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author | vlefevre <vlefevre@280ebfd0-de03-0410-8827-d642c229c3f4> | 2020-03-26 17:09:28 +0000 |
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committer | vlefevre <vlefevre@280ebfd0-de03-0410-8827-d642c229c3f4> | 2020-03-26 17:09:28 +0000 |
commit | e3dcaaf0d9e206b0acd9597622c6d3d423cb5ed5 (patch) | |
tree | 6f1103860b8da012e4c1302ea8fb329ee4185b71 | |
parent | ee1e3b9bb8484d2d844f4b3383365c9387d6bac6 (diff) | |
download | mpfr-e3dcaaf0d9e206b0acd9597622c6d3d423cb5ed5.tar.gz |
[src] Portability fixes. Avoid a potential integer overflow with huge
precisions.
(merged changesets r13792-13793,13795 from the trunk)
git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/branches/4.0@13828 280ebfd0-de03-0410-8827-d642c229c3f4
-rw-r--r-- | src/agm.c | 2 | ||||
-rw-r--r-- | src/pow.c | 11 | ||||
-rw-r--r-- | src/rem1.c | 6 |
3 files changed, 12 insertions, 7 deletions
@@ -220,7 +220,7 @@ mpfr_agm (mpfr_ptr r, mpfr_srcptr op2, mpfr_srcptr op1, mpfr_rnd_t rnd_mode) mpfr_add (vf, u, v, MPFR_RNDN); /* No overflow? */ mpfr_div_2ui (vf, vf, 1, MPFR_RNDN); /* See proof in algorithms.tex */ - if (4*eq > p) + if (eq > p / 4) { mpfr_t w; MPFR_BLOCK_DECL (flags3); @@ -34,8 +34,7 @@ mpfr_pow_is_exact (mpfr_ptr z, mpfr_srcptr x, mpfr_srcptr y, mpfr_rnd_t rnd_mode, int *inexact) { mpz_t a, c; - mpfr_exp_t d, b; - unsigned long i; + mpfr_exp_t d, b, i; int res; MPFR_ASSERTD (!MPFR_IS_SINGULAR (y)); @@ -48,7 +47,9 @@ mpfr_pow_is_exact (mpfr_ptr z, mpfr_srcptr x, mpfr_srcptr y, if (MPFR_IS_NEG (y)) return 0; /* x is not a power of two => x^-y is not exact */ - /* compute d such that y = c*2^d with c odd integer */ + /* Compute d such that y = c*2^d with c odd integer. + Since c comes from a regular MPFR number, due to the constraints on the + exponent and the precision, there can be no integer overflow below. */ mpz_init (c); d = mpfr_get_z_2exp (c, y); i = mpz_scan1 (c, 0); @@ -58,7 +59,9 @@ mpfr_pow_is_exact (mpfr_ptr z, mpfr_srcptr x, mpfr_srcptr y, /* Since y is not an integer, d is necessarily < 0 */ MPFR_ASSERTD (d < 0); - /* Compute a,b such that x=a*2^b */ + /* Compute a,b such that x=a*2^b. + Since a comes from a regular MPFR number, due to the constrainst on the + exponent and the precision, there can be no integer overflow below. */ mpz_init (a); b = mpfr_get_z_2exp (a, x); i = mpz_scan1 (a, 0); diff --git a/src/rem1.c b/src/rem1.c index 3a7173c24..0ac742749 100644 --- a/src/rem1.c +++ b/src/rem1.c @@ -100,9 +100,11 @@ mpfr_rem1 (mpfr_ptr rem, long *quo, mpfr_rnd_t rnd_q, mpz_abs (my, my); q_is_odd = 0; - /* divide my by 2^k if possible to make operations mod my easier */ + /* Divide my by 2^k if possible to make operations mod my easier. + Since my comes from a regular MPFR number, due to the constraints on the + exponent and the precision, there can be no integer overflow below. */ { - unsigned long k = mpz_scan1 (my, 0); + mpfr_exp_t k = mpz_scan1 (my, 0); ey += k; mpz_fdiv_q_2exp (my, my, k); } |