[Vm-dev] ImageFormat updates
David T. Lewis
lewis at mail.msen.com
Mon May 1 01:14:08 UTC 2017
On Sun, Apr 30, 2017 at 10:26:18PM +0530, K K Subbu wrote:
> Is there an Inbox to upload patches to VMMaker for review?
That's probably a good idea, although posting to the vm-dev list as you
are doing here is fine for ImageFormat.
> I generated a small fix to ImageFormat to generate magic pattern checks
> at offset 512 also. I think some old Etoys images use this offset with a
> launch script stuffed in the first 512 bytes. Is this deprecated now?
The 512 byte offset is a trick for letting the image file work as a
shell script, using a shebang line to run the image. I don't think it
gets used very often, but hopefully it still works, and that is the reason
for the offset check.
I don't know if it shsould go into the magic file entries, because when
set up in this manner it actually would be an executeble script. I guess
you could look at it either way though, either as a shell script or as
a Smalltalk image file.
> I also feel 'unix' should be dropped from the method's name. file(1)
> utility originated in Unix but is related to file contents and not to
> kernel. It should be available for Mac/Win too.
As far as I know it is a unix utility. It would certainly be available
on OS X (which is a unix), though I'm not sure of its status on Windows.
> I have also attached the resulting magic file and a workspace script to
> generate a bunch of test header files to test the magic file. e.g.
> $ file -m magic *.image
> Regards .. Subbu
Thanks! I'll take a look at it.
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