Build a module instead of a shared library. (#207)

Fix #202.

This commit switches the default type in CMake from `SHARED` to `MODULE`.

Using [`SUFFIX`](https://cmake.org/cmake/help/latest/prop_tgt/SUFFIX.html)
property of CMake targets to explicitly specify the module extension when building for
a XNU-based platform (macOS, iOS, watchOS, etc.) and Windows such as to allow
OpenSSL to find the provider on a given platform.

.github/workflows/windows.yml

@@ -80,11 +80,8 @@ jobs:
           key: ${{ runner.os }}-cygwinopenssl32
       - name: build oqs-provider
         run: bash -c "git config --global --add safe.directory $(cygpath -u $PWD) && liboqs_DIR='${{ env.IP }}' cmake -GNinja -DCMAKE_C_COMPILER=gcc -DOPENSSL_ROOT_DIR=/opt/openssl32 -S . -B _build && cd _build && ninja && cd .."
-      - name: Adapt oqsprovider.dll name
-        run: bash -c "cp oqsprovider-1.dll oqsprovider.dll"
-        working-directory: _build/bin
       - name: Check Openssl providers
-        run: bash -c "OPENSSL_MODULES=_build/bin /opt/openssl32/bin/openssl list -providers -provider oqsprovider -provider default"
+        run: bash -c "OPENSSL_MODULES=_build/lib /opt/openssl32/bin/openssl list -providers -provider oqsprovider -provider default"
       - name: Run tests
         run: bash -c "echo $PATH && PATH=/opt/openssl32/bin:/usr/bin ctest -V"
         working-directory: _build
@@ -200,5 +197,5 @@ jobs:
         uses: actions/upload-artifact@v3
         with:
           name: oqs-provider-msvc
-          path: D:/a/oqs-provider/oqs-provider/_build/bin/oqsprovider.dll
+          path: D:/a/oqs-provider/oqs-provider/_build/lib/oqsprovider.dll
 

oqsprov/CMakeLists.txt

@@ -31,7 +31,7 @@ set(PROVIDER_SOURCE_FILES
 set(PROVIDER_HEADER_FILES
   oqs_prov.h oqs_endecoder_local.h
 )
-add_library(oqsprovider SHARED ${PROVIDER_SOURCE_FILES})
+add_library(oqsprovider MODULE ${PROVIDER_SOURCE_FILES})
 if (USE_ENCODING_LIB)
   add_dependencies(oqsprovider encoder)
 endif()
@@ -43,8 +43,35 @@ set_target_properties(oqsprovider
     LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib"
     VERSION ${OQSPROVIDER_VERSION_TEXT}
     SOVERSION 1
+    # Compatibility version (-compatibility_version) and current version
+    # (-current_version) are not compatible with a `MODULE` library.
+    # However, `VERSION` and `SOVERSION` set these two flags.
+    # The following two flags remove them.
+    MACHO_COMPATIBILITY_VERSION OFF
+    MACHO_CURRENT_VERSION OFF
     # For Windows DLLs
     RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/bin")
+
+if (APPLE)
+  # OpenSSL looks for `.dylib` files on XNU-based platforms.
+  # Because `MODULE` writes to a `.so` file by default, we must explicitely
+  # set the suffix here.
+  set_target_properties(oqsprovider
+    PROPERTIES
+    SUFFIX ".dylib"
+  )
+endif()
+
+if (CYGWIN OR MSVC)
+  # OpenSSL looks for `.dll` files on Windows platforms.
+  # Because `MODULE` writes to a `.so` file by default, we must explicitely
+  # set the suffix here.
+  set_target_properties(oqsprovider
+    PROPERTIES
+    SUFFIX ".dll"
+  )
+endif()
+
 target_link_libraries(oqsprovider OQS::oqs ${OPENSSL_CRYPTO_LIBRARY} ${OQS_ADDL_SOCKET_LIBS})
 if (USE_ENCODING_LIB)
   target_link_libraries(oqsprovider qsc_key_encoder)

test/CMakeLists.txt

@@ -1,9 +1,5 @@
 include(GNUInstallDirs)
-if (WIN32 OR CYGWIN)
-set(OQS_PROV_BINARY_DIR ${CMAKE_BINARY_DIR}/bin)
-else()
 set(OQS_PROV_BINARY_DIR ${CMAKE_BINARY_DIR}/lib)
-endif()
 
 add_test(
   NAME oqs_signatures