cmake_export_symbol: Darwin compatibility

The Darwin platform prefixes all C symbols with an underscore.  At
link-time of a shared library, libressl generates a list of symbols to
export, but does not prefix each symbol with an underscore.

This commit addresses that issue.

1 files changed, 7 insertions, 1 deletions

diff --git a/cmake_export_symbol.cmake b/cmake_export_symbol.cmake
index 2928c6b..cbc65f2 100644
--- a/cmake_export_symbol.cmake
+++ b/cmake_export_symbol.cmake
@@ -10,7 +10,13 @@ macro(export_symbol TARGET FILENAME)
                 target_sources(${TARGET} PRIVATE ${DEF_FILENAME})
 
         elseif(APPLE)
-                set(FLAG "-exported_symbols_list ${FILENAME}")
+                file(READ ${FILENAME} SYMBOLS)
+                string(REGEX REPLACE "\n$" "" SYMBOLS ${SYMBOLS})
+                string(REPLACE "\n" "\n_" SYMBOLS ${SYMBOLS})
+                string(REGEX REPLACE "(.)$" "\\1\\n" SYMBOLS ${SYMBOLS})
+                string(REPLACE ".sym" ".exp" EXP_FILENAME ${FILENAME})
+                file(WRITE ${EXP_FILENAME} "_${SYMBOLS}")
+                set(FLAG "-exported_symbols_list ${EXP_FILENAME}")
                 set_target_properties(${TARGET} PROPERTIES LINK_FLAGS ${FLAG})
 
         elseif(CMAKE_SYSTEM_NAME MATCHES "HP-UX")