Scott Frederick created COMPRESS-550:
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Summary: 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
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
$ 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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