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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.
This commit is contained in:
Niels Möller
Pádraig Brady
parent
b938b6e289
commit
b370924c03
5
NEWS
5
NEWS
@ -18,6 +18,11 @@ GNU coreutils NEWS -*- outline -*-
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it would display an error, requiring --no-dereference to avoid the issue.
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[bug introduced in coreutils-5.3.0]
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** New features
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od accepts a new option: --endian=TYPE to handle inputs with different byte
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orders, or to provide consistent output on systems with disparate endianness.
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** Improvements
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stat and tail work better with HFS+ and HFSX. stat -f --format=%T now reports
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@ -1868,6 +1868,16 @@ none (do not print offsets).
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The default is octal.
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@item --endian=@var{order}
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@opindex --endian
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@cindex byte-swapping
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@cindex endianness
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Reorder input bytes, to handle inputs with differing byte orders,
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or to provide consistent output independent of the endian convention
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of the current system. Swapping is performed according to the
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specified @option{--type} size and endian @var{order}, which can be
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@samp{little} or @samp{big}.
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@item -j @var{bytes}
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@itemx --skip-bytes=@var{bytes}
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@opindex -j
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59
src/od.c
59
src/od.c
@ -23,6 +23,7 @@
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#include <getopt.h>
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#include <sys/types.h>
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#include "system.h"
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#include "argmatch.h"
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#include "error.h"
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#include "ftoastr.h"
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#include "quote.h"
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@ -259,13 +260,37 @@ static enum size_spec integral_type_size[MAX_INTEGRAL_TYPE_SIZE + 1];
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#define MAX_FP_TYPE_SIZE sizeof (long double)
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static enum size_spec fp_type_size[MAX_FP_TYPE_SIZE + 1];
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#ifndef WORDS_BIGENDIAN
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# define WORDS_BIGENDIAN 0
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#endif
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/* Use native endianess by default. */
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static bool input_swap;
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static char const short_options[] = "A:aBbcDdeFfHhIij:LlN:OoS:st:vw::Xx";
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/* For long options that have no equivalent short option, use a
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non-character as a pseudo short option, starting with CHAR_MAX + 1. */
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enum
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{
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TRADITIONAL_OPTION = CHAR_MAX + 1
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TRADITIONAL_OPTION = CHAR_MAX + 1,
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ENDIAN_OPTION,
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};
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enum endian_type
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{
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endian_little,
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endian_big
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};
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static char const *const endian_args[] =
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{
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"little", "big", NULL
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};
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static enum endian_type const endian_types[] =
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{
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endian_little, endian_big
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};
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static struct option const long_options[] =
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@ -278,6 +303,7 @@ static struct option const long_options[] =
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{"strings", optional_argument, NULL, 'S'},
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{"traditional", no_argument, NULL, TRADITIONAL_OPTION},
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{"width", optional_argument, NULL, 'w'},
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{"endian", required_argument, NULL, ENDIAN_OPTION },
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{GETOPT_HELP_OPTION_DECL},
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{GETOPT_VERSION_OPTION_DECL},
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@ -318,6 +344,7 @@ suffixes may be . for octal and b for multiply by 512.\n\
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fputs (_("\
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-A, --address-radix=RADIX output format for file offsets; RADIX is one\n\
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of [doxn], for Decimal, Octal, Hex or None\n\
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--endian={big|little} swap input bytes according the specified order\n\
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-j, --skip-bytes=BYTES skip BYTES input bytes first\n\
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"), stdout);
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fputs (_("\
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@ -400,13 +427,27 @@ N (size_t fields, size_t blank, void const *block, \
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char const *FMT_STRING, int width, int pad) \
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{ \
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T const *p = block; \
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uintmax_t i; \
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uintmax_t i; \
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int pad_remaining = pad; \
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for (i = fields; blank < i; i--) \
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{ \
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int next_pad = pad * (i - 1) / fields; \
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int adjusted_width = pad_remaining - next_pad + width; \
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T x = *p++; \
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T x; \
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if (input_swap && sizeof (T) > 1) \
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{ \
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size_t j; \
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union { \
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T x; \
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char b[sizeof (T)]; \
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} u; \
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for (j = 0; j < sizeof (T); j++) \
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u.b[j] = ((const char *) p)[sizeof (T) - 1 - j]; \
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x = u.x; \
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} \
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else \
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x = *p; \
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p++; \
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ACTION; \
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pad_remaining = next_pad; \
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} \
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@ -1664,6 +1705,18 @@ main (int argc, char **argv)
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traditional = true;
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break;
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case ENDIAN_OPTION:
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switch (XARGMATCH ("--endian", optarg, endian_args, endian_types))
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{
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case endian_big:
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input_swap = ! WORDS_BIGENDIAN;
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break;
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case endian_little:
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input_swap = WORDS_BIGENDIAN;
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break;
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}
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break;
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/* The next several cases map the traditional format
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specification options to the corresponding modern format
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specs. GNU od accepts any combination of old- and
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@ -239,6 +239,7 @@ all_tests = \
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tests/misc/xstrtol.pl \
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tests/tail-2/pid.sh \
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tests/misc/od.pl \
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tests/misc/od-endian.sh \
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tests/misc/od-float.sh \
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tests/misc/mktemp.pl \
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tests/misc/arch.sh \
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46
tests/misc/od-endian.sh
Executable file
46
tests/misc/od-endian.sh
Executable file
@ -0,0 +1,46 @@
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#!/bin/sh
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# verify that od --endian works properly
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# Copyright (C) 2014 Free Software Foundation, Inc.
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
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print_ver_ od
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in='0123456789abcdef'
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# rev(1) is not generally available, so here's a simplistic
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# implementation sufficient for our purposes.
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rev() {
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while read line; do
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printf '%s' "$line" | sed 's/./&\n/g' | tac | paste -s -d ''
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done
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}
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in_swapped() { printf '%s' "$in" | sed "s/.\{$1\}/&\\n/g" | rev | tr -d '\n'; }
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for e in little big; do
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test $e = little && eo=big || eo=little
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for s in 1 2 4 8 16; do
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for t in x f; do
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od -t $t$s --endian=$e /dev/null > /dev/null 2>&1 || continue
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printf '%s' "$in" | od -An -t $t$s --endian=$e > out1
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in_swapped "$s" | od -An -t $t$s --endian=$eo > out2
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compare out1 out2 || fail=1
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done
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done
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done
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Exit $fail
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