text: /****************************************************************************
   * fs/vfs/fs_write.c
   *
   *   Copyright (C) 2007-2009, 2012-2014 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/types.h>
  #include <unistd.h>
  #include <fcntl.h>
  #include <sched.h>
  #include <errno.h>
  #include <assert.h>
  
  #if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
  # include <sys/socket.h>
  #endif
  
  #include "inode/inode.h"
  
  /****************************************************************************
   * Private Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: file_write
   *
   * Description:
   *   Equivalent to the standard write() function except that is accepts a
   *   struct file instance instead of a file descriptor.  Currently used
   *   only by aio_write();
   *
   ****************************************************************************/
  
  ssize_t file_write(FAR struct file *filep, FAR const void *buf, size_t nbytes)
  {
    FAR struct inode *inode;
    int ret;
    int err;
  
    /* Was this file opened for write access? */
  
    if ((filep->f_oflags & O_WROK) == 0)
      {
        err = EBADF;
        goto errout;
      }
  
    /* Is a driver registered? Does it support the write method? */
  
    inode = filep->f_inode;
    if (!inode || !inode->u.i_ops || !inode->u.i_ops->write)
      {
        err = EBADF;
        goto errout;
      }
  
    /* Yes, then let the driver perform the write */
  
    ret = inode->u.i_ops->write(filep, buf, nbytes);
    if (ret < 0)
      {
        err = -ret;
        goto errout;
      }
  
    return ret;
  
  errout:
    set_errno(err);
    return ERROR;
  }
  
  /****************************************************************************
   * Name: write
   *
   * Description:
   *  write() writes up to nytes bytes to the file referenced by the file
   *  descriptor fd from the buffer starting at buf.
   *
   * Parameters:
   *   fd       file descriptor (or socket descriptor) to write to
   *   buf      Data to write
   *   nbytes   Length of data to write
   *
   * Returned Value:
   *  On success, the number of bytes  written are returned (zero indicates
   *  nothing was written). On error, -1 is returned, and errno is set appro-
   *  priately:
   *
   *  EAGAIN
   *    Non-blocking I/O has been selected using O_NONBLOCK and the write
   *    would block.
   *  EBADF
   *    fd is not a valid file descriptor or is not open for writing.
   *  EFAULT
   *    buf is outside your accessible address space.
   *  EFBIG
   *    An attempt was made to write a file that exceeds the implementation
   *    defined maximum file size or the process' file size limit, or
   *    to write at a position past the maximum allowed offset.
   *  EINTR
   *    The call was interrupted by a signal before any data was written.
   *  EINVAL
   *    fd is attached to an object which is unsuitable for writing; or
   *    the file was opened with the O_DIRECT flag, and either the address
   *    specified in buf, the value specified in count, or the current
   *     file offset is not suitably aligned.
   *  EIO
   *    A low-level I/O error occurred while modifying the inode.
   *  ENOSPC
   *    The device containing the file referred to by fd has no room for
   *    the data.
   *  EPIPE
   *    fd is connected to a pipe or socket whose reading end is closed.
   *    When this happens the writing process will also receive a SIGPIPE
   *    signal. (Thus, the write return value is seen only if the program
   *    catches, blocks or ignores this signal.)
   *
   * Assumptions:
   *
   ********************************************************************************************/
  
  ssize_t write(int fd, FAR const void *buf, size_t nbytes)
  {
  #if CONFIG_NFILE_DESCRIPTORS > 0
    FAR struct file *filep;
  #endif
  
    /* Did we get a valid file descriptor? */
  
  #if CONFIG_NFILE_DESCRIPTORS > 0
    if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
  #endif
      {
        /* Write to a socket descriptor is equivalent to send with flags == 0 */
  
  #if defined(CONFIG_NET_TCP) && CONFIG_NSOCKET_DESCRIPTORS > 0
        return send(fd, buf, nbytes, 0);
  #else
        set_errno(EBADF);
        return ERROR;
  #endif
      }
  
  #if CONFIG_NFILE_DESCRIPTORS > 0
    /* The descriptor is in the right range to be a file descriptor... write
     * to the file.
     */
  
    filep = fs_getfilep(fd);
    if (!filep)
      {
        /* The errno value has already been set */
  
        return ERROR;
      }
  
    /* Perform the write operation using the file descriptor as an index */
  
    return file_write(filep, buf, nbytes);
  #endif
  }
  