Resync new repository with old repo r5166

git-svn-id: http://svn.code.sf.net/p/nuttx/code/trunk@5153 42af7a65-404d-4744-a932-0658087f49c3
2026-11-01 09:31:37 +08:00 · 2012-09-17 18:18:44 +00:00
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+/****************************************************************************
+ * lib/stdio/lib_rdflush.c
+ *
+ *   Copyright (C) 2008, 2011 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Compilation Switches
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "lib_internal.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Constant Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Constant Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: lib_rdflush
+ *
+ * Description:
+ *   Flush read data from the I/O buffer and adjust the file pointer to
+ *   account for the unread data
+ *
+ ****************************************************************************/
+
+#if CONFIG_STDIO_BUFFER_SIZE > 0
+int lib_rdflush(FAR FILE *stream)
+{
+  if (!stream)
+    {
+      set_errno(EBADF);
+      return ERROR;
+    }
+
+  /* Get exclusive access to the stream */
+
+  lib_take_semaphore(stream);
+
+  /* If the buffer is currently being used for read access, then discard all
+   * of the read-ahead data.  We do not support concurrent buffered read/write
+   * access.
+   */
+
+  if (stream->fs_bufread != stream->fs_bufstart)
+    {
+      /* Now adjust the stream pointer to account for the read-ahead data that
+       * was not actually read by the user.
+       */
+
+#if CONFIG_NUNGET_CHARS > 0
+      off_t rdoffset = stream->fs_bufread - stream->fs_bufpos + stream->fs_nungotten;
+#else
+      off_t rdoffset = stream->fs_bufread - stream->fs_bufpos;
+#endif
+      /* Mark the buffer as empty (do this before calling fseek() because fseek()
+       * also calls this function).
+       */
+
+      stream->fs_bufpos = stream->fs_bufread = stream->fs_bufstart;
+#if CONFIG_NUNGET_CHARS > 0
+      stream->fs_nungotten = 0;
+#endif
+      /* Then seek to the position corresponding to the last data read by the user */
+
+      if (fseek(stream, -rdoffset, SEEK_CUR) < 0)
+        {
+          lib_give_semaphore(stream);
+          return ERROR;
+        }
+    }
+
+  lib_give_semaphore(stream);
+  return OK;
+}
+#endif /* CONFIG_STDIO_BUFFER_SIZE */
+