/*
* 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.
*
* $FreeBSD: src/sys/kern/sys_pipe.c,v 1.82 2001/06/15 20:45:01 jlemon Exp $
*/
/*
* 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. PIPE_SIZE is constrained by the
* amount of kernel virtual memory.
*/
#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/lock.h>
#include <sys/mutex.h>
#include <sys/ttycom.h>
#include <sys/stat.h>
#include <sys/poll.h>
#include <sys/selinfo.h>
#include <sys/signalvar.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/vm_zone.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 int pipe_read __P((struct file *fp, struct uio *uio,
struct ucred *cred, int flags, struct proc *p));
static int pipe_write __P((struct file *fp, struct uio *uio,
struct ucred *cred, int flags, struct proc *p));
static int pipe_close __P((struct file *fp, struct proc *p));
static int pipe_poll __P((struct file *fp, int events, struct ucred *cred,
struct proc *p));
static int pipe_kqfilter __P((struct file *fp, struct knote *kn));
static int pipe_stat __P((struct file *fp, struct stat *sb, struct proc *p));
static int pipe_ioctl __P((struct file *fp, u_long cmd, caddr_t data, struct proc *p));
static struct fileops pipeops = {
pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter,
pipe_stat, pipe_close
};
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)
/*
* Maximum amount of kva for pipes -- this is kind-of a soft limit, but
* is there so that on large systems, we don't exhaust it.
*/
#define MAXPIPEKVA (8*1024*1024)
/*
* Limit for direct transfers, we cannot, of course limit
* the amount of kva for pipes in general though.
*/
#define LIMITPIPEKVA (16*1024*1024)
/*
* Limit the number of "big" pipes
*/
#define LIMITBIGPIPES 32
static int nbigpipe;
static int amountpipekva;
static void pipeclose __P((struct pipe *cpipe));
static void pipe_free_kmem __P((struct pipe *cpipe));
static int pipe_create __P((struct pipe **cpipep));
static __inline int pipelock __P((struct pipe *cpipe, int catch));
static __inline void pipeunlock __P((struct pipe *cpipe));
static __inline void pipeselwakeup __P((struct pipe *cpipe));
#ifndef PIPE_NODIRECT
static int pipe_build_write_buffer __P((struct pipe *wpipe, struct uio *uio));
static void pipe_destroy_write_buffer __P((struct pipe *wpipe));
static int pipe_direct_write __P((struct pipe *wpipe, struct uio *uio));
static void pipe_clone_write_buffer __P((struct pipe *wpipe));
#endif
static int pipespace __P((struct pipe *cpipe, int size));
static vm_zone_t pipe_zone;
/*
* The pipe system call for the DTYPE_PIPE type of pipes
*/
/* ARGSUSED */
int
pipe(p, uap)
struct proc *p;
struct pipe_args /* {
int dummy;
} */ *uap;
{
struct filedesc *fdp = p->p_fd;
struct file *rf, *wf;
struct pipe *rpipe, *wpipe;
int fd, error;
if (pipe_zone == NULL)
pipe_zone = zinit("PIPE", sizeof(struct pipe), 0, 0, 4);
rpipe = wpipe = NULL;
if (pipe_create(&rpipe) || pipe_create(&wpipe)) {
pipeclose(rpipe);
pipeclose(wpipe);
return (ENFILE);
}
rpipe->pipe_state |= PIPE_DIRECTOK;
wpipe->pipe_state |= PIPE_DIRECTOK;
error = falloc(p, &rf, &fd);
if (error) {
pipeclose(rpipe);
pipeclose(wpipe);
return (error);
}
fhold(rf);
p->p_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.
*/
rf->f_flag = FREAD | FWRITE;
rf->f_type = DTYPE_PIPE;
rf->f_data = (caddr_t)rpipe;
rf->f_ops = &pipeops;
error = falloc(p, &wf, &fd);
if (error) {
if (fdp->fd_ofiles[p->p_retval[0]] == rf) {
fdp->fd_ofiles[p->p_retval[0]] = NULL;
fdrop(rf, p);
}
fdrop(rf, p);
/* rpipe has been closed by fdrop(). */
pipeclose(wpipe);
return (error);
}
wf->f_flag = FREAD | FWRITE;
wf->f_type = DTYPE_PIPE;
wf->f_data = (caddr_t)wpipe;
wf->f_ops = &pipeops;
p->p_retval[1] = fd;
rpipe->pipe_peer = wpipe;
wpipe->pipe_peer = rpipe;
fdrop(rf, p);
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(cpipe, size)
struct pipe *cpipe;
int size;
{
struct vm_object *object;
caddr_t buffer;
int npages, error;
npages = round_page(size)/PAGE_SIZE;
/*
* Create an object, I don't like the idea of paging to/from
* kernel_object.
* XXX -- minor change needed here for NetBSD/OpenBSD VM systems.
*/
mtx_lock(&vm_mtx);
object = vm_object_allocate(OBJT_DEFAULT, npages);
buffer = (caddr_t) vm_map_min(kernel_map);
/*
* Insert the object into the kernel map, and allocate kva for it.
* The map entry is, by default, pageable.
* XXX -- minor change needed here for NetBSD/OpenBSD VM systems.
*/
error = vm_map_find(kernel_map, object, 0,
(vm_offset_t *) &buffer, size, 1,
VM_PROT_ALL, VM_PROT_ALL, 0);
if (error != KERN_SUCCESS) {
vm_object_deallocate(object);
mtx_unlock(&vm_mtx);
return (ENOMEM);
}
/* free old resources if we're resizing */
pipe_free_kmem(cpipe);
mtx_unlock(&vm_mtx);
cpipe->pipe_buffer.object = object;
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
*/
static int
pipe_create(cpipep)
struct pipe **cpipep;
{
struct pipe *cpipe;
int error;
*cpipep = zalloc(pipe_zone);
if (*cpipep == NULL)
return (ENOMEM);
cpipe = *cpipep;
/* so pipespace()->pipe_free_kmem() doesn't follow junk pointer */
cpipe->pipe_buffer.object = NULL;
#ifndef PIPE_NODIRECT
cpipe->pipe_map.kva = NULL;
#endif
/*
* 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;
#ifndef PIPE_NODIRECT
/*
* pipe data structure initializations to support direct pipe I/O
*/
cpipe->pipe_map.cnt = 0;
cpipe->pipe_map.kva = 0;
cpipe->pipe_map.pos = 0;
cpipe->pipe_map.npages = 0;
/* cpipe->pipe_map.ms[] = invalid */
#endif
error = pipespace(cpipe, PIPE_SIZE);
if (error)
return (error);
vfs_timestamp(&cpipe->pipe_ctime);
cpipe->pipe_atime = cpipe->pipe_ctime;
cpipe->pipe_mtime = cpipe->pipe_ctime;
return (0);
}
/*
* lock a pipe for I/O, blocking other access
*/
static __inline int
pipelock(cpipe, catch)
struct pipe *cpipe;
int catch;
{
int error;
while (cpipe->pipe_state & PIPE_LOCK) {
cpipe->pipe_state |= PIPE_LWANT;
error = tsleep(cpipe, catch ? (PRIBIO | PCATCH) : PRIBIO,
"pipelk", 0);
if (error != 0)
return (error);
}
cpipe->pipe_state |= PIPE_LOCK;
return (0);
}
/*
* unlock a pipe I/O lock
*/
static __inline void
pipeunlock(cpipe)
struct pipe *cpipe;
{
cpipe->pipe_state &= ~PIPE_LOCK;
if (cpipe->pipe_state & PIPE_LWANT) {
cpipe->pipe_state &= ~PIPE_LWANT;
wakeup(cpipe);
}
}
static __inline void
pipeselwakeup(cpipe)
struct pipe *cpipe;
{
if (cpipe->pipe_state & PIPE_SEL) {
cpipe->pipe_state &= ~PIPE_SEL;
selwakeup(&cpipe->pipe_sel);
}
if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
pgsigio(cpipe->pipe_sigio, SIGIO, 0);
KNOTE(&cpipe->pipe_sel.si_note, 0);
}
/* ARGSUSED */
static int
pipe_read(fp, uio, cred, flags, p)
struct file *fp;
struct uio *uio;
struct ucred *cred;
struct proc *p;
int flags;
{
struct pipe *rpipe = (struct pipe *) fp->f_data;
int error;
int nread = 0;
u_int size;
++rpipe->pipe_busy;
error = pipelock(rpipe, 1);
if (error)
goto unlocked_error;
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;
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;
#ifndef PIPE_NODIRECT
/*
* Direct copy, bypassing a kernel buffer.
*/
} else if ((size = rpipe->pipe_map.cnt) &&
(rpipe->pipe_state & PIPE_DIRECTW)) {
caddr_t va;
if (size > (u_int) uio->uio_resid)
size = (u_int) uio->uio_resid;
va = (caddr_t) rpipe->pipe_map.kva +
rpipe->pipe_map.pos;
error = uiomove(va, size, uio);
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 = tsleep(rpipe, PRIBIO | PCATCH,
"piperd", 0)) == 0)
error = pipelock(rpipe, 1);
}
if (error)
goto unlocked_error;
}
}
pipeunlock(rpipe);
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);
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;
{
u_int size;
int i;
vm_offset_t addr, endaddr, paddr;
size = (u_int) uio->uio_iov->iov_len;
if (size > wpipe->pipe_buffer.size)
size = wpipe->pipe_buffer.size;
endaddr = round_page((vm_offset_t)uio->uio_iov->iov_base + size);
mtx_lock(&vm_mtx);
addr = trunc_page((vm_offset_t)uio->uio_iov->iov_base);
for (i = 0; addr < endaddr; addr += PAGE_SIZE, i++) {
vm_page_t m;
if (vm_fault_quick((caddr_t)addr, VM_PROT_READ) < 0 ||
(paddr = pmap_kextract(addr)) == 0) {
int j;
for (j = 0; j < i; j++)
vm_page_unwire(wpipe->pipe_map.ms[j], 1);
mtx_unlock(&vm_mtx);
return (EFAULT);
}
m = PHYS_TO_VM_PAGE(paddr);
vm_page_wire(m);
wpipe->pipe_map.ms[i] = m;
}
/*
* 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 map the buffer
*/
if (wpipe->pipe_map.kva == 0) {
/*
* We need to allocate space for an extra page because the
* address range might (will) span pages at times.
*/
wpipe->pipe_map.kva = kmem_alloc_pageable(kernel_map,
wpipe->pipe_buffer.size + PAGE_SIZE);
amountpipekva += wpipe->pipe_buffer.size + PAGE_SIZE;
}
pmap_qenter(wpipe->pipe_map.kva, wpipe->pipe_map.ms,
wpipe->pipe_map.npages);
mtx_unlock(&vm_mtx);
/*
* and update the uio data
*/
uio->uio_iov->iov_len -= size;
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;
mtx_lock(&vm_mtx);
if (wpipe->pipe_map.kva) {
pmap_qremove(wpipe->pipe_map.kva, wpipe->pipe_map.npages);
if (amountpipekva > MAXPIPEKVA) {
vm_offset_t kva = wpipe->pipe_map.kva;
wpipe->pipe_map.kva = 0;
kmem_free(kernel_map, kva,
wpipe->pipe_buffer.size + PAGE_SIZE);
amountpipekva -= wpipe->pipe_buffer.size + PAGE_SIZE;
}
}
for (i = 0; i < wpipe->pipe_map.npages; i++)
vm_page_unwire(wpipe->pipe_map.ms[i], 1);
mtx_unlock(&vm_mtx);
}
/*
* 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;
{
int size;
int pos;
size = wpipe->pipe_map.cnt;
pos = wpipe->pipe_map.pos;
bcopy((caddr_t) wpipe->pipe_map.kva + pos,
(caddr_t) wpipe->pipe_buffer.buffer, size);
wpipe->pipe_buffer.in = size;
wpipe->pipe_buffer.out = 0;
wpipe->pipe_buffer.cnt = size;
wpipe->pipe_state &= ~PIPE_DIRECTW;
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:
while (wpipe->pipe_state & PIPE_DIRECTW) {
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
}
wpipe->pipe_state |= PIPE_WANTW;
error = tsleep(wpipe, PRIBIO | PCATCH, "pipdww", 0);
if (error)
goto error1;
if (wpipe->pipe_state & PIPE_EOF) {
error = EPIPE;
goto error1;
}
}
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;
error = tsleep(wpipe, PRIBIO | PCATCH, "pipdwc", 0);
if (error)
goto error1;
if (wpipe->pipe_state & PIPE_EOF) {
error = EPIPE;
goto error1;
}
goto retry;
}
wpipe->pipe_state |= PIPE_DIRECTW;
error = pipe_build_write_buffer(wpipe, uio);
if (error) {
wpipe->pipe_state &= ~PIPE_DIRECTW;
goto error1;
}
error = 0;
while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
if (wpipe->pipe_state & PIPE_EOF) {
pipelock(wpipe, 0);
pipe_destroy_write_buffer(wpipe);
pipeunlock(wpipe);
pipeselwakeup(wpipe);
error = EPIPE;
goto error1;
}
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
}
pipeselwakeup(wpipe);
error = tsleep(wpipe, PRIBIO | PCATCH, "pipdwt", 0);
}
pipelock(wpipe,0);
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, cred, flags, p)
struct file *fp;
struct uio *uio;
struct ucred *cred;
struct proc *p;
int flags;
{
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_state & PIPE_DIRECTW) == 0 &&
(wpipe->pipe_buffer.size <= PIPE_SIZE) &&
(wpipe->pipe_buffer.cnt == 0)) {
if ((error = pipelock(wpipe,1)) == 0) {
if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
nbigpipe++;
pipeunlock(wpipe);
}
}
/*
* If an early error occured 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);
}
KASSERT(wpipe->pipe_buffer.buffer != NULL, ("pipe buffer gone"));
orig_resid = uio->uio_resid;
while (uio->uio_resid) {
int space;
#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) &&
(fp->f_flag & FNONBLOCK) == 0 &&
(wpipe->pipe_map.kva || (amountpipekva < LIMITPIPEKVA)) &&
(uio->uio_iov->iov_len >= PIPE_MINDIRECT)) {
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.
*/
retrywrite:
while (wpipe->pipe_state & PIPE_DIRECTW) {
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
}
error = tsleep(wpipe, PRIBIO | PCATCH, "pipbww", 0);
if (wpipe->pipe_state & PIPE_EOF)
break;
if (error)
break;
}
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 && (wpipe->pipe_buffer.cnt < PIPE_SIZE)) {
if ((error = pipelock(wpipe,1)) == 0) {
int size; /* Transfer size */
int segsize; /* first segment to transfer */
/*
* It is possible for a direct write to
* slip in on us... handle it here...
*/
if (wpipe->pipe_state & PIPE_DIRECTW) {
pipeunlock(wpipe);
goto retrywrite;
}
/*
* 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.
*/
if (wpipe->pipe_buffer.in + segsize !=
wpipe->pipe_buffer.size)
panic("Expected pipe buffer wraparound disappeared");
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) {
if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size)
panic("Expected wraparound bad");
wpipe->pipe_buffer.in = size - segsize;
}
wpipe->pipe_buffer.cnt += size;
if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size)
panic("Pipe buffer overflow");
}
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 | PCATCH, "pipewr", 0);
if (error != 0)
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)
vfs_timestamp(&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(fp, cmd, data, p)
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:
if (mpipe->pipe_state & PIPE_DIRECTW)
*(int *)data = mpipe->pipe_map.cnt;
else
*(int *)data = mpipe->pipe_buffer.cnt;
return (0);
case FIOSETOWN:
return (fsetown(*(int *)data, &mpipe->pipe_sigio));
case FIOGETOWN:
*(int *)data = fgetown(mpipe->pipe_sigio);
return (0);
/* This is deprecated, FIOSETOWN should be used instead. */
case TIOCSPGRP:
return (fsetown(-(*(int *)data), &mpipe->pipe_sigio));
/* This is deprecated, FIOGETOWN should be used instead. */
case TIOCGPGRP:
*(int *)data = -fgetown(mpipe->pipe_sigio);
return (0);
}
return (ENOTTY);
}
int
pipe_poll(fp, events, cred, p)
struct file *fp;
int events;
struct ucred *cred;
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_state & PIPE_DIRECTW) ||
(rpipe->pipe_buffer.cnt > 0) ||
(rpipe->pipe_state & PIPE_EOF))
revents |= events & (POLLIN | POLLRDNORM);
if (events & (POLLOUT | POLLWRNORM))
if (wpipe == NULL || (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 == NULL) ||
(wpipe->pipe_state & PIPE_EOF))
revents |= POLLHUP;
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);
}
static int
pipe_stat(fp, ub, p)
struct file *fp;
struct stat *ub;
struct proc *p;
{
struct pipe *pipe = (struct pipe *)fp->f_data;
bzero((caddr_t)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_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, p)
struct file *fp;
struct proc *p;
{
struct pipe *cpipe = (struct pipe *)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;
{
mtx_assert(&vm_mtx, MA_OWNED);
if (cpipe->pipe_buffer.buffer != NULL) {
if (cpipe->pipe_buffer.size > PIPE_SIZE)
--nbigpipe;
amountpipekva -= cpipe->pipe_buffer.size;
kmem_free(kernel_map,
(vm_offset_t)cpipe->pipe_buffer.buffer,
cpipe->pipe_buffer.size);
cpipe->pipe_buffer.buffer = NULL;
}
#ifndef PIPE_NODIRECT
if (cpipe->pipe_map.kva != NULL) {
amountpipekva -= cpipe->pipe_buffer.size + PAGE_SIZE;
kmem_free(kernel_map,
cpipe->pipe_map.kva,
cpipe->pipe_buffer.size + PAGE_SIZE);
cpipe->pipe_map.cnt = 0;
cpipe->pipe_map.kva = 0;
cpipe->pipe_map.pos = 0;
cpipe->pipe_map.npages = 0;
}
#endif
}
/*
* shutdown the pipe
*/
static void
pipeclose(cpipe)
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.
*/
while (cpipe->pipe_busy) {
wakeup(cpipe);
cpipe->pipe_state |= PIPE_WANT | PIPE_EOF;
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
*/
mtx_lock(&vm_mtx);
pipe_free_kmem(cpipe);
/* XXX: erm, doesn't zalloc already have its own locks and
* not need the giant vm lock?
*/
zfree(pipe_zone, cpipe);
mtx_unlock(&vm_mtx);
}
}
/*ARGSUSED*/
static int
pipe_kqfilter(struct file *fp, struct knote *kn)
{
struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data;
switch (kn->kn_filter) {
case EVFILT_READ:
kn->kn_fop = &pipe_rfiltops;
break;
case EVFILT_WRITE:
kn->kn_fop = &pipe_wfiltops;
cpipe = cpipe->pipe_peer;
break;
default:
return (1);
}
kn->kn_hook = (caddr_t)cpipe;
SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext);
return (0);
}
static void
filt_pipedetach(struct knote *kn)
{
struct pipe *cpipe = (struct pipe *)kn->kn_hook;
SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext);
}
/*ARGSUSED*/
static 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 ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
kn->kn_data = rpipe->pipe_map.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*/
static 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;
if (wpipe->pipe_state & PIPE_DIRECTW)
kn->kn_data = 0;
return (kn->kn_data >= PIPE_BUF);
}
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