Apple: Added a comment to explain _DARWIN_C_SOURCE

1 files changed, 9 insertions, 0 deletions

diff --git a/Xosdefs.h b/Xosdefs.h
index a0b2e3e..ee33a32 100644
--- a/Xosdefs.h
+++ b/Xosdefs.h
@@ -135,9 +135,18 @@ in this Software without prior written authorization from The Open Group.
 
 #ifdef __APPLE__
 #define NULL_NOT_ZERO
+
+/* Defining any of these will sanitize the namespace to JUST want is defined by
+ * that particular standard.  If that happens, we don't get some expected
+ * prototypes, typedefs, etc (like fd_mask).  We can define _DARWIN_C_SOURCE to
+ * loosen our belts a tad.
+ */
+#if defined(_XOPEN_SOURCE) || defined(_POSIX_SOURCE) || defined(_POSIX_C_SOURCE)
 #define _DARWIN_C_SOURCE
 #endif
 
+#endif
+
 #ifdef __GNU__
 #ifndef PATH_MAX
 #define PATH_MAX 4096