Is with-temp-buffer really temporary?

Is with-temp-buffer really temporary?

[Jean Louis]

I wish to use Emacs to accept file online and file should enter memory
and memory should be deleted thereafter.

Thus, if I use with-temp-buffer function, how sure is it that anything
that as in temporary buffer is not any more in the memory of computer?




Jean

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Re: Is with-temp-buffer really temporary?

[Stefan Monnier]

> I wish to use Emacs to accept file online and file should enter memory
> and memory should be deleted thereafter.
> Thus, if I use with-temp-buffer function, how sure is it that anything
> that as in temporary buffer is not any more in the memory of computer?

Emacs Lisp does not "scrape" the memory that it stops using.
IIRC the only kind of scraping offered is what you get with
`clear-string` and AFAIK we have nothing equivalent for buffer text.


        Stefan

Re: Is with-temp-buffer really temporary?

[Jean Louis]

* Stefan Monnier <monnier@iro.umontreal.ca> [2021-04-26 22:59]:
> > I wish to use Emacs to accept file online and file should enter memory
> > and memory should be deleted thereafter.
> > Thus, if I use with-temp-buffer function, how sure is it that anything
> > that as in temporary buffer is not any more in the memory of computer?
> 
> Emacs Lisp does not "scrape" the memory that it stops using.
> IIRC the only kind of scraping offered is what you get with
> `clear-string` and AFAIK we have nothing equivalent for buffer text.

Also good to know.

And if Emacs exits, finishes the process, is memory then scraped?


-- 
Jean

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Re: Is with-temp-buffer really temporary?

[Stefan Monnier]

> And if Emacs exits, finishes the process, is memory then scraped?

Of course not.


        Stefan

Re: Is with-temp-buffer really temporary?

[tomas]

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On Mon, Apr 26, 2021 at 06:42:30PM -0400, Stefan Monnier wrote:
> > And if Emacs exits, finishes the process, is memory then scraped?
> 
> Of course not.

I'd think this is your operating system's job.

Cheers
 - t

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Re: Is with-temp-buffer really temporary?

[Stefan Monnier]

>> > And if Emacs exits, finishes the process, is memory then scraped?
>> Of course not.
> I'd think this is your operating system's job.

Also, given the way computers are currently implemented, the cost of
having to scrape all memory immediately after use would be somewhat
high, especially compared to the benefit:

- most of that memory contains data of no significance, so most of that
  work is wasted.
- it just removes one particular attack vector, among many others, so
  the added security gain is low.


        Stefan

Re: Is with-temp-buffer really temporary?

[Jean Louis]

* Stefan Monnier <monnier@iro.umontreal.ca> [2021-04-27 19:54]:
> >> > And if Emacs exits, finishes the process, is memory then scraped?
> >> Of course not.
> > I'd think this is your operating system's job.
> 
> Also, given the way computers are currently implemented, the cost of
> having to scrape all memory immediately after use would be somewhat
> high, especially compared to the benefit:
> 
> - most of that memory contains data of no significance, so most of that
>   work is wasted.
> - it just removes one particular attack vector, among many others, so
>   the added security gain is low.

Purpose is to implement Emacs Lisp based uploading of files that are
on the fly GnuPG/PGP encrypted and would like to have zero-knowledge
privacy from hosting provider. As I see it now, it is not easy
task.

Could you give me pointers on how to accept uploaded data, should I
use (read-event) to read POST request like one byte by byte?

-- 
Jean

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