FreeBSD-5.3/sys/kern/sys_pipe.c
/*
* 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.
*/
/*
* This code has two modes of operation, a small write mode and a large
* write mode. The small write mode acts like conventional pipes with
* a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the
* "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT
* and PIPE_SIZE in size, it is fully mapped and wired into the kernel, and
* the receiving process can copy it directly from the pages in the sending
* process.
*
* If the sending process receives a signal, it is possible that it will
* go away, and certainly its address space can change, because control
* is returned back to the user-mode side. In that case, the pipe code
* arranges to copy the buffer supplied by the user process, to a pageable
* kernel buffer, and the receiving process will grab the data from the
* pageable kernel buffer. Since signals don't happen all that often,
* the copy operation is normally eliminated.
*
* The constant PIPE_MINDIRECT is chosen to make sure that buffering will
* happen for small transfers so that the system will not spend all of
* its time context switching.
*
* In order to limit the resource use of pipes, two sysctls exist:
*
* kern.ipc.maxpipekva - This is a hard limit on the amount of pageable
* address space available to us in pipe_map. This value is normally
* autotuned, but may also be loader tuned.
*
* kern.ipc.pipekva - This read-only sysctl tracks the current amount of
* memory in use by pipes.
*
* Based on how large pipekva is relative to maxpipekva, the following
* will happen:
*
* 0% - 50%:
* New pipes are given 16K of memory backing, pipes may dynamically
* grow to as large as 64K where needed.
* 50% - 75%:
* New pipes are given 4K (or PAGE_SIZE) of memory backing,
* existing pipes may NOT grow.
* 75% - 100%:
* New pipes are given 4K (or PAGE_SIZE) of memory backing,
* existing pipes will be shrunk down to 4K whenever possible.
*
* Resizing may be disabled by setting kern.ipc.piperesizeallowed=0. If
* that is set, the only resize that will occur is the 0 -> SMALL_PIPE_SIZE
* resize which MUST occur for reverse-direction pipes when they are
* first used.
*
* Additional information about the current state of pipes may be obtained
* from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail,
* and kern.ipc.piperesizefail.
*
* Locking rules: There are two locks present here: A mutex, used via
* PIPE_LOCK, and a flag, used via pipelock(). All locking is done via
* the flag, as mutexes can not persist over uiomove. The mutex
* exists only to guard access to the flag, and is not in itself a
* locking mechanism. Also note that there is only a single mutex for
* both directions of a pipe.
*
* As pipelock() may have to sleep before it can acquire the flag, it
* is important to reread all data after a call to pipelock(); everything
* in the structure may have changed.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/sys/kern/sys_pipe.c,v 1.177 2004/08/16 01:27:24 silby Exp $");
#include "opt_mac.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/filio.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mac.h>
#include <sys/mutex.h>
#include <sys/ttycom.h>
#include <sys/stat.h>
#include <sys/malloc.h>
#include <sys/poll.h>
#include <sys/selinfo.h>
#include <sys/signalvar.h>
#include <sys/sysctl.h>
#include <sys/sysproto.h>
#include <sys/pipe.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/uio.h>
#include <sys/event.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_object.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <vm/uma.h>
/*
* Use this define if you want to disable *fancy* VM things. Expect an
* approx 30% decrease in transfer rate. This could be useful for
* NetBSD or OpenBSD.
*/
/* #define PIPE_NODIRECT */
/*
* interfaces to the outside world
*/
static fo_rdwr_t pipe_read;
static fo_rdwr_t pipe_write;
static fo_ioctl_t pipe_ioctl;
static fo_poll_t pipe_poll;
static fo_kqfilter_t pipe_kqfilter;
static fo_stat_t pipe_stat;
static fo_close_t pipe_close;
static struct fileops pipeops = {
.fo_read = pipe_read,
.fo_write = pipe_write,
.fo_ioctl = pipe_ioctl,
.fo_poll = pipe_poll,
.fo_kqfilter = pipe_kqfilter,
.fo_stat = pipe_stat,
.fo_close = pipe_close,
.fo_flags = DFLAG_PASSABLE
};
static void filt_pipedetach(struct knote *kn);
static int filt_piperead(struct knote *kn, long hint);
static int filt_pipewrite(struct knote *kn, long hint);
static struct filterops pipe_rfiltops =
{ 1, NULL, filt_pipedetach, filt_piperead };
static 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)
#define MAXPIPESIZE (2*PIPE_SIZE/3)
static int amountpipes;
static int amountpipekva;
static int pipefragretry;
static int pipeallocfail;
static int piperesizefail;
static int piperesizeallowed = 1;
SYSCTL_DECL(_kern_ipc);
SYSCTL_INT(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN,
&maxpipekva, 0, "Pipe KVA limit");
SYSCTL_INT(_kern_ipc, OID_AUTO, pipes, CTLFLAG_RD,
&amountpipes, 0, "Current # of pipes");
SYSCTL_INT(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
&amountpipekva, 0, "Pipe KVA usage");
SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
&pipefragretry, 0, "Pipe allocation retries due to fragmentation");
SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
&pipeallocfail, 0, "Pipe allocation failures");
SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
&piperesizefail, 0, "Pipe resize failures");
SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
&piperesizeallowed, 0, "Pipe resizing allowed");
static void pipeinit(void *dummy __unused);
static void pipeclose(struct pipe *cpipe);
static void pipe_free_kmem(struct pipe *cpipe);
static int pipe_create(struct pipe *pipe, int backing);
static __inline int pipelock(struct pipe *cpipe, int catch);
static __inline void pipeunlock(struct pipe *cpipe);
static __inline void pipeselwakeup(struct pipe *cpipe);
#ifndef PIPE_NODIRECT
static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
static void pipe_destroy_write_buffer(struct pipe *wpipe);
static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
static void pipe_clone_write_buffer(struct pipe *wpipe);
#endif
static int pipespace(struct pipe *cpipe, int size);
static int pipespace_new(struct pipe *cpipe, int size);
static int pipe_zone_ctor(void *mem, int size, void *arg, int flags);
static void pipe_zone_dtor(void *mem, int size, void *arg);
static int pipe_zone_init(void *mem, int size, int flags);
static void pipe_zone_fini(void *mem, int size);
static uma_zone_t pipe_zone;
SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
static void
pipeinit(void *dummy __unused)
{
pipe_zone = uma_zcreate("PIPE", sizeof(struct pipepair),
pipe_zone_ctor, pipe_zone_dtor, pipe_zone_init, pipe_zone_fini,
UMA_ALIGN_PTR, 0);
KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
}
static int
pipe_zone_ctor(void *mem, int size, void *arg, int flags)
{
struct pipepair *pp;
struct pipe *rpipe, *wpipe;
KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
pp = (struct pipepair *)mem;
/*
* We zero both pipe endpoints to make sure all the kmem pointers
* are NULL, flag fields are zero'd, etc. We timestamp both
* endpoints with the same time.
*/
rpipe = &pp->pp_rpipe;
bzero(rpipe, sizeof(*rpipe));
vfs_timestamp(&rpipe->pipe_ctime);
rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
wpipe = &pp->pp_wpipe;
bzero(wpipe, sizeof(*wpipe));
wpipe->pipe_ctime = rpipe->pipe_ctime;
wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
rpipe->pipe_peer = wpipe;
rpipe->pipe_pair = pp;
wpipe->pipe_peer = rpipe;
wpipe->pipe_pair = pp;
/*
* Mark both endpoints as present; they will later get free'd
* one at a time. When both are free'd, then the whole pair
* is released.
*/
rpipe->pipe_present = 1;
wpipe->pipe_present = 1;
/*
* Eventually, the MAC Framework may initialize the label
* in ctor or init, but for now we do it elswhere to avoid
* blocking in ctor or init.
*/
pp->pp_label = NULL;
atomic_add_int(&amountpipes, 2);
return (0);
}
static void
pipe_zone_dtor(void *mem, int size, void *arg)
{
struct pipepair *pp;
KASSERT(size == sizeof(*pp), ("pipe_zone_dtor: wrong size"));
pp = (struct pipepair *)mem;
atomic_subtract_int(&amountpipes, 2);
}
static int
pipe_zone_init(void *mem, int size, int flags)
{
struct pipepair *pp;
KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
pp = (struct pipepair *)mem;
mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE);
return (0);
}
static void
pipe_zone_fini(void *mem, int size)
{
struct pipepair *pp;
KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
pp = (struct pipepair *)mem;
mtx_destroy(&pp->pp_mtx);
}
/*
* The pipe system call for the DTYPE_PIPE type of pipes. If we fail,
* let the zone pick up the pieces via pipeclose().
*/
/* ARGSUSED */
int
pipe(td, uap)
struct thread *td;
struct pipe_args /* {
int dummy;
} */ *uap;
{
struct filedesc *fdp = td->td_proc->p_fd;
struct file *rf, *wf;
struct pipepair *pp;
struct pipe *rpipe, *wpipe;
int fd, error;
pp = uma_zalloc(pipe_zone, M_WAITOK);
#ifdef MAC
/*
* The MAC label is shared between the connected endpoints. As a
* result mac_init_pipe() and mac_create_pipe() are called once
* for the pair, and not on the endpoints.
*/
mac_init_pipe(pp);
mac_create_pipe(td->td_ucred, pp);
#endif
rpipe = &pp->pp_rpipe;
wpipe = &pp->pp_wpipe;
/* Only the forward direction pipe is backed by default */
if (pipe_create(rpipe, 1) || pipe_create(wpipe, 0)) {
pipeclose(rpipe);
pipeclose(wpipe);
return (ENFILE);
}
rpipe->pipe_state |= PIPE_DIRECTOK;
wpipe->pipe_state |= PIPE_DIRECTOK;
error = falloc(td, &rf, &fd);
if (error) {
pipeclose(rpipe);
pipeclose(wpipe);
return (error);
}
/* An extra reference on `rf' has been held for us by falloc(). */
td->td_retval[0] = fd;
/*
* Warning: once we've gotten past allocation of the fd for the
* read-side, we can only drop the read side via fdrop() in order
* to avoid races against processes which manage to dup() the read
* side while we are blocked trying to allocate the write side.
*/
FILE_LOCK(rf);
rf->f_flag = FREAD | FWRITE;
rf->f_type = DTYPE_PIPE;
rf->f_data = rpipe;
rf->f_ops = &pipeops;
FILE_UNLOCK(rf);
error = falloc(td, &wf, &fd);
if (error) {
FILEDESC_LOCK(fdp);
if (fdp->fd_ofiles[td->td_retval[0]] == rf) {
fdp->fd_ofiles[td->td_retval[0]] = NULL;
fdunused(fdp, td->td_retval[0]);
FILEDESC_UNLOCK(fdp);
fdrop(rf, td);
} else {
FILEDESC_UNLOCK(fdp);
}
fdrop(rf, td);
/* rpipe has been closed by fdrop(). */
pipeclose(wpipe);
return (error);
}
/* An extra reference on `wf' has been held for us by falloc(). */
FILE_LOCK(wf);
wf->f_flag = FREAD | FWRITE;
wf->f_type = DTYPE_PIPE;
wf->f_data = wpipe;
wf->f_ops = &pipeops;
FILE_UNLOCK(wf);
fdrop(wf, td);
td->td_retval[1] = fd;
fdrop(rf, td);
return (0);
}
/*
* 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.
*/
static int
pipespace_new(cpipe, size)
struct pipe *cpipe;
int size;
{
caddr_t buffer;
int error, cnt, firstseg;
static int curfail = 0;
static struct timeval lastfail;
KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
("pipespace: resize of direct writes not allowed"));
retry:
cnt = cpipe->pipe_buffer.cnt;
if (cnt > size)
size = cnt;
size = round_page(size);
buffer = (caddr_t) vm_map_min(pipe_map);
error = vm_map_find(pipe_map, NULL, 0,
(vm_offset_t *) &buffer, size, 1,
VM_PROT_ALL, VM_PROT_ALL, 0);
if (error != KERN_SUCCESS) {
if ((cpipe->pipe_buffer.buffer == NULL) &&
(size > SMALL_PIPE_SIZE)) {
size = SMALL_PIPE_SIZE;
pipefragretry++;
goto retry;
}
if (cpipe->pipe_buffer.buffer == NULL) {
pipeallocfail++;
if (ppsratecheck(&lastfail, &curfail, 1))
printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
} else {
piperesizefail++;
}
return (ENOMEM);
}
/* copy data, then free old resources if we're resizing */
if (cnt > 0) {
if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
buffer, firstseg);
if ((cnt - firstseg) > 0)
bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
cpipe->pipe_buffer.in);
} else {
bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
buffer, cnt);
}
}
pipe_free_kmem(cpipe);
cpipe->pipe_buffer.buffer = buffer;
cpipe->pipe_buffer.size = size;
cpipe->pipe_buffer.in = cnt;
cpipe->pipe_buffer.out = 0;
cpipe->pipe_buffer.cnt = cnt;
atomic_add_int(&amountpipekva, cpipe->pipe_buffer.size);
return (0);
}
/*
* Wrapper for pipespace_new() that performs locking assertions.
*/
static int
pipespace(cpipe, size)
struct pipe *cpipe;
int size;
{
KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
("Unlocked pipe passed to pipespace"));
return (pipespace_new(cpipe, size));
}
/*
* lock a pipe for I/O, blocking other access
*/
static __inline int
pipelock(cpipe, catch)
struct pipe *cpipe;
int catch;
{
int error;
PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
while (cpipe->pipe_state & PIPE_LOCKFL) {
cpipe->pipe_state |= PIPE_LWANT;
error = msleep(cpipe, PIPE_MTX(cpipe),
catch ? (PRIBIO | PCATCH) : PRIBIO,
"pipelk", 0);
if (error != 0)
return (error);
}
cpipe->pipe_state |= PIPE_LOCKFL;
return (0);
}
/*
* unlock a pipe I/O lock
*/
static __inline void
pipeunlock(cpipe)
struct pipe *cpipe;
{
PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
("Unlocked pipe passed to pipeunlock"));
cpipe->pipe_state &= ~PIPE_LOCKFL;
if (cpipe->pipe_state & PIPE_LWANT) {
cpipe->pipe_state &= ~PIPE_LWANT;
wakeup(cpipe);
}
}
static __inline void
pipeselwakeup(cpipe)
struct pipe *cpipe;
{
PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
if (cpipe->pipe_state & PIPE_SEL) {
cpipe->pipe_state &= ~PIPE_SEL;
selwakeuppri(&cpipe->pipe_sel, PSOCK);
}
if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
}
/*
* Initialize and allocate VM and memory for pipe. The structure
* will start out zero'd from the ctor, so we just manage the kmem.
*/
static int
pipe_create(pipe, backing)
struct pipe *pipe;
int backing;
{
int error;
if (backing) {
if (amountpipekva > maxpipekva / 2)
error = pipespace_new(pipe, SMALL_PIPE_SIZE);
else
error = pipespace_new(pipe, PIPE_SIZE);
} else {
/* If we're not backing this pipe, no need to do anything. */
error = 0;
}
knlist_init(&pipe->pipe_sel.si_note, PIPE_MTX(pipe));
return (error);
}
/* ARGSUSED */
static int
pipe_read(fp, uio, active_cred, flags, td)
struct file *fp;
struct uio *uio;
struct ucred *active_cred;
struct thread *td;
int flags;
{
struct pipe *rpipe = fp->f_data;
int error;
int nread = 0;
u_int size;
PIPE_LOCK(rpipe);
++rpipe->pipe_busy;
error = pipelock(rpipe, 1);
if (error)
goto unlocked_error;
#ifdef MAC
error = mac_check_pipe_read(active_cred, rpipe->pipe_pair);
if (error)
goto locked_error;
#endif
if (amountpipekva > (3 * maxpipekva) / 4) {
if (!(rpipe->pipe_state & PIPE_DIRECTW) &&
(rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
(rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
(piperesizeallowed == 1)) {
PIPE_UNLOCK(rpipe);
pipespace(rpipe, SMALL_PIPE_SIZE);
PIPE_LOCK(rpipe);
}
}
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 > (u_int) uio->uio_resid)
size = (u_int) uio->uio_resid;
PIPE_UNLOCK(rpipe);
error = uiomove(
&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
size, uio);
PIPE_LOCK(rpipe);
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;
#ifndef PIPE_NODIRECT
/*
* Direct copy, bypassing a kernel buffer.
*/
} else if ((size = rpipe->pipe_map.cnt) &&
(rpipe->pipe_state & PIPE_DIRECTW)) {
if (size > (u_int) uio->uio_resid)
size = (u_int) uio->uio_resid;
PIPE_UNLOCK(rpipe);
error = uiomove_fromphys(rpipe->pipe_map.ms,
rpipe->pipe_map.pos, size, uio);
PIPE_LOCK(rpipe);
if (error)
break;
nread += size;
rpipe->pipe_map.pos += size;
rpipe->pipe_map.cnt -= size;
if (rpipe->pipe_map.cnt == 0) {
rpipe->pipe_state &= ~PIPE_DIRECTW;
wakeup(rpipe);
}
#endif
} 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 = msleep(rpipe, PIPE_MTX(rpipe),
PRIBIO | PCATCH,
"piperd", 0)) == 0)
error = pipelock(rpipe, 1);
}
if (error)
goto unlocked_error;
}
}
#ifdef MAC
locked_error:
#endif
pipeunlock(rpipe);
/* XXX: should probably do this before getting any locks. */
if (error == 0)
vfs_timestamp(&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);
PIPE_UNLOCK(rpipe);
return (error);
}
#ifndef PIPE_NODIRECT
/*
* Map the sending processes' buffer into kernel space and wire it.
* This is similar to a physical write operation.
*/
static int
pipe_build_write_buffer(wpipe, uio)
struct pipe *wpipe;
struct uio *uio;
{
pmap_t pmap;
u_int size;
int i, j;
vm_offset_t addr, endaddr;
PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
KASSERT(wpipe->pipe_state & PIPE_DIRECTW,
("Clone attempt on non-direct write pipe!"));
size = (u_int) uio->uio_iov->iov_len;
if (size > wpipe->pipe_buffer.size)
size = wpipe->pipe_buffer.size;
pmap = vmspace_pmap(curproc->p_vmspace);
endaddr = round_page((vm_offset_t)uio->uio_iov->iov_base + size);
addr = trunc_page((vm_offset_t)uio->uio_iov->iov_base);
for (i = 0; addr < endaddr; addr += PAGE_SIZE, i++) {
/*
* vm_fault_quick() can sleep. Consequently,
* vm_page_lock_queue() and vm_page_unlock_queue()
* should not be performed outside of this loop.
*/
race:
if (vm_fault_quick((caddr_t)addr, VM_PROT_READ) < 0) {
vm_page_lock_queues();
for (j = 0; j < i; j++)
vm_page_unhold(wpipe->pipe_map.ms[j]);
vm_page_unlock_queues();
return (EFAULT);
}
wpipe->pipe_map.ms[i] = pmap_extract_and_hold(pmap, addr,
VM_PROT_READ);
if (wpipe->pipe_map.ms[i] == NULL)
goto race;
}
/*
* set up the control block
*/
wpipe->pipe_map.npages = i;
wpipe->pipe_map.pos =
((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
wpipe->pipe_map.cnt = size;
/*
* and update the uio data
*/
uio->uio_iov->iov_len -= size;
uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
if (uio->uio_iov->iov_len == 0)
uio->uio_iov++;
uio->uio_resid -= size;
uio->uio_offset += size;
return (0);
}
/*
* unmap and unwire the process buffer
*/
static void
pipe_destroy_write_buffer(wpipe)
struct pipe *wpipe;
{
int i;
PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
vm_page_lock_queues();
for (i = 0; i < wpipe->pipe_map.npages; i++) {
vm_page_unhold(wpipe->pipe_map.ms[i]);
}
vm_page_unlock_queues();
wpipe->pipe_map.npages = 0;
}
/*
* In the case of a signal, the writing process might go away. This
* code copies the data into the circular buffer so that the source
* pages can be freed without loss of data.
*/
static void
pipe_clone_write_buffer(wpipe)
struct pipe *wpipe;
{
struct uio uio;
struct iovec iov;
int size;
int pos;
PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
size = wpipe->pipe_map.cnt;
pos = wpipe->pipe_map.pos;
wpipe->pipe_buffer.in = size;
wpipe->pipe_buffer.out = 0;
wpipe->pipe_buffer.cnt = size;
wpipe->pipe_state &= ~PIPE_DIRECTW;
PIPE_UNLOCK(wpipe);
iov.iov_base = wpipe->pipe_buffer.buffer;
iov.iov_len = size;
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
uio.uio_offset = 0;
uio.uio_resid = size;
uio.uio_segflg = UIO_SYSSPACE;
uio.uio_rw = UIO_READ;
uio.uio_td = curthread;
uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio);
PIPE_LOCK(wpipe);
pipe_destroy_write_buffer(wpipe);
}
/*
* This implements the pipe buffer write mechanism. Note that only
* a direct write OR a normal pipe write can be pending at any given time.
* If there are any characters in the pipe buffer, the direct write will
* be deferred until the receiving process grabs all of the bytes from
* the pipe buffer. Then the direct mapping write is set-up.
*/
static int
pipe_direct_write(wpipe, uio)
struct pipe *wpipe;
struct uio *uio;
{
int error;
retry:
PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
error = pipelock(wpipe, 1);
if (wpipe->pipe_state & PIPE_EOF)
error = EPIPE;
if (error) {
pipeunlock(wpipe);
goto error1;
}
while (wpipe->pipe_state & PIPE_DIRECTW) {
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
}
wpipe->pipe_state |= PIPE_WANTW;
pipeunlock(wpipe);
error = msleep(wpipe, PIPE_MTX(wpipe),
PRIBIO | PCATCH, "pipdww", 0);
if (error)
goto error1;
else
goto retry;
}
wpipe->pipe_map.cnt = 0; /* transfer not ready yet */
if (wpipe->pipe_buffer.cnt > 0) {
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
}
wpipe->pipe_state |= PIPE_WANTW;
pipeunlock(wpipe);
error = msleep(wpipe, PIPE_MTX(wpipe),
PRIBIO | PCATCH, "pipdwc", 0);
if (error)
goto error1;
else
goto retry;
}
wpipe->pipe_state |= PIPE_DIRECTW;
PIPE_UNLOCK(wpipe);
error = pipe_build_write_buffer(wpipe, uio);
PIPE_LOCK(wpipe);
if (error) {
wpipe->pipe_state &= ~PIPE_DIRECTW;
pipeunlock(wpipe);
goto error1;
}
error = 0;
while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
if (wpipe->pipe_state & PIPE_EOF) {
pipe_destroy_write_buffer(wpipe);
pipeselwakeup(wpipe);
pipeunlock(wpipe);
error = EPIPE;
goto error1;
}
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
}
pipeselwakeup(wpipe);
pipeunlock(wpipe);
error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
"pipdwt", 0);
pipelock(wpipe, 0);
}
if (wpipe->pipe_state & PIPE_EOF)
error = EPIPE;
if (wpipe->pipe_state & PIPE_DIRECTW) {
/*
* this bit of trickery substitutes a kernel buffer for
* the process that might be going away.
*/
pipe_clone_write_buffer(wpipe);
} else {
pipe_destroy_write_buffer(wpipe);
}
pipeunlock(wpipe);
return (error);
error1:
wakeup(wpipe);
return (error);
}
#endif
static int
pipe_write(fp, uio, active_cred, flags, td)
struct file *fp;
struct uio *uio;
struct ucred *active_cred;
struct thread *td;
int flags;
{
int error = 0;
int desiredsize, orig_resid;
struct pipe *wpipe, *rpipe;
rpipe = fp->f_data;
wpipe = rpipe->pipe_peer;
PIPE_LOCK(rpipe);
error = pipelock(wpipe, 1);
if (error) {
PIPE_UNLOCK(rpipe);
return (error);
}
/*
* detect loss of pipe read side, issue SIGPIPE if lost.
*/
if ((!wpipe->pipe_present) || (wpipe->pipe_state & PIPE_EOF)) {
pipeunlock(wpipe);
PIPE_UNLOCK(rpipe);
return (EPIPE);
}
#ifdef MAC
error = mac_check_pipe_write(active_cred, wpipe->pipe_pair);
if (error) {
pipeunlock(wpipe);
PIPE_UNLOCK(rpipe);
return (error);
}
#endif
++wpipe->pipe_busy;
/* Choose a larger size if it's advantageous */
desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
if (piperesizeallowed != 1)
break;
if (amountpipekva > maxpipekva / 2)
break;
if (desiredsize == BIG_PIPE_SIZE)
break;
desiredsize = desiredsize * 2;
}
/* Choose a smaller size if we're in a OOM situation */
if ((amountpipekva > (3 * maxpipekva) / 4) &&
(wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
(wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
(piperesizeallowed == 1))
desiredsize = SMALL_PIPE_SIZE;
/* Resize if the above determined that a new size was necessary */
if ((desiredsize != wpipe->pipe_buffer.size) &&
((wpipe->pipe_state & PIPE_DIRECTW) == 0)) {
PIPE_UNLOCK(wpipe);
pipespace(wpipe, desiredsize);
PIPE_LOCK(wpipe);
}
if (wpipe->pipe_buffer.size == 0) {
/*
* This can only happen for reverse direction use of pipes
* in a complete OOM situation.
*/
error = ENOMEM;
--wpipe->pipe_busy;
pipeunlock(wpipe);
PIPE_UNLOCK(wpipe);
return (error);
}
pipeunlock(wpipe);
orig_resid = uio->uio_resid;
while (uio->uio_resid) {
int space;
pipelock(wpipe, 0);
if (wpipe->pipe_state & PIPE_EOF) {
pipeunlock(wpipe);
error = EPIPE;
break;
}
#ifndef PIPE_NODIRECT
/*
* If the transfer is large, we can gain performance if
* we do process-to-process copies directly.
* If the write is non-blocking, we don't use the
* direct write mechanism.
*
* The direct write mechanism will detect the reader going
* away on us.
*/
if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) &&
(wpipe->pipe_buffer.size >= PIPE_MINDIRECT) &&
(fp->f_flag & FNONBLOCK) == 0) {
pipeunlock(wpipe);
error = pipe_direct_write(wpipe, uio);
if (error)
break;
continue;
}
#endif
/*
* Pipe buffered writes cannot be coincidental with
* direct writes. We wait until the currently executing
* direct write is completed before we start filling the
* pipe buffer. We break out if a signal occurs or the
* reader goes away.
*/
if (wpipe->pipe_state & PIPE_DIRECTW) {
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
}
pipeunlock(wpipe);
error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
"pipbww", 0);
if (error)
break;
else
continue;
}
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) {
int size; /* Transfer size */
int segsize; /* first segment to transfer */
/*
* 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 */
PIPE_UNLOCK(rpipe);
error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
segsize, uio);
PIPE_LOCK(rpipe);
if (error == 0 && segsize < size) {
KASSERT(wpipe->pipe_buffer.in + segsize ==
wpipe->pipe_buffer.size,
("Pipe buffer wraparound disappeared"));
/*
* Transfer remaining part now, to
* support atomic writes. Wraparound
* happened.
*/
PIPE_UNLOCK(rpipe);
error = uiomove(
&wpipe->pipe_buffer.buffer[0],
size - segsize, uio);
PIPE_LOCK(rpipe);
}
if (error == 0) {
wpipe->pipe_buffer.in += size;
if (wpipe->pipe_buffer.in >=
wpipe->pipe_buffer.size) {
KASSERT(wpipe->pipe_buffer.in ==
size - segsize +
wpipe->pipe_buffer.size,
("Expected wraparound bad"));
wpipe->pipe_buffer.in = size - segsize;
}
wpipe->pipe_buffer.cnt += size;
KASSERT(wpipe->pipe_buffer.cnt <=
wpipe->pipe_buffer.size,
("Pipe buffer overflow"));
}
pipeunlock(wpipe);
} 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;
pipeunlock(wpipe);
break;
}
/*
* We have no more space and have something to offer,
* wake up select/poll.
*/
pipeselwakeup(wpipe);
wpipe->pipe_state |= PIPE_WANTW;
pipeunlock(wpipe);
error = msleep(wpipe, PIPE_MTX(rpipe),
PRIBIO | PCATCH, "pipewr", 0);
if (error != 0)
break;
}
}
pipelock(wpipe, 0);
--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)
vfs_timestamp(&wpipe->pipe_mtime);
/*
* We have something to offer,
* wake up select/poll.
*/
if (wpipe->pipe_buffer.cnt)
pipeselwakeup(wpipe);
pipeunlock(wpipe);
PIPE_UNLOCK(rpipe);
return (error);
}
/*
* we implement a very minimal set of ioctls for compatibility with sockets.
*/
static int
pipe_ioctl(fp, cmd, data, active_cred, td)
struct file *fp;
u_long cmd;
void *data;
struct ucred *active_cred;
struct thread *td;
{
struct pipe *mpipe = fp->f_data;
#ifdef MAC
int error;
#endif
PIPE_LOCK(mpipe);
#ifdef MAC
error = mac_check_pipe_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
if (error) {
PIPE_UNLOCK(mpipe);
return (error);
}
#endif
switch (cmd) {
case FIONBIO:
PIPE_UNLOCK(mpipe);
return (0);
case FIOASYNC:
if (*(int *)data) {
mpipe->pipe_state |= PIPE_ASYNC;
} else {
mpipe->pipe_state &= ~PIPE_ASYNC;
}
PIPE_UNLOCK(mpipe);
return (0);
case FIONREAD:
if (mpipe->pipe_state & PIPE_DIRECTW)
*(int *)data = mpipe->pipe_map.cnt;
else
*(int *)data = mpipe->pipe_buffer.cnt;
PIPE_UNLOCK(mpipe);
return (0);
case FIOSETOWN:
PIPE_UNLOCK(mpipe);
return (fsetown(*(int *)data, &mpipe->pipe_sigio));
case FIOGETOWN:
PIPE_UNLOCK(mpipe);
*(int *)data = fgetown(&mpipe->pipe_sigio);
return (0);
/* This is deprecated, FIOSETOWN should be used instead. */
case TIOCSPGRP:
PIPE_UNLOCK(mpipe);
return (fsetown(-(*(int *)data), &mpipe->pipe_sigio));
/* This is deprecated, FIOGETOWN should be used instead. */
case TIOCGPGRP:
PIPE_UNLOCK(mpipe);
*(int *)data = -fgetown(&mpipe->pipe_sigio);
return (0);
}
PIPE_UNLOCK(mpipe);
return (ENOTTY);
}
static int
pipe_poll(fp, events, active_cred, td)
struct file *fp;
int events;
struct ucred *active_cred;
struct thread *td;
{
struct pipe *rpipe = fp->f_data;
struct pipe *wpipe;
int revents = 0;
#ifdef MAC
int error;
#endif
wpipe = rpipe->pipe_peer;
PIPE_LOCK(rpipe);
#ifdef MAC
error = mac_check_pipe_poll(active_cred, rpipe->pipe_pair);
if (error)
goto locked_error;
#endif
if (events & (POLLIN | POLLRDNORM))
if ((rpipe->pipe_state & PIPE_DIRECTW) ||
(rpipe->pipe_buffer.cnt > 0) ||
(rpipe->pipe_state & PIPE_EOF))
revents |= events & (POLLIN | POLLRDNORM);
if (events & (POLLOUT | POLLWRNORM))
if (!wpipe->pipe_present || (wpipe->pipe_state & PIPE_EOF) ||
(((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
(wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
revents |= events & (POLLOUT | POLLWRNORM);
if ((rpipe->pipe_state & PIPE_EOF) ||
(!wpipe->pipe_present) ||
(wpipe->pipe_state & PIPE_EOF))
revents |= POLLHUP;
if (revents == 0) {
if (events & (POLLIN | POLLRDNORM)) {
selrecord(td, &rpipe->pipe_sel);
rpipe->pipe_state |= PIPE_SEL;
}
if (events & (POLLOUT | POLLWRNORM)) {
selrecord(td, &wpipe->pipe_sel);
wpipe->pipe_state |= PIPE_SEL;
}
}
#ifdef MAC
locked_error:
#endif
PIPE_UNLOCK(rpipe);
return (revents);
}
/*
* We shouldn't need locks here as we're doing a read and this should
* be a natural race.
*/
static int
pipe_stat(fp, ub, active_cred, td)
struct file *fp;
struct stat *ub;
struct ucred *active_cred;
struct thread *td;
{
struct pipe *pipe = fp->f_data;
#ifdef MAC
int error;
PIPE_LOCK(pipe);
error = mac_check_pipe_stat(active_cred, pipe->pipe_pair);
PIPE_UNLOCK(pipe);
if (error)
return (error);
#endif
bzero(ub, sizeof(*ub));
ub->st_mode = S_IFIFO;
ub->st_blksize = PAGE_SIZE;
if (pipe->pipe_state & PIPE_DIRECTW)
ub->st_size = pipe->pipe_map.cnt;
else
ub->st_size = pipe->pipe_buffer.cnt;
ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
ub->st_atimespec = pipe->pipe_atime;
ub->st_mtimespec = pipe->pipe_mtime;
ub->st_ctimespec = 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 */
static int
pipe_close(fp, td)
struct file *fp;
struct thread *td;
{
struct pipe *cpipe = fp->f_data;
fp->f_ops = &badfileops;
fp->f_data = NULL;
funsetown(&cpipe->pipe_sigio);
pipeclose(cpipe);
return (0);
}
static void
pipe_free_kmem(cpipe)
struct pipe *cpipe;
{
KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
("pipe_free_kmem: pipe mutex locked"));
if (cpipe->pipe_buffer.buffer != NULL) {
atomic_subtract_int(&amountpipekva, cpipe->pipe_buffer.size);
vm_map_remove(pipe_map,
(vm_offset_t)cpipe->pipe_buffer.buffer,
(vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
cpipe->pipe_buffer.buffer = NULL;
}
#ifndef PIPE_NODIRECT
{
cpipe->pipe_map.cnt = 0;
cpipe->pipe_map.pos = 0;
cpipe->pipe_map.npages = 0;
}
#endif
}
/*
* shutdown the pipe
*/
static void
pipeclose(cpipe)
struct pipe *cpipe;
{
struct pipepair *pp;
struct pipe *ppipe;
KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
PIPE_LOCK(cpipe);
pipelock(cpipe, 0);
pp = cpipe->pipe_pair;
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;
pipeunlock(cpipe);
msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
pipelock(cpipe, 0);
}
/*
* Disconnect from peer, if any.
*/
ppipe = cpipe->pipe_peer;
if (ppipe->pipe_present != 0) {
pipeselwakeup(ppipe);
ppipe->pipe_state |= PIPE_EOF;
wakeup(ppipe);
KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0);
}
/*
* Mark this endpoint as free. Release kmem resources. We
* don't mark this endpoint as unused until we've finished
* doing that, or the pipe might disappear out from under
* us.
*/
PIPE_UNLOCK(cpipe);
pipe_free_kmem(cpipe);
PIPE_LOCK(cpipe);
cpipe->pipe_present = 0;
pipeunlock(cpipe);
knlist_clear(&cpipe->pipe_sel.si_note, 1);
knlist_destroy(&cpipe->pipe_sel.si_note);
/*
* If both endpoints are now closed, release the memory for the
* pipe pair. If not, unlock.
*/
if (ppipe->pipe_present == 0) {
PIPE_UNLOCK(cpipe);
#ifdef MAC
mac_destroy_pipe(pp);
#endif
uma_zfree(pipe_zone, cpipe->pipe_pair);
} else
PIPE_UNLOCK(cpipe);
}
/*ARGSUSED*/
static int
pipe_kqfilter(struct file *fp, struct knote *kn)
{
struct pipe *cpipe;
cpipe = kn->kn_fp->f_data;
PIPE_LOCK(cpipe);
switch (kn->kn_filter) {
case EVFILT_READ:
kn->kn_fop = &pipe_rfiltops;
break;
case EVFILT_WRITE:
kn->kn_fop = &pipe_wfiltops;
if (!cpipe->pipe_peer->pipe_present) {
/* other end of pipe has been closed */
PIPE_UNLOCK(cpipe);
return (EPIPE);
}
cpipe = cpipe->pipe_peer;
break;
default:
PIPE_UNLOCK(cpipe);
return (EINVAL);
}
knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
PIPE_UNLOCK(cpipe);
return (0);
}
static void
filt_pipedetach(struct knote *kn)
{
struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data;
PIPE_LOCK(cpipe);
if (kn->kn_filter == EVFILT_WRITE) {
if (!cpipe->pipe_peer->pipe_present) {
PIPE_UNLOCK(cpipe);
return;
}
cpipe = cpipe->pipe_peer;
}
knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
PIPE_UNLOCK(cpipe);
}
/*ARGSUSED*/
static int
filt_piperead(struct knote *kn, long hint)
{
struct pipe *rpipe = kn->kn_fp->f_data;
struct pipe *wpipe = rpipe->pipe_peer;
int ret;
PIPE_LOCK(rpipe);
kn->kn_data = rpipe->pipe_buffer.cnt;
if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
kn->kn_data = rpipe->pipe_map.cnt;
if ((rpipe->pipe_state & PIPE_EOF) ||
(!wpipe->pipe_present) || (wpipe->pipe_state & PIPE_EOF)) {
kn->kn_flags |= EV_EOF;
PIPE_UNLOCK(rpipe);
return (1);
}
ret = kn->kn_data > 0;
PIPE_UNLOCK(rpipe);
return ret;
}
/*ARGSUSED*/
static int
filt_pipewrite(struct knote *kn, long hint)
{
struct pipe *rpipe = kn->kn_fp->f_data;
struct pipe *wpipe = rpipe->pipe_peer;
PIPE_LOCK(rpipe);
if ((!wpipe->pipe_present) || (wpipe->pipe_state & PIPE_EOF)) {
kn->kn_data = 0;
kn->kn_flags |= EV_EOF;
PIPE_UNLOCK(rpipe);
return (1);
}
kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
if (wpipe->pipe_state & PIPE_DIRECTW)
kn->kn_data = 0;
PIPE_UNLOCK(rpipe);
return (kn->kn_data >= PIPE_BUF);
}