* io.c (Init_IO): added rdocs for constants.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@24780 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

io.c

@@ -6451,6 +6451,7 @@ rb_file_initialize(int argc, VALUE *argv, VALUE io)
     return io;
 }
 
+/* :nodoc: */
 static VALUE
 rb_io_s_new(int argc, VALUE *argv, VALUE klass)
 {
@@ -6519,6 +6520,7 @@ argf_alloc(VALUE klass)
 
 #undef rb_argv
 
+/* :nodoc: */
 static VALUE
 argf_initialize(VALUE argf, VALUE argv)
 {
@@ -6528,6 +6530,7 @@ argf_initialize(VALUE argf, VALUE argv)
     return argf;
 }
 
+/* :nodoc: */
 static VALUE
 argf_initialize_copy(VALUE argf, VALUE orig)
 {
@@ -9868,28 +9871,36 @@ Init_IO(void)
 
     rb_define_method(rb_cFile, "initialize",  rb_file_initialize, -1);
 
+    /* open for reading only */
     rb_file_const("RDONLY", INT2FIX(O_RDONLY));
+    /* open for writing only */
     rb_file_const("WRONLY", INT2FIX(O_WRONLY));
+    /* open for reading and writing */
     rb_file_const("RDWR", INT2FIX(O_RDWR));
+    /* append on each write */
     rb_file_const("APPEND", INT2FIX(O_APPEND));
+    /* create file if it does not exist */
     rb_file_const("CREAT", INT2FIX(O_CREAT));
+    /* error if CREAT and the file exists */
     rb_file_const("EXCL", INT2FIX(O_EXCL));
 #if defined(O_NDELAY) || defined(O_NONBLOCK)
-#   ifdef O_NONBLOCK
+# ifndef O_NONBLOCK
+#   define O_NONBLOCK O_NDELAY
+# endif
+    /* do not block on open or for data to become available */
     rb_file_const("NONBLOCK", INT2FIX(O_NONBLOCK));
-#   else
-    rb_file_const("NONBLOCK", INT2FIX(O_NDELAY));
-#   endif
 #endif
+    /* truncate size to 0 */
     rb_file_const("TRUNC", INT2FIX(O_TRUNC));
 #ifdef O_NOCTTY
+    /* not to make opened IO the controling terminal device */
     rb_file_const("NOCTTY", INT2FIX(O_NOCTTY));
 #endif
-#ifdef O_BINARY
-    rb_file_const("BINARY", INT2FIX(O_BINARY));
-#else
-    rb_file_const("BINARY", INT2FIX(0));
+#ifndef O_BINARY
+# define  O_BINARY 0
 #endif
+    /* disable line code conversion and make ASCII-8BIT */
+    rb_file_const("BINARY", INT2FIX(O_BINARY));
 #ifdef O_SYNC
     rb_file_const("SYNC", INT2FIX(O_SYNC));
 #endif
@@ -9900,9 +9911,11 @@ Init_IO(void)
     rb_file_const("RSYNC", INT2FIX(O_RSYNC));
 #endif
 #ifdef O_NOFOLLOW
+    /* do not follow symlinks */
     rb_file_const("NOFOLLOW", INT2FIX(O_NOFOLLOW)); /* FreeBSD, Linux */
 #endif
 #ifdef O_NOATIME
+    /* do not change atime */
     rb_file_const("NOATIME", INT2FIX(O_NOATIME)); /* Linux */
 #endif