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- /****************************************************************************
- * fs/mmap/fs_rammmap.c
- *
- * Copyright (C) 2011 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 <sys/mman.h>
- #include <string.h>
- #include <unistd.h>
- #include <errno.h>
- #include <debug.h>
- #include <nuttx/kmalloc.h>
- #include "inode/inode.h"
- #include "fs_rammap.h"
- #ifdef CONFIG_FS_RAMMAP
- /****************************************************************************
- * Public Data
- ****************************************************************************/
- /* This is the list of all mapped files */
- struct fs_allmaps_s g_rammaps;
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: rammap_initialize
- *
- * Description:
- * Verified that this capability has been initialized.
- *
- * Input Parameters:
- * None
- *
- * Returned Value:
- * None
- *
- ****************************************************************************/
- void rammap_initialize(void)
- {
- if (!g_rammaps.initialized)
- {
- sem_init(&g_rammaps.exclsem, 0, 1);
- g_rammaps.initialized = true;
- }
- }
- /****************************************************************************
- * Name: rammmap
- *
- * Description:
- * Support simulation of memory mapped files by copying files into RAM.
- *
- * Parameters:
- * fd file descriptor of the backing file -- required.
- * length The length of the mapping. For exception #1 above, this length
- * ignored: The entire underlying media is always accessible.
- * offset The offset into the file to map
- *
- * Returned Value:
- * On success, rammmap() returns a pointer to the mapped area. On error, the
- * value MAP_FAILED is returned, and errno is set appropriately.
- *
- * EBADF
- * 'fd' is not a valid file descriptor.
- * EINVAL
- * 'length' or 'offset' are invalid
- * ENOMEM
- * Insufficient memory is available to map the file.
- *
- ****************************************************************************/
- FAR void *rammap(int fd, size_t length, off_t offset)
- {
- FAR struct fs_rammap_s *map;
- FAR uint8_t *alloc;
- FAR uint8_t *rdbuffer;
- ssize_t nread;
- off_t fpos;
- int errcode;
- int ret;
- /* There is a major design flaw that I have not yet thought of fix for:
- * The goal is to have a single region of memory that represents a single
- * file and can be shared by many threads. That is, given a filename a
- * thread should be able to open the file, get a file descriptor, and
- * call mmap() to get a memory region. Different file descriptors opened
- * with the same file path should get the same memory region when mapped.
- *
- * The design flaw is that I don't have sufficient knowledge to know that
- * these different file descriptors map to the same file. So, for the time
- * being, a new memory region is created each time that rammap() is called.
- * Not very useful!
- */
- /* Allocate a region of memory of the specified size */
- alloc = (FAR uint8_t *)kumm_malloc(sizeof(struct fs_rammap_s) + length);
- if (!alloc)
- {
- ferr("ERROR: Region allocation failed, length: %d\n", (int)length);
- errcode = ENOMEM;
- goto errout;
- }
- /* Initialize the region */
- map = (FAR struct fs_rammap_s *)alloc;
- memset(map, 0, sizeof(struct fs_rammap_s));
- map->addr = alloc + sizeof(struct fs_rammap_s);
- map->length = length;
- map->offset = offset;
- /* Seek to the specified file offset */
- fpos = lseek(fd, offset, SEEK_SET);
- if (fpos == (off_t)-1)
- {
- /* Seek failed... errno has already been set, but EINVAL is probably
- * the correct response.
- */
- ferr("ERROR: Seek to position %d failed\n", (int)offset);
- errcode = EINVAL;
- goto errout_with_region;
- }
- /* Read the file data into the memory region */
- rdbuffer = map->addr;
- while (length > 0)
- {
- nread = read(fd, rdbuffer, length);
- if (nread < 0)
- {
- /* Handle the special case where the read was interrupted by a
- * signal.
- */
- errcode = get_errno();
- if (errcode != EINTR)
- {
- /* All other read errors are bad. errno is already set.
- * (but maybe should be forced to EINVAL?). NOTE that if
- * FS DEBUG is enabled, then the following ferr() macro will
- * destroy the errno value.
- */
- ferr("ERROR: Read failed: offset=%d errno=%d\n",
- (int)offset, errcode);
- #ifdef CONFIG_DEBUG_FS
- goto errout_with_region;
- #else
- goto errout_with_errno;
- #endif
- }
- }
- /* Check for end of file. */
- if (nread == 0)
- {
- break;
- }
- /* Increment number of bytes read */
- rdbuffer += nread;
- length -= nread;
- }
- /* Zero any memory beyond the amount read from the file */
- memset(rdbuffer, 0, length);
- /* Add the buffer to the list of regions */
- rammap_initialize();
- ret = sem_wait(&g_rammaps.exclsem);
- if (ret < 0)
- {
- goto errout_with_errno;
- }
- map->flink = g_rammaps.head;
- g_rammaps.head = map;
- sem_post(&g_rammaps.exclsem);
- return map->addr;
- errout_with_region:
- kumm_free(alloc);
- errout:
- set_errno(errcode);
- return MAP_FAILED;
- errout_with_errno:
- kumm_free(alloc);
- return MAP_FAILED;
- }
- #endif /* CONFIG_FS_RAMMAP */
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