[COMMITTED PATCH] Support after-link variable to run a final step on binaries.

[Roland McGrath <roland at hack dot frob dot com>]

I'm using this in the NaCl port to do a post-link validation step.
You can set it configparms to do some other random thing.
Nothing about the build is changed if you don't set the new variable.


Thanks,
Roland


2015-02-12  Roland McGrath  <roland@hack.frob.com>

	* Makeconfig (after-link): New variable.
	(+link-pie, +link-pie-tests): Use it.
	(+link-static, +link-static-tests): Likewise.
	(+link, +link-tests): Likewise.
	* Makerules (build-module, build-module-asneeded): Likewise.
	(lib%.so, $(common-objpfx)libc.so, $(common-objpfx)linkobj/libc.so):
	Likewise.
	* elf/Makefile ($(objpfx)ld.so): Likewise.

--- a/Makeconfig
+++ b/Makeconfig
@@ -387,6 +387,14 @@ LDFLAGS.so += $(hashstyle-LDFLAGS)
 LDFLAGS-rtld += $(hashstyle-LDFLAGS)
 endif
 
+# Command to run after every final link (executable or shared object).
+# This is invoked with $(call after-link,...), so it should operate on
+# the file $1.  This can be set to do some sort of post-processing on
+# binaries, or to perform some sort of static sanity check.
+ifndef after-link
+after-link =
+endif
+
 # Command for linking PIE programs with the C library.
 ifndef +link-pie
 +link-pie-before-libc = $(CC) -pie -Wl,-O1 -nostdlib -nostartfiles -o $@ \
@@ -400,10 +408,15 @@ ifndef +link-pie
 			  $(common-objpfx)libc% $(+postinit),$^) \
 	     $(link-extra-libs)
 +link-pie-after-libc = $(+postctorS) $(+postinit)
-+link-pie = $(+link-pie-before-libc) $(rtld-LDFLAGS) $(link-libc) \
-	    $(+link-pie-after-libc)
-+link-pie-tests = $(+link-pie-before-libc) $(rtld-tests-LDFLAGS) \
-		  $(link-libc-tests) $(+link-pie-after-libc)
+define +link-pie
+$(+link-pie-before-libc) $(rtld-LDFLAGS) $(link-libc) $(+link-pie-after-libc)
+$(call after-link,$@)
+endef
+define +link-pie-tests
+$(+link-pie-before-libc) $(rtld-tests-LDFLAGS) $(link-libc-tests) \
+			 $(+link-pie-after-libc)
+$(call after-link,$@)
+endef
 endif
 # Command for statically linking programs with the C library.
 ifndef +link-static
@@ -417,10 +430,14 @@ ifndef +link-static
 			   $(common-objpfx)libc% $(+postinit),$^) \
 	      $(link-extra-libs-static)
 +link-static-after-libc = $(+postctorT) $(+postinit)
-+link-static = $(+link-static-before-libc) $(link-libc-static) \
-	       $(+link-static-after-libc)
-+link-static-tests = $(+link-static-before-libc) $(link-libc-static-tests) \
-		     $(+link-static-after-libc)
+define +link-static
+$(+link-static-before-libc) $(link-libc-static) $(+link-static-after-libc)
+$(call after-link,$@)
+endef
+define +link-static-tests
+$(+link-static-before-libc) $(link-libc-static-tests) $(+link-static-after-libc)
+$(call after-link,$@)
+endef
 endif
 # Commands for linking programs with the C library.
 ifndef +link
@@ -436,10 +453,15 @@ ifeq (yes,$(build-shared))
 			   $(common-objpfx)libc% $(+postinit),$^) \
 	      $(link-extra-libs)
 +link-after-libc = $(+postctor) $(+postinit)
-+link = $(+link-before-libc) $(rtld-LDFLAGS) $(link-libc) \
-	$(+link-after-libc)
-+link-tests = $(+link-before-libc) $(rtld-tests-LDFLAGS) \
-	      $(link-libc-tests) $(+link-after-libc)
+define +link
+$(+link-before-libc) $(rtld-LDFLAGS) $(link-libc) $(+link-after-libc)
+$(call after-link,$@)
+endef
+define +link-tests
+$(+link-before-libc) $(rtld-tests-LDFLAGS) $(link-libc-tests) \
+		     $(+link-after-libc)
+$(call after-link,$@)
+endef
 else
 +link = $(+link-static)
 +link-tests = $(+link-static-tests)
--- a/Makerules
+++ b/Makerules
@@ -505,6 +505,7 @@ link-libc-deps = $(common-objpfx)libc.so $(common-objpfx)linkobj/libc.so \
 # to be as similar as possible to a default link with an installed libc.
 lib%.so: lib%_pic.a $(+preinit) $(+postinit) $(link-libc-deps)
 	$(build-shlib) $(link-libc-args)
+	$(call after-link,$@)
 
 define build-shlib-helper
 $(LINK.o) -shared $(static-libgcc) -Wl,-O1 $(sysdep-LDFLAGS) \
@@ -580,12 +581,14 @@ endef
 define build-module
 $(build-module-helper) -o $@ $(shlib-lds-flags) \
 	  $(csu-objpfx)abi-note.o $(build-module-objlist) $(link-libc-args)
+$(call after-link,$@)
 endef
 define build-module-asneeded
 $(build-module-helper) -o $@ $(shlib-lds-flags) \
 	  $(csu-objpfx)abi-note.o \
 	  -Wl,--as-needed $(build-module-objlist) -Wl,--no-as-needed \
 	  $(link-libc-args)
+$(call after-link,$@)
 endef
 
 build-module-helper-objlist = \
@@ -666,6 +669,7 @@ $(common-objpfx)libc.so: $(elf-objpfx)soinit.os \
 			 $(elf-objpfx)ld.so \
 			 $(shlib-lds)
 	$(build-shlib)
+	$(call after-link,$@)
 
 $(common-objpfx)linkobj/libc.so: $(elf-objpfx)soinit.os \
 			 $(common-objpfx)linkobj/libc_pic.a \
@@ -674,6 +678,7 @@ $(common-objpfx)linkobj/libc.so: $(elf-objpfx)soinit.os \
 			 $(elf-objpfx)ld.so \
 			 $(shlib-lds)
 	$(build-shlib)
+	$(call after-link,$@)
 
 ifeq ($(build-shared),yes)
 $(common-objpfx)libc.so: $(common-objpfx)libc.map
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -349,6 +349,7 @@ $(objpfx)ld.so: $(objpfx)librtld.os $(ld-map)
 		  $(filter-out $(map-file),$^) $(load-map-file)		\
 		  -Wl,-soname=$(rtld-installed-name)			\
 		  -Wl,-defsym=_begin=0
+	$(call after-link,$@.new)
 	$(READELF) -s $@.new \
 	  | $(AWK) '($$7 ~ /^UND(|EF)$$/ && $$1 != "0:" && $$4 != "REGISTER") { print; p=1 } END { exit p != 0 }'
 	mv -f $@.new $@