C library: Add fstatfs(); fix a reference counting error in fstat().

fs/vfs/Make.defs

@@ -72,9 +72,9 @@ else
 # Common file/socket descriptor support
 
 CSRCS += fs_close.c fs_dup.c fs_dup2.c fs_fcntl.c fs_dupfd.c fs_dupfd2.c
-CSRCS += fs_epoll.c fs_fstat.c fs_getfilep.c fs_ioctl.c fs_lseek.c
-CSRCS += fs_mkdir.c fs_open.c fs_poll.c  fs_read.c fs_rename.c fs_rmdir.c fs_statfs.c
-CSRCS += fs_stat.c fs_select.c fs_unlink.c fs_write.c
+CSRCS += fs_epoll.c fs_fstat.c fs_fstatfs.c fs_getfilep.c fs_ioctl.c
+CSRCS += fs_lseek.c fs_mkdir.c fs_open.c fs_poll.c  fs_read.c fs_rename.c
+CSRCS += fs_rmdir.c fs_statfs.c fs_stat.c fs_select.c fs_unlink.c fs_write.c
 
 # Certain interfaces are not available if there is no mountpoint support
 

fs/vfs/fs_fstat.c

@@ -117,7 +117,7 @@ int fstat(int fd, FAR struct stat *buf)
        * supports the fstat() method
        */
 
-      ret = OK;
+      ret = -ENOSYS;
       if (inode->u.i_mops && inode->u.i_mops->fstat)
         {
           /* Perform the fstat() operation */
@@ -137,20 +137,11 @@ int fstat(int fd, FAR struct stat *buf)
 
   if (ret < 0)
     {
-      ret = -ret;
-      goto errout_with_inode;
+      set_errno(-ret);
+      return ERROR;
     }
 
   /* Successfully fstat'ed the file */
 
-  inode_release(inode);
   return OK;
-
-/* Failure conditions always set the errno appropriately */
-
-errout_with_inode:
-  inode_release(inode);
-
-  set_errno(ret);
-  return ERROR;
 }

fs/vfs/fs_fstatfs.c

@@ -0,0 +1,147 @@
+/****************************************************************************
+ * fs/vfs/fs_fstatfs.c
+ *
+ *   Copyright (C) 2017 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/statfs.h>
+#include <string.h>
+#include <limits.h>
+#include <sched.h>
+#include <errno.h>
+
+#include "inode/inode.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: fstatfs
+ *
+ * Return: Zero on success; -1 on failure with errno set:
+ *
+ *   EACCES  Search permission is denied for one of the directories in the
+ *           path prefix of path.
+ *   EFAULT  Bad address.
+ *   ENOENT  A component of the path path does not exist, or the path is an
+ *           empty string.
+ *   ENOMEM  Out of memory
+ *   ENOTDIR A component of the path is not a directory.
+ *   ENOSYS  The file system does not support this call.
+ *
+ ****************************************************************************/
+
+int fstatfs(int fd, FAR struct statfs *buf)
+{
+  FAR struct file *filep;
+  FAR struct inode *inode;
+  int ret;
+
+  DEBUGASSERT(buf != NULL);
+
+  /* Did we get a valid file descriptor? */
+
+  if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
+    {
+      /* No networking... it is a bad descriptor in any event */
+
+      set_errno(EBADF);
+      return ERROR;
+    }
+
+  /* The descriptor is in a valid range to file descriptor... do the
+   * read.  First, get the file structure.  Note that on failure,
+   * fs_getfilep() will set the errno variable.
+   */
+
+  filep = fs_getfilep(fd);
+  if (filep == NULL)
+    {
+      /* The errno value has already been set */
+
+      return ERROR;
+    }
+
+  /* Get the inode from the file structure */
+
+  inode = filep->f_inode;
+  DEBUGASSERT(inode != NULL);
+
+  /* The way we handle the stat depends on the type of inode that we
+   * are dealing with.
+   */
+
+#ifndef CONFIG_DISABLE_MOUNTPOINT
+  if (INODE_IS_MOUNTPT(inode))
+    {
+      /* The node is a file system mointpoint. Verify that the mountpoint
+       * supports the statfs() method
+       */
+
+      ret = -ENOSYS;
+      if (inode->u.i_mops && inode->u.i_mops->statfs)
+        {
+          /* Perform the statfs() operation */
+
+          ret = inode->u.i_mops->statfs(inode, buf);
+        }
+    }
+  else
+#endif
+    {
+      /* The node is part of the root pseudo file system */
+
+      memset(buf, 0, sizeof(struct statfs));
+      buf->f_type    = PROC_SUPER_MAGIC;
+      buf->f_namelen = NAME_MAX;
+      ret            = OK;
+    }
+
+  /* Check if the fstat operation was successful */
+
+  if (ret < 0)
+    {
+      set_errno(-ret);
+      return ERROR;
+    }
+
+  /* Successfully statfs'ed the file */
+
+  return OK;
+}

fs/vfs/fs_statfs.c

@@ -68,7 +68,7 @@ static int statpseudofs(FAR struct inode *inode, FAR struct statfs *buf)
  ****************************************************************************/
 
 /****************************************************************************
- * Name: stat
+ * Name: statfs
  *
  * Return: Zero on success; -1 on failure with errno set:
  *