[glibc] Makeconfig: Move -Wl, -rpath-link options before library references

[Florian Weimer <fw at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a8ff215e56050a907189e713fd449bcafe99ff6b

commit a8ff215e56050a907189e713fd449bcafe99ff6b
Author: Florian Weimer <fweimer@redhat.com>
Date:   Fri Apr 26 07:16:30 2019 +0200

    Makeconfig: Move -Wl,-rpath-link options before library references
    
    Previously, the -Wl,-rpath-link options came after the libraries
    injected using LDLIBS-* variables on the link editor command line for
    main programs.  As a result, it could happen that installed libraries
    that reference glibc libraries used the installed glibc from the system
    directories, instead of the glibc from the build tree.  This can lead to
    link failures if the wrong version of libpthread.so.0 is used, for
    instance, due to differences in the internal GLIBC_PRIVATE interfaces,
    as seen with memusagestat and -lgd after commit
    f9b645b4b0a10c43753296ce3fa40053fa44606a ("memusagestat: use local glibc
    when linking [BZ #18465]").
    
    The isolation is necessarily imperfect because these installed
    libraries are linked against the installed glibc in the system
    directories.  However, in most cases, the built glibc will be newer
    than the installed glibc, and this link is permitted because of the
    ABI backwards compatibility glibc provides.

Diff:
---
 ChangeLog  | 15 +++++++++++++++
 Makeconfig | 19 ++++++++++++++-----
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 697f937..a4f9c9e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,20 @@
 2019-04-26  Florian Weimer  <fweimer@redhat.com>
 
+	Makeconfig: Move -Wl,-rpath-link options before library references.
+	* Makeconfig (+link-pie, +link): Add $(link-libc-rpath-link).
+	(link-libc): Remove $(link-libc-rpath-link).
+
+2019-04-25  Florian Weimer  <fweimer@redhat.com>
+
+	* Makeconfig (+link-pie-before-libc): Remove $(CC).
+	(+link-pie, +link-pie-tests, +link-pie-printers-tests): Add $(CC).
+	(+link-static-before-libc): Remove $(CC).
+	(+link-static, +link-static-tests): Add $(CC).
+	(+link-before-libc): Remove $(CC).
+	(+link, +link-pie, +link-pie-printers): Add $(CC).
+
+2019-04-26  Florian Weimer  <fweimer@redhat.com>
+
 	* Makeconfig (+link-pie-before-libc): Remove $(CC).
 	(+link-pie, +link-pie-tests, +link-pie-printers-tests): Add $(CC).
 	(+link-static-before-libc): Remove $(CC).
diff --git a/Makeconfig b/Makeconfig
index 92c9b59..0e386fb 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -428,8 +428,8 @@ ifndef +link-pie
 	     $(link-extra-libs)
 +link-pie-after-libc = $(+postctorS) $(+postinit)
 define +link-pie
-$(CC) $(+link-pie-before-libc) $(rtld-LDFLAGS) $(link-extra-flags) \
-  $(link-libc) $(+link-pie-after-libc)
+$(CC) $(link-libc-rpath-link) $(+link-pie-before-libc) $(rtld-LDFLAGS) \
+  $(link-extra-flags) $(link-libc) $(+link-pie-after-libc)
 $(call after-link,$@)
 endef
 define +link-pie-tests
@@ -490,8 +490,8 @@ else  # not build-pie-default
 	      $(link-extra-libs)
 +link-after-libc = $(+postctor) $(+postinit)
 define +link
-$(CC) $(+link-before-libc) $(rtld-LDFLAGS) $(link-extra-flags) $(link-libc) \
-  $(+link-after-libc)
+$(CC) $(link-libc-rpath-link) $(+link-before-libc) $(rtld-LDFLAGS) \
+  $(link-extra-flags) $(link-libc) $(+link-after-libc)
 $(call after-link,$@)
 endef
 define +link-tests
@@ -552,6 +552,15 @@ ifeq (yes,$(build-shared))
 link-libc-rpath = -Wl,-rpath=$(rpath-link)
 link-libc-rpath-link = -Wl,-rpath-link=$(rpath-link)
 
+# For programs which are not tests, $(link-libc-rpath-link) is added
+# directly in $(+link), $(+link-pie) above, so that -Wl,-rpath-link
+# comes before the expansion of LDLIBS-* and affects libraries added
+# there.  For shared objects, -Wl,-rpath-link is added via
+# $(build-shlib-helper) and $(build-module-helper) in Makerules (also
+# before the expansion of LDLIBS-* variables).
+
+# Tests use -Wl,-rpath instead of -Wl,-rpath-link for
+# build-hardcoded-path-in-tests.
 ifeq (yes,$(build-hardcoded-path-in-tests))
 link-libc-tests-rpath-link = $(link-libc-rpath)
 else
@@ -562,7 +571,7 @@ link-libc-before-gnulib = $(common-objpfx)libc.so$(libc.so-version) \
 			  $(common-objpfx)$(patsubst %,$(libtype.oS),c) \
 			  $(as-needed) $(elf-objpfx)ld.so \
 			  $(no-as-needed)
-link-libc = $(link-libc-rpath-link) $(link-libc-before-gnulib) $(gnulib)
+link-libc = $(link-libc-before-gnulib) $(gnulib)
 
 link-libc-tests-after-rpath-link = $(link-libc-before-gnulib) $(gnulib-tests)
 link-libc-tests = $(link-libc-tests-rpath-link) \