# HG changeset patch
# User Bruno Haible <bruno@clisp.org>
# Date 1303074973 -7200
# Node ID a5714f0caebd17d8cbc38771d27f173f231fec3d
# Parent  e0d0a4052520d2e81a35312e12e44a3ce44cadd5
nonblocking: Add comment.

* lib/fcntl.in.h (O_NONBLOCK): Add comment.

diff --git a/ChangeLog b/ChangeLog
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2011-04-17  Bruno Haible  <bruno@clisp.org>
+
+	nonblocking: Add comment.
+	* lib/fcntl.in.h (O_NONBLOCK): Add comment.
+
 2011-04-17  Bruno Haible  <bruno@clisp.org>
 
 	nonblocking: Add tests for sockets.
diff --git a/lib/fcntl.in.h b/lib/fcntl.in.h
--- a/lib/fcntl.in.h
+++ b/lib/fcntl.in.h
@@ -218,6 +218,9 @@
 # define O_NONBLOCK O_NDELAY
 #endif
 
+/* If the gnulib module 'nonblocking' is in use, guarantee a working non-zero
+   value of O_NONBLOCK.  Otherwise, O_NONBLOCK is defined (above) to O_NDELAY
+   or to 0 as fallback.  */
 #if @GNULIB_NONBLOCKING@
 # if O_NONBLOCK
 #  define GNULIB_defined_O_NONBLOCK 0