[tor-bugs] #17827 [Tor]: Different return type of backtrace function on FreeBSD

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#17827: Different return type of backtrace function on FreeBSD
---------------------------------------+-----------------------------------
 Reporter:  cypherpunks                |          Owner:
     Type:  defect                     |         Status:  new
 Priority:  Medium                     |      Milestone:  Tor:
Component:  Tor                        |  0.2.8.x-final
 Severity:  Normal                     |        Version:
 Keywords:  027-backport freebsd easy  |     Resolution:
Parent ID:                             |  Actual Points:
  Sponsor:                             |         Points:
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Changes (by nickm):

 * keywords:   => 027-backport freebsd easy


Comment:

 Replying to [comment:1 teor]:
 > We can probably just use a cast to int to avoid this issue, as long as
 we're sure the return value fits in an int.
 >
 > What's the range of the return value?

 The Linux manpage says
 {{{
        int backtrace(void **buffer, int size);
 ....
        backtrace() returns the number of addresses returned in  buffer,
 which
        is  not greater than size.
 }}}

 FreeBSD says
 {{{
      size_t
      backtrace(void **addrlist, size_t len);
 ...
      The backtrace() function returns the number of elements that were
 filled
      in the backtrace.
 }}}

 So either way, if we pass something less than INT_MAX in, we get something
 less than int_max out.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17827#comment:2>
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