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/* symlink.c
*
* Symbolic link handling for EFS
*
* (C)1995,96 Christian Vogelgsang
*
* Based on the symlink.c from minix-fs by Linus
*/
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/efs_fs.h>
#include <linux/stat.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
static int efs_readlink(struct inode *, char *, int);
static struct dentry * efs_follow_link(struct inode *, struct dentry *);
struct inode_operations efs_symlink_in_ops = {
NULL, /* no file-operations */
NULL, /* create */
NULL, /* lookup */
NULL, /* link */
NULL, /* unlink */
NULL, /* symlink */
NULL, /* mkdir */
NULL, /* rmdir */
NULL, /* mknod */
NULL, /* rename */
efs_readlink, /* readlink */
efs_follow_link, /* follow_link */
NULL,
NULL,
NULL, /* bmap */
NULL, /* truncate */
NULL /* permission */
};
/* ----- efs_getlinktarget -----
read the target of the link from the data zone of the file
*/
static char *efs_getlinktarget(struct inode *in)
{
struct buffer_head * bh;
char *name;
__u32 size = in->i_size;
__u32 block;
/* link data longer than 1024 not supported */
if(size>2*EFS_BLOCK_SIZE) {
printk("efs_getlinktarget: name too long: %lu\n",in->i_size);
return NULL;
}
/* get some memory from the kernel to store the name */
name = kmalloc(size+1,GFP_KERNEL);
if(!name) return NULL;
/* read first 512 bytes of target */
block = efs_bmap(in,0);
bh = bread(in->i_dev,block,EFS_BLOCK_SIZE);
if(!bh) {
kfree(name);
return NULL;
}
memcpy(name,bh->b_data,(size>EFS_BLOCK_SIZE)?EFS_BLOCK_SIZE:size);
brelse(bh);
/* if the linktarget is long, read the next block */
if(size>EFS_BLOCK_SIZE) {
bh = bread(in->i_dev,block+1,EFS_BLOCK_SIZE);
if(!bh) {
kfree(name);
return NULL;
}
memcpy(name+EFS_BLOCK_SIZE,bh->b_data,size-EFS_BLOCK_SIZE);
brelse(bh);
}
/* terminate string and return it */
name[size]=0;
return name;
}
/* ----- efs_follow_link -----
get the inode of the link target
*/
static struct dentry * efs_follow_link(struct inode * dir, struct dentry *base)
{
char * name;
UPDATE_ATIME(dir);
name = efs_getlinktarget(dir);
#ifdef DEBUG_EFS
printk("EFS: efs_getlinktarget(%d) returned \"%s\"\n",
dir->i_ino, name);
#endif
base = lookup_dentry(name, base, 1);
kfree(name);
return base;
}
/* ----- efs_readlink -----
read the target of a link and return the name
*/
static int efs_readlink(struct inode * dir, char * buffer, int buflen)
{
int i;
struct buffer_head * bh;
if (buflen > 1023)
buflen = 1023;
bh = bread(dir->i_dev,efs_bmap(dir,0),EFS_BLOCK_SIZE);
if (!bh)
return 0;
/* copy the link target to the given buffer */
i = 0;
#ifdef DEBUG_EFS
printk("EFS: efs_readlink returning ");
#endif
while (i<buflen && bh->b_data[i] && i < dir->i_size) {
#ifdef DEBUG_EFS
printk("%c", bh->b_data[i]);
#endif
i++;
}
#ifdef DEBUG_EFS
printk("\n");
#endif
if (copy_to_user(buffer, bh->b_data, i))
i = -EFAULT;
brelse(bh);
return i;
}
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