Add a simple named semaphore test to the OS test

include/nuttx/fs/fs.h

@@ -1,7 +1,7 @@
 /****************************************************************************
  * include/nuttx/fs/fs.h
  *
- *   Copyright (C) 2007-2009, 2011-2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011-2013 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -48,7 +48,9 @@
 #include <stdbool.h>
 #include <semaphore.h>
 
-#include <nuttx/semaphore.h>
+#ifdef CONFIG_FS_NAMED_SEMAPHORES
+#  include <nuttx/semaphore.h>
+#endif
 
 /****************************************************************************
  * Pre-processor Definitions
@@ -203,28 +205,25 @@ struct mountpt_operations
 /* Named OS resources are also maintained by the VFS.  This includes:
  *
  *   - Named semaphores:     sem_open(), sem_close(), and sem_unlink()
- *   - POSIX Message Queues: mq_open(),  mq_close(), and mq_unlink()
+ *   - POSIX Message Queues: mq_open() and mq_close()
  *   - Shared memory:        shm_open() and shm_unlink();
  *
- * These are a special case in that they do not follow the same pattern
+ * These are a special case in that they do not follow quite the same
- * as the other inode system types:
+ * pattern as the other file system types in that they have no read or
+ * write methods.
  *
- *   - All of these resources have their own open() and unlink()  interfaces.
+ * Each inode type carries a payload specific to the OS resource;
- *     All require special, additional operations at open() and unlink()
+ * Only the contents of struct special_operations is visible to the VFS.
- *     time
- *   - None of the standard VFS operations can be used with semaphores
- *     or named messages queues.  These OS resources have their own
- *     own open() and close methods that do not use file descriptors.
- *   - Only ftruncate() and close() make sense with the file descriptor
- *     returned by shm_open()
- *
- * Inode types are not defined here, but rather in:
- *
- *   - include/nuttx/semaphore.h
- *   - include/nuttx/mqueue.h, and
- *   - include/nuttx/shm.h
  */
 
+struct inode;
+struct special_operations
+{
+  int     (*open)(FAR struct inode *inode);
+  int     (*close)(FAR struct inode *inode);
+  int     (*unlink)(FAR struct inode *inode, FAR const char *relpath);
+};
+
 /* These are the various kinds of operations that can be associated with
  * an inode.
  */
@@ -236,7 +235,10 @@ union inode_ops_u
   FAR const struct block_operations     *i_bops; /* Block driver operations */
   FAR const struct mountpt_operations   *i_mops; /* Operations on a mountpoint */
 #endif
+  FAR const struct special_operations   *i_xops; /* Generic operations on OS resources */
+#ifdef CONFIG_FS_NAMED_SEMAPHORES
   FAR const struct semaphore_operations *i_sops; /* Operations for named semaphores */
+#endif
 };
 
 /* This structure represents one inode in the Nuttx pseudo-file system */

include/nuttx/semaphore.h

@@ -54,15 +54,24 @@
  * Public Data
  ****************************************************************************/
 
+#ifdef CONFIG_FS_NAMED_SEMAPHORES
 /* This is the named semaphore inode */
 
+struct inode; /* Forward reference */
 struct semaphore_operations
 {
+  /* Common inode operations */
+
+  int     (*open)(FAR struct inode *inode);
+  int     (*close)(FAR struct inode *inode);
+  int     (*unlink)(FAR struct inode *inode, FAR const char *relpath);
+
   /* Payload unique to named semaphores */
 
-  uint16_t ns_refs;           /* Number of open references to the semaphore */
+  uint16_t ns_refs;                 /* Number of open references semaphore */
-  sem_t ns_sem;               /* The semaphore itself */
+  sem_t ns_sem;                     /* The semaphore itself */
 };
+#endif
 
 /****************************************************************************
  * Public Data