Add symbol versioning

For ELF systems, turn on versioned symbols by default, and add a
configure option to enable or disable them.

TODO

@@ -4,6 +4,13 @@ Next
  * Get rid of off_t.  size_t is okay.  Use autoconf to figure out what
    type to use for offsets.
 
+ * Get rid of int/size_t/off_t inconsistencies.  MSVC 2010 can find
+   these if you add /w14267 to the compilation.  We might want to do
+   this by default.  The easiest way to fix this on Windows is to
+   modify msvc.mk to add this to both cl /c lines and run
+
+   make 2>&1 | tee build.log
+
  * Deal with portability issues from gcc 4.7.  See portability.patch
    from debian package.
 
@@ -11,52 +18,6 @@ Next
    to build and test cleanly in 2.3.1.  Hopefully the next release
    will include 64-bit binary distributions and external libraries.
 
- * Add versioned symbols.  Fix below to not use AM_CONDITIONAL.  Just
-   set some variable that can be part of LDFLAGS, like
-   LD_VERSION_SCRIPT, instead.
-
-# Check if LD supports linker scripts, and define conditional
-# HAVE_LD_VERSION_SCRIPT if so.  This functionality is currently
-# constrained to compilers using GNU ld on ELF systems or systems
-# which provide an adequate emulation thereof.
-AC_ARG_ENABLE([ld-version-script],
-  AS_HELP_STRING([--enable-ld-version-script],
-    [enable linker version script (default is disabled)]),
-    [have_ld_version_script=$enableval], [have_ld_version_script=no])
-if test "$have_ld_version_script" != no; then
-  AC_MSG_CHECKING([if LD -Wl,--version-script works])
-  save_LDFLAGS="$LDFLAGS"
-  LDFLAGS="$LDFLAGS -Wl,--version-script=conftest.map"
-  cat > conftest.map <<EOF
-VERS_1 {
-        global: sym;
-};
-
-VERS_2 {
-        global: sym;
-} VERS_1;
-EOF
-  AC_LINK_IFELSE([AC_LANG_PROGRAM([], [])],
-                 [have_ld_version_script=yes], [have_ld_version_script=no])
-  rm -f conftest.map
-  LDFLAGS="$save_LDFLAGS"
-  AC_MSG_RESULT($have_ld_version_script)
-fi
-AM_CONDITIONAL(HAVE_LD_VERSION_SCRIPT, test "$have_ld_version_script" = "yes")
-
-----
-
-if HAVE_LD_VERSION_SCRIPT
-libtiff_la_LDFLAGS += -Wl,--version-script=$(srcdir)/libtiff.map
-endif
-
-----
-
-LIBQPDF_3 {
-  global:
-    *;
-};
-
  * Provide an option to copy encryption parameters from another file.
    This would make it possible to decrypt a file, manually work with
    it, and then re-encrypt it using the original encryption parameters

autoconf.mk.in

@@ -31,3 +31,4 @@ BUILD_PDF=@BUILD_PDF@
 VALIDATE_DOC=@VALIDATE_DOC@
 SKIP_TEST_COMPARE_IMAGES=@SKIP_TEST_COMPARE_IMAGES@
 BUILDRULES=@BUILDRULES@
+HAVE_LD_VERSION_SCRIPT=@HAVE_LD_VERSION_SCRIPT@

configure.ac

@@ -41,6 +41,40 @@ AC_TYPE_UINT16_T
 AC_TYPE_UINT32_T
 AC_CHECK_FUNCS(random)
 
+# Check if LD supports linker scripts, and define conditional
+# HAVE_LD_VERSION_SCRIPT if so.  This functionality is currently
+# constrained to compilers using GNU ld on ELF systems or systems
+# which provide an adequate emulation thereof.
+AC_ARG_ENABLE([ld-version-script],
+  AS_HELP_STRING([--enable-ld-version-script],
+    [enable linker version script (default is disabled)]),
+    [have_ld_version_script=$enableval], [have_ld_version_script=yes])
+if test "$have_ld_version_script" != no; then
+  AC_MSG_CHECKING([if LD -Wl,--version-script works])
+  save_LDFLAGS="$LDFLAGS"
+  LDFLAGS="$LDFLAGS -Wl,--version-script=conftest.map"
+  cat > conftest.map <<EOF
+VERS_1 {
+        global: sym;
+};
+
+VERS_2 {
+        global: sym;
+} VERS_1;
+EOF
+  AC_LINK_IFELSE([AC_LANG_PROGRAM([], [])],
+                 [have_ld_version_script=yes], [have_ld_version_script=no])
+  rm -f conftest.map
+  LDFLAGS="$save_LDFLAGS"
+  AC_MSG_RESULT($have_ld_version_script)
+fi
+if test "$have_ld_version_script" = "yes"; then
+  HAVE_LD_VERSION_SCRIPT=1
+else
+  HAVE_LD_VERSION_SCRIPT=0
+fi
+AC_SUBST(HAVE_LD_VERSION_SCRIPT)
+
 AC_MSG_CHECKING(for gnu make >= 3.81)
 make_okay=0
 if make --version >/dev/null 2>&1; then

libqpdf.map

@@ -0,0 +1,4 @@
+LIBQPDF_8 {
+  global:
+    *;
+};

libqpdf/build.mk

@@ -64,6 +64,8 @@ $(OBJS_libqpdf): libqpdf/$(OUTPUT_DIR)/%.$(LOBJ): libqpdf/%.cc
 #
 # * If any interfaces have been removed or changed, we are not binary
 #   compatible.  Increment CURRENT, and set AGE and REVISION to 0.
+#   Also update libqpdf.map, changing the numeric portion to match
+#   CURRENT.
 #
 # * Otherwise, if any interfaces have been added since the last
 #   public release, then increment CURRENT and AGE, and set REVISION
@@ -72,4 +74,4 @@ $(OBJS_libqpdf): libqpdf/$(OUTPUT_DIR)/%.$(LOBJ): libqpdf/%.cc
 # * Otherwise, increment REVISION
 
 $(TARGETS_libqpdf): $(OBJS_libqpdf)
-	$(call makelib,$(OBJS_libqpdf),$@,$(LDFLAGS),$(LIBS),7,1,4)
+	$(call makelib,$(OBJS_libqpdf),$@,$(LDFLAGS),$(LIBS),8,0,0)

make/libtool.mk

@@ -18,6 +18,12 @@ endef
 
 # --- Private definitions ---
 
+ifeq ($(HAVE_LD_VERSION_SCRIPT), 1)
+LD_VERSION_FLAGS=-Wl,--version-script=libqpdf.map
+else
+LD_VERSION_FLAGS=
+endif
+
 # Usage: $(call libdepflags,$(basename obj))
 # Usage: $(call fixdeps,$(basename obj))
 ifeq ($(GENDEPS),1)
@@ -83,7 +89,8 @@ endef
 # Usage: $(call makelib,objs,library,ldflags,libs,current,revision,age)
 define makelib
 	$(LIBTOOL) --mode=link \
-		$(CXX) $(CXXFLAGS) -o $(2) $(1) $(3) $(4) \
+		$(CXX) $(CXXFLAGS) $(LD_VERSION_FLAGS) \
+		 -o $(2) $(1) $(3) $(4) \
 		 -rpath $(libdir) -version-info $(5):$(6):$(7)
 endef