Require shared library with dependencies in cmake - c++

I'm new to cmake, so I'm having trouble figuring out how to model the following:
My program requires a third party library that I only have access to in the form of headers and *.so files. It also ships many of its dependencies as *.so files. How do I make sure that everything compiles and links correctly, ideally in the "correct" cmake way?
I've tried this
cmake_minimum_required (VERSION 3.8)
project ("Test")
add_executable (MyApp "MyApp.cpp")
link_directories("/path/to/lib")
target_include_directories(MyApp PUBLIC "/path/to/headers")
This compiles but fails at the linking stage.
Then I tried
cmake_minimum_required (VERSION 3.8)
project ("Test")
list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
add_executable (MyApp "MyApp.cpp")
find_package(Library REQUIRED)
target_link_libraries(MyApp PUBLIC Library::Library)
And cmake/FindLibrary.cmake following https://pabloariasal.github.io/2018/02/19/its-time-to-do-cmake-right/ (truncated):
...
if(Library_FOUND AND NOT TARGET Library::Library)
add_library(Library::Library SHARED IMPORTED)
set_target_properties(Library::Library PROPERTIES
INTERFACE_INCLUDE_DIRECTORIES "${Library_INCLUDE_DIR}"
)
set_target_properties(Library::Library PROPERTIES
IMPORTED_LOCATION "/path/to/library.so"
)
endif()
This compiles and links, but the required other *.so files are not found at runtime. I suppose I need to add them also as libraries somehow, although I don't want them to be exported in FindLibrary.cmake. How do I do this correctly?

You can use IMPORTED libraries:
add_library(externalLib SHARED IMPORTED GLOBAL)
set_property(TARGET externalLib PROPERTY IMPORTED_LOCATION "/path/to/lib.so")
target_include_directories(externalLib INTERFACE "/path/to/headers")
target_link_directories(externalLib INTERFACE /path/to/libs)
target_link_libraries(externalLib INTERFACE -ldep1 -ldep2)
Then you can just depend on it:
target_link_libraries(MyApp PRIVATE externalLib)

Related

How do I include the assimp library in the project via CMake?

I followed the asssimp library's installation guide, which used Visual Studio and did all the necessary steps to include it in the project through the GUI when I did everything through pure CMake and MinGW.
I need to include headers and two library files in my project: assimp-[...].dll and assimp-[...].lib
My assimp proj hierarchy
I started to figure out how to write my own CMakeLists.txt and came up with this:
cmake_minimum_required(VERSION 3.2 FATAL_ERROR)
project(Assimp)
add_library(assimp SHARED IMPORTED GLOBAL)
file(GLOB_RECURSE ROOT_SOURCE "./assimp/*.cpp")
file(GLOB_RECURSE ROOT_INLINE "./assimp/*.inl")
file(GLOB_RECURSE ROOT_HPP "./assimp/*.hpp")
file(GLOB_RECURSE ROOT_HEADER "./assimp/*.h")
file(GLOB_RECURSE COMPILER_HEADER "./assimp/Compiler/*.h")
file(GLOB_RECURSE PORT_HEADER "./assimp/port/AndroidJNI/*.h")
source_group("Compiler Files" FILES ${COMPILER_HEADER})
source_group("Port Files" FILES ${PORT_HEADER})
include(GNUInstallDirs)
if(BUILD_STATIC_LIBS)
add_library(assimp_static STATIC
${ROOT_SOURCE} ${ROOT_INLINE} ${ROOT_HPP}
${ROOT_HEADER} ${COMPILER_HEADER} ${PORT_HEADER}
)
target_link_libraries(assimp_static PUBLIC assimp)
add_library(assimp::assimp_static ALIAS assimp_static)
endif()
if(BUILD_SHARED_LIBS)
add_library(assimp_shared SHARED
${ROOT_SOURCE} ${ROOT_INLINE} ${ROOT_HPP}
${ROOT_HEADER} ${COMPILER_HEADER} ${PORT_HEADER}
)
target_link_libraries(assimp_shared PUBLIC assimp)
add_library(assimp::assimp_shared ALIAS assimp_shared)
endif()
set_property(TARGET assimp PROPERTY IMPORTED_LOCATION "${PROJECT_SOURCE_DIR}/external/assimp/lib/assimp-vc143-mtd.dll")
set_property(TARGET assimp PROPERTY IMPORTED_IMPLIB "${PROJECT_SOURCE_DIR}/external/assimp/lib/assimp-vc143-mtd.lib")
After that I'm linking it in the main CMakeLists.txt:
add_executable(${PROJECT_NAME} [src code files here])
add_subdirectory(external/assimp)
target_link_libraries(${PROJECT_NAME} PRIVATE assimp)
But after that, I can't see any header from this library, as well as its directory, and I'm not even sure if the dynamic libraries from the "lib" folder are included correctly.
What am I doing wrong?

Deplying a C++ application on Linux- linking everything statically to simplify deployment?

I am building a C++ project from Github and want to deploy the code to a remote Linux machine. This is all new to me.
The project has a main.cpp, which includes the various headers/sources like a library.
The CMake outputs an executable (to represent main.cpp) AND a separate static library. The project also uses OpenSSL, which I have linked statically.
I presume the OpenSSL functions are included within the static library? So when I deploy, I don't need to copy-over or install any OpenSSL on the remote machine?
Is it possible to modify the CMake so the application and the library are merged in to one file?
I am trying to make deployment as simple as copying over a single file, if this is possible.
Any additional advice/references are most-welcome.
UPDATE the CMake script:
cmake_minimum_required(VERSION 3.20)
set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/CMake;${CMAKE_MODULE_PATH}")
project(helloworld C CXX)
set (CMAKE_CXX_STANDARD 20)
set (CMAKE_BUILD_TYPE Release)
set (BUILD_MAIN TRUE)
set (BUILD_SHARED_LIBS FALSE)
set (OPENSSL_USE_STATIC_LIBS TRUE)
set(CMAKE_POSITION_INDEPENDENT_CODE ON)
set( HELLOWORLD_HEADERS helloworld/File1.h helloworld/File2.h )
set( HELLOWORLD_SOURCES helloworld/File1.cpp helloworld/File2.cpp )
# Static library
add_library( helloworld ${HELLOWORLD_SOURCES} ${HELLOWORLD_HEADERS} )
# Rapidjson
include_directories(/tmp/rapidjson/include/)
# OpenSSL
if (NOT OPENSSL_FOUND)
find_package(OpenSSL REQUIRED)
endif()
add_definitions(${OPENSSL_DEFINITIONS})
target_include_directories(helloworld PUBLIC $<BUILD_INTERFACE:${OPENSSL_INCLUDE_DIR}>)
target_link_libraries(helloworld PRIVATE ${OPENSSL_LIBRARIES})
set( HELLOWORLD_INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR})
include(GNUInstallDirs)
target_include_directories(helloworld PUBLIC
$<BUILD_INTERFACE:${HELLOWORLD_INCLUDE_DIRS}/>
$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/helloworld>
)
set_target_properties(helloworld PROPERTIES PUBLIC_HEADER "${HELLOWORLD_HEADERS}")
add_library(helloworld::helloworld ALIAS helloworld)
option(HELLOWORLD_INSTALL "Install HelloWorld" TRUE)
if (HELLOWORLD_INSTALL)
install(TARGETS helloworld
EXPORT helloworld
ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/helloworld/
)
configure_file("${CMAKE_CURRENT_LIST_DIR}/helloworld-config.cmake.in" "${CMAKE_BINARY_DIR}/helloworld-config.cmake" #ONLY)
install(FILES "${CMAKE_BINARY_DIR}/helloworld-config.cmake" DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/helloworld")
install(EXPORT helloworld
FILE helloworld-targets.cmake
NAMESPACE helloworld::
DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/helloworld
)
endif()
if (BUILD_MAIN)
add_executable(main main.cpp)
target_link_libraries(main helloworld)
endif()
ITNOA
I it is very helpful to make URL of your GitHub's project, but I write some public notes about that
In generally in CMake for static linking your library to your executable, you can write simple like below (from official CMake example)
add_library(archive archive.cpp zip.cpp lzma.cpp)
add_executable(zipapp zipapp.cpp)
target_link_libraries(zipapp archive)
In above example your executable file is just work without needing .a library file and you can simple copy single file.
if you want to make all of thing static, you make sure all dependencies make static link to your project, like CMake: how to produce binaries "as static as possible"
if you want to prevent library creation, Probably in your CMake file, you can find add_library command, and add_executable command. you can remove add_library command and add all sources to add_executable command.
for example add_executable(a.out main.cpp lib.cpp)

How do I link a library using CMake?

I'm trying to add a new library to a project built using CMake and am having trouble. I'm trying to follow this. I've made a test project that looks like this:
cmake_test/
test.cpp
CMakeLists.txt
liblsl/
include/
lsl_cpp.h
CMakeLists.txt
liblsl64.dll
liblsl64.so
build/
the CMakeLists.txt in cmake_test looks like this:
cmake_minimum_required(VERSION 3.10)
# set the project name and version
project(Tutorial VERSION 1.0)
# specify the C++ standard
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED True)
add_executable(Tutorial test.cpp)
add_subdirectory(liblsl)
target_link_libraries(Tutorial PUBLIC ${LSL_LIBRARY})
and the CMakeLists.txt in liblsl looks like this:
find_path(LSL_INCLUDE_DIR lsl_cpp.h)
find_library(LSL_LIBRARY liblsl64)
include_directories(${LSL_INCLUDE_DIR})
But I keep getting the error No rule to make target '.../liblsl64.lib', needed by 'Tutorial.exe'. Stop.
Any idea what I'm doing wrong?
I'm on Windows 10 using mingw-w64 v5.4.0 if that makes any difference.
CMakeLists.txt in cmake_test:
cmake_minimum_required(VERSION 3.10)
project(Tutorial VERSION 1.0)
add_subdirectory(liblsl)
add_executable(Tutorial test.cpp)
target_compile_features(Tutorial PUBLIC cxx_std_11)
target_link_libraries(Tutorial PUBLIC liblsl)
CMakeLists.txt in liblsl:
add_library(liblsl SHARED IMPORTED GLOBAL)
set_target_properties(liblsl PROPERTIES INTERFACE_INCLUDE_DIRECTORIES "${CMAKE_CURRENT_SOURCE_DIR}/include")
set_target_properties(liblsl PROPERTIES IMPORTED_LOCATION "${CMAKE_CURRENT_SOURCE_DIR}/liblsl64.so")
For Windows use:
set_target_properties(liblsl PROPERTIES IMPORTED_LOCATION "${CMAKE_CURRENT_SOURCE_DIR}/liblsl64.dll")
set_target_properties(liblsl PROPERTIES IMPORTED_IMPLIB "${CMAKE_CURRENT_SOURCE_DIR}/liblsl64.lib")
In add_library, you say SHARED because your library is a shared one (so/dll), you say IMPORTED because you don't want to build the library, and you say GLOBAL because you want it to be visible outside liblsl.

CMake: linking against a library linked to Qt5

I have a library which uses Qt5. I build it with this CMakeLists.txt file:
cmake_minimum_required (VERSION 3.0)
project (testLib LANGUAGES CXX)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTOUIC ON)
set(CMAKE_INCLUDE_CURRENT_DIR ON)
find_package(Qt5 REQUIRED Widgets)
add_library(testLib SHARED
src/TestClass.cpp
src/TestClass.h
)
target_include_directories(testLib PUBLIC
${CMAKE_CURRENT_SOURCE_DIR}/src
)
target_link_libraries(testLib PUBLIC Qt5::Widgets)
export(TARGETS testLib FILE testLib-exports.cmake)
Now I try to link an executable against this library in the build path. This is what I've tried so far:
cmake_minimum_required (VERSION 3.0)
project(TestProject)
add_executable(myexec src/main.cpp )
include(/path/to/testLib-exports.cmake)
target_link_libraries(myexec testLib)
I am getting this error:
Target "myexec" links to target "Qt5::Widgets" but the target was not
found. Perhaps a find_package() call is missing for an IMPORTED
target, or an ALIAS target is missing?
I don't want to explicitly use find_package() in myexec's cmake file, but want it to be transitive. How should I link against testLib then? If the answer is not in the build path it is fine.
EDIT: I changed the export line to:
export(TARGETS testLib FILE testLib-exports.cmake EXPORT_LINK_INTERFACE_LIBRARIES)
This seems to be exactly what I need, but the generated files with and without EXPORT_LINK_INTERFACE_LIBRARIES are identical. Both if them say
This file does not depend on other imported targets which have
been exported from the same project but in a separate export set.
As far as I understand, it should use testLib's target LINK_INTERFACE_LIBRARIES property, but I noticed that it is NOTFOUND. maybe this is the problem? However, INTERFACE_LINK_LIBRARIES has Qt5::Widgets.

Right way of creating a library, installing it and linking to another project using CMake

I have a set of files that I want to make into a library and then use that library in another project. This it how it looks like right now
cmake_minimum_required(VERSION 2.8)
aux_source_directory(. SRC_LIST)
SET(CMAKE_CXX_FLAGS "-std=c++11 -fopenmp -fPIC")
add_library (helperlibs lib1.cpp lib2.cpp lib3.cpp lib4.cpp )
INSTALL(TARGETS helperlibs
DESTINATION "${HOME}/lib"
)
INSTALL(FILES lib1.h lib2.h lib3.h lib4.h helperheader.h
DESTINATION "${HOME}/include/helperlibs"
)
In this code Lib4 depends on Lib1-3 and Lib3 depends on Lib1-2 and Lib2 depends on Lib1. Each of these cpp files also depend on a helperheader.h file that contains some definitions and structs.
In my project I have the following CMake file
cmake_minimum_required(VERSION 2.8)
aux_source_directory(. SRC_LIST)
SET( CMAKE_CXX_FLAGS "-std=c++11 -fopenmp -fPIC")
SET(MYINCS ${HOME}/include/helperlibs)
SET(MYLIBDIR ${HOME}/lib)
SET(MYLIBS ${MYLIBDIR}/libhelperlibs.a )
include_directories(${MYINCS})
add_executable(main main.cpp)
target_link_libraries(main ${MYLIBS})
So what I am wondering if you want to create a static library and link to from a another project using cmake is this the way you should write?
Embed the search paths into the library target as properties and create an export.
This way executables in the same build tree will find the library and its include files without you having to specify paths (they become implicit).
I needed to read the cmake documentation carefully a few times before it dawned on me how it should work.
http://www.cmake.org/cmake/help/v3.0/manual/cmake-packages.7.html#creating-packages
http://www.cmake.org/cmake/help/v3.0/manual/cmake-buildsystem.7.html
excerpt from a live example:
add_library(trustportal-util ${CMAKE_CURRENT_LIST_FILE} ${_source_files} ${_disabled_source_files} )
target_link_libraries(trustportal-util ${Boost_LIBRARIES})
if(APPLE)
find_library(SECURITY_FRAMEWORK Security)
target_link_libraries(trustportal-util ${SECURITY_FRAMEWORK})
else()
find_library(LIB_SSL ssl)
find_library(LIB_CRYPTO crypto)
target_link_libraries(trustportal-util ${LIB_SSL} ${LIB_CRYPTO})
endif()
target_compile_definitions(trustportal-util PUBLIC BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE)
target_include_directories(trustportal-util PUBLIC ${Boost_INCLUDE_DIRS})
target_include_directories(trustportal-util PRIVATE
$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
$<INSTALL_INTERFACE:include>)
target_include_directories(trustportal-util SYSTEM PUBLIC
$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
$<INSTALL_INTERFACE:include>)
install(TARGETS trustportal-util
EXPORT trustportal-utilExport
DESTINATION lib
INCLUDES DESTINATION include
)
INSTALL(EXPORT trustportal-utilExport DESTINATION lib)
One option is to do what you are currently doing where you place the includes and libs in a common location, perhaps /usr/include and /usr/lib on linux, or ${HOME} on both Windows/Linux, up to you.
Another option is available if you use git. You can include the project inside another using submodules. Then use include_directory(${submodule}) and build and link directly for every project. The advantage of this approach is that dependencies are more localised. One problem with this method is if you recursively do this, you may end up with duplicates of some projects and cmake will complain that two libraries have the same name.