_chdir.c

ATMEL单片机可用的文件系统源代码

/***********************************************************************/
/*                                                                     */
/*   Module:  _chdir.c                                                 */
/*   Release: 2004.5                                                   */
/*   Version: 2002.0                                                   */
/*   Purpose: Implements chdir()                                       */
/*                                                                     */
/*---------------------------------------------------------------------*/
/*                                                                     */
/*               Copyright 2004, Blunk Microsystems                    */
/*                      ALL RIGHTS RESERVED                            */
/*                                                                     */
/*   Licensees have the non-exclusive right to use, modify, or extract */
/*   this computer program for software development at a single site.  */
/*   This program may be resold or disseminated in executable format   */
/*   only. The source code may not be redistributed or resold.         */
/*                                                                     */
/***********************************************************************/
#include "posixfsp.h"

/***********************************************************************/
/* Global Function Definitions                                         */
/***********************************************************************/

/***********************************************************************/
/*       chdir: Change the current working directory                   */
/*                                                                     */
/*       Input: path = pointer to the name of the new directory        */
/*                                                                     */
/*     Returns: 0 on success, -1 on failure                            */
/*                                                                     */
/***********************************************************************/
int chdir(const char *path)
{
  void *actual;
  int r_value = -1;
  DIR dir;

#if OS_PARM_CHECK
  /*-------------------------------------------------------------------*/
  /* If path is NULL, return -1.                                       */
  /*-------------------------------------------------------------------*/
  if (path == NULL)
  {
    set_errno(EFAULT);
    return -1;
  }
#endif

  /*-------------------------------------------------------------------*/
  /* Initialize temporary file control block.                          */
  /*-------------------------------------------------------------------*/
  FsInitFCB(&dir, FCB_DIR);

  /*-------------------------------------------------------------------*/
  /* Get exclusive access to upper file system.                        */
  /*-------------------------------------------------------------------*/
  semPend(FileSysSem, WAIT_FOREVER);

  /*-------------------------------------------------------------------*/
  /* Ensure that path is valid.                                        */
  /*-------------------------------------------------------------------*/
  actual = FSearch(&dir, &path, ACTUAL_DIR);
  if (actual == NULL)
    goto end;

  /*-------------------------------------------------------------------*/
  /* Acquire exclusive access to lower file system.                    */
  /*-------------------------------------------------------------------*/
  dir.acquire(&dir, F_READ | F_WRITE);

  /*-------------------------------------------------------------------*/
  /* Call file system specific ioctl to change directory.              */
  /*-------------------------------------------------------------------*/
  r_value = (int)dir.ioctl(&dir, CHDIR, NULL, actual);

  /*-------------------------------------------------------------------*/
  /* Release exclusive access to lower file system.                    */
  /*-------------------------------------------------------------------*/
  dir.release(&dir, F_READ | F_WRITE);

  /*-------------------------------------------------------------------*/
  /* Release exclusive access to upper file system and return result.  */
  /*-------------------------------------------------------------------*/
end:
  semPost(FileSysSem);
  return r_value;
}