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C++-Fehler "undefined reference to `dlopen'" beheben

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Problem:

Beim Kompilieren der C++-Anwendung erscheinen eine oder mehrere der folgenden oder ähnlichen Fehlermeldungen (vollständiges Fehlermeldungs-Log-Beispiel unten)

linker_error.log
dso_dlfcn.c:(.text+0x17): undefined reference to `dlopen'
/usr/bin/ld: dso_dlfcn.c:(.text+0x2a): undefined reference to `dlsym'
/usr/bin/ld: dso_dlfcn.c:(.text+0x35): undefined reference to `dlclose'
dso_dlfcn.c:(.text+0x1b7): undefined reference to `dlsym'
/usr/bin/ld: dso_dlfcn.c:(.text+0x282): undefined reference to `dlerror'
dso_dlfcn.c:(.text+0x2f5): undefined reference to `dlopen'
/usr/bin/ld: dso_dlfcn.c:(.text+0x369): undefined reference to `dlclose'
/usr/bin/ld: dso_dlfcn.c:(.text+0x3a5): undefined reference to `dlerror'
dso_dlfcn.c:(.text+0x466): undefined reference to `dladdr'
/usr/bin/ld: dso_dlfcn.c:(.text+0x4d7): undefined reference to `dlerror'

Lösung

Die dl-Bibliothek (dynamischer Linker) muss mit der ausführbaren Datei verlinkt werden. Bei manueller Ausführung von gcc die Option -ldl verwenden, zum Beispiel:

build.sh
gcc -o myexe main.cpp -ldl

Bei Verwendung von CMake:

CMakeLists.txt
add_executable(myexe main.cpp)
target_link_libraries(myexe dl)

Vollständiges Fehler-Log-Beispiel:

full_error.log
/usr/bin/ld: /home/uli/.conan/data/openssl/1.1.1k/_/_/package/6af9cc7cb931c5ad942174fd7838eb655717c709/lib/libcrypto.a(dso_dlfcn.o): in function `dlfcn_globallookup':
dso_dlfcn.c:(.text+0x17): undefined reference to `dlopen'
/usr/bin/ld: dso_dlfcn.c:(.text+0x2a): undefined reference to `dlsym'
/usr/bin/ld: dso_dlfcn.c:(.text+0x35): undefined reference to `dlclose'
/usr/bin/ld: /home/uli/.conan/data/openssl/1.1.1k/_/_/package/6af9cc7cb931c5ad942174fd7838eb655717c709/lib/libcrypto.a(dso_dlfcn.o): in function `dlfcn_bind_func':
dso_dlfcn.c:(.text+0x1b7): undefined reference to `dlsym'
/usr/bin/ld: dso_dlfcn.c:(.text+0x282): undefined reference to `dlerror'
/usr/bin/ld: /home/uli/.conan/data/openssl/1.1.1k/_/_/package/6af9cc7cb931c5ad942174fd7838eb655717c709/lib/libcrypto.a(dso_dlfcn.o): in function `dlfcn_load':
dso_dlfcn.c:(.text+0x2f5): undefined reference to `dlopen'
/usr/bin/ld: dso_dlfcn.c:(.text+0x369): undefined reference to `dlclose'
/usr/bin/ld: dso_dlfcn.c:(.text+0x3a5): undefined reference to `dlerror'
/usr/bin/ld: /home/uli/.conan/data/openssl/1.1.1k/_/_/package/6af9cc7cb931c5ad942174fd7838eb655717c709/lib/libcrypto.a(dso_dlfcn.o): in function `dlfcn_pathbyaddr':
dso_dlfcn.c:(.text+0x466): undefined reference to `dladdr'
/usr/bin/ld: dso_dlfcn.c:(.text+0x4d7): undefined reference to `dlerror'
/usr/bin/ld: /home/uli/.conan/data/openssl/1.1.1k/_/_/package/6af9cc7cb931c5ad942174fd7838eb655717c709/lib/libcrypto.a(dso_dlfcn.o): in function `dlfcn_unload':
dso_dlfcn.c:(.text+0x6b8): undefined reference to `dlclose'
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