build: add option for reducing exports (v2)

This was committed previously as 4975ae172 and reverted, because the flags were
applied even if the checks didn't pass. This is the same commit, fixed up to
actually disable the functionality when necessary.

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.

1 files changed, 78 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 7db6ebac0e..601ccf0a79 100644
--- a/configure.ac
+++ b/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 +402,36 @@ 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
+  ])
+fi
+
 LEVELDB_CPPFLAGS=
 LIBLEVELDB=
 LIBMEMENV=
@@ -426,6 +462,40 @@ AX_BOOST_PROGRAM_OPTIONS
 AX_BOOST_THREAD
 AX_BOOST_CHRONO
 
+
+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
+
+if test x$use_reduce_exports != xno; then
+    CXXFLAGS="$CXXFLAGS $RE_CXXFLAGS"
+    AX_CHECK_LINK_FLAG([[-Wl,--exclude-libs,ALL]], [RELDFLAGS="-Wl,--exclude-libs,ALL"])
+fi
+
 if test x$use_tests = xyes; then
 
   if test x$HEXDUMP = x; then
@@ -672,6 +742,13 @@ else
   AC_MSG_RESULT([no])
 fi
 
+AC_MSG_CHECKING([whether to reduce exports])
+if test x$use_reduce_exports != xno; then
+  AC_MSG_RESULT([yes])
+else
+  AC_MSG_RESULT([no])
+fi
+
 if test x$build_bitcoin_utils$build_bitcoind$bitcoin_enable_qt$use_tests = xnononono; then
   AC_MSG_ERROR([No targets! Please specify at least one of: --with-utils --with-daemon --with-gui or --enable-tests])
 fi
@@ -704,6 +781,7 @@ 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)