build: update gnulib and tests/init.sh

* gnulib: Update.
* tests/init.sh: Update from gnulib.

2 files changed, 86 insertions, 6 deletions

diff --git a/gnulib b/gnulib
-Subproject 17febe7763c9ef38ed1ced5f08f022168e19892
+Subproject 337977d216e2759bc5b4dd3cbe223cbf8e6a9eb
diff --git a/tests/init.sh b/tests/init.sh
index 373d9d4fe..e2f61190f 100644
--- a/tests/init.sh
+++ b/tests/init.sh
@@ -221,16 +221,96 @@ export MALLOC_PERTURB_
 # a partition, or to undo any other global state changes.
 cleanup_ () { :; }
 
-if ( diff -u "$0" "$0" < /dev/null ) > /dev/null 2>&1; then
-  compare () { diff -u "$@"; }
-elif ( diff -c "$0" "$0" < /dev/null ) > /dev/null 2>&1; then
-  compare () { diff -c "$@"; }
+# Emit a header similar to that from diff -u;  Print the simulated "diff"
+# command so that the order of arguments is clear.  Don't bother with @@ lines.
+emit_diff_u_header_ ()
+{
+  printf '%s\n' "diff -u $*" \
+    "--- $1	1970-01-01" \
+    "+++ $2	1970-01-01"
+}
+
+# Arrange not to let diff or cmp operate on /dev/null,
+# since on some systems (at least OSF/1 5.1), that doesn't work.
+# When there are not two arguments, or no argument is /dev/null, return 2.
+# When one argument is /dev/null and the other is not empty,
+# cat the nonempty file to stderr and return 1.
+# Otherwise, return 0.
+compare_dev_null_ ()
+{
+  test $# = 2 || return 2
+
+  if test "x$1" = x/dev/null; then
+    test -s "$2" || return 0
+    { emit_diff_u_header_ "$@"; sed 's/^/+/' -- "$2"; } >&2
+    return 1
+  fi
+
+  if test "x$2" = x/dev/null; then
+    test -s "$1" || return 0
+    { emit_diff_u_header_ "$@"; sed 's/^/-/' -- "$1"; } >&2
+    return 1
+  fi
+
+  return 2
+}
+
+if diff_out_=`( diff -u "$0" "$0" < /dev/null ) 2>/dev/null`; then
+  if test -z "$diff_out_"; then
+    compare_ () { diff -u "$@"; }
+  else
+    compare_ ()
+    {
+      if diff -u "$@" > diff.out; then
+        # No differences were found, but Solaris 'diff' produces output
+        # "No differences encountered". Hide this output.
+        rm -f diff.out
+        true
+      else
+        cat diff.out
+        rm -f diff.out
+        false
+      fi
+    }
+  fi
+elif diff_out_=`( diff -c "$0" "$0" < /dev/null ) 2>/dev/null`; then
+  if test -z "$diff_out_"; then
+    compare_ () { diff -c "$@"; }
+  else
+    compare_ ()
+    {
+      if diff -c "$@" > diff.out; then
+        # No differences were found, but AIX and HP-UX 'diff' produce output
+        # "No differences encountered" or "There are no differences between the
+        # files.". Hide this output.
+        rm -f diff.out
+        true
+      else
+        cat diff.out
+        rm -f diff.out
+        false
+      fi
+    }
+  fi
 elif ( cmp --version < /dev/null 2>&1 | grep GNU ) > /dev/null 2>&1; then
-  compare () { cmp -s "$@"; }
+  compare_ () { cmp -s "$@"; }
 else
-  compare () { cmp "$@"; }
+  compare_ () { cmp "$@"; }
 fi
 
+# Usage: compare EXPECTED ACTUAL
+#
+# Given compare_dev_null_'s preprocessing, defer to compare_ if 2 or more.
+# Otherwise, propagate $? to caller: any diffs have already been printed.
+compare ()
+{
+  compare_dev_null_ "$@"
+  case $? in
+    0|1) return $?;;
+    *) compare_ "$@";;
+  esac
+}
+
 # An arbitrary prefix to help distinguish test directories.
 testdir_prefix_ () { printf gt; }