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author | 2005-04-16 15:20:36 -0700 | |
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committer | 2005-04-16 15:20:36 -0700 | |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /fs/pipe.c | |
download | linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.bz2 linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'fs/pipe.c')
-rw-r--r-- | fs/pipe.c | 835 |
1 files changed, 835 insertions, 0 deletions
diff --git a/fs/pipe.c b/fs/pipe.c new file mode 100644 index 000000000000..25aa09f9d09d --- /dev/null +++ b/fs/pipe.c @@ -0,0 +1,835 @@ +/* + * 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 <linux/highmem.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 void anon_pipe_buf_release(struct pipe_inode_info *info, struct pipe_buffer *buf) +{ + struct page *page = buf->page; + + if (info->tmp_page) { + __free_page(page); + return; + } + info->tmp_page = page; +} + +static void *anon_pipe_buf_map(struct file *file, struct pipe_inode_info *info, struct pipe_buffer *buf) +{ + return kmap(buf->page); +} + +static void anon_pipe_buf_unmap(struct pipe_inode_info *info, struct pipe_buffer *buf) +{ + kunmap(buf->page); +} + +static struct pipe_buf_operations anon_pipe_buf_ops = { + .can_merge = 1, + .map = anon_pipe_buf_map, + .unmap = anon_pipe_buf_unmap, + .release = anon_pipe_buf_release, +}; + +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; + struct pipe_inode_info *info; + int do_wakeup; + ssize_t ret; + struct iovec *iov = (struct iovec *)_iov; + size_t total_len; + + 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)); + info = inode->i_pipe; + for (;;) { + int bufs = info->nrbufs; + if (bufs) { + int curbuf = info->curbuf; + struct pipe_buffer *buf = info->bufs + curbuf; + struct pipe_buf_operations *ops = buf->ops; + void *addr; + size_t chars = buf->len; + int error; + + if (chars > total_len) + chars = total_len; + + addr = ops->map(filp, info, buf); + error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars); + ops->unmap(info, buf); + if (unlikely(error)) { + if (!ret) ret = -EFAULT; + break; + } + ret += chars; + buf->offset += chars; + buf->len -= chars; + if (!buf->len) { + buf->ops = NULL; + ops->release(info, buf); + curbuf = (curbuf + 1) & (PIPE_BUFFERS-1); + info->curbuf = curbuf; + info->nrbufs = --bufs; + do_wakeup = 1; + } + total_len -= chars; + if (!total_len) + break; /* common path: read succeeded */ + } + if (bufs) /* More to do? */ + 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) + file_accessed(filp); + 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; + struct pipe_inode_info *info; + ssize_t ret; + int do_wakeup; + struct iovec *iov = (struct iovec *)_iov; + size_t total_len; + ssize_t chars; + + total_len = iov_length(iov, nr_segs); + /* Null write succeeds. */ + if (unlikely(total_len == 0)) + return 0; + + do_wakeup = 0; + ret = 0; + down(PIPE_SEM(*inode)); + info = inode->i_pipe; + + if (!PIPE_READERS(*inode)) { + send_sig(SIGPIPE, current, 0); + ret = -EPIPE; + goto out; + } + + /* We try to merge small writes */ + chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */ + if (info->nrbufs && chars != 0) { + int lastbuf = (info->curbuf + info->nrbufs - 1) & (PIPE_BUFFERS-1); + struct pipe_buffer *buf = info->bufs + lastbuf; + struct pipe_buf_operations *ops = buf->ops; + int offset = buf->offset + buf->len; + if (ops->can_merge && offset + chars <= PAGE_SIZE) { + void *addr = ops->map(filp, info, buf); + int error = pipe_iov_copy_from_user(offset + addr, iov, chars); + ops->unmap(info, buf); + ret = error; + do_wakeup = 1; + if (error) + goto out; + buf->len += chars; + total_len -= chars; + ret = chars; + if (!total_len) + goto out; + } + } + + for (;;) { + int bufs; + if (!PIPE_READERS(*inode)) { + send_sig(SIGPIPE, current, 0); + if (!ret) ret = -EPIPE; + break; + } + bufs = info->nrbufs; + if (bufs < PIPE_BUFFERS) { + int newbuf = (info->curbuf + bufs) & (PIPE_BUFFERS-1); + struct pipe_buffer *buf = info->bufs + newbuf; + struct page *page = info->tmp_page; + int error; + + if (!page) { + page = alloc_page(GFP_HIGHUSER); + if (unlikely(!page)) { + ret = ret ? : -ENOMEM; + break; + } + info->tmp_page = page; + } + /* Always wakeup, even if the copy fails. Otherwise + * we lock up (O_NONBLOCK-)readers that sleep due to + * syscall merging. + * FIXME! Is this really true? + */ + do_wakeup = 1; + chars = PAGE_SIZE; + if (chars > total_len) + chars = total_len; + + error = pipe_iov_copy_from_user(kmap(page), iov, chars); + kunmap(page); + if (unlikely(error)) { + if (!ret) ret = -EFAULT; + break; + } + ret += chars; + + /* Insert it into the buffer array */ + buf->page = page; + buf->ops = &anon_pipe_buf_ops; + buf->offset = 0; + buf->len = chars; + info->nrbufs = ++bufs; + info->tmp_page = NULL; + + total_len -= chars; + if (!total_len) + break; + } + if (bufs < PIPE_BUFFERS) + 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)--; + } +out: + 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) +{ + struct inode *inode = filp->f_dentry->d_inode; + struct pipe_inode_info *info; + int count, buf, nrbufs; + + switch (cmd) { + case FIONREAD: + down(PIPE_SEM(*inode)); + info = inode->i_pipe; + count = 0; + buf = info->curbuf; + nrbufs = info->nrbufs; + while (--nrbufs >= 0) { + count += info->bufs[buf].len; + buf = (buf+1) & (PIPE_BUFFERS-1); + } + up(PIPE_SEM(*inode)); + return put_user(count, (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; + struct pipe_inode_info *info = inode->i_pipe; + int nrbufs; + + poll_wait(filp, PIPE_WAIT(*inode), wait); + + /* Reading only -- no need for acquiring the semaphore. */ + nrbufs = info->nrbufs; + mask = 0; + if (filp->f_mode & FMODE_READ) { + mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0; + if (!PIPE_WRITERS(*inode) && filp->f_version != PIPE_WCOUNTER(*inode)) + mask |= POLLHUP; + } + + if (filp->f_mode & FMODE_WRITE) { + mask |= (nrbufs < PIPE_BUFFERS) ? POLLOUT | POLLWRNORM : 0; + 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)) { + free_pipe_info(inode); + } 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, +}; + +void free_pipe_info(struct inode *inode) +{ + int i; + struct pipe_inode_info *info = inode->i_pipe; + + inode->i_pipe = NULL; + for (i = 0; i < PIPE_BUFFERS; i++) { + struct pipe_buffer *buf = info->bufs + i; + if (buf->ops) + buf->ops->release(info, buf); + } + if (info->tmp_page) + __free_page(info->tmp_page); + kfree(info); +} + +struct inode* pipe_new(struct inode* inode) +{ + struct pipe_inode_info *info; + + info = kmalloc(sizeof(struct pipe_inode_info), GFP_KERNEL); + if (!info) + goto fail_page; + memset(info, 0, sizeof(*info)); + inode->i_pipe = info; + + init_waitqueue_head(PIPE_WAIT(*inode)); + PIPE_RCOUNTER(*inode) = PIPE_WCOUNTER(*inode) = 1; + + return inode; +fail_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); + f1->f_mapping = f2->f_mapping = inode->i_mapping; + + /* read file */ + f1->f_pos = f2->f_pos = 0; + f1->f_flags = O_RDONLY; + f1->f_op = &read_pipe_fops; + f1->f_mode = FMODE_READ; + f1->f_version = 0; + + /* write file */ + f2->f_flags = O_WRONLY; + f2->f_op = &write_pipe_fops; + f2->f_mode = FMODE_WRITE; + 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_pipe_info(inode); + 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); +} + +fs_initcall(init_pipe_fs); +module_exit(exit_pipe_fs); |