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Simply check for datatypes with unusual number of unused bits (#4309)

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Avoids potential undefined behavior in H5T_is_numeric_with_unusual_unused_bits
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jhendersonHDF 2024-04-03 17:40:15 -05:00 committed by GitHub
parent c22b801c9d
commit a37a049ceb
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1 changed files with 3 additions and 14 deletions
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17
src/H5T.c
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@ -6785,24 +6785,13 @@ H5T_is_numeric_with_unusual_unused_bits(const H5T_t *dt)
/* Is the correct type? */
if (H5T_INTEGER == dt->shared->type || H5T_FLOAT == dt->shared->type ||
H5T_BITFIELD == dt->shared->type) {
#if LDBL_MANT_DIG == 106
/* This currently won't work for the IBM long double type */
if (H5T_FLOAT == dt->shared->type && dt->shared->size == 16 &&
(dt->shared->u.atomic.prec == 64 || dt->shared->u.atomic.prec == 128))
HGOTO_DONE(false);
#endif
/* Has unused bits? */
if (dt->shared->u.atomic.prec < (dt->shared->size * 8)) {
unsigned surround_bits =
1U << (1 + H5VM_log2_gen((dt->shared->u.atomic.prec + dt->shared->u.atomic.offset) - 1));
if (dt->shared->size > 1 && dt->shared->u.atomic.prec < (dt->shared->size * 8))
/* Unused bits are unusually large? */
if (dt->shared->size > 1 && ((dt->shared->size * 8) > surround_bits))
HGOTO_DONE(true);
}
ret_value =
(dt->shared->size * 8) > (2 * (dt->shared->u.atomic.prec + dt->shared->u.atomic.offset));
}
done:
FUNC_LEAVE_NOAPI(ret_value)
} /* end H5T_is_numeric_with_unusual_unused_bits() */