Explicitly set visibility of public API functions when gcc is used

Windows builds already limit exporting of functions to those marked
with LZ4LIB_API tag.  The same behaviour could be achieved on other
platforms when a relatively fresh gcc is used.

This change assigns public visibility to all symbols marked with
LZ4LIB_API tag.  When the library is built in -fvisibility=hidden
mode, only these marked symbols will be exported.

diff --git a/lib/lz4.h b/lib/lz4.h
index bebe761..b0537fc 100644 (file)
--- a/lib/lz4.h
+++ b/lib/lz4.h
@@ -72,11 +72,15 @@ extern "C" {
 /*
 *  LZ4_DLL_EXPORT :
 *  Enable exporting of functions when building a Windows DLL
+*  LZ4LIB_API :
+*  Control library symbols visibility.
 */
 #if defined(LZ4_DLL_EXPORT) && (LZ4_DLL_EXPORT==1)
 #  define LZ4LIB_API __declspec(dllexport)
 #elif defined(LZ4_DLL_IMPORT) && (LZ4_DLL_IMPORT==1)
 #  define LZ4LIB_API __declspec(dllimport) /* It isn't required but allows to generate better code, saving a function pointer load from the IAT and an indirect jump.*/
+#elif defined(__GNUC__) && (__GNUC__ >= 4)
+#  define LZ4LIB_API __attribute__ ((__visibility__ ("default")))
 #else
 #  define LZ4LIB_API
 #endif

diff --git a/lib/lz4frame.h b/lib/lz4frame.h
index 9d9fe89..f33eee1 100644 (file)
--- a/lib/lz4frame.h
+++ b/lib/lz4frame.h
@@ -63,11 +63,15 @@ extern "C" {
 /*
 *  LZ4_DLL_EXPORT :
 *  Enable exporting of functions when building a Windows DLL
+*  LZ4FLIB_API :
+*  Control library symbols visibility.
 */
 #if defined(LZ4_DLL_EXPORT) && (LZ4_DLL_EXPORT==1)
 #  define LZ4FLIB_API __declspec(dllexport)
 #elif defined(LZ4_DLL_IMPORT) && (LZ4_DLL_IMPORT==1)
 #  define LZ4FLIB_API __declspec(dllimport)
+#elif defined(__GNUC__) && (__GNUC__ >= 4)
+#  define LZ4FLIB_API __attribute__ ((__visibility__ ("default")))
 #else
 #  define LZ4FLIB_API
 #endif