[#4670] unable to open zip files on Mac OS X
Summary unable to open zip files on Mac OS X
Queue Horde Framework Packages
Queue Version HEAD
Type Bug
State Resolved
Priority 1. Low
Requester reitsma (at) denison (dot) edu
Created 2006-11-16 (5177 days ago)
Updated 2006-11-16 (5177 days ago)
Resolved 2006-11-16 (5177 days ago)
Patch No

2006-11-16 19:51:08 Chuck Hagenbuch Comment #2
State ⇒ Resolved
Reply to this comment
Fixed in HEAD and FW_3 - thanks for the analysis and fix!
2006-11-16 11:53:47 reitsma (at) denison (dot) edu Comment #1
Type ⇒ Bug
State ⇒ Unconfirmed
Priority ⇒ 1. Low
Summary ⇒ unable to open zip files on Mac OS X
Queue ⇒ Horde Framework Packages
Reply to this comment
The "Download all attachments in zip file" option sometimes results in 
a file that cannot be opened by the default zip handler 
(BOMArchiveHelper) on Mac OS X. Zipinfo reports the contents of the 
file properly. The file can be "repaired" using the following steps:

zipnote file.zip >tmp

zipnote -w file.zip <tmp

In doing this we noted that 12 bytes per file get dropped from the archive.

The mailing list reports two other zip handlers having problems with 
IMP generated zip files: 7-Zip and Stuffit 11.

In Horde/Compress/zip.php I found at line 346:

         /* "Data descriptor" segment (optional but necessary if archive is

            not served as file). */

         $fr .= pack('V', $crc);

         $fr .= pack('V', $c_len);

         $fr .= pack('V', $unc_len);

This amounts to 12 bytes that gets added for each file in the archive. 
These are the 12 bytes that zipnote is stripping out for each file. 
PKWare's appnote.txt indicates there is confusion in the use of the 
data descriptor segment (should it have a signature, should it only be 
used in stream processing, which bit to set if it will be used) and 
promises a future appnote to resolve the confusion.

Since we did not want to touch every Macintosh on campus to set it to 
use a different default zip handler we went ahead and commented out 
the data descriptor segment.

Saved Queries