Android ADB 源码分析总结

Android之ADB总结

---

本文内容如下：

1. makefile分析及总结

2. adb框架介绍 

3. adbd源码分析

       3.1 adbd初始化流程分析

        3.2 adb shell流程分析

        3.3 adb root流程分析

4. adb常用命令

---

一、makefile分析及总结

   
   

     
     
     
     

      
      

       
       // 以下内容摘录自android/
       
       system/core/adb/Android.mk
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       # Copyright 2005 The Android Open Source Project
      
      
     
     

     
     
     
     

      
      

       
       #
      
      
     
     

     
     
     
     

      
      

       
       # Android.mk for adb
      
      
     
     

     
     
     
     

      
      

       
       #
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LOCAL_PATH:= $(call 
       
       my-dir)
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       // 使用HOST_OS这个宏兼容不同的PC操作系统，比如windows，linux，mac等。
      
      
     
     

     
     
     
     

      
      

       
       ife
       
       q ($(HOST_OS),windows)
      
      
     
     

     
     
     
     

      
      

       
       adb_host_clang := false 
       
       # libc++ for mingw not ready yet.
      
      
     
     

     
     
     
     

      
      

       
       else
      
      
     
     

     
     
     
     

      
      

       
       adb_host_clang := true
      
      
     
     

     
     
     
     

      
      

       
       endif
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       adb_version := $(shell git -C $(LOCAL_PATH) rev-parse --short=
       
       12 HEAD 
       
       2>
       
       /dev/null)-android
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       ADB_COMMON_CFLAGS := \
      
      
     
     

     
     
     
     

      
      

       
       -Wall -Werror \
      
      
     
     

     
     
     
     

      
      

       
       -Wno-unused-parameter \
      
      
     
     

     
     
     
     

      
      

       
       -DADB_REVISION=
       
       '"$(adb_version)"' \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       # libadb
      
      
     
     

     
     
     
     

      
      

       
       # =========================================================
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       # Much of adb is duplicated in bootable/recovery/minadb and fastboot. Changes
      
      
     
     

     
     
     
     

      
      

       
       # made to adb rarely get ported to the other two, so the trees have diverged a
      
      
     
     

     
     
     
     

      
      

       
       # bit. We'd like to stop this because it is a maintenance nightmare, but the
      
      
     
     

     
     
     
     

      
      

       
       # divergence makes this difficult to do all at once. For now, we will start
      
      
     
     

     
     
     
     

      
      

       
       # small by moving common files into a static library. Hopefully some day we can
      
      
     
     

     
     
     
     

      
      

       
       # get enough of adb in here that we no longer need minadb. https://b/17626262
      
      
     
     

     
     
     
     

      
      

       
       LIBADB_SRC_FILES := \
      
      
     
     

     
     
     
     

      
      

       
       adb.cpp \
      
      
     
     

     
     
     
     

      
      

       
       adb_auth.cpp \
      
      
     
     

     
     
     
     

      
      

       
       adb_io.cpp \
      
      
     
     

     
     
     
     

      
      

       
       adb_listeners.cpp \
      
      
     
     

     
     
     
     

      
      

       
       adb_utils.cpp \
      
      
     
     

     
     
     
     

      
      

       
       sockets.cpp \
      
      
     
     

     
     
     
     

      
      

       
       transport.cpp \
      
      
     
     

     
     
     
     

      
      

       
       transport_local.cpp \
      
      
     
     

     
     
     
     

      
      

       
       transport_usb.cpp \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LIBADB_TEST_SRCS := \
      
      
     
     

     
     
     
     

      
      

       
       adb_io_test.cpp \
      
      
     
     

     
     
     
     

      
      

       
       adb_utils_test.cpp \
      
      
     
     

     
     
     
     

      
      

       
       transport_test.cpp \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LIBADB_CFLAGS := \
      
      
     
     

     
     
     
     

      
      

       
       $(ADB_COMMON_CFLAGS) \
      
      
     
     

     
     
     
     

      
      

       
       -Wno-missing-field-initializers \
      
      
     
     

     
     
     
     

      
      

       
       -fvisibility=hidden \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LIBADB_darwin_SRC_FILES := \
      
      
     
     

     
     
     
     

      
      

       
       fdevent.cpp \
      
      
     
     

     
     
     
     

      
      

       
       get_my_path_darwin.cpp \
      
      
     
     

     
     
     
     

      
      

       
       usb_osx.cpp \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LIBADB_linux_SRC_FILES := \
      
      
     
     

     
     
     
     

      
      

       
       fdevent.cpp \
      
      
     
     

     
     
     
     

      
      

       
       get_my_path_linux.cpp \
      
      
     
     

     
     
     
     

      
      

       
       usb_linux.cpp \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LIBADB_windows_SRC_FILES := \
      
      
     
     

     
     
     
     

      
      

       
       get_my_path_windows.cpp \
      
      
     
     

     
     
     
     

      
      

       
       sysdeps_win32.cpp \
      
      
     
     

     
     
     
     

      
      

       
       usb_windows.cpp \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       include $(CLEAR_VARS)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CLANG := true
      
      
     
     

     
     
     
     

      
      

       
       // 编译生成libadbd静态库，供adbd deamon进程使用
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_MODULE := libadbd
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CFLAGS := $(LIBADB_CFLAGS) -DADB_HOST=
       
       0
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_SRC_FILES := \
      
      
     
     

     
     
     
     

      
      

       
       $(LIBADB_SRC_FILES) \
      
      
     
     

     
     
     
     

      
      

       
       adb_auth_client.cpp \
      
      
     
     

     
     
     
     

      
      

       
       fdevent.cpp \
      
      
     
     

     
     
     
     

      
      

       
       jdwp_service.cpp \
      
      
     
     

     
     
     
     

      
      

       
       qemu_tracing.cpp \
      
      
     
     

     
     
     
     

      
      

       
       usb_linux_client.cpp \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LOCAL_SHARED_LIBRARIES := libbase
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       include $(BUILD_STATIC_LIBRARY)
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       include $(CLEAR_VARS)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CLANG := $(adb_host_clang)
      
      
     
     

     
     
     
     

      
      

       
       // 编译生成libadb动态库，供pc端adb可执行文件使用
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_MODULE := libadb
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CFLAGS := $(LIBADB_CFLAGS) -DADB_HOST=
       
       1
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_SRC_FILES := \
      
      
     
     

     
     
     
     

      
      

       
       $(LIBADB_SRC_FILES) \
      
      
     
     

     
     
     
     

      
      

       
       $(LIBADB
       
       _$(HOST_OS)_SRC_FILES) \
      
      
     
     

     
     
     
     

      
      

       
       adb_auth_host.cpp \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LOCAL_SHARED_LIBRARIES := libbase
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       # Even though we're building a static library (and thus there's no link step for
      
      
     
     

     
     
     
     

      
      

       
       # this to take effect), this adds the SSL includes to our path.
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_STATIC_LIBRARIES := libcrypto_static
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       ife
       
       q ($(HOST_OS),windows)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_C_INCLUDES += development/host/windows/usb/api/
      
      
     
     

     
     
     
     

      
      

       
       endif
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       include $(BUILD_HOST_STATIC_LIBRARY)
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       include $(CLEAR_VARS)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CLANG := true
      
      
     
     

     
     
     
     

      
      

       
       // 编译生成adbd的测试程序
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_MODULE := adbd_test
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CFLAGS := -DADB_HOST=
       
       0 $(LIBADB_CFLAGS)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_SRC_FILES := $(LIBADB_TEST_SRCS)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_STATIC_LIBRARIES := libadbd
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_SHARED_LIBRARIES := liblog libbase libcutils
      
      
     
     

     
     
     
     

      
      

       
       include $(BUILD_NATIVE_TEST)
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       include $(CLEAR_VARS)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CLANG := $(adb_host_clang)
      
      
     
     

     
     
     
     

      
      

       
       // 编译生成adb的测试程序
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_MODULE := adb_test
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CFLAGS := -DADB_HOST=
       
       1 $(LIBADB_CFLAGS)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_SRC_FILES := $(LIBADB_TEST_SRCS) services.cpp
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_SHARED_LIBRARIES := liblog libbase
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_STATIC_LIBRARIES := \
      
      
     
     

     
     
     
     

      
      

       
       libadb \
      
      
     
     

     
     
     
     

      
      

       
       libcrypto_static \
      
      
     
     

     
     
     
     

      
      

       
       libcutils \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       ife
       
       q ($(HOST_OS),linux)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_LDLIBS += -lrt -ldl -lpthread
      
      
     
     

     
     
     
     

      
      

       
       endif
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       ife
       
       q ($(HOST_OS),darwin)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_LDLIBS += -framework CoreFoundation -framework IOKit
      
      
     
     

     
     
     
     

      
      

       
       endif
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       include $(BUILD_HOST_NATIVE_TEST)
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       # adb device tracker (used by ddms) test tool
      
      
     
     

     
     
     
     

      
      

       
       # =========================================================
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       ife
       
       q ($(HOST_OS),linux)
      
      
     
     

     
     
     
     

      
      

       
       include $(CLEAR_VARS)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CLANG := $(adb_host_clang)
      
      
     
     

     
     
     
     

      
      

       
       // 编译生成adb_device_tracker服务的测试程序
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_MODULE := adb_device_tracker_test
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CFLAGS := -DADB_HOST=
       
       1 $(LIBADB_CFLAGS)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_SRC_FILES := test_track_devices.cpp
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_SHARED_LIBRARIES := liblog libbase
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_STATIC_LIBRARIES := libadb libcrypto_static libcutils
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_LDLIBS += -lrt -ldl -lpthread
      
      
     
     

     
     
     
     

      
      

       
       include $(BUILD_HOST_EXECUTABLE)
      
      
     
     

     
     
     
     

      
      

       
       endif
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       # adb host tool
      
      
     
     

     
     
     
     

      
      

       
       # =========================================================
      
      
     
     

     
     
     
     

      
      

       
       include $(CLEAR_VARS)
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       ife
       
       q ($(HOST_OS),linux)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_LDLIBS += -lrt -ldl -lpthread
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CFLAGS += -DWORKAROUND_BUG6558362
      
      
     
     

     
     
     
     

      
      

       
       endif
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       ife
       
       q ($(HOST_OS),darwin)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_LDLIBS += -lpthread -framework CoreFoundation -framework IOKit -framework Carbon
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CFLAGS += -Wno-sizeof-pointer-memaccess -Wno-unused-parameter
      
      
     
     

     
     
     
     

      
      

       
       endif
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       ife
       
       q ($(HOST_OS),windows)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_LDLIBS += -lws2_32 -lgdi32
      
      
     
     

     
     
     
     

      
      

       
       EXTRA_STATIC_LIBS := AdbWinApi
      
      
     
     

     
     
     
     

      
      

       
       endif
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LOCAL_CLANG := $(adb_host_clang)
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LOCAL_SRC_FILES := \
      
      
     
     

     
     
     
     

      
      

       
       adb_main.cpp \
      
      
     
     

     
     
     
     

      
      

       
       console.cpp \
      
      
     
     

     
     
     
     

      
      

       
       commandline.cpp \
      
      
     
     

     
     
     
     

      
      

       
       adb_client.cpp \
      
      
     
     

     
     
     
     

      
      

       
       services.cpp \
      
      
     
     

     
     
     
     

      
      

       
       file_sync_client.cpp \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LOCAL_CFLAGS += \
      
      
     
     

     
     
     
     

      
      

       
       $(ADB_COMMON_CFLAGS) \
      
      
     
     

     
     
     
     

      
      

       
       -D_GNU_SOURCE \
      
      
     
     

     
     
     
     

      
      

       
       -DADB_HOST=
       
       1 \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       // 编译生成PC端的adb可执行文件，位于sdk/platform-tools/adb目录下
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_MODULE := adb
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_MODULE_TAGS := debug
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LOCAL_STATIC_LIBRARIES := \
      
      
     
     

     
     
     
     

      
      

       
       libadb \
      
      
     
     

     
     
     
     

      
      

       
       libbase \
      
      
     
     

     
     
     
     

      
      

       
       libcrypto_static \
      
      
     
     

     
     
     
     

      
      

       
       libcutils \
      
      
     
     

     
     
     
     

      
      

       
       liblog \
      
      
     
     

     
     
     
     

      
      

       
       $(EXTRA_STATIC_LIBS) \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       # libc++ not available on windows yet
      
      
     
     

     
     
     
     

      
      

       
       ifne
       
       q ($(HOST_OS),windows)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CXX_STL := libc++_static
      
      
     
     

     
     
     
     

      
      

       
       endif
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       # Don't add anything here, we don't want additional shared dependencies
      
      
     
     

     
     
     
     

      
      

       
       # on the host adb tool, and shared libraries that link against libc++
      
      
     
     

     
     
     
     

      
      

       
       # will violate ODR
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_SHARED_LIBRARIES :=
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       include $(BUILD_HOST_EXECUTABLE)
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       $(call dist-
       
       for-goals,dist_files sdk,$(LOCAL_BUILT_MODULE))
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       ife
       
       q ($(HOST_OS),windows)
      
      
     
     

     
     
     
     

      
      

       
       $(LOCAL_INSTALLED_MODULE): \
      
      
     
     

     
     
     
     

      
      

       
       $(HOST_OUT_EXECUTABLES)/AdbWinApi.dll \
      
      
     
     

     
     
     
     

      
      

       
       $(HOST_OUT_EXECUTABLES)/AdbWinUsbApi.dll
      
      
     
     

     
     
     
     

      
      

       
       endif
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       # adbd device daemon
      
      
     
     

     
     
     
     

      
      

       
       # =========================================================
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       include $(CLEAR_VARS)
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LOCAL_CLANG := true
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LOCAL_SRC_FILES := \
      
      
     
     

     
     
     
     

      
      

       
       adb_main.cpp \
      
      
     
     

     
     
     
     

      
      

       
       services.cpp \
      
      
     
     

     
     
     
     

      
      

       
       file_sync_service.cpp \
      
      
     
     

     
     
     
     

      
      

       
       framebuffer_service.cpp \
      
      
     
     

     
     
     
     

      
      

       
       remount_service.cpp \
      
      
     
     

     
     
     
     

      
      

       
       set_verity_enable_state_service.cpp \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LOCAL_CFLAGS := \
      
      
     
     

     
     
     
     

      
      

       
       $(ADB_COMMON_CFLAGS) \
      
      
     
     

     
     
     
     

      
      

       
       -DADB_HOST=
       
       0 \
      
      
     
     

     
     
     
     

      
      

       
       -D_GNU_SOURCE \
      
      
     
     

     
     
     
     

      
      

       
       -Wno-deprecated-declarations \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       // engineer模式下无需AUTH认证
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CFLAGS += -DALLOW_ADBD_NO_AUTH=$(
       
       if $(filter userdebug eng,$(TARGET_BUILD_VARIANT)),
       
       1,
       
       0)
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       ifne
       
       q (,$(filter userdebug eng,$(TARGET_BUILD_VARIANT)))
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CFLAGS += -DALLOW_ADBD_DISABLE_VERITY=
       
       1
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_CFLAGS += -DALLOW_ADBD_ROOT=
       
       1
      
      
     
     

     
     
     
     

      
      

       
       endif
      
      
     
     

     
     
     
     

      
      

       
       // 编译生成设备端或模拟器端的adbd deamon进程
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_MODULE := adbd
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LOCAL_FORCE_STATIC_EXECUTABLE := true
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_MODULE_PATH := $(TARGET_ROOT_OUT_SBIN)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_UNSTRIPPED_PATH := $(TARGET_ROOT_OUT_SBIN_UNSTRIPPED)
      
      
     
     

     
     
     
     

      
      

       
       LOCAL_C_INCLUDES += 
       
       system/extras/ext4_utils
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       LOCAL_STATIC_LIBRARIES := \
      
      
     
     

     
     
     
     

      
      

       
       libadbd \
      
      
     
     

     
     
     
     

      
      

       
       libbase \
      
      
     
     

     
     
     
     

      
      

       
       libfs_mgr \
      
      
     
     

     
     
     
     

      
      

       
       liblog \
      
      
     
     

     
     
     
     

      
      

       
       libcutils \
      
      
     
     

     
     
     
     

      
      

       
       libc \
      
      
     
     

     
     
     
     

      
      

       
       libmincrypt \
      
      
     
     

     
     
     
     

      
      

       
       libselinux \
      
      
     
     

     
     
     
     

      
      

       
       libext4_utils_static \
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       include $(BUILD_EXECUTABLE)
      
      
     
     
   
   

关键点总结：

   
   

     
     
     
     

      
      

       
       所有的adb程序（PC端和设备端）共用一套代码，只是借助于HOST_OS这个宏进行隔离，编译时会生成两个可执行文件：	
      
      
     
     

     
     
     
     

      
      

       
       1．adb/adb.exe：运行于PC端(包括Windows、Linux、MacOS等操作系统之上)，位于platform/tools/adb目录下，透过adb命令可以唤起。
      
      
     
     

     
     
     
     

      
      

       
       2．adbd：运行于Android设备上，开机时自动启动。
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       相应的，源码中也会由ADB_HOST宏用来区分本地主机(adb)和目标机(adbd)。
      
      
     
     

     
     
     
     

      
      

       
       Engineer模式下会定义ALLOW_ADBD_NO_AUTH，源码中会使用到。
      
      
     
     
   
   

二、adb框架介绍

ADB为 Android Debug Bridge（调试桥）的缩写，本质上是一个 C/S 架构的命令行工具。整个ADB模块由如下几部分组成（详细参见system/core/adb/OVERVIEW.txt和transports.txt）：

1. The ADB server(adb)：运行在PC端的一个后台应用程序，用来检测Android Devices的连接或去除，进而维护设备状态列表。另外，ADB Server也会负责协调Client、Services和Android devices之间传输数据。
2. The ADB daemon (adbd) : 运行在Android Devices或Emulator上的后台守护进程。该进程主要是用来连接ADB Server，并通过USB(或者TCP)为adb clients提供一些services服务。
3. The ADB command-line client: 执行adb 命令的终端。具体来说，会连接adb server并向adb server发送请求命令。若是发现adb server没有启动，则会自动唤起adb server.
4. Services: adb具备的一些能力可以抽象成服务(services)，供The ADB command-line client访问。可以分为 Host Services和Local Services两种，简述如下：

   
   

     
     
     
     

      
      

       
       a) Host Services: 运行于ADB 
       
       Server，不需要和devices进行数据交换。典型的就是执行adb devices命令时，只需要adb 
       
       server端返回当前的adb devices的状态即可。
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       b)Local Services: 运行于adbd守护进程，ADB 
       
       Server负责建立adb clients和Local Services之间的连接，并透传数据。
      
      
     
     
   
   

注：本篇文章只分析ADBD的实现。

三、adbd源码分析

1. adbd初始化流程分析  

    ADB分为usb adb和wifi adb两种方式，两者互斥存在，默认使用的是usb adb. 如果想默认启动wifi adb，需设置属性service.adb.tcp.port值为55555，然后重启adbd即可。ADB daemon（usb adb.）程序开机启动主要步骤如下图所示。

 

说明如下：

• DEFAULT_ADB_PORT为adb server的端口号，定义如下，一般取值为5037。有时PC上adb无法使用，可能就是由于该端口已经腾讯等手机助手等占用。

   
   

     
     
     
     

      
      

       
       #if ADB_HOST_ON_TARGET
      
      
     
     

     
     
     
     

      
      

       
       /* adb and adbd are coexisting on the target, so use 5038 for adb
      
      
     
     

     
     
     
     

      
      

       
       * to avoid conflicting with adbd's usage of 5037
      
      
     
     

     
     
     
     

      
      

       
       */
      
      
     
     

     
     
     
     

      
      

       
       # define DEFAULT_ADB_PORT 5038
      
      
     
     

     
     
     
     

      
      

       
       #else
      
      
     
     

     
     
     
     

      
      

       
       # define DEFAULT_ADB_PORT 5037
      
      
     
     

     
     
     
     

      
      

       
       #endif
      
      
     
     
   
   

• 1.1.1-init_transport_registration()分析如下：

   
   

     
     
     
     

      
      

       
       void 
       
       init_transport_registration(
       
       void)
      
      
     
     

     
     
     
     

      
      

       
       {
      
      
     
     

     
     
     
     

      
      

       
           int s[
       
       2];
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       // 创建双向通信的管道，全双工
      
      
     
     

     
     
     
     

      
      
    
       
       if(
       
       adb_socketpair(s)){
      
      
     
     

     
     
     
     

      
      
        
       
       fatal_errno(
       
       "cannot open transport registration socketpair");
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

      
      
    
       
       D(
       
       "socketpair: (%d,%d)", s[
       
       0], s[
       
       1]);
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
           transport_registration_send = s[
       
       0]; 
       
       // 发送数据
      
      
     
     

     
     
     
     

      
      

       
           transport_registration_recv = s[
       
       1]; 
       
       // 接收数据
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       // transport_registration_recv有数据接收到后，会触发transport_registration_func执行
      
      
     
     

     
     
     
     

      
      
    
       
       fdevent_install(&transport_registration_fde,
      
      
     
     

     
     
     
     

      
      

       
           transport_registration_recv,
      
      
     
     

     
     
     
     

      
      

       
           transport_registration_func,
       
       // 这个函数很重！！
      
      
     
     

     
     
     
     

      
      
    
       
       0);
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       fdevent_set(&transport_registration_fde, 
       
       FDE_READ);
      
      
     
     

     
     
     
     

      
      

       
       }
      
      
     
     
   
   

因此，接下来需要分析transport_registration_recv会接收数据，即transport_registration_send何时会发送数据。

• 1.1.2-adbd_cloexec_auth_socket()分析如下：

   
   

     
     
     
     

      
      

       
       void adbd_cloexec_auth_socket() {
      
      
     
     

     
     
     
     

      
      
    
       
       int fd = android_get_control_socket(
       
       "adbd");
      
      
     
     

     
     
     
     

      
      
    
       
       if (fd == 
       
       -1) {
      
      
     
     

     
     
     
     

      
      

       
               D(
       
       "Failed to get adbd socket\n");
      
      
     
     

     
     
     
     

      
      
        
       
       return;
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

      
      

       
           fcntl(fd, F_SETFD, FD_CLOEXEC);
      
      
     
     

     
     
     
     

      
      

       
       }
      
      
     
     
   
   

• 1.1.3-should_drop_privileges()分析如下：

   
   

     
     
     
     

      
      

       
       // adbd 默认是root权限，即最高权限。此处是为了安全需要，考虑是否要降级，即降低权限。
      
      
     
     

     
     
     
     

      
      

       
       static bool should_drop_privileges() {
      
      
     
     

     
     
     
     

      
      

       
       #if defined(ALLOW_ADBD_ROOT)
      
      
     
     

     
     
     
     

      
      
    
       
       char value[PROPERTY_VALUE_MAX];
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       // 模拟器没有降级
      
      
     
     

     
     
     
     

      
      
    
       
       // The emulator is never secure, so don't drop privileges there.
      
      
     
     

     
     
     
     

      
      
    
       
       // TODO: this seems like a bug --- shouldn't the emulator behave like a device?
      
      
     
     

     
     
     
     

      
      
    
       
       property_get(
       
       "ro.kernel.qemu", value, 
       
       "");
      
      
     
     

     
     
     
     

      
      
    
       
       if (
       
       strcmp(value, 
       
       "1") == 
       
       0) {
      
      
     
     

     
     
     
     

      
      
        
       
       return 
       
       false;
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       // The properties that affect `adb root` and `adb unroot` are ro.secure and
      
      
     
     

     
     
     
     

      
      
    
       
       // ro.debuggable. In this context the names don't make the expected behavior
      
      
     
     

     
     
     
     

      
      
    
       
       // particularly obvious.
      
      
     
     

     
     
     
     

      
      
    
       
       //
      
      
     
     

     
     
     
     

      
      
    
       
       // ro.debuggable:
      
      
     
     

     
     
     
     

      
      
    
       
       // Allowed to become root, but not necessarily the default. Set to 1 on
      
      
     
     

     
     
     
     

      
      
    
       
       // eng and userdebug builds.
      
      
     
     

     
     
     
     

      
      
    
       
       //
      
      
     
     

     
     
     
     

      
      
    
       
       // ro.secure:
      
      
     
     

     
     
     
     

      
      
    
       
       // Drop privileges by default. Set to 1 on userdebug and user builds.
      
      
     
     

     
     
     
     

      
      
    
       
       property_get(
       
       "ro.secure", value, 
       
       "1");
      
      
     
     

     
     
     
     

      
      
    
       
       bool ro_secure = (
       
       strcmp(value, 
       
       "1") == 
       
       0);
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       property_get(
       
       "ro.debuggable", value, 
       
       "");
      
      
     
     

     
     
     
     

      
      
    
       
       bool ro_debuggable = (
       
       strcmp(value, 
       
       "1") == 
       
       0);
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       // Drop privileges if ro.secure is set...
      
      
     
     

     
     
     
     

      
      
    
       
       bool drop = ro_secure;
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       property_get(
       
       "service.adb.root", value, 
       
       "");
      
      
     
     

     
     
     
     

      
      
    
       
       bool adb_root = (
       
       strcmp(value, 
       
       "1") == 
       
       0);
      
      
     
     

     
     
     
     

      
      
    
       
       bool adb_unroot = (
       
       strcmp(value, 
       
       "0") == 
       
       0);
      
      
     
     

     
     
     
     

      
      
    
       
       // 默认debug模式不会降级，即adb有root权限
      
      
     
     

     
     
     
     

      
      
    
       
       // ...except "adb root" lets you keep privileges in a debuggable build.
      
      
     
     

     
     
     
     

      
      
    
       
       if (ro_debuggable && adb_root) {
      
      
     
     

     
     
     
     

      
      

       
               drop = 
       
       false;
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       // ...and "adb unroot" lets you explicitly drop privileges.
      
      
     
     

     
     
     
     

      
      
    
       
       if (adb_unroot) {
      
      
     
     

     
     
     
     

      
      

       
               drop = 
       
       true;
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       return drop;
      
      
     
     

     
     
     
     

      
      

       
       #else
      
      
     
     

     
     
     
     

      
      
    
       
       return 
       
       true; 
       
       // "adb root" not allowed, always drop privileges.
      
      
     
     

     
     
     
     

      
      

       
       #endif /* ALLOW_ADBD_ROOT */
      
      
     
     

     
     
     
     

      
      

       
       }
      
      
     
     
   
   

• 1.1.4-usb_init()分析如下：

   
   

     
     
     
     

      
      

       
       void usb_init()
      
      
     
     

     
     
     
     

      
      

       
       {
      
      
     
     

     
     
     
     

      
      
    
       
       if (access(USB_FFS_ADB_EP0, F_OK) == 
       
       0)
      
      
     
     

     
     
     
     

      
      

       
               usb_ffs_init();
      
      
     
     

     
     
     
     

      
      
    
       
       else
      
      
     
     

     
     
     
     

      
      

       
               usb_adb_init();
       
       //走此case，接下来分析此函数
      
      
     
     

     
     
     
     

      
      

       
       }
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       继续usb_adb_init()分析...
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       static void usb_adb_init()
      
      
     
     

     
     
     
     

      
      

       
       {
      
      
     
     

     
     
     
     

      
      

       
           usb_handle* h = reinterpret_cast<usb_handle*>(calloc(
       
       1, 
       
       sizeof(usb_handle)));
      
      
     
     

     
     
     
     

      
      
    
       
       if (h == nullptr) fatal(
       
       "couldn't allocate usb_handle");
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
           h->write = usb_adb_write;
      
      
     
     

     
     
     
     

      
      

       
           h->read = usb_adb_read;
      
      
     
     

     
     
     
     

      
      

       
           h->kick = usb_adb_kick;
      
      
     
     

     
     
     
     

      
      

       
           h->fd = 
       
       -1;
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
           adb_cond_init(&h->notify, 
       
       0);
      
      
     
     

     
     
     
     

      
      

       
           adb_mutex_init(&h->
       
       lock, 
       
       0);
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       // Open the file /dev/android_adb_enable to trigger
      
      
     
     

     
     
     
     

      
      
    
       
       // the enabling of the adb USB function in the kernel.
      
      
     
     

     
     
     
     

      
      
    
       
       // We never touch this file again - just leave it open
      
      
     
     

     
     
     
     

      
      
    
       
       // indefinitely so the kernel will know when we are running
      
      
     
     

     
     
     
     

      
      
    
       
       // and when we are not.
      
      
     
     

     
     
     
     

      
      
    
       
       // 打开android_adb_enable节点，即enable adb usb
      
      
     
     

     
     
     
     

      
      
    
       
       int fd = unix_open(
       
       "/dev/android_adb_enable", O_RDWR);
      
      
     
     

     
     
     
     

      
      
    
       
       if (fd < 
       
       0) {
      
      
     
     

     
     
     
     

      
      

       
               D(
       
       "failed to open /dev/android_adb_enable\n");
      
      
     
     

     
     
     
     

      
      

       
           } 
       
       else {
      
      
     
     

     
     
     
     

      
      

       
               close_on_exec(fd);
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
           D(
       
       "[ usb_init - starting thread ]\n");
      
      
     
     

     
     
     
     

      
      

       
           adb_thread_t tid;
      
      
     
     

     
     
     
     

      
      
    
       
       if(adb_thread_create(&tid, usb_adb_open_thread, h)){
       
       //接下来分析此函数
      
      
     
     

     
     
     
     

      
      

       
               fatal_errno(
       
       "cannot create usb thread");
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

      
      

       
       }
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       继续usb_adb_open_thread()分析...
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       static 
       
       void *usb_adb_open_thread(
       
       void *x)
      
      
     
     

     
     
     
     

      
      

       
       {
      
      
     
     

     
     
     
     

      
      
    
       
       struct usb_handle *usb = (
       
       struct usb_handle *)x;
      
      
     
     

     
     
     
     

      
      
    
       
       int fd;
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       while (
       
       true) {
      
      
     
     

     
     
     
     

      
      
        
       
       // wait until the USB device needs opening
      
      
     
     

     
     
     
     

      
      

       
               adb_mutex_lock(&usb->
       
       lock);
      
      
     
     

     
     
     
     

      
      
        
       
       while (usb->fd != 
       
       -1)
      
      
     
     

     
     
     
     

      
      

       
                   adb_cond_wait(&usb->notify, &usb->
       
       lock);
      
      
     
     

     
     
     
     

      
      

       
               adb_mutex_unlock(&usb->
       
       lock);
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
               D(
       
       "[ usb_thread - opening device ]\n");
      
      
     
     

     
     
     
     

      
      
        
       
       do {
      
      
     
     

     
     
     
     

      
      
            
       
       /* XXX use inotify? */
      
      
     
     

     
     
     
     

      
      

       
                   fd = unix_open(
       
       "/dev/android_adb", O_RDWR);
       
       //打开adb节点
      
      
     
     

     
     
     
     

      
      
            
       
       if (fd < 
       
       0) {
      
      
     
     

     
     
     
     

      
      
                
       
       // to support older kernels
      
      
     
     

     
     
     
     

      
      

       
                       fd = unix_open(
       
       "/dev/android", O_RDWR);
      
      
     
     

     
     
     
     

      
      

       
                   }
      
      
     
     

     
     
     
     

      
      
            
       
       if (fd < 
       
       0) {
      
      
     
     

     
     
     
     

      
      

       
                       adb_sleep_ms(
       
       1000);
      
      
     
     

     
     
     
     

      
      

       
                   }
      
      
     
     

     
     
     
     

      
      

       
               } 
       
       while (fd < 
       
       0);
      
      
     
     

     
     
     
     

      
      

       
               D(
       
       "[ opening device succeeded ]\n");
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
               close_on_exec(fd);
      
      
     
     

     
     
     
     

      
      

       
               usb->fd = fd;
       
       //将adb节点赋值给usb->fd，重要！
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
               D(
       
       "[ usb_thread - registering device ]\n");
      
      
     
     

     
     
     
     

      
      

       
               register_usb_transport(usb, 
       
       0, 
       
       0, 
       
       1);
       
       //接下来分析此函数
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       // never gets here
      
      
     
     

     
     
     
     

      
      
    
       
       return 
       
       0;
      
      
     
     

     
     
     
     

      
      

       
       }
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       继续register_usb_transport()分析...
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       //transport.cpp
      
      
     
     

     
     
     
     

      
      

       
       void register_usb_transport(usb_handle *usb, const char *serial, const char *devpath, unsigned writeable)
      
      
     
     

     
     
     
     

      
      

       
       {
      
      
     
     

     
     
     
     

      
      

       
           atransport *t = reinterpret_cast<atransport*>(calloc(
       
       1, 
       
       sizeof(atransport)));
      
      
     
     

     
     
     
     

      
      
    
       
       if (t == nullptr) fatal(
       
       "cannot allocate USB atransport");
      
      
     
     

     
     
     
     

      
      

       
           D(
       
       "transport: %p init'ing for usb_handle %p (sn='%s')\n", t, usb, serial ? serial : 
       
       "");
      
      
     
     

     
     
     
     

      
      
    
       
       // 初始化atransport
      
      
     
     

     
     
     
     

      
      

       
           init_usb_transport(t, usb, (writeable ? CS_OFFLINE : CS_NOPERM));
      
      
     
     

     
     
     
     

      
      
    
       
       if(serial) {
      
      
     
     

     
     
     
     

      
      

       
               t->serial = strdup(serial);
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

      
      
    
       
       if(devpath) {
      
      
     
     

     
     
     
     

      
      

       
               t->devpath = strdup(devpath);
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
           adb_mutex_lock(&transport_lock);
      
      
     
     

     
     
     
     

      
      

       
           t->next = &pending_list;
      
      
     
     

     
     
     
     

      
      

       
           t->prev = pending_list.prev;
      
      
     
     

     
     
     
     

      
      

       
           t->next->prev = t;
      
      
     
     

     
     
     
     

      
      

       
           t->prev->next = t;
      
      
     
     

     
     
     
     

      
      

       
           adb_mutex_unlock(&transport_lock);
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
           register_transport(t);
       
       //接下来分析此函数
      
      
     
     

     
     
     
     

      
      

       
       }
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       继续register_transport(t)分析...
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       /* the fdevent select pump is single threaded */
      
      
     
     

     
     
     
     

      
      

       
       static void register_transport(atransport *transport)
      
      
     
     

     
     
     
     

      
      

       
       {
      
      
     
     

     
     
     
     

      
      

       
           tmsg m;
      
      
     
     

     
     
     
     

      
      

       
           m.transport = transport;
      
      
     
     

     
     
     
     

      
      

       
           m.action = 
       
       1;
      
      
     
     

     
     
     
     

      
      

       
           D(
       
       "transport: %s registered\n", transport->serial);
      
      
     
     

     
     
     
     

      
      
    
       
       //看到这个socket fd: transport_registration_send, 我们想到了1.1.1-            init_transport_registration()中遗留的问题。让我们继续。。。
      
      
     
     

     
     
     
     

      
      
    
       
       if(transport_write_action(transport_registration_send, &m)) {
      
      
     
     

     
     
     
     

      
      

       
               fatal_errno(
       
       "cannot write transport registration socket\n");
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

      
      

       
       }
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       继续transport_write_action(transport_registration_send, &m)分析...
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
       static int
      
      
     
     

     
     
     
     

      
      

       
       transport_write_action(
       
       int fd, struct tmsg* m)
      
      
     
     

     
     
     
     

      
      

       
       {
      
      
     
     

     
     
     
     

      
      
    
       
       char *p = (
       
       char*)m;
      
      
     
     

     
     
     
     

      
      
    
       
       int len = 
       
       sizeof(*m);
      
      
     
     

     
     
     
     

      
      
    
       
       int r;
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       while(len > 
       
       0) {
      
      
     
     

     
     
     
     

      
      

       
               r = adb_write(fd, p, len);
       
       // 此处即为向transport_registration_send写数据！！！！
      
      
     
     

     
     
     
     

      
      
        
       
       if(r > 
       
       0) {
      
      
     
     

     
     
     
     

      
      

       
               len -= r;
      
      
     
     

     
     
     
     

      
      

       
               p += r;
      
      
     
     

     
     
     
     

      
      

       
           } 
       
       else {
      
      
     
     

     
     
     
     

      
      
        
       
       if((r < 
       
       0) && (errno == EINTR)) 
       
       continue;
      
      
     
     

     
     
     
     

      
      

       
                   D(
       
       "transport_write_action: on fd %d, error %d: %s\n",
      
      
     
     

     
     
     
     

      
      

       
                   fd, errno, strerror(errno));
      
      
     
     

     
     
     
     

      
      
            
       
       return 
       
       -1;
      
      
     
     

     
     
     
     

      
      

       
               }
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

      
      
    
       
       return 
       
       0;
      
      
     
     

     
     
     
     

      
      

       
       }
      
      
     
     
   
   

• 紧接着会调用transport_registration_func(int _fd, unsigned ev, void *data)

   
   

     
     
     
     

      
      

       
       static 
       
       void transport_registration_func(
       
       int _fd, unsigned ev, 
       
       void *data)
      
      
     
     

     
     
     
     

      
      

       
       {
      
      
     
     

     
     
     
     

      
      
    
       
       int s[
       
       2];
      
      
     
     

     
     
     
     

      
      

       
           ......
      
      
     
     

     
     
     
     

      
      
    
       
       if(adb_socketpair(s)) {
      
      
     
     

     
     
     
     

      
      

       
               fatal_errno(
       
       "cannot open transport socketpair");
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

      
      

       
           D(
       
       "transport: %s socketpair: (%d,%d) starting", t->serial, s[
       
       0], s[
       
       1]);
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
           t->transport_socket = s[
       
       0];
      
      
     
     

     
     
     
     

      
      

       
           t->fd = s[
       
       1];
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
           fdevent_install(&(t->transport_fde), t->transport_socket,transport_socket_events,t);
       
       //重要
      
      
     
     

     
     
     
     

     
     
     
     

      
      

       
           fdevent_set(&(t->transport_fde), FDE_READ);
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       // 从adb驱动的角度来看，创建adb输入通道
      
      
     
     

     
     
     
     

      
      
    
       
       if(adb_thread_create(&input_thread_ptr, input_thread, t)){
      
      
     
     

     
     
     
     

      
      

       
               fatal_errno(
       
       "cannot create input thread");
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

     
     
     
     

      
      
    
       
       // 从adb驱动的角度来看，创建adb输出通道
      
      
     
     

     
     
     
     

      
      
    
       
       if(adb_thread_create(&output_thread_ptr, output_thread, t)){
      
      
     
     

     
     
     
     

      
      

       
               fatal_errno(
       
       "cannot create output thread");
      
      
     
     

     
     
     
     

      
      

       
           }
      
      
     
     

     
     
     
     

      
      

       
           ......
      
      
     
     

     
     
     
     

      
      

       
       }
      
      
     
     
   
   

后续大概流程为：

至此，adbd的主要初始化过程已分析完毕。其中最为关键的是初始化了adb驱动节点，然后创建output_thread不断的读取节点内容变化

2. adb shell流程分析

由3.1节知，output_thread从adb驱动节点读取数据后，调用write_packet(t->fd, t->serial, &p))会触发调用transport_socket_events()函数进行数据处理。

3. adb root流程分析

 

 

四、adb常用命令

adb 命令一般格式为：adb [-e | -d | -s <设备序列号>] <子命令>

• adb version，查看adb版本
• adb tcpip 5555，设置属性ersist.adb.tcp.port=5555，重启adbd进入adb wifi模式。
• adb devices , 获取设备列表及设备状态

   
   

     
     
     
     

      
      

       
       a．device：设备正常连接
      
      
     
     

     
     
     
     

      
      

       
       b．offline：连接出现异常，设备无响应
      
      
     
     

     
     
     
     

      
      

       
       c．unknown：没有连接设备
      
      
     
     
   
   

• adb get-state , 获取设备的状态，设备的状态有 3 钟，device , offline , unknown
• adb kill-server , adb start-server 

   
   

     
     
     
     

      
      

       
       结束 adb 服务， 启动 adb 服务，通常两个命令一起用。
      
      
     
     

     
     
     
     

      
      

       
       一般在连接出现异常，使用 adb devices 未正常列出设备， 设备状态异常时使用 kill-
       
       server，然后运行 start-
       
       server 进行重启服务
      
      
     
     
   
   

• adb logcat , 打印 Android 的系统日志
• adb bugreport 

   
   

     
     
     
     

      
      

       
       打印dumpsys、dumpstate、logcat的输出，也是用于分析错误
      
      
     
     

     
     
     
     

      
      

       
       输出比较多，建议重定向到一个文件中
      
      
     
     

     
     
     
     

      
      

       
       adb bugreport > d:\bugreport.
       
       log
      
      
     
     
   
   

• adb install 

安装应用，覆盖安装是使用 -r 选项
   
   

• adb uninstall

   
   

     
     
     
     

      
      

       
       卸载应用，后面跟的参数是应用的包名，请区别于 apk 文件名
      
      
     
     

     
     
     
     

      
      

       
       '-k' means keep the data and cache directories , -k 选项，卸载时保存数据和缓存目录
      
      
     
     
   
   

• adb pull , 将 Android 设备上的文件或者文件夹复制到本地
• adb push , 推送本地文件至 Android 设备
• adb root , adb remount, 获取 root 权限，并挂载系统文件系统为可读写状态
• adb reboot , 重启 Android 设备
• adb reboot loader , 重启设备，进入 fastboot 模式，同 adb reboot-bootloader 命令
• adb reboot recovery , 重启设备，进入 recovery 模式
• adb connect <device-ip-address>/adb disconnect <device-ip-address>

上述为adb程序自带的命令，与android无关，而Android系统自身的命令，实现位于system/bin（pm，am，screenrecord，getprop，input，ime，wm，settings，monkey，dumpsys，logcat，log，uiautomator等）。除此之外，就是linux自带的命令，自行查阅。

后记：因adb实际开发需要，研究了下adb源码，上述算是一个总结。本着开源的精神，大家共同进步！

参考文章：

https://blog.csdn.net/wlwl0071986/article/details/50935496

https://blog.csdn.net/qq_35970872/article/details/78912611

https://www.cnblogs.com/zzb-Dream-90Time/p/8166223.html