add C++ linkage fixes + allow disabling tests

CMakeLists.txt

@@ -8,22 +8,24 @@ target_compile_definitions(base122 PUBLIC BASE122_STATIC)
 target_compile_definitions(base122 PRIVATE BASE122_COMPILING)
 target_compile_definitions(base122_shared PRIVATE BASE122_COMPILING)
 
-add_executable (test-libbase122 test/test.c test/assertions.c)
-target_link_libraries(test-libbase122 base122)
-# Use C99 in test-libbase122.
-set_property(TARGET test-libbase122 PROPERTY C_STANDARD 99)
-if (ENABLE_FUZZER)
-    message ("Enabling fuzzer targets")
-    add_executable (fuzz-libbase122 test/fuzz.c test/assertions.c)
-    target_compile_options(fuzz-libbase122 PRIVATE -fsanitize=fuzzer)
-    target_link_options(fuzz-libbase122 PRIVATE -fsanitize=fuzzer)
-    target_link_libraries(fuzz-libbase122 base122)
-    set_property(TARGET fuzz-libbase122 PROPERTY C_STANDARD 99)
+if (ENABLE_BASE122_TEST)
+    add_executable (test-libbase122 test/test.c test/assertions.c)
+    target_link_libraries(test-libbase122 base122)
+    # Use C99 in test-libbase122.
+    set_property(TARGET test-libbase122 PROPERTY C_STANDARD 99)
+    if (ENABLE_FUZZER)
+        message ("Enabling fuzzer targets")
+        add_executable (fuzz-libbase122 test/fuzz.c test/assertions.c)
+        target_compile_options(fuzz-libbase122 PRIVATE -fsanitize=fuzzer)
+        target_link_options(fuzz-libbase122 PRIVATE -fsanitize=fuzzer)
+        target_link_libraries(fuzz-libbase122 base122)
+        set_property(TARGET fuzz-libbase122 PROPERTY C_STANDARD 99)
+    endif()
+    target_include_directories(test-libbase122 PRIVATE ${CMAKE_SOURCE_DIR})
+
+    enable_testing()
+    add_test (NAME test-libbase122 COMMAND test-libbase122)
 endif()
-target_include_directories(test-libbase122 PRIVATE ${CMAKE_SOURCE_DIR})
-
-enable_testing()
-add_test (NAME test-libbase122 COMMAND test-libbase122)
 
 add_executable (b122 src/b122.c)
 target_link_libraries(b122 base122)

src/base122.h

@@ -1,6 +1,10 @@
 #ifndef LIBBASE122_H
 #define LIBBASE122_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #include <stddef.h> /* for size_t */
 
 typedef struct {
@@ -34,4 +38,9 @@ int BASE122_EXPORT base122_encode(const unsigned char *in, size_t in_len, unsign
 int BASE122_EXPORT base122_decode(const unsigned char *in, size_t in_len, unsigned char *out,
                                   size_t out_len, size_t *out_written, base122_error_t *error);
 
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* LIBBASE122_H */

src/util.h

@@ -1,6 +1,10 @@
 #ifndef LIBBASE_122_UTIL_H
 #define LIBBASE_122_UTIL_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #include <assert.h>
 #include <stddef.h> /* for size_t */
 
@@ -142,4 +146,9 @@ static int bitwriter_write(bitwriter_t *writer, size_t nbits, unsigned char in)
   return 0;
 }
 
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* LIBBASE_122_UTIL_H */