8239563: Reduce public exports in dynamic libraries built from JDK st…

…atic libraries

Reviewed-by: dholmes, ihse

make/autoconf/flags-cflags.m4

@@ -697,7 +697,10 @@ AC_DEFUN([FLAGS_SETUP_CFLAGS_HELPER],
   # JDK libraries.
   STATIC_LIBS_CFLAGS="-DSTATIC_BUILD=1"
   if test "x$TOOLCHAIN_TYPE" = xgcc || test "x$TOOLCHAIN_TYPE" = xclang; then
-    STATIC_LIBS_CFLAGS="$STATIC_LIBS_CFLAGS -ffunction-sections -fdata-sections"
+    STATIC_LIBS_CFLAGS="$STATIC_LIBS_CFLAGS -ffunction-sections -fdata-sections \
+      -DJNIEXPORT='__attribute__((visibility(\"hidden\")))'"
+  else
+    STATIC_LIBS_CFLAGS="$STATIC_LIBS_CFLAGS -DJNIEXPORT="
   fi
   if test "x$TOOLCHAIN_TYPE" = xgcc; then
     # Disable relax-relocation to enable compatibility with older linkers

src/java.base/unix/native/include/jni_md.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -29,16 +29,26 @@
 #ifndef __has_attribute
   #define __has_attribute(x) 0
 #endif
+
+#ifndef JNIEXPORT
+  #if (defined(__GNUC__) && ((__GNUC__ > 4) || (__GNUC__ == 4) && (__GNUC_MINOR__ > 2))) || __has_attribute(visibility)
+    #ifdef ARM
+      #define JNIEXPORT     __attribute__((externally_visible,visibility("default")))
+    #else
+      #define JNIEXPORT     __attribute__((visibility("default")))
+    #endif
+  #else
+    #define JNIEXPORT
+  #endif
+#endif
+
 #if (defined(__GNUC__) && ((__GNUC__ > 4) || (__GNUC__ == 4) && (__GNUC_MINOR__ > 2))) || __has_attribute(visibility)
   #ifdef ARM
-    #define JNIEXPORT     __attribute__((externally_visible,visibility("default")))
     #define JNIIMPORT     __attribute__((externally_visible,visibility("default")))
   #else
-    #define JNIEXPORT     __attribute__((visibility("default")))
     #define JNIIMPORT     __attribute__((visibility("default")))
   #endif
 #else
-  #define JNIEXPORT
   #define JNIIMPORT
 #endif
 

src/java.base/windows/native/include/jni_md.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 1998, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,7 +26,9 @@
 #ifndef _JAVASOFT_JNI_MD_H_
 #define _JAVASOFT_JNI_MD_H_
 
-#define JNIEXPORT __declspec(dllexport)
+#ifndef JNIEXPORT
+  #define JNIEXPORT __declspec(dllexport)
+#endif
 #define JNIIMPORT __declspec(dllimport)
 #define JNICALL __stdcall