[tor-bugs] #23061 [Core Tor/Tor]: crypto_rand_double() should produce all possible outputs on platforms with 32-bit int

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#23061: crypto_rand_double() should produce all possible outputs on platforms with
32-bit int
-------------------------------------------------+-------------------------
 Reporter:  teor                                 |          Owner:  nickm
     Type:  defect                               |         Status:
                                                 |  needs_review
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.3.2.x-final
Component:  Core Tor/Tor                         |        Version:  Tor:
                                                 |  0.2.2.14-alpha
 Severity:  Normal                               |     Resolution:
 Keywords:  tor-relay, security-low, privcount,  |  Actual Points:  0.5
  031-backport, 030-backport, 029-backport, 028  |
  -backport-maybe, 027-backport-maybe, 026       |
  -backport-maybe, review-group-22               |
Parent ID:                                       |         Points:  0.1
 Reviewer:                                       |        Sponsor:
                                                 |  SponsorQ
-------------------------------------------------+-------------------------

Comment (by yawning):

 If the test assuming `f(n-1) < f(n) < f(n+1)` is ok, then you can do:

 {{{
   double expected_increment = pow(FLT_RADIX, -DBL_MANT_DIG);

   assert(uint64_to_dbl_0_1(1) == expected_increment);

   // Hell, stick this in a for loop that randomly samples n, and asserts
 if you really care.
   assert(uint64_to_dbl_0_1(2) - uint64_to_dbl_0_1(1) ==
 expected_increment);
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/23061#comment:28>
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