Android Hidl开发

1、环境准备

首先准备一份Android源码。

#源码中编译生成hidl-gen

make hidl-gen

下面是hidl-gen的语法：

usage: hidl-gen [-p <root path>] -o <output path> -L <language> [-O <owner>] (-r <interface root>)+ [-R] [-v] [-d <depfile>] FQNAME...

Process FQNAME, PACKAGE(.SUBPACKAGE)*@[0-9]+.[0-9]+(::TYPE)?, to create output.

-h: Prints this menu.
-L <language>: The following options are available:
check : Parses the interface to see if valid but doesn't write any files.
c++ : (internal) (deprecated) Generates C++ interface files for talking to HIDL interfaces.
c++-headers : (internal) Generates C++ headers for interface files for talking to HIDL interfaces.
c++-sources : (internal) Generates C++ sources for interface files for talking to HIDL interfaces.
export-header : Generates a header file from @export enumerations to help maintain legacy code.
c++-impl : Generates boilerplate implementation of a hidl interface in C++ (for convenience).
c++-impl-headers: c++-impl but headers only.
c++-impl-sources: c++-impl but sources only.
c++-adapter : Takes a x.(y+n) interface and mocks an x.y interface.
c++-adapter-headers: c++-adapter but helper headers only.
c++-adapter-sources: c++-adapter but helper sources only.
c++-adapter-main: c++-adapter but the adapter binary source only.
java : (internal) Generates Java library for talking to HIDL interfaces in Java.
java-constants : (internal) Like export-header but for Java (always created by -Lmakefile if @export exists).
vts : (internal) Generates vts proto files for use in vtsd.
makefile : (removed) Used to generate makefiles for -Ljava and -Ljava-constants.
androidbp : (internal) Generates Soong bp files for -Lc++-headers, -Lc++-sources, -Ljava, -Ljava-constants, and -Lc++-adapter.
androidbp-impl : Generates boilerplate bp files for implementation created with -Lc++-impl.
hash : Prints hashes of interface in `current.txt` format to standard out.
function-count : Prints the total number of functions added by the package or interface.
dependencies : Prints all depended types.
-O <owner>: The owner of the module for -Landroidbp(-impl)?.
-o <output path>: Location to output files.
-p <root path>: Android build root, defaults to $ANDROID_BUILD_TOP or pwd.
-R: Do not add default package roots if not specified in -r.
-r <package:path root>: E.g., android.hardware:hardware/interfaces.
-v: verbose output.
-d <depfile>: location of depfile to write to.

2、创建hidl

在vendor/qcom/proprietary/interfaces下创建howie目录，在howie下创建1.0目录，在1.0目录下创建接口IHowie.hal，包名设置为自定义vendor.oem.hardware.howie的创建目录default。

package vendor.qcom.hardware.howie@1.0;interface IHowie{helloWorld(string name) generates (string result);
};

这时候，目录结构为：

howie/

└── 1.0

├── default

└── IHowie.hal

在1.0下写一个hidl-gen.sh脚本

# -o <output path>: Location to output files.
# -r <package:path root>: E.g., android.hardware:hardware/interfaces.
# -L <language>
#   androidbp : (internal) Generates Soong bp files for -Lc++-headers, -Lc++-sources, -Ljava, -Ljava-constants, and -Lc++-adapter.
#   androidbp-impl : Generates boilerplate bp files for implementation created with -Lc++-impl.
#   c++-impl : Generates boilerplate implementation of a hidl interface in C++ (for convenience).PACKAGE=vendor.qcom.hardware.howie@1.0
LOC=default
# 生成Android.bp
hidl-gen -L androidbp -r vendor.qcom.hardware:vendor/qcom/proprietary/interfaces -r android.hidl:system/libhidl/transport $PACKAGE
# 生成Android.bp
hidl-gen -o $LOC -L androidbp-impl -r vendor.qcom.hardware:vendor/qcom/proprietary/interfaces -r android.hidl:system/libhidl/transport $PACKAGE
# 生成C++文件
hidl-gen -o $LOC -L c++-impl -r vendor.qcom.hardware:vendor/qcom/proprietary/interfaces -r android.hidl:system/libhidl/transport $PACKAGE

运行后，目录结构为：

.
└── 1.0
├── Android.bp
├── default
│   ├── Android.bp
│   ├── Howie.cpp
│   └── Howie.h
├── hidl-gen.sh
└── IHowie.hal

2 directories, 6 files

1.0目录下的Android.bp

// This file is autogenerated by hidl-gen -Landroidbp.hidl_interface {name: "vendor.qcom.hardware.howie@1.0",root: "vendor.qcom.hardware",system_ext_specific: true,srcs: ["IHowie.hal",],interfaces: ["android.hidl.base@1.0",],gen_java: true,
}

我们稍作修改

// This file is autogenerated by hidl-gen -Landroidbp.hidl_interface {name: "vendor.qcom.hardware.howie@1.0",root: "vendor.qcom.hardware.howie",required: ["manifest_vendor.qcom.hardware.howie.xml"],//vendor: true,srcs: ["IHowie.hal",],interfaces: ["android.hidl.base@1.0",],gen_java: true,
}

1.0/default目录下的Android.bp

// FIXME: your file license if you have onecc_library_shared {// FIXME: this should only be -impl for a passthrough hal.// In most cases, to convert this to a binderized implementation, you should:// - change '-impl' to '-service' here and make it a cc_binary instead of a//   cc_library_shared.// - add a *.rc file for this module.// - delete HIDL_FETCH_I* functions.// - call configureRpcThreadpool and registerAsService on the instance.// You may also want to append '-impl/-service' with a specific identifier like// '-vendor' or '-<hardware identifier>' etc to distinguish it.name: "vendor.qcom.hardware.howie@1.0-impl",relative_install_path: "hw",// FIXME: this should be 'vendor: true' for modules that will eventually be// on AOSP.proprietary: true,srcs: ["Howie.cpp",],shared_libs: ["libhidlbase","libutils","vendor.qcom.hardware.howie@1.0",],
}

稍作修改

cc_library_shared {// FIXME: this should only be -impl for a passthrough hal.// In most cases, to convert this to a binderized implementation, you should:// - change '-impl' to '-service' here and make it a cc_binary instead of a//   cc_library_shared.// - add a *.rc file for this module.// - delete HIDL_FETCH_I* functions.// - call configureRpcThreadpool and registerAsService on the instance.// You may also want to append '-impl/-service' with a specific identifier like// '-vendor' or '-<hardware identifier>' etc to distinguish it.name: "vendor.qcom.hardware.howie@1.0-impl",//relative_install_path: "hw",// FIXME: this should be 'vendor: true' for modules that will eventually be// on AOSP.vendor: true,srcs: ["Howie.cpp",],shared_libs: ["libhidlbase","libutils","vendor.qcom.hardware.howie@1.0",],
}

Howie.h

// FIXME: your file license if you have one#pragma once#include <vendor/qcom/hardware/howie/1.0/IHowie.h>
#include <hidl/MQDescriptor.h>
#include <hidl/Status.h>namespace vendor::qcom::hardware::howie::implementation {using ::android::hardware::hidl_array;
using ::android::hardware::hidl_memory;
using ::android::hardware::hidl_string;
using ::android::hardware::hidl_vec;
using ::android::hardware::Return;
using ::android::hardware::Void;
using ::android::sp;struct Howie : public V1_0::IHowie {// Methods from ::vendor::qcom::hardware::howie::V1_0::IHowie follow.Return<void> helloWorld(const hidl_string& name, helloWorld_cb _hidl_cb) override;// Methods from ::android::hidl::base::V1_0::IBase follow.};// FIXME: most likely delete, this is only for passthrough implementations
// extern "C" IHowie* HIDL_FETCH_IHowie(const char* name);}  // namespace vendor::qcom::hardware::howie::implementation

Howie.cpp

// FIXME: your file license if you have one#include "Howie.h"namespace vendor::qcom::hardware::howie::implementation {// Methods from ::vendor::qcom::hardware::howie::V1_0::IHowie follow.
Return<void> Howie::helloWorld(const hidl_string& name, helloWorld_cb _hidl_cb) {// TODO implementreturn Void();
}// Methods from ::android::hidl::base::V1_0::IBase follow.//IHowie* HIDL_FETCH_IHowie(const char* /* name */) {//return new Howie();
//}
//
}  // namespace vendor::qcom::hardware::howie::implementation

如上面的注释所说，如果将下面的几行注释去掉，hidl将采用直通式通信方式。

// extern "C" IHowie* HIDL_FETCH_IHowie(const char* name);

//IHowie* HIDL_FETCH_IHowie(const char* /* name */) {
//return new Howie();
//}

下面，润色一下Howie.cpp

// FIXME: your file license if you have one#include "Howie.h"namespace vendor::qcom::hardware::howie::implementation {// Methods from ::vendor::qcom::hardware::howie::V1_0::IHowie follow.
Return<void> Howie::helloWorld(const hidl_string& name, helloWorld_cb _hidl_cb) {char buf[128];::memset(buf, 0, 128);::snprintf(buf, 128, "Hello World, %s", name.c_str());hidl_string result(buf);_hidl_cb(result);return Void();
}// Methods from ::android::hidl::base::V1_0::IBase follow.//IHowie* HIDL_FETCH_IHowie(const char* /* name */) {//return new Howie();
//}
//
}  // namespace vendor::qcom::hardware::howie::implementation

我希望hidl接口和实现都编译到vendor分区，因此需要做出一点改动：

vendor.qcom.hardware.howie@1.0的root修改为"vendor.qcom.hardware.howie"；

将1.0/Android.bp的"system_ext_specific: true,"改成"vendor: true,"；

将1.0/default/Android.bp的"proprietary: true,"改成"vendor: true,"，后面碰到编译问题，这一行可以注释掉；

vendor.qcom.hardware.howie@1.0-impl移除relative_install_path: "hw"，因为会碰到找不到该动态库的问题；

除此以外，在howie目录下新增Android.bp

subdirs = ["1.0",
]hidl_package_root {name: "vendor.qcom.hardware.howie",path: "vendor/qcom/proprietary/interface/howie",
}

3、构建service

为了能调用到先前创建的hidl接口，我们在default下面再创建一个service.cpp，通过直通式注册服务。

#define LOG_TAG "vendor.qcom..hardware.howie@1.0-service"#include <vendor/qcom/hardware/howie/1.0/IHowie.h>
#include <hidl/LegacySupport.h>using vendor::qcom::hardware::howie::V1_0::IHowie;
using android::hardware::defaultPassthroughServiceImplementation;int main() {return defaultPassthroughServiceImplementation<IHowie>(10);//10表示与/dev/hwbinder通信的最大的线程数
}

绑定式写法：

#define LOG_TAG "vendor.qcom..hardware.howie@1.0-service"#include <utils/Log.h>
#include "android/log.h"
#include <hidl/HidlSupport.h>
#include <hidl/HidlTransportSupport.h>
#include <utils/String16.h>
#include <vendor/qcom/hardware/howie/1.0/IHowie.h>
#include <hidl/LegacySupport.h>
#include "Howie.h"using vendor::qcom::hardware::howie::V1_0::IHowie;
using vendor::qcom::hardware::howie::implementation::Howie;
using android::hardware::configureRpcThreadpool;
using android::hardware::joinRpcThreadpool;
using android::sp;
using android::status_t;
using android::OK;int main() {configureRpcThreadpool(10, true);sp<IHowie> howie = new Howie();status_t status = howie->registerAsService();LOG_ALWAYS_FATAL_IF(status != OK, "Could not register IHowie");// other interface registration comes herejoinRpcThreadpool();return 0;
}

同时在default目录下创建rc文件——vendor.qcom.hardware.howie@1.0-service.rc，用于启动vendor.qcom..hardware.howie@1.0-service。

service howie_service /vendor/bin/hw/vendor.qcom.hardware.howie@1.0-serviceclass haluser systemgroup system

由于新增了两个文件，想要将这两个文件也编进系统，需要再次编辑1.0/default下的Android.bp，如下为新增的：

//新增如下
cc_binary {name: "vendor.qcom.hardware.howie@1.0-service",defaults: ["hidl_defaults"],vendor: true,relative_install_path: "hw",srcs: ["service.cpp"],init_rc: ["vendor.qcom.hardware.howie@1.0-service.rc"],shared_libs: ["libhidlbase","libhidltransport","libutils","liblog","vendor.qcom.hardware.howie@1.0","vendor.qcom.hardware.howie@1.0-impl",],
}

4、设备清单和框架清单

为了能为server被client访问到，在howie目录下新增目录vintf，在vintf目录下新增设备清单manifest_vendor.qcom.hardware.howie.xml和框架清单vendor_framework_compatibility_matrix.xml。

<manifest version="1.0" type="device"><!-- Howie service--><hal format="hidl"><name>vendor.qcom.hardware.howie</name><transport>hwbinder</transport><version>1.0</version><interface><name>IHowie</name><instance>default</instance></interface></hal>
</manifest>

<compatibility-matrix version="1.0" type="framework"><hal format="hidl" optional="true"><name>vendor.qcom.hardware.howie</name><impl level="generic"></impl><version>1.0</version><interface><name>IHowie</name><instance>default</instance></interface></hal>
</compatibility-matrix>

将两个清单文件加入编译，新增vendor_framework_compatibility_matrix.mk

DEVICE_FRAMEWORK_COMPATIBILITY_MATRIX_FILE += \vendor/qcom/proprietary/interface/howie/vintf/vendor_framework_compatibility_matrix.xml

新增Android.bp

prebuilt_etc_xml {name: "manifest_vendor.qcom.hardware.howie.xml",src: "manifest_vendor.qcom.hardware.howie.xml",vendor: true,installable: true,sub_dir: "vintf/manifest",
}

同时，为了vintf下新增的vendor_framework_compatibility_matrix.mk被编译到，在howie目录下新增Android.mk

LOCAL_PATH := $(call my-dir)include $(call all-makefiles-under,$(LOCAL_PATH))

将vintf也加入到howie下的Android.bp

subdirs = ["1.0","vintf",
]

5、新增测试client

在1.0目录下新增test目录，在test下面新增如下文件：

HowieTest.cpp

#include <vendor/qcom/hardware/howie/1.0/IHowie.h>
#include <hidl/Status.h>
#include <hidl/LegacySupport.h>
#include <utils/misc.h>
#include <hidl/HidlSupport.h>
#include <stdio.h>using ::android::hardware::hidl_string;
using ::android::sp;
using vendor::qcom::hardware::howie::V1_0::IHowie;int main(){android::sp<IHowie> service = IHowie::getService();if (service == nullptr){printf("Failed to get service\n");return -1;}service->helloWorld("Howie", [&](hidl_string result){printf("%s\n", result.c_str());});return 0;
}

Android.bp

cc_binary {name: "howie_client",defaults: ["hidl_defaults"],vendor: true,relative_install_path: "hw",srcs: ["HowieTest.cpp"],shared_libs: ["liblog","libhardware","libhidlbase","libhidltransport","libutils","vendor.qcom.hardware.howie@1.0",],}

重新修改目录howie下的Android.bp，将test加入其中。

subdirs = ["1.0","vintf","test",
]

6、编译

mmm vendor/qcom/proprietary/interfaces/howie

按照之前的编译规则，我们可以在以下的路径中找到编译产物，out/target/product/${PRODUCT}/下，找到这些产物后，push到手机对应目录下即可：

/vendor/lib64/vendor.qcom.hardware.howie@1.0.so

/vendor/lib64/vendor.qcom.hardware.howie@1.0-impl.so

/vendor/bin/hw/vendor.qcom.hardware.howie@1.0-service

/vendor/etc/init/vendor.qcom.hardware.howie@1.0-service.rc

/vendor/etc/vintf/manifest/manifest_vendor.qcom.hardware.howie.xml

产物vendor_framework_compatibility_matrix.xml没找到，需要将手机中的/vendor/etc/vintf/compatibility_matrix.xml手动pull出来，然后添加以下内容，并push手机中原文件位置处。

    <hal format="hidl" optional="true"><name>vendor.qcom.hardware.howie</name><impl level="generic"></impl><version>1.0</version><interface><name>IHowie</name><instance>default</instance></interface></hal>

7、运行测试

上述文件全部push后重启手机。重启后，在终端模拟器中做如下操作：

#获取root权限

adb root

#运行service

adb shell

cd vendor/bin/hw

./vendor.qcom.hardware.howie@1.0-service

另起一个终端模拟器

adb shell

cd vendor/bin/hw

./howie_client

这时候，终端模拟器会打印信息：

Hello World, Howie

8、添加HIDL接口的hash值

上述添加hidl接口后，会报VTS问题，这时候需要添加hidl接口的hash值

通过修改hidl-gen.sh，注意，这里需要将之前的生成C++文件和bp文件的语句注释掉，否则前面写的内容就全部没了。

# -o <output path>: Location to output files.
# -r <package:path root>: E.g., android.hardware:hardware/interfaces.
# -L <language>
#   androidbp : (internal) Generates Soong bp files for -Lc++-headers, -Lc++-sources, -Ljava, -Ljava-constants, and -Lc++-adapter.
#   androidbp-impl : Generates boilerplate bp files for implementation created with -Lc++-impl.
#   c++-impl : Generates boilerplate implementation of a hidl interface in C++ (for convenience).PACKAGE=vendor.qcom.hardware.howie@1.0
# 生成Android.bp
#hidl-gen -Landroidbp -rvendor.qcom.hardware.howie:vendor/qcom/proprietary/interfaces/howie -randroid.hidl:system/libhidl/transport $PACKAGE
#LOC=default
# 生成C++文件
#hidl-gen -o $LOC -Lc++-impl -rvendor.qcom.hardware:vendor/qcom/proprietary/interfaces -randroid.hidl:system/libhidl/transport $PACKAGE
# 生成Android.bp
#hidl-gen -o $LOC -Landroidbp-impl -rvendor.qcom.hardware:vendor/qcom/proprietary/interfaces -randroid.hidl:system/libhidl/transport $PACKAGE
CURRENT_PATH="$(dirname $(readlink -f "$0"))"
CURRENT_FILE="${CURRENT_PATH}/../current.txt"
if [ ! -f ${CURRENT_FILE} ]
thentouch ${CURRENT_FILE}
fi
hidl-gen -Lhash -rvendor.qcom.hardware.howie:vendor/qcom/proprietary/interfaces/howie $PACKAGE >> ${CURRENT_FILE}

然后运行脚本，就会在vendor/qcom/proprietary/interfaces/howie下看到current.txt文件了

9c2be150b345854b44ea713cbd64ea64e45932f78ff30770e736286100df5777 vendor.qcom.hardware.howie@1.0::IHowie

9、资源链接

androidhidlhowie.zip-Android文档类资源-CSDN下载

参考文章：

[1] HIDL最全编译流程_Gunder的博客-CSDN博客_hidl编译

[2] https://www.jianshu.com/p/fd73ab98e423

[3] https://www.jianshu.com/p/ca6823b897b5

[4] Android P HIDL服务绑定模式与直通模式的分析 (原创) - five.li - 博客园

[5] 添加HIDL接口hash值（解VTS问题）_JoggingPig的博客-CSDN博客