configure: add symbols versioning option

Allow, at configure time, the production of versioned symbols. The
symbols will look like "CURL_<FLAVOUR>_<VERSION> <SYMBOL>", where
<FLAVOUR> represents the SSL flavour (e.g. OPENSSL, GNUTLS, NSS, ...),
<VERSION> is the major SONAME version and <SYMBOL> is the actual symbol
name. If no SSL library is enabled the symbols will be just
"CURL_<VERSION> <SYMBOL>".

4 files changed, 74 insertions, 2 deletions

diff --git a/Makefile.am b/Makefile.am
index 6c2010966..c2a9cb4a6 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -36,7 +36,7 @@ winbuild/MakefileBuild.vc winbuild/Makefile.vc
 EXTRA_DIST = CHANGES COPYING maketgz Makefile.dist curl-config.in	\
  curl-style.el sample.emacs RELEASE-NOTES buildconf 	\
  libcurl.pc.in vc6curl.dsw MacOSX-Framework Android.mk $(CMAKE_DIST)	\
- Makefile.msvc.names $(WINBUILD_DIST)
+ Makefile.msvc.names $(WINBUILD_DIST) lib/libcurl.vers.in
 
 bin_SCRIPTS = curl-config
 
diff --git a/configure.ac b/configure.ac
index 3e95b0cdc..cc7f88897 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2347,6 +2347,60 @@ if test X"$OPT_LIBRTMP" != Xno; then
 fi
 
 dnl **********************************************************************
+dnl Check for linker switch for versioned symbols
+dnl **********************************************************************
+
+AC_MSG_CHECKING([if libraries can be versioned])
+GLD=`$LD --help < /dev/null 2>/dev/null | grep version-script`
+if test -z "$GLD"; then
+    versioned_symbols_flavour=
+    AC_MSG_RESULT(no)
+    AC_MSG_WARN(***
+*** You need an ld version supporting the --version-script option.
+)
+else
+    AC_MSG_RESULT(yes)
+
+AC_MSG_CHECKING([whether versioned symbols are wanted])
+versioned_symbols_flavour=
+
+AC_ARG_ENABLE(versioned-symbols,
+AC_HELP_STRING([--enable-versioned-symbols], [Enable versioned symbols in shared library])
+AC_HELP_STRING([--disable-versioned-symbols], [Disable versioned symbols in shared library]),
+[ case "$enableval" in
+  yes) AC_MSG_RESULT(yes)
+    if test "x$OPENSSL_ENABLED" = "x1"; then
+      versioned_symbols_flavour="OPENSSL_"
+    elif test "x$GNUTLS_ENABLED" == "x1"; then
+      versioned_symbols_flavour="GNUTLS_"
+    elif test "x$NSS_ENABLED" == "x1"; then
+      versioned_symbols_flavour="NSS_"
+    elif test "x$POLARSSL_ENABLED" == "x1"; then
+      versioned_symbols_flavour="POLARSSL_"
+    elif test "x$CYASSL_ENABLED" == "x1"; then
+      versioned_symbols_flavour="CYASSL_"
+    elif test "x$AXTLS_ENABLED" == "x1"; then
+      versioned_symbols_flavour="AXTLS_"
+    else
+      versioned_symbols_flavour=""
+    fi
+    versioned_symbols="yes"
+    ;;
+
+  *)   AC_MSG_RESULT(no)
+    ;;
+  esac
+], [
+AC_MSG_RESULT(no)
+]
+)
+fi
+
+AC_SUBST(VERSIONED_FLAVOUR, ["$versioned_symbols_flavour"])
+AM_CONDITIONAL(VERSIONED_SYMBOLS, test "x$versioned_symbols" = "xyes")
+
+
+dnl **********************************************************************
 dnl Check for the presence of IDN libraries and headers
 dnl **********************************************************************
 
@@ -3215,6 +3269,7 @@ AC_CONFIG_FILES([Makefile \
            include/curl/Makefile \
            src/Makefile \
            lib/Makefile \
+           lib/libcurl.vers \
            tests/Makefile \
            tests/data/Makefile \
            tests/server/Makefile \
diff --git a/lib/Makefile.am b/lib/Makefile.am
index f2e54db95..d764274fc 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -116,7 +116,11 @@ if MIMPURE
 MIMPURE = -mimpure-text
 endif
 
-libcurl_la_LDFLAGS = $(UNDEF) $(VERSIONINFO) $(MIMPURE) $(LIBCURL_LIBS)
+if VERSIONED_SYMBOLS
+VERSIONED_SYMBOLS = -Wl,--version-script=libcurl.vers
+endif
+
+libcurl_la_LDFLAGS = $(UNDEF) $(VERSIONINFO) $(MIMPURE) $(VERSIONED_SYMBOLS) $(LIBCURL_LIBS)
 
 # unit testing static library built only along with unit tests
 if BUILD_UNITTESTS
diff --git a/lib/libcurl.vers.in b/lib/libcurl.vers.in
new file mode 100644
index 000000000..8294557b8
--- /dev/null
+++ b/lib/libcurl.vers.in
@@ -0,0 +1,13 @@
+HIDDEN
+{
+  local:
+    __*;
+    _rest*;
+    _save*;
+};
+
+CURL_@VERSIONED_FLAVOUR@4
+{
+  global: curl_*;
+  local: *;
+};