Restructure OS::get_cpu_xxx functions a bit

In particular if sysconf fails, fall back to std::thread if
that is available instead of falling back to return 1 right away.

1 files changed, 15 insertions, 19 deletions

diff --git a/src/lib/utils/os_utils.cpp b/src/lib/utils/os_utils.cpp
index 098edaaf4..ec5b4c108 100644
--- a/src/lib/utils/os_utils.cpp
+++ b/src/lib/utils/os_utils.cpp
@@ -206,32 +206,28 @@ uint64_t OS::get_cpu_cycle_counter()
 
 size_t OS::get_cpu_total()
    {
-   size_t tt = 1;
 #if defined(BOTAN_TARGET_OS_HAS_POSIX1) && defined(_SC_NPROCESSORS_CONF)
-   long res;
-   if ((res = ::sysconf(_SC_NPROCESSORS_CONF)) <= 0)
-     {
-          return 1;
-     }
-     tt = static_cast<size_t>(res);
-#elif defined(BOTAN_TARGET_OS_HAS_THREADS)
-     tt = static_cast<size_t>(std::thread::hardware_concurrency());
-#endif
-     return tt;
+   const long res = ::sysconf(_SC_NPROCESSORS_CONF);
+   if(res > 0)
+      return static_cast<size_t>(res);
+#endif
+
+#if defined(BOTAN_TARGET_OS_HAS_THREADS)
+   return static_cast<size_t>(std::thread::hardware_concurrency());
+#else
+   return 1;
+#endif
    }
 
 size_t OS::get_cpu_available()
    {
 #if defined(BOTAN_TARGET_OS_HAS_POSIX1) && defined(_SC_NPROCESSORS_ONLN)
-   long res;
-   if ((res = ::sysconf(_SC_NPROCESSORS_ONLN)) <= 0)
-     {
-       return 1;
-     }
-   return static_cast<size_t>(res);
-#else
-   return get_cpu_total();
+   const long res = ::sysconf(_SC_NPROCESSORS_ONLN);
+   if(res > 0)
+      return static_cast<size_t>(res);
 #endif
+
+   return OS::get_cpu_total();
    }
 
 uint64_t OS::get_high_resolution_clock()