tests: avoid false failures with LD_PRELOAD=libasan.so.2

The LD_PRELOAD checks by -fsanitize=address are overly strict:
https://groups.google.com/forum/#!topic/address-sanitizer/jEvOJgkDqQk
A workaround is to first export LD_PRELOAD=libasan.so.2
The tests below are adjusted so that workaround is not discarded.

* tests/cp/no-ctx.sh: Append to $LD_PRELOAD.
* tests/df/no-mtab-status.sh: Likewise.
* tests/df/skip-duplicates.sh: Likewise.
* tests/ls/getxattr-speedup.sh: Likewise.
* tests/rm/r-root.sh: Likewise.
* tests/cp/nfs-removal-race.sh: Likewise.  Also check that
LD_PRELOAD is effective to aid future maintainability
and avoid false failure if libasan.so.2 is not preloaded.

2 files changed, 8 insertions, 4 deletions

diff --git a/tests/cp/nfs-removal-race.sh b/tests/cp/nfs-removal-race.sh
index 70276a384..fdac03f7d 100755
--- a/tests/cp/nfs-removal-race.sh
+++ b/tests/cp/nfs-removal-race.sh
@@ -35,6 +35,7 @@ require_gcc_shared_
 # Replace each stat call with a call to this wrapper.
 cat > k.c <<'EOF' || framework_failure_
 #define _GNU_SOURCE
+#include <stdio.h>
 #include <sys/types.h>
 #include <dlfcn.h>
 
@@ -49,6 +50,7 @@ int
 __xstat (int ver, const char *path, struct stat *st)
 {
   static int (*real_stat)(int ver, const char *path, struct stat *st) = NULL;
+  fclose(fopen("preloaded", "w"));
   if (!real_stat)
     real_stat = dlsym (RTLD_NEXT, "__xstat");
   /* When asked to stat nonexistent "d",
@@ -65,7 +67,9 @@ touch d2 || framework_failure_
 echo xyz > src || framework_failure_
 
 # Finally, run the test:
-LD_PRELOAD=./k.so cp src d || fail=1
+LD_PRELOAD=$LD_PRELOAD:./k.so cp src d || fail=1
+
+test -f preloaded || skip_ 'LD_PRELOAD was ineffective?'
 
 compare src d || fail=1
 Exit $fail
diff --git a/tests/cp/no-ctx.sh b/tests/cp/no-ctx.sh
index 377d203b0..852b8e641 100755
--- a/tests/cp/no-ctx.sh
+++ b/tests/cp/no-ctx.sh
@@ -50,14 +50,14 @@ gcc_shared_ k.c k.so \
 touch file_src
 
 # New file with SELinux context optionally included
-LD_PRELOAD=./k.so cp -a file_src file_dst || fail=1
+LD_PRELOAD=$LD_PRELOAD:./k.so cp -a file_src file_dst || fail=1
 
 # Existing file with SELinux context optionally included
-LD_PRELOAD=./k.so cp -a file_src file_dst || fail=1
+LD_PRELOAD=$LD_PRELOAD:./k.so cp -a file_src file_dst || fail=1
 
 # ENODATA should give an immediate error when required to preserve ctx
 # This is debatable, and maybe we should not fail when no context available?
-( export LD_PRELOAD=./k.so
+( export LD_PRELOAD=$LD_PRELOAD:./k.so
   returns_ 1 cp --preserve=context file_src file_dst ) || fail=1
 
 test -e preloaded || skip_ 'LD_PRELOAD interception failed'