incubator-nuttx/fs/vfs/fs_sendfile.c

138 lines
4.8 KiB
C

/****************************************************************************
* 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 <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <assert.h>
#include <nuttx/sched.h>
#include <nuttx/net/net.h>
#ifdef CONFIG_NET_SENDFILE
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* 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, off_t *offset, size_t count)
{
#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 = sockfd_socket(outfd);
if (psock != NULL)
{
FAR struct file *filep;
int ret;
/* This appears to be a file-to-socket transfer. Get the file
* structure.
*/
ret = fs_getfilep(infd, &filep);
if (ret < 0)
{
set_errno(-ret);
return ERROR;
}
DEBUGASSERT(filep != NULL);
/* Then let psock_sendfile do the work. */
ret = psock_sendfile(psock, filep, offset, count);
if (ret >= 0 || get_errno() != 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
* lib_sendfile() can handle that case.
*/
return lib_sendfile(outfd, infd, offset, count);
}
#endif /* CONFIG_NET_SENDFILE */