build: add option for reducing exports

Enabled automatically if boost >= 1.49.
See: https://svn.boost.org/trac/boost/ticket/2309

Also, check for a default visibility attribute, so that we can mark future
api functions correctly.

configure.ac

@@ -90,6 +90,12 @@ AC_ARG_ENABLE([hardening],
   [use_hardening=$enableval],
   [use_hardening=yes])
 
+AC_ARG_ENABLE([reduce-exports],
+  [AS_HELP_STRING([--enable-reduce-exports],
+  [attempt to reduce exported symbols in the resulting executables (default is yes)])],
+  [use_reduce_exports=$enableval],
+  [use_reduce_exports=auto])
+
 AC_ARG_ENABLE([ccache],
   [AS_HELP_STRING([--enable-ccache],
   [use ccache for building (default is yes if ccache is found)])],
@@ -396,6 +402,40 @@ AC_TRY_COMPILE([#include <sys/socket.h>],
 
 AC_SEARCH_LIBS([clock_gettime],[rt])
 
+AC_MSG_CHECKING([for visibility attribute])
+AC_LINK_IFELSE([AC_LANG_SOURCE([
+  int foo_def( void ) __attribute__((visibility("default")));
+  int main(){}
+  ])],
+  [
+    AC_DEFINE(HAVE_VISIBILITY_ATTRIBUTE,1,[Define if the visibility attribute is supported.])
+    AC_MSG_RESULT(yes)
+  ],
+  [
+    AC_MSG_RESULT(no)
+    if test x$use_reduce_exports = xyes; then
+      AC_MSG_ERROR([Cannot find a working visibility attribute. Use --disable-reduced-exports.])
+    fi
+      AC_MSG_WARN([Cannot find a working visibility attribute. Disabling reduced exports.])
+      use_reduce_exports=no
+  ]
+)
+
+if test x$use_reduce_exports != xno; then
+  AX_CHECK_COMPILE_FLAG([-fvisibility=hidden],[RE_CXXFLAGS="-fvisibility=hidden"],
+  [
+    if test x$use_reduce_exports = xyes; then
+      AC_MSG_ERROR([Cannot set default symbol visibility. Use --disable-reduced-exports.])
+    fi
+    AC_MSG_WARN([Cannot set default symbol visibility. Disabling reduced exports.])
+    use_reduce_exports=no
+  ])
+  if test x$use_reduce_exports != xno; then
+    AX_CHECK_LINK_FLAG([[-Wl,--exclude-libs,ALL]], [RELDFLAGS="-Wl,--exclude-libs,ALL"])
+    CXXFLAGS="$CXXFLAGS $RE_CXXFLAGS"
+  fi
+fi
+
 LEVELDB_CPPFLAGS=
 LIBLEVELDB=
 LIBMEMENV=
@@ -420,6 +460,35 @@ fi
 
 dnl Check for boost libs
 AX_BOOST_BASE
+
+if test x$use_reduce_exports != xno; then
+  AC_MSG_CHECKING([for working boost reduced exports])
+  TEMP_CPPFLAGS="$CPPFLAGS"
+  CPPFLAGS="$BOOST_CPPFLAGS $CPPFLAGS"
+  AC_PREPROC_IFELSE([AC_LANG_PROGRAM([[
+      @%:@include <boost/version.hpp>
+    ]], [[
+      #if BOOST_VERSION >= 104900
+      // Everything is okay
+      #else
+      #  error Boost version is too old
+      #endif
+    ]])],[
+      AC_MSG_RESULT(yes)
+    ],[:
+    if test x$use_reduce_exports = xauto; then
+      use_reduce_exports=no
+    else
+      if test x$use_reduce_exports = xyes; then
+        AC_MSG_ERROR([boost versions < 1.49 are known to be broken with reduced exports. Use --disable-reduced-exports.])
+      fi
+    fi
+    AC_MSG_RESULT(no)
+    AC_MSG_WARN([boost versions < 1.49 are known to have symbol visibility issues. Disabling reduced exports.])
+  ])
+  CPPFLAGS="$TEMP_CPPFLAGS"
+fi
+
 AX_BOOST_SYSTEM
 AX_BOOST_FILESYSTEM
 AX_BOOST_PROGRAM_OPTIONS
@@ -672,6 +741,13 @@ else
   AC_MSG_RESULT([no])
 fi
 
+AC_MSG_CHECKING([whether to reduce exports])
+if test x$use_reduce_exports != xno; then
+  AC_MSG_RESULT([yes])
+else
+  AC_MSG_RESULT([no])
+fi
+
 if test "x$use_tests$build_bitcoind$use_qt" = "xnonono"; then
   AC_MSG_ERROR([No targets! Please specify at least one of: --enable-cli --enable-daemon --enable-gui or --enable-tests])
 fi
@@ -704,6 +780,7 @@ AC_SUBST(CLIENT_VERSION_IS_RELEASE, _CLIENT_VERSION_IS_RELEASE)
 AC_SUBST(COPYRIGHT_YEAR, _COPYRIGHT_YEAR)
 
 
+AC_SUBST(RELDFLAGS)
 AC_SUBST(LIBTOOL_LDFLAGS)
 AC_SUBST(USE_UPNP)
 AC_SUBST(USE_QRCODE)

src/Makefile.am

@@ -262,6 +262,7 @@ endif
 
 bitcoind_LDADD += $(BOOST_LIBS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS)
 bitcoind_CPPFLAGS = $(BITCOIN_INCLUDES)
+bitcoind_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS)
 
 # bitcoin-cli binary #
 bitcoin_cli_LDADD = \
@@ -299,10 +300,12 @@ endif
 bitcoin_tx_SOURCES = bitcoin-tx.cpp
 bitcoin_tx_CPPFLAGS = $(BITCOIN_INCLUDES)
 #
+bitcoin_tx_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS)
 
 if TARGET_WINDOWS
 bitcoin_cli_SOURCES += bitcoin-cli-res.rc
 endif
+bitcoin_cli_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS)
 
 CLEANFILES = leveldb/libleveldb.a leveldb/libmemenv.a *.gcda *.gcno
 

src/Makefile.qt.include

@@ -362,7 +362,7 @@ qt_bitcoin_qt_LDADD += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL)
 if USE_LIBSECP256K1
   qt_bitcoin_qt_LDADD += secp256k1/libsecp256k1.la
 endif
-qt_bitcoin_qt_LDFLAGS = $(AM_LDFLAGS) $(QT_LDFLAGS)
+qt_bitcoin_qt_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(QT_LDFLAGS)
 
 #locale/foo.ts -> locale/foo.qm
 QT_QM=$(QT_TS:.ts=.qm)

src/Makefile.qttest.include

@@ -36,7 +36,7 @@ qt_test_test_bitcoin_qt_LDADD += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBIT
 if USE_LIBSECP256K1
   qt_test_test_bitcoin_qt_LDADD += secp256k1/libsecp256k1.la
 endif
-qt_test_test_bitcoin_qt_LDFLAGS = $(AM_LDFLAGS) $(QT_LDFLAGS)
+qt_test_test_bitcoin_qt_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(QT_LDFLAGS)
 
 CLEAN_BITCOIN_QT_TEST = $(TEST_QT_MOC_CPP) qt/test/*.gcda qt/test/*.gcno
 

src/Makefile.test.include

@@ -75,6 +75,7 @@ if USE_LIBSECP256K1
 endif
 
 test_test_bitcoin_LDADD += $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS)
+test_test_bitcoin_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS)
 
 nodist_test_test_bitcoin_SOURCES = $(GENERATED_TEST_FILES)