/* $OpenBSD: sys_pipe.c,v 1.59 2011/05/27 08:53:15 nicm Exp $ */ /* * Copyright (c) 1996 John S. Dyson * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice immediately at the beginning of the file, without modification, * this list of conditions, and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Absolutely no warranty of function or purpose is made by the author * John S. Dyson. * 4. Modifications may be freely made to this file if the above conditions * are met. */ /* * This file contains a high-performance replacement for the socket-based * pipes scheme originally used in FreeBSD/4.4Lite. It does not support * all features of sockets, but does do everything that pipes normally * do. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * interfaces to the outside world */ int pipe_read(struct file *, off_t *, struct uio *, struct ucred *); int pipe_write(struct file *, off_t *, struct uio *, struct ucred *); int pipe_close(struct file *, struct proc *); int pipe_poll(struct file *, int events, struct proc *); int pipe_kqfilter(struct file *fp, struct knote *kn); int pipe_ioctl(struct file *, u_long, caddr_t, struct proc *); int pipe_stat(struct file *fp, struct stat *ub, struct proc *p); static struct fileops pipeops = { pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter, pipe_stat, pipe_close }; void filt_pipedetach(struct knote *kn); int filt_piperead(struct knote *kn, long hint); int filt_pipewrite(struct knote *kn, long hint); struct filterops pipe_rfiltops = { 1, NULL, filt_pipedetach, filt_piperead }; struct filterops pipe_wfiltops = { 1, NULL, filt_pipedetach, filt_pipewrite }; /* * Default pipe buffer size(s), this can be kind-of large now because pipe * space is pageable. The pipe code will try to maintain locality of * reference for performance reasons, so small amounts of outstanding I/O * will not wipe the cache. */ #define MINPIPESIZE (PIPE_SIZE/3) /* * Limit the number of "big" pipes */ #define LIMITBIGPIPES 32 int nbigpipe; static int amountpipekva; struct pool pipe_pool; void pipeclose(struct pipe *); void pipe_free_kmem(struct pipe *); int pipe_create(struct pipe *); int pipelock(struct pipe *); void pipeunlock(struct pipe *); void pipeselwakeup(struct pipe *); int pipespace(struct pipe *, u_int); /* * The pipe system call for the DTYPE_PIPE type of pipes */ /* ARGSUSED */ int sys_opipe(struct proc *p, void *v, register_t *retval) { struct filedesc *fdp = p->p_fd; struct file *rf, *wf; struct pipe *rpipe, *wpipe; int fd, error; fdplock(fdp); rpipe = pool_get(&pipe_pool, PR_WAITOK); error = pipe_create(rpipe); if (error != 0) goto free1; wpipe = pool_get(&pipe_pool, PR_WAITOK); error = pipe_create(wpipe); if (error != 0) goto free2; error = falloc(p, &rf, &fd); if (error != 0) goto free2; rf->f_flag = FREAD | FWRITE; rf->f_type = DTYPE_PIPE; rf->f_data = rpipe; rf->f_ops = &pipeops; retval[0] = fd; error = falloc(p, &wf, &fd); if (error != 0) goto free3; wf->f_flag = FREAD | FWRITE; wf->f_type = DTYPE_PIPE; wf->f_data = wpipe; wf->f_ops = &pipeops; retval[1] = fd; rpipe->pipe_peer = wpipe; wpipe->pipe_peer = rpipe; FILE_SET_MATURE(rf); FILE_SET_MATURE(wf); fdpunlock(fdp); return (0); free3: fdremove(fdp, retval[0]); closef(rf, p); rpipe = NULL; free2: (void)pipeclose(wpipe); free1: if (rpipe != NULL) (void)pipeclose(rpipe); fdpunlock(fdp); return (error); } /* * Allocate kva for pipe circular buffer, the space is pageable. * This routine will 'realloc' the size of a pipe safely, if it fails * it will retain the old buffer. * If it fails it will return ENOMEM. */ int pipespace(struct pipe *cpipe, u_int size) { caddr_t buffer; buffer = (caddr_t)uvm_km_valloc(kernel_map, size); if (buffer == NULL) { return (ENOMEM); } /* free old resources if we are resizing */ pipe_free_kmem(cpipe); cpipe->pipe_buffer.buffer = buffer; cpipe->pipe_buffer.size = size; cpipe->pipe_buffer.in = 0; cpipe->pipe_buffer.out = 0; cpipe->pipe_buffer.cnt = 0; amountpipekva += cpipe->pipe_buffer.size; return (0); } /* * initialize and allocate VM and memory for pipe */ int pipe_create(struct pipe *cpipe) { int error; /* so pipe_free_kmem() doesn't follow junk pointer */ cpipe->pipe_buffer.buffer = NULL; /* * protect so pipeclose() doesn't follow a junk pointer * if pipespace() fails. */ bzero(&cpipe->pipe_sel, sizeof cpipe->pipe_sel); cpipe->pipe_state = 0; cpipe->pipe_peer = NULL; cpipe->pipe_busy = 0; error = pipespace(cpipe, PIPE_SIZE); if (error != 0) return (error); getnanotime(&cpipe->pipe_ctime); cpipe->pipe_atime = cpipe->pipe_ctime; cpipe->pipe_mtime = cpipe->pipe_ctime; cpipe->pipe_pgid = NO_PID; return (0); } /* * lock a pipe for I/O, blocking other access */ int pipelock(struct pipe *cpipe) { int error; while (cpipe->pipe_state & PIPE_LOCK) { cpipe->pipe_state |= PIPE_LWANT; if ((error = tsleep(cpipe, PRIBIO|PCATCH, "pipelk", 0))) return error; } cpipe->pipe_state |= PIPE_LOCK; return 0; } /* * unlock a pipe I/O lock */ void pipeunlock(struct pipe *cpipe) { cpipe->pipe_state &= ~PIPE_LOCK; if (cpipe->pipe_state & PIPE_LWANT) { cpipe->pipe_state &= ~PIPE_LWANT; wakeup(cpipe); } } void pipeselwakeup(struct pipe *cpipe) { if (cpipe->pipe_state & PIPE_SEL) { cpipe->pipe_state &= ~PIPE_SEL; selwakeup(&cpipe->pipe_sel); } else KNOTE(&cpipe->pipe_sel.si_note, 0); if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_pgid != NO_PID) gsignal(cpipe->pipe_pgid, SIGIO); } /* ARGSUSED */ int pipe_read(struct file *fp, off_t *poff, struct uio *uio, struct ucred *cred) { struct pipe *rpipe = (struct pipe *) fp->f_data; int error; int nread = 0; int size; error = pipelock(rpipe); if (error) return (error); ++rpipe->pipe_busy; while (uio->uio_resid) { /* * normal pipe buffer receive */ if (rpipe->pipe_buffer.cnt > 0) { size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; if (size > rpipe->pipe_buffer.cnt) size = rpipe->pipe_buffer.cnt; if (size > uio->uio_resid) size = uio->uio_resid; error = uiomove(&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], size, uio); if (error) { break; } rpipe->pipe_buffer.out += size; if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) rpipe->pipe_buffer.out = 0; rpipe->pipe_buffer.cnt -= size; /* * If there is no more to read in the pipe, reset * its pointers to the beginning. This improves * cache hit stats. */ if (rpipe->pipe_buffer.cnt == 0) { rpipe->pipe_buffer.in = 0; rpipe->pipe_buffer.out = 0; } nread += size; } else { /* * detect EOF condition * read returns 0 on EOF, no need to set error */ if (rpipe->pipe_state & PIPE_EOF) break; /* * If the "write-side" has been blocked, wake it up now. */ if (rpipe->pipe_state & PIPE_WANTW) { rpipe->pipe_state &= ~PIPE_WANTW; wakeup(rpipe); } /* * Break if some data was read. */ if (nread > 0) break; /* * Unlock the pipe buffer for our remaining processing. * We will either break out with an error or we will * sleep and relock to loop. */ pipeunlock(rpipe); /* * Handle non-blocking mode operation or * wait for more data. */ if (fp->f_flag & FNONBLOCK) { error = EAGAIN; } else { rpipe->pipe_state |= PIPE_WANTR; if ((error = tsleep(rpipe, PRIBIO|PCATCH, "piperd", 0)) == 0) error = pipelock(rpipe); } if (error) goto unlocked_error; } } pipeunlock(rpipe); if (error == 0) getnanotime(&rpipe->pipe_atime); unlocked_error: --rpipe->pipe_busy; /* * PIPE_WANT processing only makes sense if pipe_busy is 0. */ if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); wakeup(rpipe); } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { /* * Handle write blocking hysteresis. */ if (rpipe->pipe_state & PIPE_WANTW) { rpipe->pipe_state &= ~PIPE_WANTW; wakeup(rpipe); } } if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) pipeselwakeup(rpipe); return (error); } int pipe_write(struct file *fp, off_t *poff, struct uio *uio, struct ucred *cred) { int error = 0; int orig_resid; struct pipe *wpipe, *rpipe; rpipe = (struct pipe *) fp->f_data; wpipe = rpipe->pipe_peer; /* * detect loss of pipe read side, issue SIGPIPE if lost. */ if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { return (EPIPE); } ++wpipe->pipe_busy; /* * If it is advantageous to resize the pipe buffer, do * so. */ if ((uio->uio_resid > PIPE_SIZE) && (nbigpipe < LIMITBIGPIPES) && (wpipe->pipe_buffer.size <= PIPE_SIZE) && (wpipe->pipe_buffer.cnt == 0)) { if ((error = pipelock(wpipe)) == 0) { if (pipespace(wpipe, BIG_PIPE_SIZE) == 0) nbigpipe++; pipeunlock(wpipe); } } /* * If an early error occurred unbusy and return, waking up any pending * readers. */ if (error) { --wpipe->pipe_busy; if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); wakeup(wpipe); } return (error); } orig_resid = uio->uio_resid; while (uio->uio_resid) { int space; retrywrite: if (wpipe->pipe_state & PIPE_EOF) { error = EPIPE; break; } space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; /* Writes of size <= PIPE_BUF must be atomic. */ if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) space = 0; if (space > 0) { if ((error = pipelock(wpipe)) == 0) { int size; /* Transfer size */ int segsize; /* first segment to transfer */ /* * If a process blocked in uiomove, our * value for space might be bad. * * XXX will we be ok if the reader has gone * away here? */ if (space > wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) { pipeunlock(wpipe); goto retrywrite; } /* * Transfer size is minimum of uio transfer * and free space in pipe buffer. */ if (space > uio->uio_resid) size = uio->uio_resid; else size = space; /* * First segment to transfer is minimum of * transfer size and contiguous space in * pipe buffer. If first segment to transfer * is less than the transfer size, we've got * a wraparound in the buffer. */ segsize = wpipe->pipe_buffer.size - wpipe->pipe_buffer.in; if (segsize > size) segsize = size; /* Transfer first segment */ error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], segsize, uio); if (error == 0 && segsize < size) { /* * Transfer remaining part now, to * support atomic writes. Wraparound * happened. */ #ifdef DIAGNOSTIC if (wpipe->pipe_buffer.in + segsize != wpipe->pipe_buffer.size) panic("Expected pipe buffer wraparound disappeared"); #endif error = uiomove(&wpipe->pipe_buffer.buffer[0], size - segsize, uio); } if (error == 0) { wpipe->pipe_buffer.in += size; if (wpipe->pipe_buffer.in >= wpipe->pipe_buffer.size) { #ifdef DIAGNOSTIC if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size) panic("Expected wraparound bad"); #endif wpipe->pipe_buffer.in = size - segsize; } wpipe->pipe_buffer.cnt += size; #ifdef DIAGNOSTIC if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size) panic("Pipe buffer overflow"); #endif } pipeunlock(wpipe); } if (error) break; } else { /* * If the "read-side" has been blocked, wake it up now. */ if (wpipe->pipe_state & PIPE_WANTR) { wpipe->pipe_state &= ~PIPE_WANTR; wakeup(wpipe); } /* * don't block on non-blocking I/O */ if (fp->f_flag & FNONBLOCK) { error = EAGAIN; break; } /* * We have no more space and have something to offer, * wake up select/poll. */ pipeselwakeup(wpipe); wpipe->pipe_state |= PIPE_WANTW; error = tsleep(wpipe, (PRIBIO + 1)|PCATCH, "pipewr", 0); if (error) break; /* * If read side wants to go away, we just issue a * signal to ourselves. */ if (wpipe->pipe_state & PIPE_EOF) { error = EPIPE; break; } } } --wpipe->pipe_busy; if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); wakeup(wpipe); } else if (wpipe->pipe_buffer.cnt > 0) { /* * If we have put any characters in the buffer, we wake up * the reader. */ if (wpipe->pipe_state & PIPE_WANTR) { wpipe->pipe_state &= ~PIPE_WANTR; wakeup(wpipe); } } /* * Don't return EPIPE if I/O was successful */ if ((wpipe->pipe_buffer.cnt == 0) && (uio->uio_resid == 0) && (error == EPIPE)) { error = 0; } if (error == 0) getnanotime(&wpipe->pipe_mtime); /* * We have something to offer, wake up select/poll. */ if (wpipe->pipe_buffer.cnt) pipeselwakeup(wpipe); return (error); } /* * we implement a very minimal set of ioctls for compatibility with sockets. */ int pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, struct proc *p) { struct pipe *mpipe = (struct pipe *)fp->f_data; switch (cmd) { case FIONBIO: return (0); case FIOASYNC: if (*(int *)data) { mpipe->pipe_state |= PIPE_ASYNC; } else { mpipe->pipe_state &= ~PIPE_ASYNC; } return (0); case FIONREAD: *(int *)data = mpipe->pipe_buffer.cnt; return (0); case SIOCSPGRP: mpipe->pipe_pgid = *(int *)data; return (0); case SIOCGPGRP: *(int *)data = mpipe->pipe_pgid; return (0); } return (ENOTTY); } int pipe_poll(struct file *fp, int events, struct proc *p) { struct pipe *rpipe = (struct pipe *)fp->f_data; struct pipe *wpipe; int revents = 0; wpipe = rpipe->pipe_peer; if (events & (POLLIN | POLLRDNORM)) { if ((rpipe->pipe_buffer.cnt > 0) || (rpipe->pipe_state & PIPE_EOF)) revents |= events & (POLLIN | POLLRDNORM); } /* NOTE: POLLHUP and POLLOUT/POLLWRNORM are mutually exclusive */ if ((rpipe->pipe_state & PIPE_EOF) || (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) revents |= POLLHUP; else if (events & (POLLOUT | POLLWRNORM)) { if ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF) revents |= events & (POLLOUT | POLLWRNORM); } if (revents == 0) { if (events & (POLLIN | POLLRDNORM)) { selrecord(p, &rpipe->pipe_sel); rpipe->pipe_state |= PIPE_SEL; } if (events & (POLLOUT | POLLWRNORM)) { selrecord(p, &wpipe->pipe_sel); wpipe->pipe_state |= PIPE_SEL; } } return (revents); } int pipe_stat(struct file *fp, struct stat *ub, struct proc *p) { struct pipe *pipe = (struct pipe *)fp->f_data; bzero(ub, sizeof(*ub)); ub->st_mode = S_IFIFO; ub->st_blksize = pipe->pipe_buffer.size; ub->st_size = pipe->pipe_buffer.cnt; ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; ub->st_atim = pipe->pipe_atime; ub->st_mtim = pipe->pipe_mtime; ub->st_ctim = pipe->pipe_ctime; ub->st_uid = fp->f_cred->cr_uid; ub->st_gid = fp->f_cred->cr_gid; /* * Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen. * XXX (st_dev, st_ino) should be unique. */ return (0); } /* ARGSUSED */ int pipe_close(struct file *fp, struct proc *p) { struct pipe *cpipe = (struct pipe *)fp->f_data; fp->f_ops = NULL; fp->f_data = NULL; pipeclose(cpipe); return (0); } void pipe_free_kmem(struct pipe *cpipe) { if (cpipe->pipe_buffer.buffer != NULL) { if (cpipe->pipe_buffer.size > PIPE_SIZE) --nbigpipe; amountpipekva -= cpipe->pipe_buffer.size; uvm_km_free(kernel_map, (vaddr_t)cpipe->pipe_buffer.buffer, cpipe->pipe_buffer.size); cpipe->pipe_buffer.buffer = NULL; } } /* * shutdown the pipe */ void pipeclose(struct pipe *cpipe) { struct pipe *ppipe; if (cpipe) { pipeselwakeup(cpipe); /* * If the other side is blocked, wake it up saying that * we want to close it down. */ cpipe->pipe_state |= PIPE_EOF; while (cpipe->pipe_busy) { wakeup(cpipe); cpipe->pipe_state |= PIPE_WANT; tsleep(cpipe, PRIBIO, "pipecl", 0); } /* * Disconnect from peer */ if ((ppipe = cpipe->pipe_peer) != NULL) { pipeselwakeup(ppipe); ppipe->pipe_state |= PIPE_EOF; wakeup(ppipe); ppipe->pipe_peer = NULL; } /* * free resources */ pipe_free_kmem(cpipe); pool_put(&pipe_pool, cpipe); } } int pipe_kqfilter(struct file *fp, struct knote *kn) { struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; struct pipe *wpipe = rpipe->pipe_peer; switch (kn->kn_filter) { case EVFILT_READ: kn->kn_fop = &pipe_rfiltops; SLIST_INSERT_HEAD(&rpipe->pipe_sel.si_note, kn, kn_selnext); break; case EVFILT_WRITE: if (wpipe == NULL) { /* other end of pipe has been closed */ return (EPIPE); } kn->kn_fop = &pipe_wfiltops; SLIST_INSERT_HEAD(&wpipe->pipe_sel.si_note, kn, kn_selnext); break; default: return (EINVAL); } return (0); } void filt_pipedetach(struct knote *kn) { struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; struct pipe *wpipe = rpipe->pipe_peer; switch (kn->kn_filter) { case EVFILT_READ: SLIST_REMOVE(&rpipe->pipe_sel.si_note, kn, knote, kn_selnext); break; case EVFILT_WRITE: if (wpipe == NULL) return; SLIST_REMOVE(&wpipe->pipe_sel.si_note, kn, knote, kn_selnext); break; } } /*ARGSUSED*/ int filt_piperead(struct knote *kn, long hint) { struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; struct pipe *wpipe = rpipe->pipe_peer; kn->kn_data = rpipe->pipe_buffer.cnt; if ((rpipe->pipe_state & PIPE_EOF) || (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { kn->kn_flags |= EV_EOF; return (1); } return (kn->kn_data > 0); } /*ARGSUSED*/ int filt_pipewrite(struct knote *kn, long hint) { struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; struct pipe *wpipe = rpipe->pipe_peer; if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { kn->kn_data = 0; kn->kn_flags |= EV_EOF; return (1); } kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; return (kn->kn_data >= PIPE_BUF); } void pipe_init(void) { pool_init(&pipe_pool, sizeof(struct pipe), 0, 0, 0, "pipepl", &pool_allocator_nointr); }