Proposal: Add 'fillBytes' to Foreign.Marshal.Utils

[David Feuer]

 I don't know which systems do and don't guarantee what is already cleared;
are you careful not to repeat someone else's work?

On Wed, Nov 12, 2014 at 9:21 AM, Alex Petrov <oleksandr.petrov at gmail.com>
wrote:

> Hi everyone,
>
> Currently the memory allocated with (Foreign.Marshal.Alloc) malloc may
> potentially be dirty. In C this problem is usually solved by using memset.
>
> This would be extremely useful for FFI / C interop, when a data structure
> is allocated within Haskell code. With memset, you can do something like
>
> customMem <- malloc_         <- memset (castPtr customMem) 0 #{size custom_t}
>
> This will fill a block of allocated memory with zeroes.
>
> For example, I've been working on FFI bindings for collectd, and when I
> was allocating memory, previously used within the process, it was dirty, so
> my CString contained a value of
>
> "custom name7e0700490, test_plugin_LTX_module_register): symbol nd"
>
> Instead of just
>
> "custom name"
>
> After using memset and filling everything with zeroes, problem never
> appeared again.
>
> This can be implemented in user applications, too, although it would be
> really nice to have it by default.
>
> This is a common practice in C world, and this function is not only useful
> for cases when the memory was just allocated from Haskell process, but also
> when one receives a dirty memory buffer from C code.
>
>
> The patch for proposal was implemented and is available on Phabricator:
> https://phabricator.haskell.org/D465
>
>
>
> Please share your thoughts.
>
>
> Alex
> https://twitter.com/ifesdjeen
>
> http://clojurewerkz.org/
>
> _______________________________________________
> Libraries mailing list
> Libraries at haskell.org
> http://www.haskell.org/mailman/listinfo/libraries
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/libraries/attachments/20141112/e344f642/attachment.html>