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Posted to issues@commons.apache.org by "Peter Lee (Jira)" <ji...@apache.org> on 2020/09/07 06:37:00 UTC
[jira] [Updated] (COMPRESS-550) Support writing self-extracting
preamble data to a zip archive
[ https://issues.apache.org/jira/browse/COMPRESS-550?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Peter Lee updated COMPRESS-550:
-------------------------------
Assignee: Peter Lee
> Support writing self-extracting preamble data to a zip archive
> --------------------------------------------------------------
>
> Key: COMPRESS-550
> URL: https://issues.apache.org/jira/browse/COMPRESS-550
> Project: Commons Compress
> Issue Type: New Feature
> Components: Archivers
> Affects Versions: 1.20
> Reporter: Scott Frederick
> Assignee: Peter Lee
> Priority: Major
> Time Spent: 1h 40m
> Remaining Estimate: 0h
>
> On Linux, it is possible to create a self-extracting zip file by prepending a script or other executable to the zip file. For example, this can be done from the command line with the following commands:
> {code:bash}
> $ echo "test file text" > test.txt
> $ zip test.zip test.txt
> adding: test.txt (stored 0%)
> $ cat /usr/bin/unzipsfx test.zip > test
> $ zipinfo test
> Archive: test
> Zip file size: 101568 bytes, number of entries: 1
> warning [test]: 101392 extra bytes at beginning or within zipfile
> (attempting to process anyway)
> -rw-r--r-- 3.0 unx 10 tx stor 20-Jul-30 15:43 test.txt
> 1 file, 10 bytes uncompressed, 10 bytes compressed: 0.0%
> $ zip --adjust-sfx test.zip
> Zip entry offsets appear off by 101392 bytes - correcting...
> $ zipinfo test
> Archive: test
> Zip file size: 101568 bytes, number of entries: 1
> -rw-r--r-- 3.0 unx 10 tx stor 20-Jul-30 15:43 test.txt
> 1 file, 10 bytes uncompressed, 10 bytes compressed: 0.0%
> $ chmod 755 test
> {code}
> Note that the first invocation of "zipinfo" reports that the central directory is invalid because of extra bytes at the beginning of the zip file. "zip --adjust-sfx" can be used to adjust the central directory to account for the self-extracting preamble bytes.
> It would be nice to be able to prepend this kind of self-extracting preamble to a zip using Apache Commons Compress.
> A method like the following on ZipArchiveOutputStream seems to provide this behavior:
> {code:java}
> public void writePreamble(byte[] preamble) throws IOException {
> if (entry != null) {
> throw new IllegalStateException("Preamble must be written before creating an entry");
> }
> this.streamCompressor.writeCounted(preamble);
> }
> {code}
>
>
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