Bug 20918 - Building with --enable-nss-crypt fails tst-linkall-static

Some configurations may use NSS cryptographic routines but have no
static library for those routines. The following changes allow glibc to
be built and tested with --enable-nss-crypt, but without having a static
NSS library. At a high level the change does two things:

(1) Detect at configure time if static NSS crypto libraries are
    available.  Assumes libfreebl3.a (instead of the existing Fedora
    libfreebl.a which is incomplete) which matches libfreebl3.so.

(2) If static NSS crypto libraries are _not_ available then adjust the
    way in which we build tst-linkall-static. This includes excluding a
    reference to crypt and not linking against libcrypt.a, all of which
    will fail otherwise.

Testing assumptions:
* Static library is named libfreebl3.a (not libfreebl.a as is currently
  provided in Fedora), matching libfreebl3.so shared link name.

Tested on x86_64 on Fedora with:

(a) --enable-nss-crypt, with no static NSS library support: PASS
    (previous FAIL)

(b) --enable-nss-crypt, with faked static NSS library support: PASS
    (unsupported)
	* Requires changing elf/Makefile to include a stub
	  /lib64/libfreebl3.a for testing purposes.

(c) --disable-nss-crypt: PASS
    (default)

No regressions on x86_64.

For details see:
https://www.sourceware.org/ml/libc-alpha/2016-11/msg00647.html

2 files changed, 32 insertions, 2 deletions

diff --git a/elf/Makefile b/elf/Makefile
index ebdcbc6..f57927f 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -337,6 +337,16 @@ $(objpfx)tst-_dl_addr_inside_object: $(objpfx)dl-addr-obj.os
 CFLAGS-tst-_dl_addr_inside_object.c += $(PIE-ccflag)
 endif
 
+# By default tst-linkall-static should try to use crypt routines to test
+# static libcrypt use.
+CFLAGS-tst-linkall-static.c = -DUSE_CRYPT=1
+# However, if we are using NSS crypto and we don't have a static
+# library, then we exclude the use of crypt functions in the test.
+# We similarly exclude libcrypt.a from the static link (see below).
+ifeq (yesno,$(nss-crypt)$(static-nss-crypt))
+CFLAGS-tst-linkall-static.c = -DUSE_CRYPT=0
+endif
+
 include ../Rules
 
 ifeq (yes,$(build-shared))
@@ -1307,12 +1317,30 @@ $(objpfx)tst-ldconfig-X.out : tst-ldconfig-X.sh $(objpfx)ldconfig
 
 $(objpfx)tst-dlsym-error: $(libdl)
 
+# Test static linking of all the libraries we can possibly link
+# together.  Note that in some configurations this may be less than the
+# complete list of libraries we build but we try to maxmimize this list.
 $(objpfx)tst-linkall-static: \
   $(common-objpfx)math/libm.a \
-  $(common-objpfx)crypt/libcrypt.a \
   $(common-objpfx)resolv/libresolv.a \
   $(common-objpfx)dlfcn/libdl.a \
   $(common-objpfx)login/libutil.a \
   $(common-objpfx)rt/librt.a \
   $(common-objpfx)resolv/libanl.a \
-  $(static-thread-library) \
+  $(static-thread-library)
+
+# If we are using NSS crypto and we have the ability to link statically
+# then we include libcrypt.a, otherwise we leave out libcrypt.a and
+# link as much as we can into the tst-linkall-static test.  This assumes
+# that linking with libcrypt.a does everything required to include the
+# static NSS crypto library.
+ifeq (yesyes,$(nss-crypt)$(static-nss-crypt))
+$(objpfx)tst-linkall-static: \
+  $(common-objpfx)crypt/libcrypt.a
+endif
+# If we are not using NSS crypto then we always have the ability to link
+# with libcrypt.a.
+ifeq (no,$(nss-crypt))
+$(objpfx)tst-linkall-static: \
+  $(common-objpfx)crypt/libcrypt.a
+endif
diff --git a/elf/tst-linkall-static.c b/elf/tst-linkall-static.c
index 7a4aacc..cc77f07 100644
--- a/elf/tst-linkall-static.c
+++ b/elf/tst-linkall-static.c
@@ -32,7 +32,9 @@ void *references[] =
   {
     &pow,                       /* libm */
     &pthread_create,            /* libpthread */
+#if USE_CRYPT
     &crypt,                     /* libcrypt */
+#endif
     &res_send,                  /* libresolv */
     &dlopen,                    /* libdl */
     &login,                     /* libutil */