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ea6029b19c
This patch fixes bug 16770, spurious "invalid" exceptions from scalb when testing whether the second argument is an integer, by inserting appropriate range checks to determine whether a cast to int is safe. (Note that invalid_fn is a function that handles both nonintegers and large integers, distinguishing them reliably using functions such as __rint; note also that there are no issues with scalb needing to avoid spurious "inexact" exceptions - it's an old-POSIX XSI function, not a standard C function bound to an IEEE 754 operation - although the return value is still fully determined.) Tested x86_64 and x86. [BZ #16770] * math/e_scalb.c (__ieee754_scalb): Check second argument is not too large before casting to int. * math/e_scalbf.c (__ieee754_scalbf): Likewise. * math/e_scalbl.c (__ieee754_scalbl): Likewise. * math/libm-test.inc (scalb_test_data): Add more tests.
59 lines
1.6 KiB
C
59 lines
1.6 KiB
C
/* Copyright (C) 2011-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <fenv.h>
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#include <math.h>
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#include <math_private.h>
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static double
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__attribute__ ((noinline))
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invalid_fn (double x, double fn)
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{
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if (__rint (fn) != fn)
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{
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feraiseexcept (FE_INVALID);
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return __nan ("");
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}
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else if (fn > 65000.0)
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return __scalbn (x, 65000);
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else
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return __scalbn (x,-65000);
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}
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double
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__ieee754_scalb (double x, double fn)
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{
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if (__glibc_unlikely (__isnan (x)))
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return x * fn;
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if (__glibc_unlikely (!__finite (fn)))
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{
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if (__isnan (fn) || fn > 0.0)
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return x * fn;
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if (x == 0.0)
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return x;
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return x / -fn;
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}
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if (__glibc_unlikely (fabs (fn) >= 0x1p31 || (double) (int) fn != fn))
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return invalid_fn (x, fn);
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return __scalbn (x, (int) fn);
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}
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strong_alias (__ieee754_scalb, __scalb_finite)
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