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incubator-nuttx/fs/vfs/fs_sendfile.c

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/****************************************************************************
* fs/vfs/fs_sendfile.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/sendfile.h>
#include <stdbool.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/net/net.h>
#include "fs_heap.h"
/****************************************************************************
* Private Functions
****************************************************************************/
static ssize_t copyfile(FAR struct file *outfile, FAR struct file *infile,
FAR off_t *offset, size_t count)
{
FAR uint8_t *iobuffer;
FAR uint8_t *wrbuffer;
off_t startpos = 0;
ssize_t nbytesread;
ssize_t nbyteswritten;
size_t ntransferred;
bool endxfr;
/* Get the current file position. */
if (offset)
{
off_t newpos;
/* Use file_seek to get the current file position */
startpos = file_seek(infile, 0, SEEK_CUR);
if (startpos < 0)
{
return startpos;
}
/* Use file_seek again to set the new file position */
newpos = file_seek(infile, *offset, SEEK_SET);
if (newpos < 0)
{
return newpos;
}
}
/* Allocate an I/O buffer */
iobuffer = fs_heap_malloc(CONFIG_SENDFILE_BUFSIZE);
if (!iobuffer)
{
return -ENOMEM;
}
/* Now transfer 'count' bytes from the infile to the outfile */
for (ntransferred = 0, endxfr = false; ntransferred < count && !endxfr; )
{
/* Loop until the read side of the transfer comes to some conclusion */
do
{
/* Read a buffer of data from the infile */
nbytesread = count - ntransferred;
if (nbytesread > CONFIG_SENDFILE_BUFSIZE)
{
nbytesread = CONFIG_SENDFILE_BUFSIZE;
}
nbytesread = file_read(infile, iobuffer, nbytesread);
/* Check for end of file */
if (nbytesread == 0)
{
/* End of file. Break out and return current number of bytes
* transferred.
*/
endxfr = true;
break;
}
/* Check for a read ERROR. EINTR is a special case. This function
* should break out and return an error if EINTR is returned and
* no data has been transferred. But what should it do if some
* data has been transferred? I suppose just continue?
*/
else if (nbytesread < 0)
{
/* EINTR is not an error (but will still stop the copy) */
if (nbytesread != -EINTR || ntransferred == 0)
{
/* Read error. Break out and return the error condition. */
ntransferred = nbytesread;
endxfr = true;
break;
}
}
}
while (nbytesread < 0);
/* Was anything read? */
if (!endxfr)
{
/* Yes.. Loop until the read side of the transfer comes to some
* conclusion.
*/
wrbuffer = iobuffer;
do
{
/* Write the buffer of data to the outfile */
nbyteswritten = file_write(outfile, wrbuffer, nbytesread);
/* Check for a complete (or partial) write. write() should not
* return zero.
*/
if (nbyteswritten >= 0)
{
/* Advance the buffer pointer and decrement the number of
* bytes remaining in the iobuffer. Typically, nbytesread
* will now be zero.
*/
wrbuffer += nbyteswritten;
nbytesread -= nbyteswritten;
/* Increment the total number of bytes successfully
* transferred.
*/
ntransferred += nbyteswritten;
}
/* Otherwise an error occurred */
else
{
/* Check for a write ERROR. EINTR is a special case. This
* function should break out and return an error if EINTR
* is returned and no data has been transferred. But what
* should it do if some data has been transferred? I
* suppose just continue?
*/
if (nbyteswritten != -EINTR || ntransferred == 0)
{
/* Write error. Break out and return the error
* condition.
*/
ntransferred = nbyteswritten;
endxfr = true;
break;
}
}
}
while (nbytesread > 0);
}
}
/* Release the I/O buffer */
fs_heap_free(iobuffer);
/* Return the current file position */
if (offset)
{
/* Use file_seek to get the current file position */
off_t curpos = file_seek(infile, 0, SEEK_CUR);
if (curpos < 0)
{
return curpos;
}
/* Return the current file position */
*offset = curpos;
/* Use file_seek again to restore the original file position */
startpos = file_seek(infile, startpos, SEEK_SET);
if (startpos < 0)
{
return startpos;
}
}
/* Finally return the number of bytes actually transferred (or ERROR
* if any failure occurred).
*/
return ntransferred;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: file_sendfile
*
* Description:
* Equivalent to the standard sendfile function except that is accepts a
* struct file instance instead of a file descriptor.
*
****************************************************************************/
ssize_t file_sendfile(FAR struct file *outfile, FAR struct file *infile,
FAR off_t *offset, size_t count)
{
if (count == 0)
{
nwarn("WARNING: sendfile count is zero\n");
return 0;
}
#ifdef CONFIG_NET_SENDFILE
/* Check the destination file descriptor: Is it a (probable) file
* descriptor? Check the source file: Is it a normal file?
*/
FAR struct socket *psock;
psock = file_socket(outfile);
if (psock != NULL)
{
/* Then let psock_sendfile do the work. */
int ret = psock_sendfile(psock, infile, offset, count);
if (ret >= 0 || ret != -ENOSYS)
{
return ret;
}
/* Fall back to the slow path if errno equals ENOSYS,
* because psock_sendfile fail to optimize this transfer.
*/
}
#endif
/* No... then this is probably a file-to-file transfer. The generic
* copyfile() can handle that case.
*/
return copyfile(outfile, infile, offset, count);
}
/****************************************************************************
* Name: sendfile
*
* Description:
* sendfile() copies data between one file descriptor and another.
* Used with file descriptors it basically just wraps a sequence of
* reads() and writes() to perform a copy.
*
* If the destination descriptor is a socket, it gives a better
* performance than simple reds() and writes(). The data is read directly
* into the net buffer and the whole tcp window is filled if possible.
*
* 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 Parameters:
* 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)
{
FAR struct file *outfile;
FAR struct file *infile;
int ret;
ret = fs_getfilep(outfd, &outfile);
if (ret < 0)
{
goto errout;
}
ret = fs_getfilep(infd, &infile);
if (ret < 0)
{
fs_putfilep(outfile);
goto errout;
}
ret = file_sendfile(outfile, infile, offset, count);
fs_putfilep(outfile);
fs_putfilep(infile);
if (ret < 0)
{
goto errout;
}
return ret;
errout:
set_errno(-ret);
return ERROR;
}
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