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/*
* linux/fs/proc/fd.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* proc fd directory handling functions
*
* 01-May-98 Edgar Toernig <froese@gmx.de>
* Added support for more than 256 fds.
* Limit raised to 32768.
*/
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <asm/uaccess.h>
static int proc_readfd(struct file *, void *, filldir_t);
static int proc_lookupfd(struct inode *, struct dentry *);
static struct file_operations proc_fd_operations = {
NULL, /* lseek - default */
NULL, /* read - bad */
NULL, /* write - bad */
proc_readfd, /* readdir */
NULL, /* poll - default */
NULL, /* ioctl - default */
NULL, /* mmap */
NULL, /* no special open code */
NULL, /* flush */
NULL, /* no special release code */
NULL /* can't fsync */
};
/*
* proc directories can do almost nothing..
*/
struct inode_operations proc_fd_inode_operations = {
&proc_fd_operations, /* default base directory file-ops */
NULL, /* create */
proc_lookupfd, /* lookup */
NULL, /* link */
NULL, /* unlink */
NULL, /* symlink */
NULL, /* mkdir */
NULL, /* rmdir */
NULL, /* mknod */
NULL, /* rename */
NULL, /* readlink */
NULL, /* follow_link */
NULL, /* readpage */
NULL, /* writepage */
NULL, /* bmap */
NULL, /* truncate */
proc_permission /* permission */
};
/*
* NOTE! Normally we'd indicate that a file does not
* exist by creating a negative dentry and returning
* a successful return code. However, for this case
* we do not want to create negative dentries, because
* the state of the world can change behind our backs.
*
* Thus just return -ENOENT instead.
*/
static int proc_lookupfd(struct inode * dir, struct dentry * dentry)
{
unsigned int ino, pid, fd, c;
struct task_struct * p;
struct file * file;
struct inode *inode;
const char *name;
int len, err;
err = -ENOENT;
if (!dir)
goto out;
ino = dir->i_ino;
pid = ino >> 16;
ino &= 0x0000ffff;
if (!pid || ino != PROC_PID_FD || !S_ISDIR(dir->i_mode))
goto out;
fd = 0;
len = dentry->d_name.len;
name = dentry->d_name.name;
while (len-- > 0) {
c = *name - '0';
name++;
if (c > 9)
goto out;
fd *= 10;
fd += c;
if (fd & 0xffff8000)
goto out;
}
read_lock(&tasklist_lock);
file = NULL;
p = find_task_by_pid(pid);
if (p)
file = fcheck_task(p, fd);
read_unlock(&tasklist_lock);
/*
* File handle is invalid if it is out of range, if the process
* has no files (Zombie) if the file is closed, or if its inode
* is NULL
*/
if (!file || !file->f_dentry)
goto out;
ino = (pid << 16) + PROC_PID_FD_DIR + fd;
inode = proc_get_inode(dir->i_sb, ino, NULL);
if (inode) {
dentry->d_op = &proc_dentry_operations;
d_add(dentry, inode);
err = 0;
}
out:
return err;
}
#define NUMBUF 10
static int proc_readfd(struct file * filp, void * dirent, filldir_t filldir)
{
struct inode *inode = filp->f_dentry->d_inode;
struct task_struct * p, **tarrayp;
unsigned int fd, pid, ino;
int retval;
char buf[NUMBUF];
retval = -EBADF;
if (!inode || !S_ISDIR(inode->i_mode))
goto out;
retval = 0;
ino = inode->i_ino;
pid = ino >> 16;
ino &= 0x0000ffff;
if (ino != PROC_PID_FD)
goto out;
for (fd = filp->f_pos; fd < 2; fd++, filp->f_pos++) {
ino = inode->i_ino;
if (fd)
ino = (ino & 0xffff0000) | PROC_PID_INO;
if (filldir(dirent, "..", fd+1, fd, ino) < 0)
goto out;
}
read_lock(&tasklist_lock);
p = find_task_by_pid(pid);
if (!p)
goto out_unlock;
tarrayp = p->tarray_ptr;
for (fd -= 2 ; p->files && fd < p->files->max_fds; fd++, filp->f_pos++)
{
struct file * file = fcheck_task(p, fd);
unsigned int i,j;
if (!file || !file->f_dentry)
continue;
j = NUMBUF;
i = fd;
do {
j--;
buf[j] = '0' + (i % 10);
i /= 10;
} while (i);
/* Drop the task lock, as the filldir function may block */
read_unlock(&tasklist_lock);
ino = (pid << 16) + PROC_PID_FD_DIR + fd;
if (filldir(dirent, buf+j, NUMBUF-j, fd+2, ino) < 0)
goto out;
read_lock(&tasklist_lock);
/* filldir() might have slept, so we must re-validate "p" */
if (p != *tarrayp || p->pid != pid)
break;
}
out_unlock:
read_unlock(&tasklist_lock);
out:
return retval;
}
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