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/******************************************************************************

*                                                                             *

* License Agreement                                                           *

*                                                                             *

* Copyright (c) 2004 Altera Corporation, San Jose, California, USA.           *

* All rights reserved.                                                        *

*                                                                             *

* Permission is hereby granted, free of charge, to any person obtaining a     *

* copy of this software and associated documentation files (the "Software"),  *

* to deal in the Software without restriction, including without limitation   *

* the rights to use, copy, modify, merge, publish, distribute, sublicense,    *

* and/or sell copies of the Software, and to permit persons to whom the       *

* Software is furnished to do so, subject to the following conditions:        *

*                                                                             *

* The above copyright notice and this permission notice shall be included in  *

* all copies or substantial portions of the Software.                         *

*                                                                             *

* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  *

* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,    *

* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE *

* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER      *

* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING     *

* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER         *

* DEALINGS IN THE SOFTWARE.                                                   *

*                                                                             *

* This agreement shall be governed in all respects by the laws of the State   *

* of California and by the laws of the United States of America.              *

*                                                                             *

* Altera does not recommend, suggest or require that this reference design    *

* file be used in conjunction or combination with any other product.          *

******************************************************************************/

#include "sys/alt_errno.h"

#include "sys/alt_warning.h"

#include "priv/alt_file.h"

#include "alt_types.h"

#include "os/alt_syscall.h"

#ifdef ALT_USE_DIRECT_DRIVERS

int ALT_OPEN (const char* file, int flags, int mode)

{

  /* Generate a link time warning, should this function ever be called. */

  ALT_STUB_WARNING(open);

  /* Indicate an error */

  ALT_ERRNO = ENOSYS;

  return -1;

}

#else /* !ALT_USE_DIRECT_DRIVERS */

extern alt_llist alt_dev_list;

/*

 * alt_file_locked() is used by open() to ensure that a device has not been

 * previously locked for exclusive access using ioctl(). This test is only

 * performed for devices. Filesystems are required to handle the ioctl() call

 * themselves, and report the error from the filesystems open() function.

 */

static int alt_file_locked (alt_fd* fd)

{

  alt_u32 i;

  /*

   * Mark the file descriptor as belonging to a device.

   */

  fd->fd_flags |= ALT_FD_DEV;

  /*

   * Loop through all current file descriptors searching for one that's locked

   * for exclusive access. If a match is found, generate an error.

   */

  for (i = 0; i <= alt_max_fd; i++)

  {

    if ((alt_fd_list[i].dev == fd->dev) &&

        (alt_fd_list[i].fd_flags & ALT_FD_EXCL) &&

        (&alt_fd_list[i] != fd))

    {

      return -EACCES;

    }

  }

  /* The device is not locked */

  return 0;

}

/*

 * open() is called in order to get a file descriptor that reference the file

 * or device named "name". This descriptor can then be used to manipulate the

 * file/device using the standard system calls, e.g. write(), read(), ioctl()

 * etc.

 *

 * This is equivalent to the standard open() system call.

 *

 * ALT_OPEN is mapped onto the open() system call in alt_syscall.h

 */

int ALT_OPEN (const char* file, int flags, int mode)

{

  alt_dev* dev;

  alt_fd*  fd;

  int index  = -1;

  int status = -ENODEV;

  int isafs = 0;

  /*

   * Check the device list, to see if a device with a matching name is

   * registered.

   */

  if (!(dev = alt_find_dev (file, &alt_dev_list)))

  {

    /* No matching device, so try the filesystem list */

    dev   = alt_find_file (file);

    isafs = 1;

  }

  /*

   * If a matching device or filesystem is found, allocate a file descriptor.

   */

  if (dev)

  {

    if ((index = alt_get_fd (dev)) < 0)

    {

      status = index;

    }

    else

    {

      fd = &alt_fd_list[index];

      fd->fd_flags = (flags & ~ALT_FD_FLAGS_MASK);

      /* If this is a device, ensure it isn't already locked */

      if (isafs || ((status = alt_file_locked (fd)) >= 0))

      {

        /*

         * If the device or filesystem provides an open() callback function,

         * call it now to perform any device/filesystem specific operations.

         */

        status = (dev->open) ? dev->open(fd, file, flags, mode): 0;

      }

    }

  }

  else

  {

    status = -ENODEV;

  }

  /* Allocation failed, so clean up and return an error */

  if (status < 0)

  {

    alt_release_fd (index);

    ALT_ERRNO = -status;

    return -1;

  }

  /* return the reference upon success */

  return index;

}

#endif /* ALT_USE_DIRECT_DRIVERS */