cmake: use readelf to extract soname from shared elf library

cmake/macros.cmake

@@ -208,9 +208,14 @@ function(target_get_dynamic_library DEST TARGET)
       endif()
     endforeach()
   else()
+    if(UNIX AND NOT APPLE)
+      find_program(READELF_BIN NAMES readelf)
+    endif()
     # 1. find the target library a file might be symbolic linking to
-    # 2. find all other files in the same folder that symbolic link to it
+    # 2. if readelf is available, parse the output of `readelf -d` and output the "(SONAME)" line
-    # 3. sort all these files, and select the 1st item on Linux, and last on macOS
+    # 3. Else:
+    #     1. find all other files in the same folder that symbolic link to it
+    #     2. sort all these files, and select the 1st item on Linux, and last on macOS
     set(location_properties IMPORTED_LOCATION)
     if(CMAKE_BUILD_TYPE)
       list(APPEND location_properties IMPORTED_LOCATION_${CMAKE_BUILD_TYPE})
@@ -228,6 +233,16 @@ function(target_get_dynamic_library DEST TARGET)
         get_target_property(library_path "${TARGET}" ${location_property})
         message(DEBUG "get_target_property(${TARGET} ${location_property}) -> ${library_path}")
         if(EXISTS "${library_path}")
+          if(READELF_BIN)
+            execute_process(COMMAND "${READELF_BIN}" -d "${library_path}" RESULTS_VARIABLE readelf_result OUTPUT_VARIABLE readelf_output)
+            if(readelf_output)
+              string(REGEX MATCH "\\(SONAME\\).*\\[([0-9A-Za-z_.-]+)\\]" soname "${readelf_output}")
+              if(soname)
+                set(result "${CMAKE_MATCH_1}")
+              endif()
+            endif()
+          endif()
+          if(NOT result)
             get_filename_component(library_path "${library_path}" ABSOLUTE)
             while (IS_SYMLINK "${library_path}")
               read_absolute_symlink(library_path "${library_path}")
@@ -257,6 +272,7 @@ function(target_get_dynamic_library DEST TARGET)
             get_filename_component(result "${item}" NAME)
           endif()
         endif()
+      endif()
     endforeach()
   endif()
   if(result)