2-8.条件式编译

system/core/libusbhost$ cat Android.bp
cc_library {
    name: "libusbhost",
    vendor_available: true,
    vndk: {
    enabled: true,
},
host_supported: true,
srcs: ["usbhost.c"],
cflags: ["-Werror"],
export_include_dirs: ["include"],
target: {
android: {
//编译Android上运⾏的程序
cflags: [
    "-g",
    "-DUSE_LIBLOG",
],
shared_libs: ["liblog"],
},
darwin: {
    //编译darwin上运⾏的程序
    enabled: false,
        },
    },
}