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/* nbdkit
* Copyright Red Hat
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of Red Hat nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <errno.h>
#include <assert.h>
#include "checked-overflow.h"
#include "vector.h"
static int
calculate_capacity (struct generic_vector *v, size_t n, size_t itemsize,
size_t *newcap_r, size_t *newbytes_r, bool exactly)
{
size_t reqcap, reqbytes, newcap, newbytes, t;
/* New capacity requested. We must allocate this minimum (or fail).
* reqcap = v->cap + n
* reqbytes = reqcap * itemsize
*/
if (ADD_OVERFLOW (v->cap, n, &reqcap) ||
MUL_OVERFLOW (reqcap, itemsize, &reqbytes)) {
errno = ENOMEM;
return -1;
}
/* However for the sake of optimization, scale buffer by 3/2 so that
* repeated reservations don't call realloc often.
* newcap = v->cap + (v->cap + 1) / 2
* newbytes = newcap * itemsize
*/
if (exactly ||
ADD_OVERFLOW (v->cap, 1u, &t) ||
ADD_OVERFLOW (v->cap, t/2, &newcap) ||
MUL_OVERFLOW (newcap, itemsize, &newbytes) ||
newbytes < reqbytes) {
/* If that either overflows or is less than the minimum requested,
* fall back to the requested capacity.
*/
newcap = reqcap;
newbytes = reqbytes;
}
*newcap_r = newcap;
*newbytes_r = newbytes;
return 0;
}
int
generic_vector_reserve (struct generic_vector *v, size_t n, size_t itemsize,
bool exactly)
{
void *newptr;
size_t newcap, newbytes;
if (calculate_capacity (v, n, itemsize, &newcap, &newbytes, exactly) == -1)
return -1;
newptr = realloc (v->ptr, newbytes);
if (newptr == NULL)
return -1;
v->ptr = newptr;
v->cap = newcap;
return 0;
}
/* Always allocates a buffer which is page aligned (both base and size). */
int
generic_vector_reserve_page_aligned (struct generic_vector *v,
size_t n, size_t itemsize)
{
#ifdef HAVE_POSIX_MEMALIGN
int r;
#endif
void *newptr;
size_t newcap, newbytes;
long pagesize;
size_t extra, extra_items;
pagesize = sysconf (_SC_PAGESIZE);
assert (pagesize > 1);
assert (pagesize % itemsize == 0);
if (calculate_capacity (v, n, itemsize, &newcap, &newbytes, true) == -1)
return -1;
/* If the new size (in bytes) is not a full page then we have to
* round up to the next page.
*/
extra = newbytes & (pagesize - 1);
if (extra > 0) {
extra_items = (pagesize - extra) / itemsize;
if (ADD_OVERFLOW (newcap, extra_items, &newcap) ||
ADD_OVERFLOW (newbytes, extra_items * itemsize, &newbytes)) {
errno = ENOMEM;
return -1;
}
}
#ifdef HAVE_POSIX_MEMALIGN
if ((r = posix_memalign (&newptr, pagesize, newbytes)) != 0) {
errno = r;
return -1;
}
#elif HAVE_VALLOC
newptr = valloc (newbytes);
if (newptr == NULL)
return -1;
#else
#error "this platform does not have posix_memalign or valloc"
#endif
/* How much to copy here?
*
* vector_reserve always makes the buffer larger so we don't have to
* deal with the case of a shrinking buffer.
*
* Like the underlying realloc we do not have to zero the newly
* reserved elements.
*
* However (like realloc) we have to copy the existing elements even
* those that are not allocated and only reserved (between 'len' and
* 'cap').
*
* The spec of vector is not clear on the last two points, but
* existing code depends on this undocumented behaviour.
*/
memcpy (newptr, v->ptr, v->cap * itemsize);
free (v->ptr);
v->ptr = newptr;
v->cap = newcap;
return 0;
}
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