Marshall, FYI — While safe in this specific example, this is not a correct transform to make in the general case. POSIX very clearly specifies that -1 is the error code for this and similar APIs. This matters for APIs like mmap() which can return "negative" values that not an error.
davez On Feb 7, 2013, at 1:48 PM, Marshall Clow <[email protected]> wrote: > Author: marshall > Date: Thu Feb 7 12:48:09 2013 > New Revision: 174642 > > URL: http://llvm.org/viewvc/llvm-project?rev=174642&view=rev > Log: > Belt and suspenders when calling sysconf > > Modified: > libcxx/trunk/src/thread.cpp > > Modified: libcxx/trunk/src/thread.cpp > URL: > http://llvm.org/viewvc/llvm-project/libcxx/trunk/src/thread.cpp?rev=174642&r1=174641&r2=174642&view=diff > ============================================================================== > --- libcxx/trunk/src/thread.cpp (original) > +++ libcxx/trunk/src/thread.cpp Thu Feb 7 12:48:09 2013 > @@ -69,7 +69,9 @@ thread::hardware_concurrency() _NOEXCEPT > long result = sysconf(_SC_NPROCESSORS_ONLN); > // sysconf returns -1 if the name is invalid, the option does not exist or > // does not have a definite limit. > - if (result == -1) > + // if sysconf returns some other negative number, we have no idea > + // what is going on. Default to something safe. > + if (result < 0) > return 0; > return static_cast<unsigned>(result); > #else // defined(CTL_HW) && defined(HW_NCPU) > > > _______________________________________________ > cfe-commits mailing list > [email protected] > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
