nuttx/include/sys/sendfile.h

/****************************************************************************
 * include/sys/sendfile.h
 *
 *   Copyright (C) 2012 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.
 *
 ****************************************************************************/

#ifndef __INCLUDE_SYS_SENDFILE_H
#define __INCLUDE_SYS_SENDFILE_H

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>

/****************************************************************************
 * Pre-Processor Definitions
 ****************************************************************************/
/* Configuration ************************************************************/

#ifndef CONFIG_LIB_SENDFILE_BUFSIZE
#  define CONFIG_LIB_SENDFILE_BUFSIZE 512
#endif

/****************************************************************************
 * Public Type Definitions
 ****************************************************************************/

/****************************************************************************
 * Public Function Prototypes
 ****************************************************************************/

#undef EXTERN
#if defined(__cplusplus)
#define EXTERN extern "C"
extern "C" {
#else
#define EXTERN extern
#endif

/************************************************************************
 * Name: sendfile
 *
 * Description:
 *   sendfile() copies data between one file descriptor and another.
 *   sendfile() basically just wraps a sequence of reads() and writes()
 *   to perform a copy.  It serves a purpose in systems where there is
 *   a penalty for copies to between user and kernal space, but really
 *   nothing in NuttX but provide some Linux compatible (and adding
 *   another 'almost standard' interface).
 *
 *   NOTE: This interface is *not* specified in POSIX.1-2001, or other
 *   standards.  The implementation here is very similar to the Linux
 *   sendfile interface.  Other UNIX systems implement sendfile() with
 *   different semantics and prototypes.  sendfile() should not be used
 *   in portable programs.
 *
 * Input Parmeters:
 *   infd   - A file (or socket) descriptor opened for reading
 *   outfd  - A descriptor opened for writing.
 *   offset - If 'offset' is not NULL, then it points to a variable
 *            holding the file offset from which sendfile() will start
 *            reading data from 'infd'.  When sendfile() returns, this
 *            variable will be set to the offset of the byte following
 *            the last byte that was read.  If 'offset' is not NULL,
 *            then sendfile() does not modify the current file offset of
 *            'infd'; otherwise the current file offset is adjusted to
 *            reflect the number of bytes read from 'infd.'
 *
 *            If 'offset' is NULL, then data will be read from 'infd'
 *            starting at the current file offset, and the file offset
 *            will be updated by the call.
 *   count -  The number of bytes to copy between the file descriptors.
 *
 * Returned Value:
 *   If the transfer was successful, the number of bytes written to outfd is
 *   returned.  On error, -1 is returned, and errno is set appropriately.
 *   There error values are those returned by read() or write() plus:
 *
 *   EINVAL - Bad input parameters.
 *   ENOMEM - Could not allocated an I/O buffer
 *
 ************************************************************************/

ssize_t sendfile(int outfd, int infd, FAR off_t *offset, size_t count);

#undef EXTERN
#if defined(__cplusplus)
}
#endif

#endif /* __INCLUDE_SYS_SENDFILE_H */