[Vm-dev] Issue 101 in cog: Snapshot primitive with 512byte image header

[Camillo Bruni]

On 2012-10-14, at 18:50, David T. Lewis <lewis at mail.msen.com> wrote:

> 
> On Sun, Oct 14, 2012 at 11:09:25AM +0000, cog at googlecode.com wrote:
>> 
>> Status: Accepted
>> Owner: camillob... at gmail.com
>> Labels: Type-Defect Priority-Medium
>> 
>> New issue 101 by camillob... at gmail.com: Snapshot primitive with 512byte  
>> image header
>> http://code.google.com/p/cog/issues/detail?id=101
>> 
>> I would like to add proper shebang support to our image files.
>> Hence I need a proper primitive which allows me to inject the 512bytes  
>> header with a proper shebang (or other user data..)
>> 
>> This could be handled the same way as the quit primitive by checking for an 
>> optional argument, the header, and pass it along to #writeImageFile:
> 
> FYI, the hook for this is a macro in platforms/Cross/vm/sq.h:
> 
>  #define sqImageFileStartLocation(fileRef, fileName, size)  0
> 
> If you implement this as a function that writes the shebang line followed
> by <lf>, and pads with null for the first 512 bytes, then answers 512 as
> the result, you will have what you want. You should probably set the image
> file writable while you're at it.

thanks, I will have a look at it possibly next week.

cami