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/*
* linux/fs/umsdos/file.c
*
* Written 1992 by Jacques Gelinas
* inspired from linux/fs/msdos/file.c Werner Almesberger
*
* Extended MS-DOS regular file handling primitives
*/
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/msdos_fs.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/umsdos_fs.h>
#include <linux/malloc.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#define PRINTK(x)
#define Printk(x) printk x
/*
Read the data associate with the symlink.
Return length read in buffer or a negative error code.
*/
static int umsdos_readlink_x (
struct inode *inode,
char *buffer,
long (*msdos_read)(struct inode *, struct file *, char *, unsigned long),
int bufsiz)
{
int ret = inode->i_size;
struct file filp;
filp.f_pos = 0;
filp.f_reada = 0;
if (ret > bufsiz) ret = bufsiz;
if ((*msdos_read) (inode, &filp, buffer,ret) != ret){
ret = -EIO;
}
return ret;
}
/*
Follow a symbolic link chain by calling open_namei recursively
until an inode is found.
Return 0 if ok, or a negative error code if not.
*/
static int UMSDOS_follow_link(
struct inode * dir,
struct inode * inode,
int flag,
int mode,
struct inode ** res_inode)
{
int ret = -ELOOP;
*res_inode = NULL;
if (current->link_count < 5) {
char *path = (char*)kmalloc(PATH_MAX,GFP_KERNEL);
if (path == NULL){
ret = -ENOMEM;
}else{
if (!dir) {
dir = current->fs[1].root;
dir->i_count++;
}
if (!inode){
PRINTK (("symlink: inode = NULL\n"));
ret = -ENOENT;
}else if (!S_ISLNK(inode->i_mode)){
PRINTK (("symlink: Not ISLNK\n"));
*res_inode = inode;
inode = NULL;
ret = 0;
}else{
ret = umsdos_readlink_x (inode,path
,umsdos_file_read_kmem,PATH_MAX-1);
if (ret > 0){
path[ret] = '\0';
PRINTK (("follow :%s: %d ",path,ret));
iput(inode);
inode = NULL;
current->link_count++;
ret = open_namei(path,flag,mode,res_inode,dir);
current->link_count--;
dir = NULL;
}else{
ret = -EIO;
}
}
kfree (path);
}
}
iput(inode);
iput(dir);
PRINTK (("follow_link ret %d\n",ret));
return ret;
}
static int UMSDOS_readlink(struct inode * inode, char * buffer, int buflen)
{
int ret = -EINVAL;
if (S_ISLNK(inode->i_mode)) {
ret = umsdos_readlink_x (inode,buffer,fat_file_read,buflen);
}
PRINTK (("readlink %d %x bufsiz %d\n",ret,inode->i_mode,buflen));
iput(inode);
return ret;
}
static struct file_operations umsdos_symlink_operations = {
NULL, /* lseek - default */
NULL, /* read */
NULL, /* write */
NULL, /* readdir - bad */
NULL, /* select - default */
NULL, /* ioctl - default */
NULL, /* mmap */
NULL, /* no special open is needed */
NULL, /* release */
NULL /* fsync */
};
struct inode_operations umsdos_symlink_inode_operations = {
&umsdos_symlink_operations, /* default file operations */
NULL, /* create */
NULL, /* lookup */
NULL, /* link */
NULL, /* unlink */
NULL, /* symlink */
NULL, /* mkdir */
NULL, /* rmdir */
NULL, /* mknod */
NULL, /* rename */
UMSDOS_readlink, /* readlink */
UMSDOS_follow_link, /* follow_link */
NULL, /* readpage */
NULL, /* writepage */
NULL, /* bmap */
NULL, /* truncate */
NULL /* permission */
};
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