Created attachment 281656 [details] [review]
Remove couple of dead conditions.

"xmlIO.c"

if (filename == NULL)
        return(NULL);

Above conditions already checks if filename is NULL. No need to do Null check again for path.
as path=filename;

"xmlmemory.c"
p = (MEMHDR *) malloc(RESERVE_SIZE+size);
    if (!p) {
      goto error;
    }
It already checks if P is NULL.

s = (char *) HDR_2_CLIENT(p);
It assigns some memory of p, so cannot be Null.
so, checking s to NUll is not required.

Please apply attached patch.