[tor-bugs] #22870 [Core Tor/Tor]: consdiff test fails on OS X

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#22870: consdiff test fails on OS X
--------------------------+------------------------------------
 Reporter:  pastly        |          Owner:
     Type:  defect        |         Status:  merge_ready
 Priority:  Low           |      Milestone:  Tor: 0.3.1.x-final
Component:  Core Tor/Tor  |        Version:
 Severity:  Normal        |     Resolution:
 Keywords:                |  Actual Points:
Parent ID:                |         Points:
 Reviewer:                |        Sponsor:
--------------------------+------------------------------------

Comment (by pastly):

 Replying to [comment:3 teor]:
 >
 > What versions of macOS does this fail on?
 > (We should test on it more often.)
 >

 10.11.6 (I'm calling it OS X on purpose :p)

 > On macOS 10.12.5, Xcode 8.3.3, clang 3.9.1 I see:
 > {{{
 > consdiff/base64cmp: OK
 > }}}
 >
 > But I also see in the macOS memcmp man page:
 >
 >      The memcmp() function returns zero if the two strings are
 identical, oth-
 >      erwise returns the difference between the first two differing bytes
 >      (treated as unsigned char values, so that `\200' is greater than
 `\0',
 >      for example).  Zero-length strings are always identical.  This
 behavior
 >      is not required by C and portable code should only depend on the
 sign of
 >      the returned value.
 >
 > Whereas strcmp is ambiguous:
 >
 >      The strcmp() and strncmp() functions return an integer greater
 than,
 >      equal to, or less than 0, according as the string s1 is greater
 than,
 >      equal to, or less than the string s2.  The comparison is done using
 >      unsigned characters, so that `\200' is greater than `\0'.

 The behavior I saw was definitely more in line with what you've quoted for
 memcmp.

 I'm very weak on OS X/macOS development. I don't seem to have Xcode
 installed. `clang --version` says

 {{{
 Apple LLVM version 8.0.0 (clang-800.0.42.1)
 Target: x86_64-apple-darwin15.6.0
 Thread model: posix
 InstalledDir: /Library/Developer/CommandLineTools/usr/bin
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22870#comment:4>
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