grub/grub-core/lib/division.c
Andrei Borzenkov f11db3c7fc core: avoid NULL derefrence in grub_divmod64s
It can be called with NULL for third argument.  grub_divmod32* for
now are called only from within wrappers, so skip check.

Reported-By: Michael Zimmermann <sigmaepsilon92@gmail.com>
2015-04-06 19:30:51 +03:00

74 lines
1.6 KiB
C

/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2015 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/misc.h>
#include <grub/dl.h>
GRUB_MOD_LICENSE ("GPLv3+");
static grub_uint64_t
abs64(grub_int64_t a)
{
return a > 0 ? a : -a;
}
grub_int64_t
grub_divmod64s (grub_int64_t n,
grub_int64_t d,
grub_int64_t *ro)
{
grub_uint64_t ru;
grub_int64_t q, r;
q = grub_divmod64 (abs64(n), abs64(d), &ru);
r = ru;
/* Now: |n| = |d| * q + r */
if (n < 0)
{
/* -|n| = |d| * (-q) + (-r) */
q = -q;
r = -r;
}
/* Now: n = |d| * q + r */
if (d < 0)
{
/* n = (-|d|) * (-q) + r */
q = -q;
}
/* Now: n = d * q + r */
if (ro)
*ro = r;
return q;
}
grub_uint32_t
grub_divmod32 (grub_uint32_t n, grub_uint32_t d, grub_uint32_t *ro)
{
grub_uint64_t q, r;
q = grub_divmod64 (n, d, &r);
*ro = r;
return q;
}
grub_int32_t
grub_divmod32s (grub_int32_t n, grub_int32_t d, grub_int32_t *ro)
{
grub_int64_t q, r;
q = grub_divmod64s (n, d, &r);
*ro = r;
return q;
}