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/*

 *  open() - POSIX 1003.1 5.3.1 - Open a File

 *

 *  COPYRIGHT (c) 1989-1999.

 *  On-Line Applications Research Corporation (OAR).

 *

 *  The license and distribution terms for this file may be

 *  found in the file LICENSE in this distribution or at

 *  http://www.OARcorp.com/rtems/license.html.

 *

 *  $Id: open.c,v 1.2 2001-09-27 12:01:15 chris Exp $

 */

#include "libio_.h"

#include <unistd.h>

/*

 *  Returns file descriptor on success or -1 and errno set to one of the

 *  following:

 *

 *    EACCESS  - Seach permission is denied on a component of the path prefix,

 *               or the file exists and the permissions specified by the

 *               flags are denied, or the file does not exist and write

 *               permission is denied for the parent directory of the file

 *               to be created, or O_TRUNC is specified and write permission

 *               is denied.

 *    EEXIST   - O_CREAT and O_EXCL are set and the named file exists.

 *    EINTR    - The open( operation was interrupted by a signal.

 *    EINVAL   - This implementation does not support synchronized IO for this

 *               file.

 *    EISDIR   - The named file is a directory and the flags argument

 *               specified write or read/write access.

 *    EMFILE   - Too many file descriptors are in used by this process.

 *    ENAMETOOLONG -

 *               The length of the path exceeds PATH_MAX or a pathname

 *               component is longer than NAME_MAX while POSIX_NO_TRUNC

 *               is in effect.

 *    ENFILE   - Too many files are open in the system.

 *    ENOENT   - O_CREAT is not set and and the anmed file does not exist,

 *               or O_CREAT is set and eitehr the path prefix does not exist

 *               or the path argument points to an empty string.

 *    ENOSPC   - The directory or file system that would contain the new file

 *               cannot be extended.

 *    ENOTDIR  - A component of the path prefix is not a directory.

 *    ENXIO    - O_NONBLOCK is set, the named file is a FIFO, O_WRONLY is

 *               set, and no process has the file open for reading.

 *    EROFS    - The named file resides on a read-only file system and either

 *               O_WRONLY, O_RDWR, O_CREAT (if the file does not exist), or

 *               O_TRUNC is set in the flags argument.

 */

int open(

  const char   *pathname,

  int           flags,

  ...

)

{

  va_list                             ap;

  int                                 mode;

  int                                 rc;

  rtems_libio_t                      *iop = 0;

  int                                 status;

  rtems_filesystem_location_info_t    loc;

  int                                 eval_flags;

  /*

   * Set the Evaluation flags

   */

  eval_flags = 0;

  status = flags + 1;

  if ( ( status & _FREAD ) == _FREAD )

    eval_flags |= RTEMS_LIBIO_PERMS_READ;

  if ( ( status & _FWRITE ) == _FWRITE )

    eval_flags |= RTEMS_LIBIO_PERMS_WRITE;

  va_start(ap, flags);

  mode = va_arg( ap, int );

  /*

   * NOTE: This comment is OBSOLETE.  The proper way to do this now

   *       would be to support a magic mounted file system.

   *

   *             Additional external I/O handlers would be supported by adding

   *             code to pick apart the pathname appropriately. The networking

   *             code does not require changes here since network file

   *             descriptors are obtained using socket(), not open().

   */

  /* allocate a file control block */

  iop = rtems_libio_allocate();

  if ( iop == 0 ) {

    rc = ENFILE;

    goto done;

  }

  /*

   *  See if the file exists.

   */

  status = rtems_filesystem_evaluate_path(

     pathname, eval_flags, &loc, TRUE );

  if ( status == -1 ) {

    if ( errno != ENOENT ) {

      rc = errno;

      goto done;

    }

    /* If the file does not exist and we are not trying to create it--> error */

    if ( !(flags & O_CREAT) ) {

      rc = ENOENT;

      goto done;

    }

    /* Create the node for the new regular file */

    rc = mknod( pathname, S_IFREG | mode, 0LL );

    if ( rc ) {

      rc = errno;

      goto done;

    }

    /* Sanity check to see if the file name exists after the mknod() */

    status = rtems_filesystem_evaluate_path( pathname, 0x0, &loc, TRUE );

    if ( status != 0 ) {   /* The file did not exist */

      rc = EACCES;

      goto done;

    }

  } else if ((flags & (O_EXCL|O_CREAT)) == (O_EXCL|O_CREAT)) {

    /* We were trying to create a file that already exists */

    rc = EEXIST;

    goto done;

  }

  /*

   *  Fill in the file control block based on the loc structure

   *  returned by successful path evaluation.

   */

  iop->offset     = 0;

  iop->handlers   = loc.handlers;

  iop->file_info  = loc.node_access;

  iop->flags     |= rtems_libio_fcntl_flags( flags );

  iop->pathinfo   = loc;

  if ( !iop->handlers->open ) {

    rc = ENOTSUP;

    goto done;

  }

  rc = (*iop->handlers->open)( iop, pathname, flags, mode );

  if ( rc )

    goto done;

  /*

   *  Optionally truncate the file.

   */

  if ( (flags & O_TRUNC) == O_TRUNC ) {

    rc = ftruncate( iop - rtems_libio_iops, 0 );

  }

  /*

   *  Single exit and clean up path.

   */

done:

  va_end(ap);

  if ( rc ) {

    if ( iop )

      rtems_libio_free( iop );

    set_errno_and_return_minus_one( rc );

  }

  rtems_filesystem_freenode( &loc );

  return iop - rtems_libio_iops;

}

/*

 *  _open_r

 *

 *  This is the Newlib dependent reentrant version of open().

 */

#if defined(RTEMS_NEWLIB)

#include <reent.h>

int _open_r(

  struct _reent *ptr,

  const char    *buf,

  int            flags,

  int            mode

)

{

  return open( buf, flags, mode );

}

#endif