[XEN PATCH v2] libs: Fix unstable libs build on FreeBSD, auto-generate version-script

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

Unfortunatly, --default-symver doesn't work with LLVM's LD, LLD.
Instead, we will generate a temporary version-script.

In order to allow regenerating the script, we'll have a different
filename. In order to check if the content is up-to-date, we'll always
generated it and compare.

Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Fixes: 98d95437edb6 ("libs: Fix auto-generation of version-script for unstable 
libs")
Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---

Notes:
    v2:
    - Replace "VERS" by "lib$(LIB_FILE_NAME)" in the new .map file.
    - Set version-script to lib$(LIB_FILE_NAME).map.tmp, like the filename
      used by the library binaries. (instead of libxen$(LIBNAME).map.tmp)
    - Write temporary file in the same directory as the target (in case the
      target is in a different directory)
    - remove temporary file generated by the new rule, in case it isn't
      removed by move-if-changed..
    - use ?= to set version-script, this mean that version-script has now a
      deferred expansion instead of immediate, hoping nothing break.
    
    CC: Jan Beulich <jbeulich@xxxxxxxx>

 tools/libs/libs.mk | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/libs/libs.mk b/tools/libs/libs.mk
index 0e4b5e0bd0..ffb6c9f064 100644
--- a/tools/libs/libs.mk
+++ b/tools/libs/libs.mk
@@ -5,6 +5,7 @@
 #   MAJOR:   major version of lib (Xen version if empty)
 #   MINOR:   minor version of lib (0 if empty)
 #   version-script: Specify the name of a version script to the linker.
+#     (If empty, a temporary one for unstable library is created)
 
 LIBNAME := $(notdir $(CURDIR))
 
@@ -27,6 +28,8 @@ ifneq ($(nosharedlibs),y)
 TARGETS += lib$(LIB_FILE_NAME).so
 endif
 
+version-script ?= lib$(LIB_FILE_NAME).map.tmp
+
 PKG_CONFIG ?= $(LIB_FILE_NAME).pc
 PKG_CONFIG_NAME ?= Xen$(LIBNAME)
 PKG_CONFIG_DESC ?= The $(PKG_CONFIG_NAME) library for Xen hypervisor
@@ -72,6 +75,10 @@ headers.lst: FORCE
        @{ set -e; $(foreach h,$(LIBHEADERS),echo $(h);) } > $@.tmp
        @$(call move-if-changed,$@.tmp,$@)
 
+lib$(LIB_FILE_NAME).map.tmp: FORCE
+       echo 'lib$(LIB_FILE_NAME)_$(MAJOR).$(MINOR) { global: *; };' 
>$(@D)/.$(@F)
+       $(call move-if-changed,$(@D)/.$(@F),$@)
+
 lib$(LIB_FILE_NAME).a: $(OBJS-y)
        $(AR) rc $@ $^
 
@@ -81,7 +88,7 @@ lib$(LIB_FILE_NAME).so.$(MAJOR): 
lib$(LIB_FILE_NAME).so.$(MAJOR).$(MINOR)
        $(SYMLINK_SHLIB) $< $@
 
 lib$(LIB_FILE_NAME).so.$(MAJOR).$(MINOR): $(PIC_OBJS) $(version-script)
-       $(CC) $(LDFLAGS) $(PTHREAD_LDFLAGS) -Wl,$(SONAME_LDFLAG) 
-Wl,lib$(LIB_FILE_NAME).so.$(MAJOR) -Wl,$(if 
$(version-script),--version-script=$(version-script),--default-symver) 
$(SHLIB_LDFLAGS) -o $@ $(PIC_OBJS) $(LDLIBS) $(APPEND_LDFLAGS)
+       $(CC) $(LDFLAGS) $(PTHREAD_LDFLAGS) -Wl,$(SONAME_LDFLAG) 
-Wl,lib$(LIB_FILE_NAME).so.$(MAJOR) -Wl,--version-script=$(version-script) 
$(SHLIB_LDFLAGS) -o $@ $(PIC_OBJS) $(LDLIBS) $(APPEND_LDFLAGS)
 
 # If abi-dumper is available, write out the ABI analysis
 ifneq ($(ABI_DUMPER),)
@@ -120,7 +127,7 @@ TAGS:
 clean::
        rm -rf $(TARGETS) *~ $(DEPS_RM) $(OBJS-y) $(PIC_OBJS)
        rm -f lib$(LIB_FILE_NAME).so.$(MAJOR).$(MINOR) 
lib$(LIB_FILE_NAME).so.$(MAJOR)
-       rm -f headers.chk headers.lst
+       rm -f headers.chk headers.lst lib*.map.tmp .*.tmp
 
 .PHONY: distclean
 distclean: clean
-- 
Anthony PERARD