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/*
* linux/fs/proc/link.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* /proc link-file handling code
*/
#include <asm/segment.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/minix_fs.h>
#include <linux/stat.h>
static int proc_readlink(struct inode *, char *, int);
static int proc_follow_link(struct inode *, struct inode *, int, int, struct inode **);
/*
* links can't do much...
*/
struct inode_operations proc_link_inode_operations = {
NULL, /* no file-operations */
NULL, /* create */
NULL, /* lookup */
NULL, /* link */
NULL, /* unlink */
NULL, /* symlink */
NULL, /* mkdir */
NULL, /* rmdir */
NULL, /* mknod */
NULL, /* rename */
proc_readlink, /* readlink */
proc_follow_link, /* follow_link */
NULL, /* bmap */
NULL, /* truncate */
NULL /* permission */
};
static int proc_follow_link(struct inode * dir, struct inode * inode,
int flag, int mode, struct inode ** res_inode)
{
unsigned int pid, ino;
struct task_struct * p;
int i;
*res_inode = NULL;
if (dir)
iput(dir);
if (!inode)
return -ENOENT;
if (!permission(inode, MAY_EXEC)) {
iput(inode);
return -EACCES;
}
ino = inode->i_ino;
pid = ino >> 16;
ino &= 0x0000ffff;
iput(inode);
for (i = 0 ; i < NR_TASKS ; i++)
if ((p = task[i]) && p->pid == pid)
break;
if (i >= NR_TASKS)
return -ENOENT;
inode = NULL;
switch (ino) {
case 4:
inode = p->pwd;
break;
case 5:
inode = p->root;
break;
case 6:
inode = p->executable;
break;
default:
switch (ino >> 8) {
case 1:
ino &= 0xff;
if (ino < NR_OPEN && p->filp[ino])
inode = p->filp[ino]->f_inode;
break;
case 2:
ino &= 0xff;
{ int j = ino;
struct vm_area_struct * mpnt;
for(mpnt = p->mmap; mpnt && j >= 0;
mpnt = mpnt->vm_next){
if(mpnt->vm_inode) {
if(j == 0) {
inode = mpnt->vm_inode;
break;
};
j--;
}
}
};
}
}
if (!inode)
return -ENOENT;
*res_inode = inode;
inode->i_count++;
return 0;
}
static int proc_readlink(struct inode * inode, char * buffer, int buflen)
{
int i;
unsigned int dev,ino;
char buf[64];
if (!S_ISLNK(inode->i_mode)) {
iput(inode);
return -EINVAL;
}
i = proc_follow_link(NULL, inode, 0, 0, &inode);
if (i)
return i;
if (!inode)
return -EIO;
dev = inode->i_dev;
ino = inode->i_ino;
iput(inode);
i = sprintf(buf,"[%04x]:%u", dev, ino);
if (buflen > i)
buflen = i;
i = 0;
while (i < buflen)
put_fs_byte(buf[i++],buffer++);
return i;
}