corinthia-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Edward Zimmermann <Edward.Zimmerm...@cib.de>
Subject AW: More on the xmalloc project
Date Fri, 27 Feb 2015 11:52:38 GMT
Correct malloc(0) is defined in the specification. What is, however, implementation defined
is what is returned: a null pointer or a pointer with which one should not try to access its
objects (since it is allocated with 0 bytes it can only be assumed that it is only the empty
set). The implementation decision of null versus pointer with 0 bytes allocated is driven
by factors beyond the scope of our concerns--- but there are some very specific use cases
where it could be useful (think realloc where it does not need to move the block). NOTE: malloc(0)
when it does not return a NULL can consume memory and needs to be freed-- since free(NULL)
is OK we can readily free any pointer result of a malloc without worries.


> -----Ursprüngliche Nachricht-----
> Von: Peter Kelly [mailto:pmkelly@apache.org]
> Gesendet: Freitag, 27. Februar 2015 11:11
> An: dev@corinthia.incubator.apache.org
> Betreff: Re: More on the xmalloc project
> 
> > On 27 Feb 2015, at 3:59 am, Gabriela Gibson
> <gabriela.gibson@gmail.com> wrote:
> >
> > Hi Peter, (and everyone else!)
> >
> > I read your JIRA comment, and that's an interesting thing with the
> > missing headerfiles.  My build report[1] was OK so, maybe  different
> > compilers take headers in a different order?
> >
> > Regards the clang build, should/could we have this as a regular build
> > option in the CMake file?
> 
> I don’t really have an opinion on this personally… it’s the default
> compiler on OS X. Depends if people want to use clang on linux/windows
> as well.
> 
> I wouldn’t regard it as a priority right now.
> 
> > Another thing to notice was that my test had quite a lot of malloc 0
> > calls, so whatever is run there, maybe it could do with a check, or
> > perhaps xmalloc should check for if (!size) … ?
> 
> It’s valid to call malloc with a request of 0 bytes.
> 
> —
> Dr Peter M. Kelly
> pmkelly@apache.org
> 
> PGP key: http://www.kellypmk.net/pgp-key <http://www.kellypmk.net/pgp-
> key> (fingerprint 5435 6718 59F0 DD1F BFA0 5E46 2523 BAA1 44AE 2966)

Mime
View raw message