On Thu, Jan 30, 2014 at 1:53 PM, Barry Smith <[email protected]> wrote:
> > On Jan 30, 2014, at 12:46 PM, Brad Aagaard <[email protected]> wrote: > > > On 01/30/2014 10:34 AM, Jed Brown wrote: > >> Brad Aagaard <[email protected]> writes: > >> > >>> Matt and Jed, > >>> > >>> I see that Jed pushed some changes (jed/malloc-zero) for PetscMalloc to > >>> deal with memory alignment and a zero size. It looks like the pointer > >>> will NOT be NULL for a size of 0. Is this true? > >> > >> Yes, just like malloc(), it can be either a unique pointer or NULL. You > >> need the size anyway to know how many elements are in the array. > > > > I thought it was a nice feature that PETSc improved on malloc() and > free() by returning NULL for zero sized allocation (although this wasn't > true for --with-debugging=0 due to memory alignment) and set pointers to > NULL after freeing. > > With PetscMalloc() we could certainly return NULL on 0 mallocs but the > code is a bit more involved for the PetscMallocn() case. > > Here is what I suggestion. Someone suggest (i.e.. write) a > refactorization of PetscMalloc(), PetscMallocn() that handles correctly any > of the sizes being zero correctly in a branch and see how it goes. I have pushed it. It looks simple to me Matt > > Barry > > > > > > What is the rationale for not returning NULL for mallocs of size zero > other than conforming to C malloc behavior? > > > > Brad > > > > > > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
