如何在CMake中链接自行编译的libgpiod C++绑定库

我需要把libgpiod的C++绑定库链接到项目里，研究了好几天都没搞定。希望把这个仓库作为子模块引入，构建后和项目链接，这样生成的二进制文件（包括模块的二进制）能移植到没网的目标设备上。现在虽然能下载预编译包，但更想实现自包含构建。

项目结构 #

dependencies/
├─ libgpiod/
CMakeLists.txt
main.cpp

原CMake配置 #

cmake_minimum_required(VERSION 3.16.3)
project(my_project VERSION 0.1.0)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)


set(GPIOD_DIR ${CMAKE_CURRENT_SOURCE_DIR}/dependencies/libgpiod)
set(GPIOD_BIN ${CMAKE_CURRENT_BINARY_DIR}/dependencies/libgpiod)
set(GPIOD_LIB_DIR ${GPIOD_BIN}/lib)
set(GPIOD_INCLUDE_DIR ${GPIOD_BIN}/include)
ExternalProject_Add(libgpiod-project
        PREFIX ${GPIOD_BIN}
        SOURCE_DIR ${GPIOD_DIR}
        CONFIGURE_COMMAND ${GPIOD_DIR}/autogen.sh --enable-tools=no --prefix=${GPIOD_BIN} --enable-bindings-cxx
        BUILD_COMMAND make && make install
        # INSTALL_COMMAND make install
        BUILD_BYPRODUCTS ${GPIOD_LIB_DIR}/libgpiodcxx.so
    )



add_executable(my_project main.cpp)

target_link_libraries(my_project PRIVATE
    # todo what to link against?
)

解决方案 #

关键修改点 #

• 让可执行文件依赖libgpiod的构建目标，确保编译顺序正确
• 明确指定libgpiod的头文件搜索路径
• 同时链接C++绑定库libgpiodcxx及其依赖的底层C库libgpiod
• 通过导入库目标让CMake更好地管理依赖关系

修改后的完整CMakeLists.txt #

cmake_minimum_required(VERSION 3.16.3)
project(my_project VERSION 0.1.0)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

set(GPIOD_DIR ${CMAKE_CURRENT_SOURCE_DIR}/dependencies/libgpiod)
set(GPIOD_BIN ${CMAKE_CURRENT_BINARY_DIR}/dependencies/libgpiod)
set(GPIOD_LIB_DIR ${GPIOD_BIN}/lib)
set(GPIOD_INCLUDE_DIR ${GPIOD_BIN}/include)

ExternalProject_Add(libgpiod-project
        PREFIX ${GPIOD_BIN}
        SOURCE_DIR ${GPIOD_DIR}
        CONFIGURE_COMMAND ${GPIOD_DIR}/autogen.sh --enable-tools=no --prefix=${GPIOD_BIN} --enable-bindings-cxx
        BUILD_COMMAND make
        INSTALL_COMMAND make install
        BUILD_BYPRODUCTS ${GPIOD_LIB_DIR}/libgpiod.so ${GPIOD_LIB_DIR}/libgpiodcxx.so
)

# 创建导入库目标，统一管理库文件
add_library(libgpiod SHARED IMPORTED)
add_library(libgpiodcxx SHARED IMPORTED)

# 设置导入库的属性
set_target_properties(libgpiod PROPERTIES
        IMPORTED_LOCATION ${GPIOD_LIB_DIR}/libgpiod.so
        INTERFACE_INCLUDE_DIRECTORIES ${GPIOD_INCLUDE_DIR}
)

set_target_properties(libgpiodcxx PROPERTIES
        IMPORTED_LOCATION ${GPIOD_LIB_DIR}/libgpiodcxx.so
        INTERFACE_INCLUDE_DIRECTORIES ${GPIOD_INCLUDE_DIR}
        INTERFACE_LINK_LIBRARIES libgpiod
)

# 确保导入库在libgpiod构建完成后再被使用
add_dependencies(libgpiod libgpiod-project)
add_dependencies(libgpiodcxx libgpiod-project)

add_executable(my_project main.cpp)

# 链接C++绑定库
target_link_libraries(my_project PRIVATE libgpiodcxx)

额外说明 #

• 自包含构建验证：构建完成后，${GPIOD_BIN}目录下会生成完整的头文件和库文件。移植到目标设备时，需要将libgpiod.so和libgpiodcxx.so复制到设备的系统库路径（如/usr/lib），或者通过LD_LIBRARY_PATH环境变量指定库的所在目录。
• 交叉编译适配：如果需要针对嵌入式设备交叉编译，需在CONFIGURE_COMMAND中添加交叉编译工具链参数，例如--host=arm-linux-gnueabihf，确保生成对应架构的库文件。

内容的提问来源于stack exchange，提问作者Moritz