Daniel Barkalow wrote: > The code to ignore trailing zeros from: > > * gzip.c (get_method): Don't complain about trailing zeros at > the end of a gzipped file, as they're commonly appended to fill > out a block (e.g. by GNU tar). > > has a rare bug: if there is exactly one trailing zero (because, for > example, your compressed tar file was one byte short of a block), gzip > gets only the first byte of the magic, and it's zero, but then it hits the > end of the file on the second byte of the magic. > > I think this should affect only that case, and make it not fail:
Thank you! I've applied your patch (small enough to get by without a copyright assignment) http://git.sv.gnu.org/cgit/gzip.git/commit/?id=118a107f2d3ae5267b and added tests to exercise that bit of code: http://git.sv.gnu.org/cgit/gzip.git/commit/?id=8842154f6e88c37af3 >From 118a107f2d3ae5267b42e1aaac58a8b5ce9d1925 Mon Sep 17 00:00:00 2001 From: Daniel Barkalow <barka...@iabervon.org> Date: Sat, 10 Oct 2009 11:35:13 +0200 Subject: [PATCH 1/2] gzip: don't fail when there is exactly one trailing NUL byte * gzip.c (get_method): Require the second byte of magic only if the first byte was nonzero. --- gzip.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/gzip.c b/gzip.c index 8543128..b0f792a 100644 --- a/gzip.c +++ b/gzip.c @@ -1266,8 +1266,13 @@ local int get_method(in) /* If try_byte returned EOF, magic[1] == (char) EOF. */ } else { magic[0] = (char)get_byte(); - magic[1] = (char)get_byte(); - imagic1 = 0; /* avoid lint warning */ + if (magic[0]) { + magic[1] = (char)get_byte(); + imagic1 = 0; /* avoid lint warning */ + } else { + imagic1 = try_byte (); + magic[1] = (char) imagic1; + } } method = -1; /* unknown yet */ part_nb++; /* number of parts in gzip file */ -- 1.6.5.rc3.227.g2ff1c >From 8842154f6e88c37af3b62a4b5d11fdcb10aeb395 Mon Sep 17 00:00:00 2001 From: Jim Meyering <meyer...@redhat.com> Date: Sat, 10 Oct 2009 11:29:33 +0200 Subject: [PATCH 2/2] gzip: add tests for today's bug fix * tests/trailing-nul: New file. Test for today's fix. * Makefile.am (TESTS): Add new script. * NEWS (Bug fixes): Mention it. --- Makefile.am | 6 ++++-- NEWS | 3 +++ tests/trailing-nul | 42 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 49 insertions(+), 2 deletions(-) create mode 100755 tests/trailing-nul diff --git a/Makefile.am b/Makefile.am index 206d5bf..3bca0ee 100644 --- a/Makefile.am +++ b/Makefile.am @@ -100,9 +100,11 @@ check-local: $(FILES_TO_CHECK) $(bin_PROGRAMS) gzip.doc.gz test "`cat $$k | ./gzip -dc $$k - $$k`" = aaa && rm $$k @echo 'Test succeeded.' -TESTS = \ - tests/zdiff \ +TESTS = \ + tests/trailing-nul \ + tests/zdiff \ tests/zgrep-f + EXTRA_DIST += $(TESTS) install-exec-hook: remove-installed-links diff --git a/NEWS b/NEWS index 5071241..5aeee71 100644 --- a/NEWS +++ b/NEWS @@ -4,6 +4,9 @@ GNU gzip NEWS -*- outline -*- ** Bug fixes + gzip no longer fails when there is exactly one trailing NUL byte + gzip has always accepted trailing NUL bytes. Note the plural. + zdiff would exit with status 2 (indicating an error) rather than 1 to indicate differences when both inputs were compressed and different. diff --git a/tests/trailing-nul b/tests/trailing-nul new file mode 100755 index 0000000..08b6c02 --- /dev/null +++ b/tests/trailing-nul @@ -0,0 +1,42 @@ +#!/bin/sh +# gzip accepts trailing NUL bytes; don't fail if there is exactly one. +# Before gzip-1.4, this would fail. + +# Copyright (C) 2009 Free Software Foundation, Inc. + +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. + +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. + +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. +# limit so don't run it by default. + +if test "$VERBOSE" = yes; then + set -x + gzip --version +fi + +. $srcdir/tests/test-lib.sh + +(echo 0 | gzip; printf '\0') > 0.gz || framework_failure +(echo 00 | gzip; printf '\0\0') > 00.gz || framework_failure +(echo 1 | gzip; printf '\1') > 1.gz || framework_failure + +fail=0 + +for i in 0 00 1; do + gzip -d $i.gz; ret=$? + test $ret -eq $i || fail=1 + test $ret = 1 && continue + echo $i > exp || fail=1 + compare $i exp || fail=1 +done + +Exit $fail -- 1.6.5.rc3.227.g2ff1c
