| /* |
| * linux/fs/pipe.c |
| * |
| * Copyright (C) 1991, 1992, 1999 Linus Torvalds |
| */ |
| |
| #include <linux/mm.h> |
| #include <linux/file.h> |
| #include <linux/poll.h> |
| #include <linux/slab.h> |
| #include <linux/module.h> |
| #include <linux/init.h> |
| #include <linux/fs.h> |
| #include <linux/mount.h> |
| #include <linux/pipe_fs_i.h> |
| #include <linux/uio.h> |
| #include <asm/uaccess.h> |
| #include <asm/ioctls.h> |
| |
| /* |
| * We use a start+len construction, which provides full use of the |
| * allocated memory. |
| * -- Florian Coosmann (FGC) |
| * |
| * Reads with count = 0 should always return 0. |
| * -- Julian Bradfield 1999-06-07. |
| * |
| * FIFOs and Pipes now generate SIGIO for both readers and writers. |
| * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16 |
| * |
| * pipe_read & write cleanup |
| * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09 |
| */ |
| |
| /* Drop the inode semaphore and wait for a pipe event, atomically */ |
| void pipe_wait(struct inode * inode) |
| { |
| DEFINE_WAIT(wait); |
| |
| prepare_to_wait(PIPE_WAIT(*inode), &wait, TASK_INTERRUPTIBLE); |
| up(PIPE_SEM(*inode)); |
| schedule(); |
| finish_wait(PIPE_WAIT(*inode), &wait); |
| down(PIPE_SEM(*inode)); |
| } |
| |
| static inline int |
| pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len) |
| { |
| unsigned long copy; |
| |
| while (len > 0) { |
| while (!iov->iov_len) |
| iov++; |
| copy = min_t(unsigned long, len, iov->iov_len); |
| |
| if (copy_from_user(to, iov->iov_base, copy)) |
| return -EFAULT; |
| to += copy; |
| len -= copy; |
| iov->iov_base += copy; |
| iov->iov_len -= copy; |
| } |
| return 0; |
| } |
| |
| static inline int |
| pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len) |
| { |
| unsigned long copy; |
| |
| while (len > 0) { |
| while (!iov->iov_len) |
| iov++; |
| copy = min_t(unsigned long, len, iov->iov_len); |
| |
| if (copy_to_user(iov->iov_base, from, copy)) |
| return -EFAULT; |
| from += copy; |
| len -= copy; |
| iov->iov_base += copy; |
| iov->iov_len -= copy; |
| } |
| return 0; |
| } |
| |
| static ssize_t |
| pipe_readv(struct file *filp, const struct iovec *_iov, |
| unsigned long nr_segs, loff_t *ppos) |
| { |
| struct inode *inode = filp->f_dentry->d_inode; |
| int do_wakeup; |
| ssize_t ret; |
| struct iovec *iov = (struct iovec *)_iov; |
| size_t total_len; |
| |
| /* pread is not allowed on pipes. */ |
| if (unlikely(ppos != &filp->f_pos)) |
| return -ESPIPE; |
| |
| total_len = iov_length(iov, nr_segs); |
| /* Null read succeeds. */ |
| if (unlikely(total_len == 0)) |
| return 0; |
| |
| do_wakeup = 0; |
| ret = 0; |
| down(PIPE_SEM(*inode)); |
| for (;;) { |
| int size = PIPE_LEN(*inode); |
| if (size) { |
| char *pipebuf = PIPE_BASE(*inode) + PIPE_START(*inode); |
| ssize_t chars = PIPE_MAX_RCHUNK(*inode); |
| |
| if (chars > total_len) |
| chars = total_len; |
| if (chars > size) |
| chars = size; |
| |
| if (pipe_iov_copy_to_user(iov, pipebuf, chars)) { |
| if (!ret) ret = -EFAULT; |
| break; |
| } |
| ret += chars; |
| |
| PIPE_START(*inode) += chars; |
| PIPE_START(*inode) &= (PIPE_SIZE - 1); |
| PIPE_LEN(*inode) -= chars; |
| total_len -= chars; |
| do_wakeup = 1; |
| if (!total_len) |
| break; /* common path: read succeeded */ |
| } |
| if (PIPE_LEN(*inode)) /* test for cyclic buffers */ |
| continue; |
| if (!PIPE_WRITERS(*inode)) |
| break; |
| if (!PIPE_WAITING_WRITERS(*inode)) { |
| /* syscall merging: Usually we must not sleep |
| * if O_NONBLOCK is set, or if we got some data. |
| * But if a writer sleeps in kernel space, then |
| * we can wait for that data without violating POSIX. |
| */ |
| if (ret) |
| break; |
| if (filp->f_flags & O_NONBLOCK) { |
| ret = -EAGAIN; |
| break; |
| } |
| } |
| if (signal_pending(current)) { |
| if (!ret) ret = -ERESTARTSYS; |
| break; |
| } |
| if (do_wakeup) { |
| wake_up_interruptible_sync(PIPE_WAIT(*inode)); |
| kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT); |
| } |
| pipe_wait(inode); |
| } |
| up(PIPE_SEM(*inode)); |
| /* Signal writers asynchronously that there is more room. */ |
| if (do_wakeup) { |
| wake_up_interruptible(PIPE_WAIT(*inode)); |
| kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT); |
| } |
| if (ret > 0) |
| update_atime(inode); |
| return ret; |
| } |
| |
| static ssize_t |
| pipe_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) |
| { |
| struct iovec iov = { .iov_base = buf, .iov_len = count }; |
| return pipe_readv(filp, &iov, 1, ppos); |
| } |
| |
| static ssize_t |
| pipe_writev(struct file *filp, const struct iovec *_iov, |
| unsigned long nr_segs, loff_t *ppos) |
| { |
| struct inode *inode = filp->f_dentry->d_inode; |
| ssize_t ret; |
| size_t min; |
| int do_wakeup; |
| struct iovec *iov = (struct iovec *)_iov; |
| size_t total_len; |
| |
| /* pwrite is not allowed on pipes. */ |
| if (unlikely(ppos != &filp->f_pos)) |
| return -ESPIPE; |
| |
| total_len = iov_length(iov, nr_segs); |
| /* Null write succeeds. */ |
| if (unlikely(total_len == 0)) |
| return 0; |
| |
| do_wakeup = 0; |
| ret = 0; |
| min = total_len; |
| if (min > PIPE_BUF) |
| min = 1; |
| down(PIPE_SEM(*inode)); |
| for (;;) { |
| int free; |
| if (!PIPE_READERS(*inode)) { |
| send_sig(SIGPIPE, current, 0); |
| if (!ret) ret = -EPIPE; |
| break; |
| } |
| free = PIPE_FREE(*inode); |
| if (free >= min) { |
| /* transfer data */ |
| ssize_t chars = PIPE_MAX_WCHUNK(*inode); |
| char *pipebuf = PIPE_BASE(*inode) + PIPE_END(*inode); |
| /* Always wakeup, even if the copy fails. Otherwise |
| * we lock up (O_NONBLOCK-)readers that sleep due to |
| * syscall merging. |
| */ |
| do_wakeup = 1; |
| if (chars > total_len) |
| chars = total_len; |
| if (chars > free) |
| chars = free; |
| |
| if (pipe_iov_copy_from_user(pipebuf, iov, chars)) { |
| if (!ret) ret = -EFAULT; |
| break; |
| } |
| ret += chars; |
| |
| PIPE_LEN(*inode) += chars; |
| total_len -= chars; |
| if (!total_len) |
| break; |
| } |
| if (PIPE_FREE(*inode) && ret) { |
| /* handle cyclic data buffers */ |
| min = 1; |
| continue; |
| } |
| if (filp->f_flags & O_NONBLOCK) { |
| if (!ret) ret = -EAGAIN; |
| break; |
| } |
| if (signal_pending(current)) { |
| if (!ret) ret = -ERESTARTSYS; |
| break; |
| } |
| if (do_wakeup) { |
| wake_up_interruptible_sync(PIPE_WAIT(*inode)); |
| kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN); |
| do_wakeup = 0; |
| } |
| PIPE_WAITING_WRITERS(*inode)++; |
| pipe_wait(inode); |
| PIPE_WAITING_WRITERS(*inode)--; |
| } |
| up(PIPE_SEM(*inode)); |
| if (do_wakeup) { |
| wake_up_interruptible(PIPE_WAIT(*inode)); |
| kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN); |
| } |
| if (ret > 0) |
| inode_update_time(inode, 1); /* mtime and ctime */ |
| return ret; |
| } |
| |
| static ssize_t |
| pipe_write(struct file *filp, const char __user *buf, |
| size_t count, loff_t *ppos) |
| { |
| struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = count }; |
| return pipe_writev(filp, &iov, 1, ppos); |
| } |
| |
| static ssize_t |
| bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos) |
| { |
| return -EBADF; |
| } |
| |
| static ssize_t |
| bad_pipe_w(struct file *filp, const char __user *buf, size_t count, loff_t *ppos) |
| { |
| return -EBADF; |
| } |
| |
| static int |
| pipe_ioctl(struct inode *pino, struct file *filp, |
| unsigned int cmd, unsigned long arg) |
| { |
| switch (cmd) { |
| case FIONREAD: |
| return put_user(PIPE_LEN(*pino), (int __user *)arg); |
| default: |
| return -EINVAL; |
| } |
| } |
| |
| /* No kernel lock held - fine */ |
| static unsigned int |
| pipe_poll(struct file *filp, poll_table *wait) |
| { |
| unsigned int mask; |
| struct inode *inode = filp->f_dentry->d_inode; |
| |
| poll_wait(filp, PIPE_WAIT(*inode), wait); |
| |
| /* Reading only -- no need for acquiring the semaphore. */ |
| mask = POLLIN | POLLRDNORM; |
| if (PIPE_EMPTY(*inode)) |
| mask = POLLOUT | POLLWRNORM; |
| if (!PIPE_WRITERS(*inode) && filp->f_version != PIPE_WCOUNTER(*inode)) |
| mask |= POLLHUP; |
| if (!PIPE_READERS(*inode)) |
| mask |= POLLERR; |
| |
| return mask; |
| } |
| |
| /* FIXME: most Unices do not set POLLERR for fifos */ |
| #define fifo_poll pipe_poll |
| |
| static int |
| pipe_release(struct inode *inode, int decr, int decw) |
| { |
| down(PIPE_SEM(*inode)); |
| PIPE_READERS(*inode) -= decr; |
| PIPE_WRITERS(*inode) -= decw; |
| if (!PIPE_READERS(*inode) && !PIPE_WRITERS(*inode)) { |
| struct pipe_inode_info *info = inode->i_pipe; |
| inode->i_pipe = NULL; |
| free_page((unsigned long) info->base); |
| kfree(info); |
| } else { |
| wake_up_interruptible(PIPE_WAIT(*inode)); |
| kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN); |
| kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT); |
| } |
| up(PIPE_SEM(*inode)); |
| |
| return 0; |
| } |
| |
| static int |
| pipe_read_fasync(int fd, struct file *filp, int on) |
| { |
| struct inode *inode = filp->f_dentry->d_inode; |
| int retval; |
| |
| down(PIPE_SEM(*inode)); |
| retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode)); |
| up(PIPE_SEM(*inode)); |
| |
| if (retval < 0) |
| return retval; |
| |
| return 0; |
| } |
| |
| |
| static int |
| pipe_write_fasync(int fd, struct file *filp, int on) |
| { |
| struct inode *inode = filp->f_dentry->d_inode; |
| int retval; |
| |
| down(PIPE_SEM(*inode)); |
| retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode)); |
| up(PIPE_SEM(*inode)); |
| |
| if (retval < 0) |
| return retval; |
| |
| return 0; |
| } |
| |
| |
| static int |
| pipe_rdwr_fasync(int fd, struct file *filp, int on) |
| { |
| struct inode *inode = filp->f_dentry->d_inode; |
| int retval; |
| |
| down(PIPE_SEM(*inode)); |
| |
| retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode)); |
| |
| if (retval >= 0) |
| retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode)); |
| |
| up(PIPE_SEM(*inode)); |
| |
| if (retval < 0) |
| return retval; |
| |
| return 0; |
| } |
| |
| |
| static int |
| pipe_read_release(struct inode *inode, struct file *filp) |
| { |
| pipe_read_fasync(-1, filp, 0); |
| return pipe_release(inode, 1, 0); |
| } |
| |
| static int |
| pipe_write_release(struct inode *inode, struct file *filp) |
| { |
| pipe_write_fasync(-1, filp, 0); |
| return pipe_release(inode, 0, 1); |
| } |
| |
| static int |
| pipe_rdwr_release(struct inode *inode, struct file *filp) |
| { |
| int decr, decw; |
| |
| pipe_rdwr_fasync(-1, filp, 0); |
| decr = (filp->f_mode & FMODE_READ) != 0; |
| decw = (filp->f_mode & FMODE_WRITE) != 0; |
| return pipe_release(inode, decr, decw); |
| } |
| |
| static int |
| pipe_read_open(struct inode *inode, struct file *filp) |
| { |
| /* We could have perhaps used atomic_t, but this and friends |
| below are the only places. So it doesn't seem worthwhile. */ |
| down(PIPE_SEM(*inode)); |
| PIPE_READERS(*inode)++; |
| up(PIPE_SEM(*inode)); |
| |
| return 0; |
| } |
| |
| static int |
| pipe_write_open(struct inode *inode, struct file *filp) |
| { |
| down(PIPE_SEM(*inode)); |
| PIPE_WRITERS(*inode)++; |
| up(PIPE_SEM(*inode)); |
| |
| return 0; |
| } |
| |
| static int |
| pipe_rdwr_open(struct inode *inode, struct file *filp) |
| { |
| down(PIPE_SEM(*inode)); |
| if (filp->f_mode & FMODE_READ) |
| PIPE_READERS(*inode)++; |
| if (filp->f_mode & FMODE_WRITE) |
| PIPE_WRITERS(*inode)++; |
| up(PIPE_SEM(*inode)); |
| |
| return 0; |
| } |
| |
| /* |
| * The file_operations structs are not static because they |
| * are also used in linux/fs/fifo.c to do operations on FIFOs. |
| */ |
| struct file_operations read_fifo_fops = { |
| .llseek = no_llseek, |
| .read = pipe_read, |
| .readv = pipe_readv, |
| .write = bad_pipe_w, |
| .poll = fifo_poll, |
| .ioctl = pipe_ioctl, |
| .open = pipe_read_open, |
| .release = pipe_read_release, |
| .fasync = pipe_read_fasync, |
| }; |
| |
| struct file_operations write_fifo_fops = { |
| .llseek = no_llseek, |
| .read = bad_pipe_r, |
| .write = pipe_write, |
| .writev = pipe_writev, |
| .poll = fifo_poll, |
| .ioctl = pipe_ioctl, |
| .open = pipe_write_open, |
| .release = pipe_write_release, |
| .fasync = pipe_write_fasync, |
| }; |
| |
| struct file_operations rdwr_fifo_fops = { |
| .llseek = no_llseek, |
| .read = pipe_read, |
| .readv = pipe_readv, |
| .write = pipe_write, |
| .writev = pipe_writev, |
| .poll = fifo_poll, |
| .ioctl = pipe_ioctl, |
| .open = pipe_rdwr_open, |
| .release = pipe_rdwr_release, |
| .fasync = pipe_rdwr_fasync, |
| }; |
| |
| struct file_operations read_pipe_fops = { |
| .llseek = no_llseek, |
| .read = pipe_read, |
| .readv = pipe_readv, |
| .write = bad_pipe_w, |
| .poll = pipe_poll, |
| .ioctl = pipe_ioctl, |
| .open = pipe_read_open, |
| .release = pipe_read_release, |
| .fasync = pipe_read_fasync, |
| }; |
| |
| struct file_operations write_pipe_fops = { |
| .llseek = no_llseek, |
| .read = bad_pipe_r, |
| .write = pipe_write, |
| .writev = pipe_writev, |
| .poll = pipe_poll, |
| .ioctl = pipe_ioctl, |
| .open = pipe_write_open, |
| .release = pipe_write_release, |
| .fasync = pipe_write_fasync, |
| }; |
| |
| struct file_operations rdwr_pipe_fops = { |
| .llseek = no_llseek, |
| .read = pipe_read, |
| .readv = pipe_readv, |
| .write = pipe_write, |
| .writev = pipe_writev, |
| .poll = pipe_poll, |
| .ioctl = pipe_ioctl, |
| .open = pipe_rdwr_open, |
| .release = pipe_rdwr_release, |
| .fasync = pipe_rdwr_fasync, |
| }; |
| |
| struct inode* pipe_new(struct inode* inode) |
| { |
| unsigned long page; |
| |
| page = __get_free_page(GFP_USER); |
| if (!page) |
| return NULL; |
| |
| inode->i_pipe = kmalloc(sizeof(struct pipe_inode_info), GFP_KERNEL); |
| if (!inode->i_pipe) |
| goto fail_page; |
| |
| init_waitqueue_head(PIPE_WAIT(*inode)); |
| PIPE_BASE(*inode) = (char*) page; |
| PIPE_START(*inode) = PIPE_LEN(*inode) = 0; |
| PIPE_READERS(*inode) = PIPE_WRITERS(*inode) = 0; |
| PIPE_WAITING_WRITERS(*inode) = 0; |
| PIPE_RCOUNTER(*inode) = PIPE_WCOUNTER(*inode) = 1; |
| *PIPE_FASYNC_READERS(*inode) = *PIPE_FASYNC_WRITERS(*inode) = NULL; |
| |
| return inode; |
| fail_page: |
| free_page(page); |
| return NULL; |
| } |
| |
| static struct vfsmount *pipe_mnt; |
| static int pipefs_delete_dentry(struct dentry *dentry) |
| { |
| return 1; |
| } |
| static struct dentry_operations pipefs_dentry_operations = { |
| .d_delete = pipefs_delete_dentry, |
| }; |
| |
| static struct inode * get_pipe_inode(void) |
| { |
| struct inode *inode = new_inode(pipe_mnt->mnt_sb); |
| |
| if (!inode) |
| goto fail_inode; |
| |
| if(!pipe_new(inode)) |
| goto fail_iput; |
| PIPE_READERS(*inode) = PIPE_WRITERS(*inode) = 1; |
| inode->i_fop = &rdwr_pipe_fops; |
| |
| /* |
| * Mark the inode dirty from the very beginning, |
| * that way it will never be moved to the dirty |
| * list because "mark_inode_dirty()" will think |
| * that it already _is_ on the dirty list. |
| */ |
| inode->i_state = I_DIRTY; |
| inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR; |
| inode->i_uid = current->fsuid; |
| inode->i_gid = current->fsgid; |
| inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
| inode->i_blksize = PAGE_SIZE; |
| return inode; |
| |
| fail_iput: |
| iput(inode); |
| fail_inode: |
| return NULL; |
| } |
| |
| int do_pipe(int *fd) |
| { |
| struct qstr this; |
| char name[32]; |
| struct dentry *dentry; |
| struct inode * inode; |
| struct file *f1, *f2; |
| int error; |
| int i,j; |
| |
| error = -ENFILE; |
| f1 = get_empty_filp(); |
| if (!f1) |
| goto no_files; |
| |
| f2 = get_empty_filp(); |
| if (!f2) |
| goto close_f1; |
| |
| inode = get_pipe_inode(); |
| if (!inode) |
| goto close_f12; |
| |
| error = get_unused_fd(); |
| if (error < 0) |
| goto close_f12_inode; |
| i = error; |
| |
| error = get_unused_fd(); |
| if (error < 0) |
| goto close_f12_inode_i; |
| j = error; |
| |
| error = -ENOMEM; |
| sprintf(name, "[%lu]", inode->i_ino); |
| this.name = name; |
| this.len = strlen(name); |
| this.hash = inode->i_ino; /* will go */ |
| dentry = d_alloc(pipe_mnt->mnt_sb->s_root, &this); |
| if (!dentry) |
| goto close_f12_inode_i_j; |
| dentry->d_op = &pipefs_dentry_operations; |
| d_add(dentry, inode); |
| f1->f_vfsmnt = f2->f_vfsmnt = mntget(mntget(pipe_mnt)); |
| f1->f_dentry = f2->f_dentry = dget(dentry); |
| |
| /* read file */ |
| f1->f_pos = f2->f_pos = 0; |
| f1->f_flags = O_RDONLY; |
| f1->f_op = &read_pipe_fops; |
| f1->f_mode = 1; |
| f1->f_version = 0; |
| |
| /* write file */ |
| f2->f_flags = O_WRONLY; |
| f2->f_op = &write_pipe_fops; |
| f2->f_mode = 2; |
| f2->f_version = 0; |
| |
| fd_install(i, f1); |
| fd_install(j, f2); |
| fd[0] = i; |
| fd[1] = j; |
| return 0; |
| |
| close_f12_inode_i_j: |
| put_unused_fd(j); |
| close_f12_inode_i: |
| put_unused_fd(i); |
| close_f12_inode: |
| free_page((unsigned long) PIPE_BASE(*inode)); |
| kfree(inode->i_pipe); |
| inode->i_pipe = NULL; |
| iput(inode); |
| close_f12: |
| put_filp(f2); |
| close_f1: |
| put_filp(f1); |
| no_files: |
| return error; |
| } |
| |
| /* |
| * pipefs should _never_ be mounted by userland - too much of security hassle, |
| * no real gain from having the whole whorehouse mounted. So we don't need |
| * any operations on the root directory. However, we need a non-trivial |
| * d_name - pipe: will go nicely and kill the special-casing in procfs. |
| */ |
| |
| static struct super_block *pipefs_get_sb(struct file_system_type *fs_type, |
| int flags, const char *dev_name, void *data) |
| { |
| return get_sb_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC); |
| } |
| |
| static struct file_system_type pipe_fs_type = { |
| .name = "pipefs", |
| .get_sb = pipefs_get_sb, |
| .kill_sb = kill_anon_super, |
| }; |
| |
| static int __init init_pipe_fs(void) |
| { |
| int err = register_filesystem(&pipe_fs_type); |
| if (!err) { |
| pipe_mnt = kern_mount(&pipe_fs_type); |
| if (IS_ERR(pipe_mnt)) { |
| err = PTR_ERR(pipe_mnt); |
| unregister_filesystem(&pipe_fs_type); |
| } |
| } |
| return err; |
| } |
| |
| static void __exit exit_pipe_fs(void) |
| { |
| unregister_filesystem(&pipe_fs_type); |
| mntput(pipe_mnt); |
| } |
| |
| module_init(init_pipe_fs) |
| module_exit(exit_pipe_fs) |