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- /****************************************************************************
- * fs/procfs/fs_procfsutil.c
- *
- * Copyright (C) 2013 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.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <sys/types.h>
- #include <string.h>
- #include <nuttx/fs/procfs.h>
- #if !defined(CONFIG_DISABLE_MOUNTPOINT) && defined(CONFIG_FS_PROCFS)
- /****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
- #ifndef MIN
- # define MIN(a,b) ((a < b) ? a : b)
- #endif
- #ifndef MAX
- # define MAX(a,b) ((a > b) ? a : b)
- #endif
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: procfs_memcpy
- *
- * Description:
- * procfs/ file data may be read by the user with different user buffer
- * sizes to receive the data. If the amount of data to be returned is
- * large or if the callers receive buffer is small, then multiple read
- * operations will be required.
- *
- * If multiple read operations are required, then each read operation will
- * be identical accept that file position (f_pos) will be incremented with
- * each read: f_pos must be incremented by the read method after each
- * read operation to provide the 'offset' for the next read.
- *
- * procfs_memcpy() is a helper function. Each read() method should
- * provide data in a local data buffer ('src' and 'srclen'). This
- * will transfer the data to the user receive buffer ('dest' and 'destlen'),
- * respecting both (1) the size of the destination buffer so that it will
- * write beyond the user receiver and (1) the file position, 'offset'.
- *
- * This function will skip over data until the under of bytes specified
- * by 'offset' have been skipped. Then it will transfer data from the
- * the procfs/ 'src' buffer into the user receive buffer. No more than
- * 'destlen' bytes will be transferred.
- *
- * Input Parameters:
- * src - The address of the intermediate procfs/ buffer containing the
- * data to be returned.
- * srclen - The number of bytes of data in the 'src' buffer
- * dest - The address of the user's receive buffer.
- * destlen - The size (in bytes) of the user's receive buffer.
- * offset - On input, this is the number of bytes to skip before returning
- * data; If bytes were skipped, this offset will be decremented.
- * Data will not be transferred until this offset decrements to
- * zero.
- *
- * Returned Value:
- * The number of bytes actually transferred into the user's receive buffer.
- *
- ****************************************************************************/
- size_t procfs_memcpy(FAR const char *src, size_t srclen,
- FAR char *dest, size_t destlen,
- off_t *offset)
- {
- size_t copysize;
- size_t lnoffset;
- /* Will this line take us past the offset? */
- lnoffset = *offset;
- if (srclen < lnoffset)
- {
- /* No... decrement the offset and return without doing anything */
- *offset -= srclen;
- return 0;
- }
- /* Handle the remaining offset */
- srclen -= lnoffset;
- src += lnoffset;
- *offset = 0;
- /* Copy the line into the user destination buffer */
- copysize = MIN(srclen, destlen);
- memcpy(dest, src, copysize);
- return copysize;
- }
- #endif /* !CONFIG_DISABLE_MOUNTPOINT && CONFIG_FS_PROCFS */
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