Linking the static cryptographic OpenSSL library in CMake

Question

I want to statically link the libraries listed below:

set_target_properties(exec PROPERTIES LINK_SEARCH_START_STATIC 1) set_target_properties(exec PROPERTIES LINK_SEARCH_END_STATIC 1) set(CMAKE_FIND_LIBRARY_SUFFIXES .a ${CMAKE_FIND_LIBRARY_SUFFIXES}) find_library(SODIUM_LIB libsodium.a REQUIRED) find_library(SSL_LIB libssl.a REQUIRED) find_library(CRYPTO_LIB libcrypto.a REQUIRED) find_library(DL_LIB libdl.a REQUIRED) message(${SODIUM_LIB}) message(${SSL_LIB}) message(${CRYPTO_LIB}) set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -static-libgcc -static-libstdc++") target_link_libraries( exec ${SODIUM_LIB} ${SSL_LIB} ${CRYPTO_LIB} ${DL_LIB} 

I do not want to add -static to CMAKE_EXE_LINKER_FLAGS , because in this case everything is related to static. CMake finds static libraries:

 /usr/local/lib/libsodium.a /usr/lib/x86_64-linux-gnu/libssl.a /usr/lib/x86_64-linux-gnu/libcrypto.a 

and it seems that everything is connected statically, except libcrypto :

 readelf -d exec 0x0000000000000001 (NEEDED) Shared library: [libcrypto.so.1.0.0] 0x0000000000000001 (NEEDED) Shared library: [libc.so.6] 0x0000000000000001 (NEEDED) Shared library: [ld-linux-x86-64.so.2] 

How can I link libcrypto statically with my executable?

Answer 1

The CMake documentation, starting with version 3.4 on the FindOpenSSL page, says:

Set OPENSSL_USE_STATIC_LIBS to TRUE to search for static libraries.

(Assuming they are found, they will be used)

Example:

 cmake_minimum_required(VERSION 3.4) project(Foo) set(SOURCE_FILES main.cpp) find_package(OpenSSL REQUIRED) if(OPENSSL_FOUND) set(OPENSSL_USE_STATIC_LIBS TRUE) endif() add_executable(${PROJECT_NAME} ${SOURCE_FILES}) target_link_libraries(${PROJECT_NAME} OpenSSL::Crypto)