[tor-bugs] #13192 [Tor]: Collect aggregate stats of total hidden service usage vs total exit usage in Tor network

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#13192: Collect aggregate stats of total hidden service usage vs total exit usage
in Tor network
-----------------------------+---------------------------------------
     Reporter:  arma         |      Owner:
         Type:  enhancement  |     Status:  needs_revision
     Priority:  normal       |  Milestone:  Tor: 0.2.7.x-final
    Component:  Tor          |    Version:
   Resolution:               |   Keywords:  SponsorR tor-relay tor-hs
Actual Points:               |  Parent ID:
       Points:               |
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Comment (by teor):

 Once these changes are made, the test fails the clang x86_64 (3.7.0 (trunk
 230165) / x86_64-apple-darwin14.1.0) integer undefined behaviour sanitiser
 with:
 {{{
 util/cast_double_to_int64: src/test/test_util.c:4250:3: runtime error:
 left shift of negative value -1
 }}}

 This can be resolved by casting the constant `-1` to `uint64_t` not
 `int64_t`:
 {{{
   tt_i64_op(((uint64_t) -1) << 53, ==,
             cast_double_to_int64(-1.0 * pow(2.0, 53.0)));
   tt_i64_op((((uint64_t) -1) << 53) + 1, ==,
             cast_double_to_int64(-1.0 * pow(2.0, 53.0) + 1.0));
 }}}

 See http://stackoverflow.com/a/22734721
 <blockquote>
 The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated bits
 are filled with zeros. If E1 has an unsigned type, the value of the result
 is E1×2E2, reduced modulo one more than the maximum value representable in
 the result type. If E1 has a signed type and non-negative value, and
 E1×2E2 is representable in the result type, then that is the resulting
 value; otherwise, the behaviour is undefined.
 ...
 If E1 is a signed type with negative value then the behaviour of left
 shifting is undefined. This is an easy route to undefined behaviour which
 may easily get overlooked.
 </blockquote>

 The tests then succeed on OS X 10.10.2 / Xcode 6.3 beta / clang 3.7.0 with
 integer undefined behaviour checks / x86_64.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13192#comment:61>
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