[PATCH 2/2] (g)unzip: Optimize inflate_codes()

[Joakim Tjernlund]

Denys Vlasenko <vda.linux at googlemail.com> wrote on 2010/02/12 00:28:44:
>
> On Friday 12 February 2010 00:14, Joakim Tjernlund wrote:
> >
> > Denys Vlasenko <vda.linux at googlemail.com> wrote on 2010/02/11 23:52:30:
> >
> > > From: Denys Vlasenko <vda.linux at googlemail.com>
> > > To: Joakim Tjernlund <joakim.tjernlund at transmode.se>
> > > Cc: busybox at busybox.net, Rob Landley <rob at landley.net>
> > > Date: 2010/02/11 23:52
> > > Subject: Re: [PATCH 2/2] (g)unzip: Optimize inflate_codes()
> > >
> > > On Thursday 11 February 2010 08:42, Joakim Tjernlund wrote:
> > > > >
> > > > > Great. But looks like you forgot to send the patch without this debug.
> > > > > The only patch I found has this:
> > > > >
> > > > > +                                       /* Align out addr */
> > > > > +                                       if (e < 3)
> > > > > +                                               fprintf(stderr, "error
> > > len:%d\n", e);
> > > >
> > > > Hehe, here we go then. Looking at the gzip code I think it is crap though.
> > > > The upstream gzip code is old and unoptimized. One should just scrap
> > > > it and redo it with zlib instead.
> > > >
> >
> > >
> > > It segfaults on 277 Mb gz file (a source tree of old openoffice version):
> >
> > what arch?
>
> x86-32
>
> > >
> > > # time ./busybox_old gunzip <OOo_2.0.2_src.tar.gz >/dev/null
> > >
> > > real    0m13.616s
> > > user    0m13.493s
> > > sys     0m0.116s
> > > # time ./busybox gunzip <OOo_2.0.2_src.tar.gz >/dev/null
> > > /bin/bash: line 1: 15635 Segmentation fault      ./busybox gunzip < OOo_2.0.
> > > 2_src.tar.gz > /dev/null
> > >
> > > real    0m2.198s
> > > user    0m2.186s
> > > sys     0m0.011s
> >
> > Maybe you could stick that debug printout back?
>
> # ./busybox gunzip <OOo_2.0.2_src.tar.gz | md5sum
> gunzip: error len:2
> gunzip: error len:2
> 85bff4b99d1516ace2e8d11bcc4718f5  -

I was afraid this could happen. Either this .gz is compressed with an old
faulty gzip or my patch is buggy :(
Could you try to recompress the archive with latest gzip?
I guess we must fix it either way, does this work for you?

>From 39b4ff13430651bc000d542d0b9fc973449f84c8 Mon Sep 17 00:00:00 2001
From: Joakim Tjernlund <Joakim.Tjernlund at transmode.se>
Date: Fri, 12 Feb 2010 00:43:42 +0100
Subject: [PATCH] unzip: need to guard against len < 3

---
 archival/libunarchive/decompress_unzip.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/archival/libunarchive/decompress_unzip.c b/archival/libunarchive/decompress_unzip.c
index 111d7fc..e64b60d 100644
--- a/archival/libunarchive/decompress_unzip.c
+++ b/archival/libunarchive/decompress_unzip.c
@@ -603,6 +603,8 @@ static NOINLINE int inflate_codes(STATE_PARAM_ONLY)
 						gunzip_window[w++] = gunzip_window[dd++];
 						--e;
 					}
+					if (e < 2)
+						goto less_than_two;
 					/* Use pre increment as it is faster on some arch's */
 					sout = (unsigned short *) (gunzip_window + w - 2);
 					if (delta > 2) {
@@ -630,6 +632,7 @@ static NOINLINE int inflate_codes(STATE_PARAM_ONLY)
 					}
 					w += e & ~1;
 					dd += e & ~1;
+				less_than_two:
 					if (e & 1)
 						gunzip_window[w++] = gunzip_window[dd++];
 				}
--
1.6.4.4