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Diffstat (limited to 'src/lib/intmath/muldiv.c')
| -rw-r--r-- | src/lib/intmath/muldiv.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/src/lib/intmath/muldiv.c b/src/lib/intmath/muldiv.c index 6a292db7ba..875cf1bbf2 100644 --- a/src/lib/intmath/muldiv.c +++ b/src/lib/intmath/muldiv.c @@ -1,6 +1,6 @@ /* Copyright (c) 2003-2004, Roger Dingledine * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. - * Copyright (c) 2007-2019, The Tor Project, Inc. */ + * Copyright (c) 2007-2020, The Tor Project, Inc. */ /* See LICENSE for licensing information */ /** @@ -69,6 +69,20 @@ gcd64(uint64_t a, uint64_t b) return a; } +/** Return the unsigned integer product of <b>a</b> and <b>b</b>. If overflow + * is detected, return UINT64_MAX instead. */ +uint64_t +tor_mul_u64_nowrap(uint64_t a, uint64_t b) +{ + if (a == 0 || b == 0) { + return 0; + } else if (PREDICT_UNLIKELY(UINT64_MAX / a < b)) { + return UINT64_MAX; + } else { + return a*b; + } +} + /* Given a fraction *<b>numer</b> / *<b>denom</b>, simplify it. * Requires that the denominator is greater than 0. */ void |