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/*
* symlink.c
*
* Copyright (c) 1999 Al Smith
*
* Portions derived from work (c) 1995,1996 Christian Vogelgsang.
*/
#include <linux/malloc.h>
#include <linux/efs_fs.h>
static int efs_readlink(struct dentry *, char *, int);
static struct dentry * efs_follow_link(struct dentry *, struct dentry *, unsigned int);
struct inode_operations efs_symlink_inode_operations = {
NULL, /* no symlink 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, /* readpage */
NULL, /* writepage */
NULL, /* bmap */
NULL, /* truncate */
NULL, /* permission */
NULL /* smap */
};
static char *efs_linktarget(struct inode *in, int *len) {
char *name;
struct buffer_head * bh;
efs_block_t size = in->i_size;
if (size > 2 * EFS_BLOCKSIZE) {
printk(KERN_ERR "EFS: linktarget(): name too long: %lu\n", in->i_size);
return NULL;
}
if (!(name = kmalloc(size + 1, GFP_KERNEL)))
return NULL;
/* read first 512 bytes of link target */
bh = bread(in->i_dev, efs_bmap(in, 0), EFS_BLOCKSIZE);
if (!bh) {
kfree(name);
printk(KERN_ERR "EFS: linktarget(): couldn't read block %d\n", efs_bmap(in, 0));
return NULL;
}
memcpy(name, bh->b_data, (size > EFS_BLOCKSIZE) ? EFS_BLOCKSIZE : size);
brelse(bh);
if (size > EFS_BLOCKSIZE) {
bh = bread(in->i_dev, efs_bmap(in, 1), EFS_BLOCKSIZE);
if (!bh) {
kfree(name);
printk(KERN_ERR "EFS: linktarget(): couldn't read block %d\n", efs_bmap(in, 1));
return NULL;
}
memcpy(name + EFS_BLOCKSIZE, bh->b_data, size - EFS_BLOCKSIZE);
brelse(bh);
}
name[size] = (char) 0;
if (len) *len = size;
return name;
}
static struct dentry *efs_follow_link(struct dentry *dentry, struct dentry *base, unsigned int follow) {
char *name;
struct inode *inode = dentry->d_inode;
if (!(name = efs_linktarget(inode, NULL))) {
dput(base);
return ERR_PTR(-ELOOP);
}
base = lookup_dentry(name, base, follow);
kfree(name);
return base;
}
static int efs_readlink(struct dentry * dir, char * buf, int bufsiz) {
int rc;
char *name;
struct inode *inode = dir->d_inode;
if (!(name = efs_linktarget(inode, &bufsiz))) return 0;
rc = copy_to_user(buf, name, bufsiz) ? -EFAULT : bufsiz;
kfree(name);
return rc;
}
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