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nuttx/libs/libc/misc/lib_sendfile.c
Alin Jerpelea b7c451c5a4 libs: Gregory Nutt: update licenses to Apache 
Gregory Nutt has submitted the SGA and we can migrate the licenses
 to Apache.

Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
2021-04-02 11:12:25 -05:00

289 lines
9.0 KiB
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/****************************************************************************
* libs/libc/misc/lib_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 <nuttx/fs/fs.h>
#include "libc.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: sendfile / lib_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 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
*
****************************************************************************/
#ifdef CONFIG_NET_SENDFILE
ssize_t lib_sendfile(int outfd, int infd, off_t *offset, size_t count)
#else
ssize_t sendfile(int outfd, int infd, off_t *offset, size_t count)
#endif
{
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 lseek to get the current file position */
startpos = _NX_SEEK(infd, 0, SEEK_CUR);
if (startpos < 0)
{
int errcode = _NX_GETERRNO(startpos);
_NX_SETERRNO(errcode);
return ERROR;
}
/* Use lseek again to set the new file position */
newpos = _NX_SEEK(infd, *offset, SEEK_SET);
if (newpos < 0)
{
int errcode = _NX_GETERRNO(newpos);
_NX_SETERRNO(errcode);
return ERROR;
}
}
/* Allocate an I/O buffer */
iobuffer = (FAR void *)lib_malloc(CONFIG_LIB_SENDFILE_BUFSIZE);
if (!iobuffer)
{
set_errno(ENOMEM);
return ERROR;
}
/* Now transfer 'count' bytes from the infd to the outfd */
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 infd */
nbytesread = _NX_READ(infd, iobuffer, CONFIG_LIB_SENDFILE_BUFSIZE);
/* 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)
{
int errcode = _NX_GETERRNO(nbytesread);
/* EINTR is not an error (but will still stop the copy) */
if (errcode != EINTR || ntransferred == 0)
{
/* Read error. Break out and return the error condition. */
_NX_SETERRNO(nbytesread);
ntransferred = ERROR;
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 outfd */
nbyteswritten = _NX_WRITE(outfd, wrbuffer, nbytesread);
/* Check for a complete (or parial) 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
{
int errcode = _NX_GETERRNO(nbyteswritten);
/* 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?
*/
if (errcode != EINTR || ntransferred == 0)
{
/* Write error. Break out and return the error
* condition.
*/
_NX_SETERRNO(nbyteswritten);
ntransferred = ERROR;
endxfr = true;
break;
}
}
}
while (nbytesread > 0);
}
}
/* Release the I/O buffer */
lib_free(iobuffer);
/* Return the current file position */
if (offset)
{
/* Use lseek to get the current file position */
off_t curpos = _NX_SEEK(infd, 0, SEEK_CUR);
if (curpos < 0)
{
int errcode = _NX_GETERRNO(curpos);
_NX_SETERRNO(errcode);
return ERROR;
}
/* Return the current file position */
*offset = curpos;
/* Use lseek again to restore the original file position */
startpos = _NX_SEEK(infd, startpos, SEEK_SET);
if (startpos < 0)
{
int errcode = _NX_GETERRNO(startpos);
_NX_SETERRNO(errcode);
return ERROR;
}
}
/* Finally return the number of bytes actually transferred (or ERROR
* if any failure occurred).
*/
return ntransferred;
}
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