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Diffstat (limited to 'nuttx/fs/mmap/fs_mmap.c')
| -rw-r--r-- | nuttx/fs/mmap/fs_mmap.c | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/nuttx/fs/mmap/fs_mmap.c b/nuttx/fs/mmap/fs_mmap.c new file mode 100644 index 000000000..5764b16f1 --- /dev/null +++ b/nuttx/fs/mmap/fs_mmap.c @@ -0,0 +1,174 @@ +/**************************************************************************** + * fs/mmap/fs_mmap.c + * + * Copyright (C) 2008-2009, 2011 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <spudmonkey@racsa.co.cr> + * + * 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 <sys/ioctl.h> +#include <stdint.h> +#include <errno.h> +#include <debug.h> + +#include "fs_internal.h" +#include "fs_rammap.h" + +/**************************************************************************** + * Global Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: mmap + * + * Description: + * NuttX operates in a flat open address space. Therefore, it generally + * does not require mmap() functionality. There are two exceptions: + * + * 1. mmap() is the API that is used to support direct access to random + * access media under the following very restrictive conditions: + * + * a. The filesystem supports the FIOC_MMAP ioctl command. Any file + * system that maps files contiguously on the media should support + * this ioctl. (vs. file system that scatter files over the media + * in non-contiguous sectors). As of this writing, ROMFS is the + * only file system that meets this requirement. + * b. The underlying block driver supports the BIOC_XIPBASE ioctl + * command that maps the underlying media to a randomly accessible + * address. At present, only the RAM/ROM disk driver does this. + * + * 2. If CONFIG_FS_RAMMAP is defined in the configuration, then mmap() will + * support simulation of memory mapped files by copying files whole + * into RAM. + * + * Parameters: + * start A hint at where to map the memory -- ignored. The address + * of the underlying media is fixed and cannot be re-mapped without + * MMU support. + * length The length of the mapping. For exception #1 above, this length + * ignored: The entire underlying media is always accessible. + * prot See the PROT_* definitions in sys/mman.h. + * PROT_NONE - Will cause an error + * PROT_READ - PROT_WRITE and PROT_EXEC also assumed + * PROT_WRITE - PROT_READ and PROT_EXEC also assumed + * PROT_EXEC - PROT_READ and PROT_WRITE also assumed + * flags See the MAP_* definitions in sys/mman.h. + * MAP_SHARED - Required + * MAP_PRIVATE - Will cause an error + * MAP_FIXED - Will cause an error + * MAP_FILE - Ignored + * MAP_ANONYMOUS - Will cause an error + * MAP_ANON - Will cause an error + * MAP_GROWSDOWN - Ignored + * MAP_DENYWRITE - Will cause an error + * MAP_EXECUTABLE - Ignored + * MAP_LOCKED - Ignored + * MAP_NORESERVE - Ignored + * MAP_POPULATE - Ignored + * MAP_NONBLOCK - Ignored + * fd file descriptor of the backing file -- required. + * offset The offset into the file to map + * + * Returned Value: + * On success, mmap() returns a pointer to the mapped area. On error, the + * value MAP_FAILED is returned, and errno is set appropriately. + * + * ENOSYS + * Returned if any of the unsupported mmap() features are attempted + * EBADF + * 'fd' is not a valid file descriptor. + * EINVAL + * Length is 0. flags contained neither MAP_PRIVATE or MAP_SHARED, or + * contained both of these values. + * ENODEV + * The underlying filesystem of the specified file does not support + * memory mapping. + * + ****************************************************************************/ + +FAR void *mmap(FAR void *start, size_t length, int prot, int flags, + int fd, off_t offset) +{ + FAR void *addr; + int ret; + + /* Since only a tiny subset of mmap() functionality, we have to verify many + * things. + */ + +#ifdef CONFIG_DEBUG + if (prot == PROT_NONE || + (flags & (MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS|MAP_DENYWRITE)) != 0) + { + fdbg("Unsupported options, prot=%x flags=%04x\n", prot, flags); + errno = ENOSYS; + return MAP_FAILED; + } + + if (length == 0 || (flags & MAP_SHARED) == 0) + { + fdbg("Invalid options, lengt=%d flags=%04x\n", length, flags); + errno = EINVAL; + return MAP_FAILED; + } +#endif + + /* Okay now we can assume a shared mapping from a file. This is the + * only option supported + * + * Perform the ioctl to get the base address of the file in 'mapped' + * in memory. (casting to uintptr_t first eliminates complaints on some + * architectures where the sizeof long is different from the size of + * a pointer). + */ + + ret = ioctl(fd, FIOC_MMAP, (unsigned long)((uintptr_t)&addr)); + if (ret < 0) + { +#ifdef CONFIG_FS_RAMMAP + return rammap(fd, length, offset); +#else + fdbg("ioctl(FIOC_MMAP) failed: %d\n", errno); + return MAP_FAILED; +#endif + } + + /* Return the offset address */ + + return (void*)(((uint8_t*)addr) + offset); +} |