RFR: 8255380: (zipfs) ZipFileSystem::readExtra can fail if zipinfo-time is not set to false

[Claes Redestad]

On Sun, 1 Nov 2020 20:09:32 GMT, Lance Andersen <lancea at openjdk.org> wrote:

> Hi,
> 
> Please review the fix for JDK-8255380 which addresses an issue when the Zip file is > 4GB.  Zip FS when processing the CEN extra data does not take into account the fact that there is no specific order to how the extra data fields are written.  Info-ZIP writes the fields in a different order than Zip FS which presents a problem when evaluating the Info-ZIP extended timestamp and the LOC offset is 0XFFFFFFFF therefore the LOC offset needs to be read from the EXTID_ZIP64 extra data prior to attempting to read the LOC extra data field.
> 
> The fix will defer reading of the LOC extra data field, if needed until all of the CEN extra data has been processed.
> 
> Using jdk.nio.zipfs.ZipInfo, you can see the ordering difference of the CEND extra data fields when using Zip FS and info-zip.
> 
> Info-zip is included with Mac OS so the test uses ProcessBuilder to execute zip on Mac OS and Linux.  
> 
> Mach5 tests jdk-tier1, jdk-tier2, and jdk-tier3 run cleanly.
> 
> Best,
> Lance

LGTM. Some nits inline.

I guess the test can be cause for issues in some test systems since it needs to write out the 4Gb+ file. Is this why you've only enabled it on linux and mac? Perhaps someone might have ideas on how to improve this.

src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipFileSystem.java line 2993:

> 2991:             // We need to read the LOC extra data and the LOC offset was obtained
> 2992:             // from the EXTID_ZIP64 field.
> 2993:             if(hasZip64LocOffset) {

Suggestion:

            if (hasZip64LocOffset) {

src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipFileSystem.java line 2978:

> 2976:                     // prior to reading the LOC extra data field in order to obtain
> 2977:                     // the Info-ZIP Extended Timestamp.
> 2978:                     if(locoff != ZIP64_MINVAL) {

Suggestion:

                    if (locoff != ZIP64_MINVAL) {

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Marked as reviewed by redestad (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/987