Subject: bug#3410 closed by Stefan Monnier <[email-masked]> (Re: bug#3410: tar mode fails to open many valid files)

From: [email-masked] (Emacs bug Tracking System)
Date: Thu, 04 Jun 2009 21:55:06 +0000

This is an automatic notification regarding your bug report
which was filed against the emacs package:

#3410: tar mode fails to open many valid files

It has been closed by Stefan Monnier <[email-masked]>.

Their explanation is attached below along with your original report.
If this explanation is unsatisfactory and you have not received a
better one in a separate message then please contact Stefan Monnier <[email-masked]> by
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3410: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=3410
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Subject: Re: bug#3410: tar mode fails to open many valid files
From: Stefan Monnier <[email-masked]>
To: Paul Pogonyshev <[email-masked]>
Cc: [email-masked]
Date: Thu, 04 Jun 2009 16:48:56 -0400

> I.e. it works fine with
>    emacs -Q ~/tmp/poi-bin-3.5-beta5-20090219.tar.gz
> but shows your problem with
>    emacs -Q -f url-handler-mode; C-x C-f http://.../poi... RET

In the end you were right, and I have no idea how I managed to get the
above results.  url-handler-mode makes no difference, and the 64bit
thingy makes a difference (it somehow hides the bug, so it doesn't
signal an error but instead misinterprets the middle of the tar file,
while the beginning and the end are still just fine, so my cursory check
didn't see the corruption).

I've just installed the patch below, which should fix the problem,

        Stefan

--- tar-mode.el.~1.139.~	2009-03-20 16:24:31.000000000 -0400
+++ tar-mode.el	2009-06-04 16:41:49.000000000 -0400
@@ -276,7 +276,10 @@
             (setq link-p 5))            ; directory
 
         (if (and (equal name "././@LongLink")
-                 (equal magic-str "ustar ")) ;OLDGNU_MAGIC.
+                 ;; Supposedly @LongLink is only used for GNUTAR
+                 ;; format (i.e. "ustar ") but some POSIX Tar files
+                 ;; (with "ustar\0") have been seen using it as well.
+                 (member magic-str '("ustar " "ustar\0")))
             ;; This is a GNU Tar long-file-name header.
             (let* ((size (tar-parse-octal-integer
                           string tar-size-offset tar-time-offset))

Subject: tar mode fails to open many valid files
From: Paul Pogonyshev <[email-masked]>
To: [email-masked]
Date: Thu, 28 May 2009 17:05:14 +0300

When I open a 'tar.gz' file in Emacs, it quite often fails with a
message similar to:

    File mode specification error: (error
    "ntWorkbookBuilder.SheetRecordCollectingListener.html\"
    title=\"class in org.apache.poi.hssf.eventuserm has size
    -137265917 - corrupted")

E.g. file at

    http://apache.promotionalpro.com/poi/dev/bin/poi-bin-3.5-beta5-20090219.tar.gz

exhibits this error.  It can be extracted without problems with 'tar
-xzf ...' at command line, so it must be a bug in Emacs' tar mode.
Maybe it is too strict or doesn't handle some extension properly.

Paul