4 * Copyright (C) 1991, 1992, 1999 Linus Torvalds
8 #include <linux/file.h>
9 #include <linux/poll.h>
10 #include <linux/slab.h>
11 #include <linux/module.h>
12 #include <linux/init.h>
14 #include <linux/mount.h>
15 #include <linux/pipe_fs_i.h>
16 #include <linux/uio.h>
17 #include <asm/uaccess.h>
18 #include <asm/ioctls.h>
21 * We use a start+len construction, which provides full use of the
23 * -- Florian Coosmann (FGC)
25 * Reads with count = 0 should always return 0.
26 * -- Julian Bradfield 1999-06-07.
28 * FIFOs and Pipes now generate SIGIO for both readers and writers.
29 * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
31 * pipe_read & write cleanup
32 * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
35 /* Drop the inode semaphore and wait for a pipe event, atomically */
36 void pipe_wait(struct inode * inode)
40 prepare_to_wait(PIPE_WAIT(*inode), &wait, TASK_INTERRUPTIBLE);
43 finish_wait(PIPE_WAIT(*inode), &wait);
44 down(PIPE_SEM(*inode));
48 pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len)
55 copy = min_t(unsigned long, len, iov->iov_len);
57 if (copy_from_user(to, iov->iov_base, copy))
61 iov->iov_base += copy;
68 pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len)
75 copy = min_t(unsigned long, len, iov->iov_len);
77 if (copy_to_user(iov->iov_base, from, copy))
81 iov->iov_base += copy;
88 pipe_readv(struct file *filp, const struct iovec *_iov,
89 unsigned long nr_segs, loff_t *ppos)
91 struct inode *inode = filp->f_dentry->d_inode;
94 struct iovec *iov = (struct iovec *)_iov;
97 /* pread is not allowed on pipes. */
98 if (unlikely(ppos != &filp->f_pos))
101 total_len = iov_length(iov, nr_segs);
102 /* Null read succeeds. */
103 if (unlikely(total_len == 0))
108 down(PIPE_SEM(*inode));
110 int size = PIPE_LEN(*inode);
112 char *pipebuf = PIPE_BASE(*inode) + PIPE_START(*inode);
113 ssize_t chars = PIPE_MAX_RCHUNK(*inode);
115 if (chars > total_len)
120 if (pipe_iov_copy_to_user(iov, pipebuf, chars)) {
121 if (!ret) ret = -EFAULT;
126 PIPE_START(*inode) += chars;
127 PIPE_START(*inode) &= (PIPE_SIZE - 1);
128 PIPE_LEN(*inode) -= chars;
132 break; /* common path: read succeeded */
134 if (PIPE_LEN(*inode)) /* test for cyclic buffers */
136 if (!PIPE_WRITERS(*inode))
138 if (!PIPE_WAITING_WRITERS(*inode)) {
139 /* syscall merging: Usually we must not sleep
140 * if O_NONBLOCK is set, or if we got some data.
141 * But if a writer sleeps in kernel space, then
142 * we can wait for that data without violating POSIX.
146 if (filp->f_flags & O_NONBLOCK) {
151 if (signal_pending(current)) {
152 if (!ret) ret = -ERESTARTSYS;
156 wake_up_interruptible_sync(PIPE_WAIT(*inode));
157 kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
161 up(PIPE_SEM(*inode));
162 /* Signal writers asynchronously that there is more room. */
164 wake_up_interruptible(PIPE_WAIT(*inode));
165 kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
173 pipe_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
175 struct iovec iov = { .iov_base = buf, .iov_len = count };
176 return pipe_readv(filp, &iov, 1, ppos);
180 pipe_writev(struct file *filp, const struct iovec *_iov,
181 unsigned long nr_segs, loff_t *ppos)
183 struct inode *inode = filp->f_dentry->d_inode;
187 struct iovec *iov = (struct iovec *)_iov;
190 /* pwrite is not allowed on pipes. */
191 if (unlikely(ppos != &filp->f_pos))
194 total_len = iov_length(iov, nr_segs);
195 /* Null write succeeds. */
196 if (unlikely(total_len == 0))
204 down(PIPE_SEM(*inode));
207 if (!PIPE_READERS(*inode)) {
208 send_sig(SIGPIPE, current, 0);
209 if (!ret) ret = -EPIPE;
212 free = PIPE_FREE(*inode);
215 ssize_t chars = PIPE_MAX_WCHUNK(*inode);
216 char *pipebuf = PIPE_BASE(*inode) + PIPE_END(*inode);
217 /* Always wakeup, even if the copy fails. Otherwise
218 * we lock up (O_NONBLOCK-)readers that sleep due to
222 if (chars > total_len)
227 if (pipe_iov_copy_from_user(pipebuf, iov, chars)) {
228 if (!ret) ret = -EFAULT;
233 PIPE_LEN(*inode) += chars;
238 if (PIPE_FREE(*inode) && ret) {
239 /* handle cyclic data buffers */
243 if (filp->f_flags & O_NONBLOCK) {
244 if (!ret) ret = -EAGAIN;
247 if (signal_pending(current)) {
248 if (!ret) ret = -ERESTARTSYS;
252 wake_up_interruptible_sync(PIPE_WAIT(*inode));
253 kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
256 PIPE_WAITING_WRITERS(*inode)++;
258 PIPE_WAITING_WRITERS(*inode)--;
260 up(PIPE_SEM(*inode));
262 wake_up_interruptible(PIPE_WAIT(*inode));
263 kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
266 inode_update_time(inode, 1); /* mtime and ctime */
271 pipe_write(struct file *filp, const char __user *buf,
272 size_t count, loff_t *ppos)
274 struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = count };
275 return pipe_writev(filp, &iov, 1, ppos);
279 bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
285 bad_pipe_w(struct file *filp, const char __user *buf, size_t count, loff_t *ppos)
291 pipe_ioctl(struct inode *pino, struct file *filp,
292 unsigned int cmd, unsigned long arg)
296 return put_user(PIPE_LEN(*pino), (int __user *)arg);
302 /* No kernel lock held - fine */
304 pipe_poll(struct file *filp, poll_table *wait)
307 struct inode *inode = filp->f_dentry->d_inode;
309 poll_wait(filp, PIPE_WAIT(*inode), wait);
311 /* Reading only -- no need for acquiring the semaphore. */
312 mask = POLLIN | POLLRDNORM;
313 if (PIPE_EMPTY(*inode))
314 mask = POLLOUT | POLLWRNORM;
315 if (!PIPE_WRITERS(*inode) && filp->f_version != PIPE_WCOUNTER(*inode))
317 if (!PIPE_READERS(*inode))
323 /* FIXME: most Unices do not set POLLERR for fifos */
324 #define fifo_poll pipe_poll
327 pipe_release(struct inode *inode, int decr, int decw)
329 down(PIPE_SEM(*inode));
330 PIPE_READERS(*inode) -= decr;
331 PIPE_WRITERS(*inode) -= decw;
332 if (!PIPE_READERS(*inode) && !PIPE_WRITERS(*inode)) {
333 struct pipe_inode_info *info = inode->i_pipe;
334 inode->i_pipe = NULL;
335 free_page((unsigned long) info->base);
338 wake_up_interruptible(PIPE_WAIT(*inode));
339 kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
340 kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
342 up(PIPE_SEM(*inode));
348 pipe_read_fasync(int fd, struct file *filp, int on)
350 struct inode *inode = filp->f_dentry->d_inode;
353 down(PIPE_SEM(*inode));
354 retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode));
355 up(PIPE_SEM(*inode));
365 pipe_write_fasync(int fd, struct file *filp, int on)
367 struct inode *inode = filp->f_dentry->d_inode;
370 down(PIPE_SEM(*inode));
371 retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode));
372 up(PIPE_SEM(*inode));
382 pipe_rdwr_fasync(int fd, struct file *filp, int on)
384 struct inode *inode = filp->f_dentry->d_inode;
387 down(PIPE_SEM(*inode));
389 retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode));
392 retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode));
394 up(PIPE_SEM(*inode));
404 pipe_read_release(struct inode *inode, struct file *filp)
406 pipe_read_fasync(-1, filp, 0);
407 return pipe_release(inode, 1, 0);
411 pipe_write_release(struct inode *inode, struct file *filp)
413 pipe_write_fasync(-1, filp, 0);
414 return pipe_release(inode, 0, 1);
418 pipe_rdwr_release(struct inode *inode, struct file *filp)
422 pipe_rdwr_fasync(-1, filp, 0);
423 decr = (filp->f_mode & FMODE_READ) != 0;
424 decw = (filp->f_mode & FMODE_WRITE) != 0;
425 return pipe_release(inode, decr, decw);
429 pipe_read_open(struct inode *inode, struct file *filp)
431 /* We could have perhaps used atomic_t, but this and friends
432 below are the only places. So it doesn't seem worthwhile. */
433 down(PIPE_SEM(*inode));
434 PIPE_READERS(*inode)++;
435 up(PIPE_SEM(*inode));
441 pipe_write_open(struct inode *inode, struct file *filp)
443 down(PIPE_SEM(*inode));
444 PIPE_WRITERS(*inode)++;
445 up(PIPE_SEM(*inode));
451 pipe_rdwr_open(struct inode *inode, struct file *filp)
453 down(PIPE_SEM(*inode));
454 if (filp->f_mode & FMODE_READ)
455 PIPE_READERS(*inode)++;
456 if (filp->f_mode & FMODE_WRITE)
457 PIPE_WRITERS(*inode)++;
458 up(PIPE_SEM(*inode));
464 * The file_operations structs are not static because they
465 * are also used in linux/fs/fifo.c to do operations on FIFOs.
467 struct file_operations read_fifo_fops = {
474 .open = pipe_read_open,
475 .release = pipe_read_release,
476 .fasync = pipe_read_fasync,
479 struct file_operations write_fifo_fops = {
483 .writev = pipe_writev,
486 .open = pipe_write_open,
487 .release = pipe_write_release,
488 .fasync = pipe_write_fasync,
491 struct file_operations rdwr_fifo_fops = {
496 .writev = pipe_writev,
499 .open = pipe_rdwr_open,
500 .release = pipe_rdwr_release,
501 .fasync = pipe_rdwr_fasync,
504 struct file_operations read_pipe_fops = {
511 .open = pipe_read_open,
512 .release = pipe_read_release,
513 .fasync = pipe_read_fasync,
516 struct file_operations write_pipe_fops = {
520 .writev = pipe_writev,
523 .open = pipe_write_open,
524 .release = pipe_write_release,
525 .fasync = pipe_write_fasync,
528 struct file_operations rdwr_pipe_fops = {
533 .writev = pipe_writev,
536 .open = pipe_rdwr_open,
537 .release = pipe_rdwr_release,
538 .fasync = pipe_rdwr_fasync,
541 struct inode* pipe_new(struct inode* inode)
545 page = __get_free_page(GFP_USER);
549 inode->i_pipe = kmalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
553 init_waitqueue_head(PIPE_WAIT(*inode));
554 PIPE_BASE(*inode) = (char*) page;
555 PIPE_START(*inode) = PIPE_LEN(*inode) = 0;
556 PIPE_READERS(*inode) = PIPE_WRITERS(*inode) = 0;
557 PIPE_WAITING_WRITERS(*inode) = 0;
558 PIPE_RCOUNTER(*inode) = PIPE_WCOUNTER(*inode) = 1;
559 *PIPE_FASYNC_READERS(*inode) = *PIPE_FASYNC_WRITERS(*inode) = NULL;
567 static struct vfsmount *pipe_mnt;
568 static int pipefs_delete_dentry(struct dentry *dentry)
572 static struct dentry_operations pipefs_dentry_operations = {
573 .d_delete = pipefs_delete_dentry,
576 static struct inode * get_pipe_inode(void)
578 struct inode *inode = new_inode(pipe_mnt->mnt_sb);
585 PIPE_READERS(*inode) = PIPE_WRITERS(*inode) = 1;
586 inode->i_fop = &rdwr_pipe_fops;
589 * Mark the inode dirty from the very beginning,
590 * that way it will never be moved to the dirty
591 * list because "mark_inode_dirty()" will think
592 * that it already _is_ on the dirty list.
594 inode->i_state = I_DIRTY;
595 inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
596 inode->i_uid = current->fsuid;
597 inode->i_gid = current->fsgid;
598 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
599 inode->i_blksize = PAGE_SIZE;
612 struct dentry *dentry;
613 struct inode * inode;
614 struct file *f1, *f2;
619 f1 = get_empty_filp();
623 f2 = get_empty_filp();
627 inode = get_pipe_inode();
631 error = get_unused_fd();
633 goto close_f12_inode;
636 error = get_unused_fd();
638 goto close_f12_inode_i;
642 sprintf(name, "[%lu]", inode->i_ino);
644 this.len = strlen(name);
645 this.hash = inode->i_ino; /* will go */
646 dentry = d_alloc(pipe_mnt->mnt_sb->s_root, &this);
648 goto close_f12_inode_i_j;
649 dentry->d_op = &pipefs_dentry_operations;
650 d_add(dentry, inode);
651 f1->f_vfsmnt = f2->f_vfsmnt = mntget(mntget(pipe_mnt));
652 f1->f_dentry = f2->f_dentry = dget(dentry);
653 f1->f_mapping = f2->f_mapping = inode->i_mapping;
656 f1->f_pos = f2->f_pos = 0;
657 f1->f_flags = O_RDONLY;
658 f1->f_op = &read_pipe_fops;
663 f2->f_flags = O_WRONLY;
664 f2->f_op = &write_pipe_fops;
679 free_page((unsigned long) PIPE_BASE(*inode));
680 kfree(inode->i_pipe);
681 inode->i_pipe = NULL;
692 * pipefs should _never_ be mounted by userland - too much of security hassle,
693 * no real gain from having the whole whorehouse mounted. So we don't need
694 * any operations on the root directory. However, we need a non-trivial
695 * d_name - pipe: will go nicely and kill the special-casing in procfs.
698 static struct super_block *pipefs_get_sb(struct file_system_type *fs_type,
699 int flags, const char *dev_name, void *data)
701 return get_sb_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC);
704 static struct file_system_type pipe_fs_type = {
706 .get_sb = pipefs_get_sb,
707 .kill_sb = kill_anon_super,
710 static int __init init_pipe_fs(void)
712 int err = register_filesystem(&pipe_fs_type);
714 pipe_mnt = kern_mount(&pipe_fs_type);
715 if (IS_ERR(pipe_mnt)) {
716 err = PTR_ERR(pipe_mnt);
717 unregister_filesystem(&pipe_fs_type);
723 static void __exit exit_pipe_fs(void)
725 unregister_filesystem(&pipe_fs_type);
729 module_init(init_pipe_fs)
730 module_exit(exit_pipe_fs)