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https://issues.apache.org/jira/browse/COMPRESS-395?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16010712#comment-16010712
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Stefan Bodewig commented on COMPRESS-395:
-----------------------------------------
{{addRawArchiveEntry}} has been added fairly recently and we've likely not
thought through all possible combinations, thanks.
I wouldn't expect too much of a difference when we skipped the data descriptor,
though.
> [Zip] Do not add data descriptor record when CRC and size values are known
> --------------------------------------------------------------------------
>
> Key: COMPRESS-395
> URL: https://issues.apache.org/jira/browse/COMPRESS-395
> Project: Commons Compress
> Issue Type: Improvement
> Components: Archivers
> Reporter: Plamen Totev
> Priority: Minor
>
> Hi,
> Currently {{ZipArchiveOutputStream}} will add data descriptor record when the
> output do not provide random access. But if you add an entry using
> {{addRawArchiveEntry}} then the CRC, compressed size and uncompressed size
> could be know and there is no need for data descriptor record as those values
> could be set in the local file header. The current implementation does both -
> it sets the correct value in the local file header and adds additional data
> descriptor record. Here is the relevant code from
> {{ZipArchiveOutputStream#putArchiveEntry}}:
> {code:java}
> // just a placeholder, real data will be in data
> // descriptor or inserted later via SeekableByteChannel
> ZipEightByteInteger size = ZipEightByteInteger.ZERO;
> ZipEightByteInteger compressedSize = ZipEightByteInteger.ZERO;
> if (phased){
> size = new ZipEightByteInteger(entry.entry.getSize());
> compressedSize = new
> ZipEightByteInteger(entry.entry.getCompressedSize());
> } else if (entry.entry.getMethod() == STORED
> && entry.entry.getSize() != ArchiveEntry.SIZE_UNKNOWN) {
> // actually, we already know the sizes
> size = new ZipEightByteInteger(entry.entry.getSize());
> compressedSize = size;
> }
> z64.setSize(size);
> z64.setCompressedSize(compressedSize);
> {code}
> Maybe {{ZipArchiveOutputStream}} could be improved to not add data
> descriptor record when the CRC and size values are known in advance.
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