cmake - 是否可以在运行时将可执行文件链接到具有相对路径的共享库？

Question

Lets say I have this:

../project_dir
    main.cpp
    mylib.cpp
    mylib.h

Building steps will be:

g++ -c mylib.cpp -o mylib.o
g++ -shared -o libmylib.so mylib.o
g++ -L$(pwd) -Wl,-rpath='$ORIGIN' -o exec main.cpp -lmylib

exec will be my binary executable output. When I testing with:

ldd exec

the output line is:

libmylib.so => /full/path/to/build/directory/libmylib.so (0x00007f75fdd1f000)

That output line is my question, is it possible to get:

libmylib.so => ./libmylib.so

so whenever I move the executable file, I can move the shared library along with it. If it is possible, how to do this with cmake?

Answer 1

Juste add in your CMakefiles.txt

set(CMAKE_INSTALL_RPATH "$ORIGIN")
set(CMAKE_BUILD_WITH_INSTALL_RPATH TRUE) # only if you want copy from the build tree

Answer 2

When you launch ldd to check your app shared library dependencies, it always prints absolute paths. But if you are using the -rpath oprtion together with the $ORIGIN variable, everything will work as you expect. You can move the executable and the shared library, remove the original build directory and you will still be able to launch your app.

This is how you can do it using cmake :

project(myapp)
cmake_minimum_required(VERSION 2.8)

set(APP_SRC main.cpp)
set(LIB_SRC mylib.cpp)

link_directories(${CMAKE_CURRENT_BINARY_DIR})

SET(CMAKE_EXE_LINKER_FLAGS
          "${CMAKE_EXE_LINKER_FLAGS} -Wl,-rpath -Wl,$ORIGIN")

add_library(mylib SHARED ${LIB_SRC})

add_executable(${PROJECT_NAME} ${APP_SRC})

target_link_libraries(${PROJECT_NAME} mylib)

Answer 3

I had to put curly braces around ${ORIGIN} and add path for the library to link:

SET(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -L${CMAKE_BINARY_DIR} -lmyLibrary -Wl,-rpath -Wl,${ORIGIN}")
set(CMAKE_INSTALL_RPATH "${ORIGIN}")
set(CMAKE_BUILD_WITH_INSTALL_RPATH TRUE)