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/**
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 * @file
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 * @brief  DVFS interface implementation
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 * @author Denis Deryugin
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 * @date   11 Mar 2014
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 */
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#include <assert.h>
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#include <errno.h>
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#include <stddef.h>
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#include <drivers/block_dev.h> /* block_dev_block_size */
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#include <fs/dentry.h>
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#include <fs/file_desc.h>
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#include <fs/kfile.h>
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#include <fs/dvfs.h>
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#include <util/math.h>
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/**
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 * @brief Uninitialize file descriptor
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 * @param desc File descriptor to be uninitialized
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 *
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 * @return Negative error code
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 * @retval  0 Ok
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 * @retval -1 Descriptor fields are inconsistent
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 */
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int kclose(struct file_desc *desc) {
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	if (!desc || !desc->f_inode || !desc->f_dentry)
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		return -1;
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	if (!(desc->f_dentry->flags & VFS_DIR_VIRTUAL)) {
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		assert(desc->f_ops);
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	}
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	if (desc->f_ops && desc->f_ops->close) {
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		desc->f_ops->close(desc);
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	}
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	if (!dentry_ref_dec(desc->f_dentry))
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		dvfs_destroy_dentry(desc->f_dentry);
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	dvfs_destroy_file(desc);
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	return 0;
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}
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/**
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 * @brief Application level interface to write the file
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 * @param desc  File to be written
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 * @param buf   Source of the data
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 * @param count Length of the data
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 *
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 * @return Bytes written or negative error code
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 * @retval       0 Ok
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 * @retval -ENOSYS Function is not implemented in file system driver
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 */
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int kwrite(struct file_desc *desc, char *buf, int count) {
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	int res = 0; /* Assign to avoid compiler warning when use -O2 */
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	int retcode = count;
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	struct inode *inode;
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	if (!desc) {
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		return -EINVAL;
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	}
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	inode = desc->f_inode;
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	assert(inode);
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	if (!(inode->i_mode & DVFS_NO_LSEEK)
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	    && ((inode->i_size - desc->f_pos) < count)) {
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		if (inode->i_ops && inode->i_ops->ino_truncate) {
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			res = inode->i_ops->ino_truncate(desc->f_inode, desc->f_pos + count);
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			if (res) {
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				retcode = -EFBIG;
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			}
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		}
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		else {
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			retcode = -EFBIG;
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		}
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	}
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	if (desc->f_ops && desc->f_ops->write) {
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		res = desc->f_ops->write(desc, buf, count);
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	}
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	else {
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		retcode = -ENOSYS;
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	}
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	if (res > 0) {
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		desc->f_pos += res;
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	}
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	return retcode;
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}
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/**
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 * @brief Application level interface to read the file
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 * @param desc  File to be read
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 * @param buf   Destination
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 * @param count Length of the data
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 *
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 * @return Bytes read or negative error code
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 * @retval       0 Ok
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 * @retval -ENOSYS Function is not implemented in file system driver
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 */
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int kread(struct file_desc *desc, char *buf, int count) {
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	int res;
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	int sz;
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	if (!desc) {
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		return -1;
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	}
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	sz = min(count, desc->f_inode->i_size - desc->f_pos);
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	if (sz <= 0) {
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		return 0;
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	}
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	if (desc->f_ops && desc->f_ops->read) {
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		res = desc->f_ops->read(desc, buf, count);
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	}
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	else {
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		return -ENOSYS;
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	}
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	if (res > 0) {
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		desc->f_pos += res;
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	}
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	return res;
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}
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int kfstat(struct file_desc *desc, struct stat *sb) {
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	size_t block_size;
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	*sb = (struct stat){
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	    .st_size = desc->f_inode->i_size,
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	    .st_mode = desc->f_inode->i_mode,
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	    .st_uid = 0,
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	    .st_gid = 0,
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	};
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	sb->st_blocks = sb->st_size;
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	if (desc->f_inode->i_sb->bdev) {
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		block_size = block_dev_block_size(desc->f_inode->i_sb->bdev);
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		sb->st_blocks /= block_size;
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		sb->st_blocks += ((sb->st_blocks % block_size) != 0);
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	}
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	return 0;
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}
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int kioctl(struct file_desc *fp, int request, void *data) {
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	return fp->f_ops->ioctl(fp, request, data);
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}
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