[jira] [Updated] (COMPRESS-664) Prevent to throw ZipException from ZipArchiveInputStream.getNextEntry() for empty file

["Radek Kraus (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/COMPRESS-664?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Radek Kraus updated COMPRESS-664:
---------------------------------
    Summary: Prevent to throw ZipException from ZipArchiveInputStream.getNextEntry() for empty file  (was: Prevent to throw ZipException from ZipArchiveInputStream.getNextEnry() for empty file)

> Prevent to throw ZipException from ZipArchiveInputStream.getNextEntry() for empty file
> --------------------------------------------------------------------------------------
>
>                 Key: COMPRESS-664
>                 URL: https://issues.apache.org/jira/browse/COMPRESS-664
>             Project: Commons Compress
>          Issue Type: Bug
>          Components: Archivers
>    Affects Versions: 1.26.0
>            Reporter: Radek Kraus
>            Priority: Major
>
> The version {{1.26.0}} (regression against {{{}1.25.0{}}}) changes behavior of {{ZipArchiveInputStream.getNextEntry()}} for empty file (zero size). Currently {{ZipException("Cannot find zip signature within the file")}} is thrown instead of return null value, when first entry is requested.
> This was caused by:
>  * [https://github.com/apache/commons-compress/pull/471] (Support preamble garbage in ZipArchiveInputStream)
>  * [https://github.com/apache/commons-compress/commit/7d2fde71046c31508483ca80abbdfcdb4d5c78b9]
> I guess it is a really regression error, because I don't see a reason why {{ZipException}} should be thrown, even when ??zip can ignore any garbage at the beginning of file up to certain size??.
> The _standard_ java {{ZipInputStream}} implementation returns null value too, when {{java.util.zip.ZipInputStream.getNextEntry()}} is invoked.
> {code:java}
> @Test
> public void testGetFirstEntryEmptyZip_Java() throws IOException {
>   try (ZipInputStream zin = new ZipInputStream(new ByteArrayInputStream(new byte[0]))) {
>     ZipEntry entry = zin.getNextEntry();
>     assertNull(entry);
>   }
> }
> {code}
> I guess {{commons-compress 1.26.0}} ({{{}ZipArchiveInputStream{}}}) should preserve the same behavior like in version 1.25.0 and like java {{{}ZipInputStream{}}}.
> Here is my PR with simple change:
> The key is to don't catch {{EOFException}} and transform it into {{{}ZipException{}}}, but simply throw it into {{ZipArchiveInputStream.getNextZipEntry()}} method, where null value is returned (like in case of second and next entries).
> Please check/review PR deeply, because I don't understand the complex way how "Garbage" is skipped in {{ZipArchiveInputStream.readFirstLocalFileHeader()}} method.



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