1/* mpfr_check -- Check if a floating-point number has not been corrupted.
2
3Copyright 2003-2004, 2006-2023 Free Software Foundation, Inc.
4Contributed by the AriC and Caramba projects, INRIA.
5
6This file is part of the GNU MPFR Library.
7
8The GNU MPFR Library is free software; you can redistribute it and/or modify
9it under the terms of the GNU Lesser General Public License as published by
10the Free Software Foundation; either version 3 of the License, or (at your
11option) any later version.
12
13The GNU MPFR Library is distributed in the hope that it will be useful, but
14WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
16License for more details.
17
18You should have received a copy of the GNU Lesser General Public License
19along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
20https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
2151 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
22
23#include "mpfr-impl.h"
24
25/*
26 * Check if x is a valid mpfr_t initialized by mpfr_init
27 * Returns 0 if isn't valid
28 *
29 * Note: Due to the MPFR_GET_ALLOC_SIZE test, this function must not
30 * be called on statically allocated numbers (only used inside MPFR).
31 * Anyway, this test should not be useful on such numbers.
32 */
33int
34mpfr_check (mpfr_srcptr x)
35{
36  mp_size_t s, i;
37  mp_limb_t tmp;
38  volatile mp_limb_t *xm;
39  mpfr_prec_t prec;
40  int rw;
41
42  /* Check sign */
43  if (MPFR_SIGN(x) != MPFR_SIGN_POS &&
44      MPFR_SIGN(x) != MPFR_SIGN_NEG)
45    return 0;
46  /* Check precision */
47  prec = MPFR_PREC(x);
48  if (! MPFR_PREC_COND (prec))
49    return 0;
50  /* Check mantissa */
51  xm = MPFR_MANT(x);
52  if (xm == NULL)
53    return 0;
54  /* Check size of mantissa */
55  s = MPFR_GET_ALLOC_SIZE(x);
56  if (s <= 0 || s > MP_SIZE_T_MAX ||
57      prec > (mpfr_prec_t) s * GMP_NUMB_BITS)
58    return 0;
59  /* Access all the mp_limb of the mantissa: may do a seg fault */
60  for (i = 0 ; i < s ; i++)
61    tmp = xm[i];
62  /* Check singular numbers (do not use MPFR_IS_PURE_FP() in order to avoid
63     any assertion checking, as this function mpfr_check() does something
64     similar by returning a Boolean instead of doing an abort if the format
65     is incorrect). */
66  if (MPFR_IS_SINGULAR (x))
67    return MPFR_IS_ZERO(x) || MPFR_IS_NAN(x) || MPFR_IS_INF(x);
68  /* Check the most significant limb (its MSB must be 1) */
69  if (! MPFR_IS_NORMALIZED (x))
70    return 0;
71  /* Check the least significant limb (the trailing bits must be 0) */
72  rw = prec % GMP_NUMB_BITS;
73  if (rw != 0)
74    {
75      tmp = MPFR_LIMB_MASK (GMP_NUMB_BITS - rw);
76      if ((xm[0] & tmp) != 0)
77        return 0;
78    }
79  /* Check exponent range */
80  return MPFR_EXP_IN_RANGE (MPFR_EXP (x));
81}
82