[PATCH v3] elf: Install a symbolic link to ld.so as /usr/bin/ld.so

[Florian Weimer <fweimer@redhat.com>]

This makes ld.so features such as --preload, --audit,
and --list-diagnostics more accessible to end users because they
do not need to know the ABI name of the dynamic loader.

---
v2: Use $(make-link).
v3: Update NEWS entry.

 NEWS         | 3 +++
 elf/Makefile | 7 ++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/NEWS b/NEWS
index 8744a92532..3a04befe8e 100644
--- a/NEWS
+++ b/NEWS
@@ -79,6 +79,9 @@ Major new features:
   variables.  The GNU C Library manual has details on integration of
   Restartable Sequences.
 
+* A symbolic link to the dynamic linker is now installed under
+  /usr/bin/ld.so (or more precisely, '${bindir}/ld.so').
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * The r_version update in the debugger interface makes the glibc binary
diff --git a/elf/Makefile b/elf/Makefile
index ef36008673..d0bb0daa7e 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -110,7 +110,7 @@ endif
 ifeq (yes,$(build-shared))
 extra-objs	= $(all-rtld-routines:%=%.os) sofini.os interp.os
 generated	+= librtld.os dl-allobjs.os ld.so ldd
-install-others	= $(inst_rtlddir)/$(rtld-installed-name)
+install-others	= $(inst_rtlddir)/$(rtld-installed-name) $(inst_bindir)/ld.so
 install-bin-script = ldd
 endif
 
@@ -692,6 +692,11 @@ $(inst_rtlddir)/$(rtld-installed-name): $(objpfx)ld.so $(+force)
 	$(make-target-directory)
 	$(do-install-program)
 
+# Creates the relative /usr/bin/ld.so symbolic link.
+$(inst_bindir)/ld.so: $(inst_rtlddir)/$(rtld-installed-name)
+	$(make-target-directory)
+	$(make-link)
+
 # Special target called by parent to install just the dynamic linker.
 .PHONY: ldso_install
 ldso_install: $(inst_rtlddir)/$(rtld-installed-name)