/****************************************************************************
* drivers/loop.c
*
* Copyright (C) 2008 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/stat.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <debug.h>
#include <errno.h>
#include <nuttx/fs.h>
/****************************************************************************
* Private Definitions
****************************************************************************/
/****************************************************************************
* Private Types
****************************************************************************/
struct loop_struct_s
{
uint32 nsectors; /* Number of sectors on device */
uint16 sectsize; /* The size of one sector */
#ifdef CONFIG_FS_WRITABLE
boolean writeenabled; /* TRUE: can write to device */
#endif
int fd; /* Descriptor of char device/file */
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static int loop_open(FAR struct inode *inode);
static int loop_close(FAR struct inode *inode);
static ssize_t loop_read(FAR struct inode *inode, unsigned char *buffer,
size_t start_sector, unsigned int nsectors);
#ifdef CONFIG_FS_WRITABLE
static ssize_t loop_write(FAR struct inode *inode, const unsigned char *buffer,
size_t start_sector, unsigned int nsectors);
#endif
static int loop_geometry(FAR struct inode *inode, struct geometry *geometry);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct block_operations g_bops =
{
loop_open, /* open */
loop_close, /* close */
loop_read, /* read */
#ifdef CONFIG_FS_WRITABLE
loop_write, /* write */
#else
NULL, /* write */
#endif
loop_geometry, /* geometry */
NULL /* ioctl */
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: loop_open
*
* Description: Open the block device
*
****************************************************************************/
static int loop_open(FAR struct inode *inode)
{
return OK;
}
/****************************************************************************
* Name: loop_closel
*
* Description: close the block device
*
****************************************************************************/
static int loop_close(FAR struct inode *inode)
{
return OK;
}
/****************************************************************************
* Name: loop_read
*
* Description: Read the specified numer of sectors
*
****************************************************************************/
static ssize_t loop_read(FAR struct inode *inode, unsigned char *buffer,
size_t start_sector, unsigned int nsectors)
{
struct loop_struct_s *dev;
size_t nbytesread;
off_t offset;
int ret;
DEBUGASSERT(inode && inode->i_private);
dev = (struct loop_struct_s *)inode->i_private;
/* Calculate the offset to read the sectors and seek to the position */
offset = start_sector * dev->sectsize;
ret = lseek(dev->fd, offset, SEEK_SET);
if (ret == (off_t)-1)
{
dbg("Seek failed for offset=%d: %d\n", (int)offset, errno);
}
/* Then read the requested number of sectors from that position */
do
{
nbytesread = read(dev->fd, buffer, nsectors * dev->sectsize);
if (nbytesread < 0 && errno != EINTR)
{
dbg("Read failed: %d\n", errno);
return -errno;
}
}
while (nbytesread < 0);
/* Return the number of sectors read */
return nbytesread / dev->sectsize;
}
/****************************************************************************
* Name: loop_write
*
* Description: Write the specified number of sectors
*
****************************************************************************/
#ifdef CONFIG_FS_WRITABLE
static ssize_t loop_write(FAR struct inode *inode, const unsigned char *buffer,
size_t start_sector, unsigned int nsectors)
{
struct loop_struct_s *dev;
size_t nbyteswritten;
off_t offset;
int ret;
DEBUGASSERT(inode && inode->i_private);
dev = (struct loop_struct_s *)inode->i_private;
/* Calculate the offset to write the sectors and seek to the position */
offset = start_sector * dev->sectsize;
ret = lseek(dev->fd, offset, SEEK_SET);
if (ret == (off_t)-1)
{
dbg("Seek failed for offset=%d: %d\n", (int)offset, errno);
}
/* Then write the requested number of sectors to that position */
do
{
nbyteswritten = write(dev->fd, buffer, nsectors * dev->sectsize);
if (nbyteswritten < 0 && errno != EINTR)
{
dbg("Write failed: %d\n", errno);
return -errno;
}
}
while (nbyteswritten < 0);
/* Return the number of sectors written */
return nbyteswritten / dev->sectsize;
}
#endif
/****************************************************************************
* Name: loop_geometry
*
* Description: Return device geometry
*
****************************************************************************/
static int loop_geometry(FAR struct inode *inode, struct geometry *geometry)
{
struct loop_struct_s *dev;
DEBUGASSERT(inode);
if (geometry)
{
dev = (struct loop_struct_s *)inode->i_private;
geometry->geo_available = TRUE;
geometry->geo_mediachanged = FALSE;
#ifdef CONFIG_FS_WRITABLE
geometry->geo_writeenabled = dev->writeenabled;
#else
geometry->geo_writeenabled = FALSE;
#endif
geometry->geo_nsectors = dev->nsectors;
geometry->geo_sectorsize = dev->sectsize;
return OK;
}
return -EINVAL;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: losetup
*
* Description:
* Setup the loop device so that it exports the file referenced by 'name'
* as a block device.
*
****************************************************************************/
int losetup(const char *name, int minor, uint16 sectsize)
{
struct loop_struct_s *dev;
struct stat sb;
char devname[16];
int ret;
/* Sanity check */
#ifdef CONFIG_DEBUG
if (minor < 0 || minor > 255 || !name || !sectsize)
{
return -EINVAL;
}
#endif
/* Get the size of the file */
ret = stat(name, &sb);
if (ret < 0)
{
dbg("Failed to stat %s: %d\n", name, errno);
return -errno;
}
/* Check if the file system is big enough for one block */
if (sb.st_size < sectsize)
{
dbg("File is too small for blocksize\n");
return -ERANGE;
}
/* Allocate a loop device structure */
dev = (struct loop_struct_s *)malloc(sizeof(struct loop_struct_s));
if (!dev)
{
return -ENOMEM;
}
/* Open the file. First try to open the device W/R */
#ifdef CONFIG_FS_WRITABLE
dev->writeenabled = FALSE; /* Assume failure */
dev->fd = open(name, O_RDWR);
if (dev->fd >= 0)
{
dev->writeenabled = TRUE; /* Success */
}
else
#endif
{
/* If that fails, then try to open the device read-only */
dev->fd = open(name, O_RDWR);
if (dev->fd < 0)
{
dbg("Failed to open %s: %d\n", name, errno);
free(dev);
return -errno;
}
}
/* Initialize the remaining fields */
dev->nsectors = sb.st_size / sectsize; /* Number of sectors on device */
dev->sectsize = sectsize; /* The size of one sector */
/* Create a loop device name */
snprintf(devname, 16, "/dev/loop%d", minor);
/* Inode private data is a reference to the loop device stgructure */
ret = register_blockdriver(devname, &g_bops, 0, dev);
if (ret < 0)
{
fdbg("register_blockdriver failed: %d\n", -ret);
free(dev);
}
return ret;
}
