Zip file problem on Mac

[Brian Milby]

I imagine this one isn’t documented due to the issues where you can’t read properties from an existing zip file.  I think I found it when digging into the source.

I’m sure there are some that could be found by looking at the source code that is still available.

Sent from my iPhone

> On May 8, 2022, at 1:33 PM, Klaus major-k via use-livecode <use-livecode at lists.runrev.com> wrote:
> 
> Hi all,
> 
>>> Am 08.05.2022 um 03:18 schrieb Neville Smythe via use-livecode <use-livecode at lists.runrev.com>:
>>>> On 8 May 2022, at 2:00 am, Brian Milby wrote:
>>> It is a bug somewhere. See this big report:
>>> https://quality.livecode.com/show_bug.cgi?id=21447 <https://quality.livecode.com/show_bug.cgi?id=21447>
>>> I actually think it is related. The zip should be created as a Unix variant and not Fat and file attributes should be stored. One thing that could be tried is to manually set the executable bit when creating the archive. I was able to store a link in a zip using this method, but there is no way to read the file attributes in LC.
>> Brian, utter genius!
>> Not only do you pinpoint the bug — revZip is creating a ‘fat’ zip not a ‘unx’ zip and not adding the external attributes – but it looks like you have provided the workaround (for my problem of execute permissions at least)
>> I tried the implausible trick of using the undocumented revZipSetItemAttributes
>> put 0x80000000 into tExtAttributes -- regular file
>> add 0x01ED0000 to tExtAttributes -- rwxrwxr-x -- modify as per file (and may only do for Mac,Linux?)
>> revZipSetItemAttributes pArchive, pName, 3, tExtAttributes  — 3 for unix system
>> for each file as it is added to the archive. I didn’t really expect this to work as the file is already added to the archive in ‘fat’ format.
>> Not only does unzip -Z report that the archive items are now in ‘unx’ format with permissions rwxrwxr-x, but astonishingly the zip actually decompresses to a working executable – well, only so far briefly tested on a Mac but it seems likely this is going to work on all platforms. 
>> As you point out in your bug 21447 report, revZip probably won’t be able to decompress the archive correctly because of other deficiencies, but I only need the user's system to unpack it. And I will have to modify the permissions for each individual file in the archive. 
>> I never thought I would use the expression, but, like , awesome! OK sorry I went there, but jolly well done, that man!
>> 
>> Neville
> 
> I really wonder how much more useful features are undocumented and why they do not find their way into the dictionary!?
> 
> --
> Klaus Major
> https://www.major-k.de
> https://www.major-k.de/bass
> klaus at major-k.de
> 
> 
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