od: add an --endian option to control byte swapping

* src/od.c (main): Handle the new --endian option,
taking "little" and "big" as parameters.
(usage): Describe the new option.
(PRINT_FIELDS): Adjust to swap bytes if required.
* tests/misc/od-endian.sh: A new test to verify
the byte swapping operations for hex (ints) and floats
for all sizes between 1 and 16 inclusive.
* test/local.mk: Reference the new test.
* doc/coreutils.texi (od invocation): Describe the new option.
* NEWS: Mention the new feature.

1 files changed, 46 insertions, 0 deletions

diff --git a/tests/misc/od-endian.sh b/tests/misc/od-endian.sh
new file mode 100755
index 000000000..5ee17e617
--- /dev/null
+++ b/tests/misc/od-endian.sh
@@ -0,0 +1,46 @@
+#!/bin/sh
+# verify that od --endian works properly
+
+# Copyright (C) 2014 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
+print_ver_ od
+
+in='0123456789abcdef'
+
+# rev(1) is not generally available, so here's a simplistic
+# implementation sufficient for our purposes.
+rev() {
+  while read line; do
+    printf '%s' "$line" | sed 's/./&\n/g' | tac | paste -s -d ''
+  done
+}
+
+in_swapped() { printf '%s' "$in" | sed "s/.\{$1\}/&\\n/g" | rev | tr -d '\n'; }
+
+for e in little big; do
+  test $e = little && eo=big || eo=little
+  for s in 1 2 4 8 16; do
+    for t in x f; do
+      od -t $t$s --endian=$e /dev/null > /dev/null 2>&1 || continue
+      printf '%s' "$in" | od -An -t $t$s --endian=$e  > out1
+      in_swapped  "$s"  | od -An -t $t$s --endian=$eo > out2
+      compare out1 out2 || fail=1
+    done
+  done
+done
+
+Exit $fail