From 909f8e14dbe4073d75a776b4a9f50e5cc450f161 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Fri, 13 Nov 2015 12:03:46 +0000 Subject: Fix ldbl-128ibm strtold overflow handling (bug 14551). For ldbl-128ibm, if the result of strtold overflows in the final conversion from MPN to IBM long double (because the exponent for a 106-bit IEEE result is 1023 but the high part would end up as 0x1p1024, which overflows), that conversion code fails to handle this and produces an invalid long double value (high part infinite, low part not zero) without raising exceptions or setting errno. This patch adds an explicit check for this case to ensure an appropriate result is returned in a way that ensures the right exceptions are raised, with errno set. Tested for powerpc. [BZ #14551] * sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c: Include . (__mpn_construct_long_double): If high part overflows to infinity, set errno and recompute overflowed result of the correct sign. * sysdeps/ieee754/ldbl-128ibm/Makefile [$(subdir) = stdlib] (tests): Add tst-strtold-ldbl-128ibm. [$(subdir) = stdlib] ($(objpfx)tst-strtold-ldbl-128ibm): Depend on $(libm). * sysdeps/ieee754/ldbl-128ibm/tst-strtold-ldbl-128ibm.c: New file. --- sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c') diff --git a/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c b/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c index bacb2cc..90dae93 100644 --- a/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c +++ b/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c @@ -18,6 +18,7 @@ #include "gmp.h" #include "gmp-impl.h" #include +#include #include #include @@ -111,6 +112,14 @@ __mpn_construct_long_double (mp_srcptr frac_ptr, int expt, int sign) { hi >>= 1; u.d[0].ieee.exponent++; + if (u.d[0].ieee.exponent == IEEE754_DOUBLE_BIAS + DBL_MAX_EXP) + { + /* Overflow. The appropriate overflowed result must + be produced (if an infinity, that means the low + part must be zero). */ + __set_errno (ERANGE); + return (sign ? -LDBL_MAX : LDBL_MAX) * LDBL_MAX; + } } u.d[1].ieee.negative = !sign; lo = (1LL << 53) - lo; -- cgit v1.1