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From "Stefan Bodewig (JIRA)" <j...@apache.org>
Subject [jira] Commented: (SANDBOX-176) Enable creation of tool-readable ZIP archives with file names containing non-ASCII characters
Date Thu, 12 Feb 2009 10:59:59 GMT

    [ https://issues.apache.org/jira/browse/SANDBOX-176?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12672947#action_12672947
] 

Stefan Bodewig commented on SANDBOX-176:
----------------------------------------

My, this is getting complex, in particular since we are having parallel discussions in JIRA
and the mailing list - I'd prefer to stick to one and use the dev list.

Since this issue is currently assigned to me, I should point out that even though there is
a lot of activity around it just now, it may take some time until I get around to it (time
constraints due to personal issues).

IMHO we have a bunch of separate issues and I'll try to address them as short as possible
here.

* Encoding within the constraints of "older" zip clients - i.e. any InfoZIP based client <
3.x for example.

  This seems to be taken care of in OutputStream and ZipFile via setEncoding and it is known
to work since this is what Ant has been using for years now.

  There currently is some discussion whether the default should be UTF-8 (compatible with
java.util.zip) or the platform's default encoding (compatible with Ant's code base).

* More modern ways to specify the encoding.

  All of these can only be optional IMHO.  I'm very grateful of the patches and the tests
you've performed and I promise to review the thoroughly, I may just be slower than you'd hope.

* ZipInputStream

  I haven't looked at any code (GPLed code is a no-go, I'd rather see how the nice folks at
Harmony have implemented it) yet, but given that java.util.zip only uses the LFH part of the
extra fields I suspect the code is cheating.

  My guess is that ZipInputStream only reads the LFH parts and completely ignores the central
directory - we could do that as well.  If I'm correct then the implementation may return wrong
results, it is perfectly valid for an archive to contain "dead" local file data created by
tools that updated an existing archive (they just append a new local file data block and rewrite
the central directory pointing at the new location, leaving the old file data in place).

* "build ZIP for Java consumers":

   use JarArchiveOutputStream which explicitly sets the encoding to UTF-8 and it works.  This
is how Ant writes jar files.

* JDK version

  It has been decided to require JDK 1.4.  Up until now there is no pressing reason to drop
1.3 support (there is a LinkedHashMap somewhere, but that can be worked around) but should
be discussed with the community.

> Enable creation of tool-readable ZIP archives with file names containing non-ASCII characters
> ---------------------------------------------------------------------------------------------
>
>                 Key: SANDBOX-176
>                 URL: https://issues.apache.org/jira/browse/SANDBOX-176
>             Project: Commons Sandbox
>          Issue Type: Improvement
>          Components: Compress
>         Environment: Any / All
>            Reporter: Christian Gosch
>            Assignee: Stefan Bodewig
>         Attachments: commons-compress-utf8-creation-svn741897.patch, utf8-7zip-test.zip,
utf8-winzip-test.zip
>
>
> Currently it is not possible to generate externally readable ZIP archives with java.util.zip.*
or org.apache.commons.compress.* when entries to include shall have names with characters
outside US-ASCII. This should be changed to enable at least org.apache.commons.compress.*
to produce ZIP archives in international context which are readable by usual ZIP archiver
tools like pkzip, gzip, WinZIP, PowerArchiver, WinRAR / rar, StuffIt...
> For java.util.zip.* this is due to a really old flaw on handling entry names: They are
just always rendered as UTF-8, which is kind of Java specific, and not as Cp437, which is
expected and written by most ZIP archiver tools (or eventually all). For more details see:
> http://bugs.sun.com/bugdatabase/view_bug.do;:YfiG?bug_id=4244499
> http://bugs.sun.com/bugdatabase/view_bug.do;:YfiG?bug_id=4820807
> For org.apache.commons.compress.archivers.zip.* the "compress & save" operation can
be easily improved by extending ZipArchive:
> // Add member:
>     protected String m_encoding = null;
> // Add constructor:
>     public ZipArchive(String encoding) {
>         m_encoding = encoding;
>     }
> // Extend doSave(FileOutputStream):
> // ...
> 		// Pack-Operation
> 		ZipOutputStream out = null;
> 		try {
> 			out = new ZipOutputStream(new BufferedOutputStream(output));
>             if (m_encoding != null) {   // added
>                 out.setEncoding(m_encoding);   // added
>             }  // added
> 			while(iterator.hasNext()) {
> // ...
> Now it is possible to instantiate a ZipArchive with "Cp437" as encoding, and external
tools can figure out the original entry names even if they contain non-ASCII characters. (On
the other hand, Java cannot read back & deflate such an archive since it expects UTF-8!)
> The "read & deflate" operation for ZipArchive is more difficult to extend since it
currently relies completely on java.util.zip.* . The other reason is, that ZIP archives do
not contain any hint on the character encoding used for file names etc. It seems that the
usual tools simply use Cp437 and Java simply uses UTF-8 -- without any declaration of reasons.
Thus a deflater has to try.
> For TarArchive the problem is unclear. Here the commons-compress implementation does
not rely on third-party code as far as I can see, and TAR is no Java-bound file type (like
JAR, which is Java-bound). Thus chances are, that everything works well, even when entry names
with non-ASCII characters come into play.

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