nvram-vfs.c
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/*
* Copyright (C) 2016 Eistec AB
*
* This file is subject to the terms and conditions of the GNU Lesser General
* Public License v2.1. See the file LICENSE in the top level directory for more
* details.
*/
#if MODULE_VFS
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include "nvram.h"
#include "vfs.h"
/**
* @ingroup nvram
* @{
*
* @file
*
* @brief NVRAM generic VFS operations
*
* This allows the nvram driver to register as a node on DevFS
*
* See boards/mulle or tests/unittests/tests-devfs for examples on how to use.
*
* Tested with nvram_spi on Mulle
*
* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
*/
static int nvram_vfs_fstat(vfs_file_t *filp, struct stat *buf);
static off_t nvram_vfs_lseek(vfs_file_t *filp, off_t off, int whence);
static ssize_t nvram_vfs_read(vfs_file_t *filp, void *dest, size_t nbytes);
static ssize_t nvram_vfs_write(vfs_file_t *filp, const void *src, size_t nbytes);
const vfs_file_ops_t nvram_vfs_ops = {
.fstat = nvram_vfs_fstat,
.lseek = nvram_vfs_lseek,
.read = nvram_vfs_read,
.write = nvram_vfs_write,
};
static int nvram_vfs_fstat(vfs_file_t *filp, struct stat *buf)
{
if (buf == NULL) {
return -EFAULT;
}
nvram_t *dev = filp->private_data.ptr;
if (dev == NULL) {
return -EFAULT;
}
buf->st_nlink = 1;
buf->st_size = dev->size;
return 0;
}
static off_t nvram_vfs_lseek(vfs_file_t *filp, off_t off, int whence)
{
nvram_t *dev = filp->private_data.ptr;
if (dev == NULL) {
return -EFAULT;
}
switch (whence) {
case SEEK_SET:
break;
case SEEK_CUR:
off += filp->pos;
break;
case SEEK_END:
off += dev->size;
break;
default:
return -EINVAL;
}
if (off < 0) {
/* the resulting file offset would be negative */
return -EINVAL;
}
/* POSIX allows seeking past the end of the file */
filp->pos = off;
return off;
}
static ssize_t nvram_vfs_read(vfs_file_t *filp, void *dest, size_t nbytes)
{
nvram_t *dev = filp->private_data.ptr;
if (dev == NULL) {
return -EFAULT;
}
uint32_t src = filp->pos;
if (src >= dev->size) {
return 0;
}
if (src + nbytes > dev->size) {
nbytes = dev->size - src;
}
int res = dev->read(dev, dest, src, nbytes);
if (res < 0) {
return res;
}
/* Advance file position */
filp->pos += res;
return res;
}
static ssize_t nvram_vfs_write(vfs_file_t *filp, const void *src, size_t nbytes)
{
nvram_t *dev = filp->private_data.ptr;
if (dev == NULL) {
return -EFAULT;
}
uint32_t dest = filp->pos;
if (dest >= dev->size) {
return 0;
}
if (dest + nbytes > dev->size) {
nbytes = dev->size - dest;
}
int res = dev->write(dev, src, dest, nbytes);
if (res < 0) {
return res;
}
/* Advance file position */
filp->pos += res;
return res;
}
/** @} */
#else
typedef int dont_be_pedantic;
#endif /* MODULE_VFS */