Merge pull request #18003 from JuliaLang/jn/14874

Remove nonstandard header sys/sysctl.h when unneeded

Author: vtjnash

src/sys.c

@@ -10,19 +10,23 @@
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
+#include <errno.h>
+#include <signal.h>
+#include <fcntl.h>
+
 #ifdef _OS_WINDOWS_
 #include <psapi.h>
 #else
+#include <unistd.h>
+#if !defined(_SC_NPROCESSORS_ONLN) || defined(_OS_FREEBSD_) || defined(_OS_DARWIN_)
+// try secondary location for _SC_NPROCESSORS_ONLN, or for HW_AVAILCPU on BSDs
 #include <sys/sysctl.h>
+#endif
 #include <sys/wait.h>
 #include <sys/ptrace.h>
-#include <unistd.h>
 #include <sys/mman.h>
 #include <dlfcn.h>
 #endif
-#include <errno.h>
-#include <signal.h>
-#include <fcntl.h>
 
 #ifndef _OS_WINDOWS_
 // for getrusage
@@ -355,7 +359,10 @@ JL_DLLEXPORT int jl_cpu_cores(void)
     }
     return count;
 #elif defined(_SC_NPROCESSORS_ONLN)
-    return sysconf(_SC_NPROCESSORS_ONLN);
+    long count = sysconf(_SC_NPROCESSORS_ONLN);
+    if (count < 1)
+        return 1;
+    return count;
 #elif defined(_OS_WINDOWS_)
     //Try to get WIN7 API method
     GAPC gapc = (GAPC) jl_dlsym_e(
@@ -372,6 +379,7 @@ JL_DLLEXPORT int jl_cpu_cores(void)
         return info.dwNumberOfProcessors;
     }
 #else
+#warning "cpu core detection not defined for this platform"
     return 1;
 #endif
 }