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| author | Aurelien Jarno <aurelien@aurel32.net> | 2014-05-20 14:41:44 +0200 |
|---|---|---|
| committer | Aurelien Jarno <aurelien@aurel32.net> | 2014-05-20 18:44:28 +0200 |
| commit | 4406c41c1d6088abf01c216e49700cd3f8f01fcc (patch) | |
| tree | 6f257fdf8bf4d27212a380a049548f24cdf7f389 /stdlib | |
| parent | ae75a883f2eb312165d1e1f423cea320f3c92ef5 (diff) | |
| download | glibc-4406c41c1d6088abf01c216e49700cd3f8f01fcc.tar.gz | |
Fix strtold on 32-bit sparc (and probably others) (BZ #16965)
This patch fixes an issue observed running the tst-strtod-round test on
32 bit sparc. In some conditions, strtold calls round_and_return, which in
turn calls __mpn_rshift with cnt = 0, while stdlib/rshift.c explicitly says
that cnts should satisfy 0 < CNT < BITS_PER_MP_LIMB. In this case, the code
end up doing a logical shift right of the same amount than the register,
which is undefined in the C standard.
Due to this bug, 32-bit sparc does not correctly convert the value
"0x1p-16446", but it is likely that other architectures are also
affected for other input values.
Diffstat (limited to 'stdlib')
| -rw-r--r-- | stdlib/strtod_l.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/stdlib/strtod_l.c b/stdlib/strtod_l.c index 6707e482a4..3c449c7d54 100644 --- a/stdlib/strtod_l.c +++ b/stdlib/strtod_l.c @@ -243,9 +243,14 @@ round_and_return (mp_limb_t *retval, intmax_t exponent, int negative, more_bits |= ((round_limb & ((((mp_limb_t) 1) << round_bit) - 1)) != 0); - (void) __mpn_rshift (retval, &retval[shift / BITS_PER_MP_LIMB], - RETURN_LIMB_SIZE - (shift / BITS_PER_MP_LIMB), - shift % BITS_PER_MP_LIMB); + /* __mpn_rshift requires 0 < shift < BITS_PER_MP_LIMB. */ + if ((shift % BITS_PER_MP_LIMB) != 0) + (void) __mpn_rshift (retval, &retval[shift / BITS_PER_MP_LIMB], + RETURN_LIMB_SIZE - (shift / BITS_PER_MP_LIMB), + shift % BITS_PER_MP_LIMB); + else + for (i = 0; i < RETURN_LIMB_SIZE - (shift / BITS_PER_MP_LIMB); i++) + retval[i] = retval[i + (shift / BITS_PER_MP_LIMB)]; MPN_ZERO (&retval[RETURN_LIMB_SIZE - (shift / BITS_PER_MP_LIMB)], shift / BITS_PER_MP_LIMB); } |