304 lines
10 KiB
C
304 lines
10 KiB
C
/************************************************************************
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* libc/misc/lib_sendfile.c
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*
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* Copyright (C) 2007, 2009, 2011, 2013 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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************************************************************************/
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/************************************************************************
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* Included Files
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************************************************************************/
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#include <nuttx/config.h>
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#include <sys/sendfile.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <errno.h>
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#include "lib_internal.h"
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#if CONFIG_NSOCKET_DESCRIPTORS > 0 || CONFIG_NFILE_DESCRIPTORS > 0
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/************************************************************************
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* Private types
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************************************************************************/
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/************************************************************************
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* Private Variables
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************************************************************************/
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/************************************************************************
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* Public Variables
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************************************************************************/
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/************************************************************************
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* Private Functions
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************************************************************************/
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/************************************************************************
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* Public Functions
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************************************************************************/
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/************************************************************************
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* Name: sendfile / lib_sendfile
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*
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* Description:
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* sendfile() copies data between one file descriptor and another.
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* sendfile() basically just wraps a sequence of reads() and writes()
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* to perform a copy. It serves a purpose in systems where there is
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* a penalty for copies to between user and kernal space, but really
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* nothing in NuttX but provide some Linux compatible (and adding
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* another 'almost standard' interface).
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*
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* NOTE: This interface is *not* specified in POSIX.1-2001, or other
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* standards. The implementation here is very similar to the Linux
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* sendfile interface. Other UNIX systems implement sendfile() with
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* different semantics and prototypes. sendfile() should not be used
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* in portable programs.
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*
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* Input Parmeters:
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* infd - A file (or socket) descriptor opened for reading
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* outfd - A descriptor opened for writing.
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* offset - If 'offset' is not NULL, then it points to a variable
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* holding the file offset from which sendfile() will start
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* reading data from 'infd'. When sendfile() returns, this
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* variable will be set to the offset of the byte following
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* the last byte that was read. If 'offset' is not NULL,
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* then sendfile() does not modify the current file offset of
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* 'infd'; otherwise the current file offset is adjusted to
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* reflect the number of bytes read from 'infd.'
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*
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* If 'offset' is NULL, then data will be read from 'infd'
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* starting at the current file offset, and the file offset
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* will be updated by the call.
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* count - The number of bytes to copy between the file descriptors.
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*
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* Returned Value:
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* If the transfer was successful, the number of bytes written to outfd is
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* returned. On error, -1 is returned, and errno is set appropriately.
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* There error values are those returned by read() or write() plus:
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*
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* EINVAL - Bad input parameters.
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* ENOMEM - Could not allocated an I/O buffer
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*
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************************************************************************/
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#ifdef CONFIG_NET_SENDFILE
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ssize_t lib_sendfile(int outfd, int infd, off_t *offset, size_t count)
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#else
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ssize_t sendfile(int outfd, int infd, off_t *offset, size_t count)
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#endif
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{
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FAR uint8_t *iobuffer;
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FAR uint8_t *wrbuffer;
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off_t startpos = 0;
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ssize_t nbytesread;
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ssize_t nbyteswritten;
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size_t ntransferred;
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bool endxfr;
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/* Get the current file position. */
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if (offset)
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{
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/* Use lseek to get the current file position */
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startpos = lseek(infd, 0, SEEK_CUR);
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if (startpos == (off_t)-1)
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{
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return ERROR;
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}
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/* Use lseek again to set the new file position */
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if (lseek(infd, *offset, SEEK_SET) == (off_t)-1)
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{
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return ERROR;
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}
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}
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/* Allocate an I/O buffer */
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iobuffer = (FAR void *)lib_malloc(CONFIG_LIB_SENDFILE_BUFSIZE);
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if (!iobuffer)
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{
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set_errno(ENOMEM);
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return ERROR;
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}
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/* Now transfer 'count' bytes from the infd to the outfd */
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for (ntransferred = 0, endxfr = false; ntransferred < count && !endxfr; )
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{
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/* Loop until the read side of the transfer comes to some conclusion */
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do
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{
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/* Read a buffer of data from the infd */
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nbytesread = read(infd, iobuffer, CONFIG_LIB_SENDFILE_BUFSIZE);
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/* Check for end of file */
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if (nbytesread == 0)
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{
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/* End of file. Break out and return current number of bytes
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* transferred.
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*/
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endxfr = true;
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break;
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}
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/* Check for a read ERROR. EINTR is a special case. This function
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* should break out and return an error if EINTR is returned and
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* no data has been transferred. But what should it do if some
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* data has been transferred? I suppose just continue?
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*/
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else if (nbytesread < 0)
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{
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/* EINTR is not an error (but will still stop the copy) */
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#ifndef CONFIG_DISABLE_SIGNALS
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if (errno != EINTR || ntransferred == 0)
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#endif
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{
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/* Read error. Break out and return the error condition. */
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ntransferred = ERROR;
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endxfr = true;
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break;
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}
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}
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}
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while (nbytesread < 0);
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/* Was anything read? */
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if (!endxfr)
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{
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/* Yes.. Loop until the read side of the transfer comes to some
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* conclusion.
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*/
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wrbuffer = iobuffer;
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do
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{
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/* Write the buffer of data to the outfd */
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nbyteswritten = write(outfd, wrbuffer, nbytesread);
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/* Check for a complete (or parial) write. write() should not
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* return zero.
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*/
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if (nbyteswritten >= 0)
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{
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/* Advance the buffer pointer and decrement the number of bytes
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* remaining in the iobuffer. Typically, nbytesread will now
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* be zero.
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*/
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wrbuffer += nbyteswritten;
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nbytesread -= nbyteswritten;
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/* Increment the total number of bytes successfully transferred. */
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ntransferred += nbyteswritten;
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}
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/* Otherwise an error occurred */
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else
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{
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/* Check for a read ERROR. EINTR is a special case. This
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* function should break out and return an error if EINTR
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* is returned and no data has been transferred. But what
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* should it do if some data has been transferred? I
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* suppose just continue?
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*/
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#ifndef CONFIG_DISABLE_SIGNALS
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if (errno != EINTR || ntransferred == 0)
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#endif
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{
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/* Write error. Break out and return the error condition */
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ntransferred = ERROR;
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endxfr = true;
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break;
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}
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}
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}
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while (nbytesread > 0);
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}
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}
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/* Release the I/O buffer */
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lib_free(iobuffer);
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/* Return the current file position */
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if (offset)
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{
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/* Use lseek to get the current file position */
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off_t curpos = lseek(infd, 0, SEEK_CUR);
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if (curpos == (off_t)-1)
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{
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return ERROR;
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}
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/* Return the current file position */
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*offset = curpos;
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/* Use lseek again to restore the original file position */
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if (lseek(infd, startpos, SEEK_SET) == (off_t)-1)
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{
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return ERROR;
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}
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}
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/* Finally return the number of bytes actually transferred (or ERROR
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* if any failure occurred).
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*/
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return ntransferred;
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}
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#endif /* CONFIG_NSOCKET_DESCRIPTORS > 0 || CONFIG_NFILE_DESCRIPTORS > 0 */
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