[Info-vax] ZIP and UNZIP maximum file size

[Steven Schweda]

On Nov 28, 11:54 pm, Lester Dreckow <lester.drec... at gmail.com> wrote:

> [...] do we know what the upper limit is?

   Assuming that "[un]zip -v" mentions (both):

        LARGE_FILE_SUPPORT
        ZIP64_SUPPORT

they should be limited only by the local C run-time or 63
bits, whichever comes first.

> Best info [...] http://www.info-zip.org/FAQ.html#limits

   Eeew.  Ob-so-lete.  The Zip64 archive format extensions
alleviate any 2GB/4GB size limit, and the 64K (16-bit) file
count limit is now a 4G (32-bit) limit.  I'll see if I can
get that Web page updated.


> But trying it (before finding the above), it has successfully zipped
> and unzipped a 40GB backup saveset via an 11GB zip file.  "Unzip -t"
> was OK and DIFF confirmed the resultant unzipped saveset had no
> differences.

   What could go wrong?  (The stuff was tested on files and
archives at least bigger than 4GB, and with counts above 64K,
so I don't expect any size-related problems.  There have been
some bug fixes in the subsequent beta kits, but none directly
size related, so far as I can recall.)


> $ set rms/extend=64000

   Note that there's code in [Un]Zip:[.vms]vms.c which should
set (non-default) large values for some RMS parameters, even
when the victim doesn't do things like that.  With enough
"-v" options on the command line, you should get some
diagnostic messages which reveal what's being done.