Re: [libvirt] [PATCH]: don't harcode buffer for getgrnam_r

Hi, On Thu, Apr 16, 2009 at 10:40 PM, Daniel P. Berrange <berrange(a)redhat.com&gt; wrote: > On Thu, Apr 16, 2009 at 02:14:13PM +0200, Guido G?nther wrote: >> On Thu, Apr 16, 2009 at 09:56:27AM +0200, Daniel Veillard wrote: >> > On Thu, Apr 16, 2009 at 09:19:38AM +0200, Guido Günther wrote: >> > > Hi, >> > > determines the maximum needed buffersize for getgrnam_r using sysconf >> > > instead of hardcoding it to 1024 and increases the buffer on ERANGE. >> > > The latter is needed since sysconf is allowed to return -1. Furthermore >> > > some glibc versions seem to return a too small buffer on amd64 >> > > (http://bugs.debian.org/520744). O.k. to apply? >> > >> >   It looks a bit weird, using sysconf but 1/ allowing it to fail so >> > doing the 2/ 1024 value and loop on ERANGE , but well if I understand >> > correctly taht's forced by some glibc broken behaviour. >> Yes, sysconf is allowed to return -1 here. >> >> >   My take is that the *= 2 size loop should be bounded to avoid eating >> > all memory on some intermediate not size related error. Can we really >> glibc shouldn't return ERANGE then, but better safe than sorry. I've >> added that check in the attched patch. > > ACK. I think it's more useful that such a function is implemented as a wrapper function like virGetUserDirectory() in util.c, because other drivers might use the function. Actually my patch sent just now implements virGetGIDByGroupname() in util.c ;-)