symlink.c

嵌入式linux下基于SRAM的内存文件系统

/*
 * FILE NAME fs/pramfs/symlink.c
 *
 * BRIEF DESCRIPTION
 *
 * Symlink operations
 *
 * Author: Steve Longerbeam <[e-mail], or [e-mail]>
 *
 * Copyright 2003 Sony Corporation
 * Copyright 2003 Matsushita Electric Industrial Co., Ltd.
 * 2003-2004 (c) MontaVista Software, Inc. This file is licensed under
 * the terms of the GNU General Public License version 2. This program
 * is licensed "as is" without any warranty of any kind, whether express
 * or implied.
 */
#include <linux/fs.h>
#include <linux/pram_fs.h>

int pram_block_symlink(struct inode *inode, const char *symname, int len)
{
	struct super_block * sb = inode->i_sb;
	pram_off_t block;
	char* blockp;
	int err;

	err = pram_alloc_blocks (inode, 0, 1);
	if (err)
		return err;

	block = pram_find_data_block(inode, 0);
	blockp = pram_get_block(sb, block);

	pram_backup_add_block(sb, blockp);
	pram_lock_block(sb, blockp);
	memcpy(blockp, symname, len);
	blockp[len] = '\0';
	pram_unlock_block(sb, blockp);
	pram_backup_del_block(sb, blockp);
	return 0;
}

static int pram_readlink(struct dentry *dentry, char __user *buffer, int buflen)
{
	struct inode * inode = dentry->d_inode;
	struct super_block * sb = inode->i_sb;
	pram_off_t block;
	char* blockp;

	block = pram_find_data_block(inode, 0);
	blockp = pram_get_block(sb, block);
	return vfs_readlink(dentry, buffer, buflen, blockp);
}

static void * pram_follow_link(struct dentry *dentry, struct nameidata *nd)
{
	struct inode * inode = dentry->d_inode;
	struct super_block * sb = inode->i_sb;
	pram_off_t block;
	char* blockp;

	block = pram_find_data_block(inode, 0);
	blockp = pram_get_block(sb, block);
	return ERR_PTR(vfs_follow_link(nd, blockp));
}

const struct inode_operations pram_symlink_inode_operations = {
	.readlink	= pram_readlink,
	.follow_link	= pram_follow_link,
};