ref: 25139465363b2230b69789013e3e0b5f82d76564
dir: /sys/src/9/port/devstream.c/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
typedef struct Stream Stream;
typedef struct Iocom Iocom;
struct Stream
{
Ref;
Lock;
int iounit;
int noseek;
Ref nrp;
Ref nwp;
Ref nwq;
Proc *rp[4];
Proc *wp[2];
Block *rlist;
vlong soff;
vlong roff;
vlong woff;
QLock rcl;
QLock wcl;
QLock rql;
QLock wql;
Rendez wz;
Queue *rq;
Queue *wq;
Chan *f;
};
struct Iocom
{
Proc *p;
QLock *q;
Stream *s;
Block *b;
};
static void
putstream(Stream *s)
{
if(decref(s))
return;
freeblist(s->rlist);
qfree(s->rq);
qfree(s->wq);
if(s->f != nil)
cclose(s->f);
free(s);
}
#define BOFF(b) (*(vlong*)((b)->rp - sizeof(vlong)))
#define BDONE (1<<15)
#define BERROR (1<<14)
static Block*
sblock(Stream *s)
{
Block *b;
b = allocb(sizeof(vlong)+s->iounit);
b->flag &= ~(BDONE|BERROR);
b->wp += sizeof(vlong);
b->rp = b->wp;
return b;
}
static void
iocom(void *arg, int complete)
{
Iocom *io = arg;
Stream *s;
QLock *q;
Proc *p;
p = io->p;
if(complete && p == up){
up->iocomfun = nil;
up->iocomarg = nil;
}
q = io->q;
if(q != nil && p == up){
io->q = nil;
qunlock(q);
}
s = io->s;
if(complete && s != nil && s->noseek){
io->s = nil;
lock(s);
BOFF(io->b) = s->soff;
s->soff += s->iounit;
unlock(s);
}
}
static void
ioq(Iocom *io, QLock *q)
{
eqlock(q); /* unlocked in iocom() above */
io->p = up;
io->q = q;
io->s = nil;
io->b = nil;
up->iocomarg = io;
up->iocomfun = iocom;
}
static void
streamreader(void *arg)
{
Stream *s = arg;
Iocom io;
Chan *f;
Block *b, *l, **ll;
vlong o;
int id, n;
id = incref(&s->nrp) % nelem(s->rp);
s->rp[id] = up;
f = s->f;
b = sblock(s);
qlock(&s->rql);
if(waserror()){
qhangup(s->rq, up->errstr);
goto Done;
}
if(s->noseek == -1){
BOFF(b) = 0;
n = devtab[f->type]->read(f, b->wp, s->iounit, 0x7fffffffffffffLL);
if(n > 0){
b->wp += n;
b->flag |= BDONE;
b->next = nil;
s->rlist = b;
s->soff = s->iounit;
s->roff = 0;
s->noseek = 1;
b = sblock(s);
} else {
s->noseek = 0;
}
}
while(!qisclosed(s->rq)) {
ll = &s->rlist;
while((l = *ll) != nil){
if((l->flag & BDONE) == 0 || BOFF(l) != s->roff){
if(s->noseek){
ll = &l->next;
continue;
}
break;
}
if((l->flag & BERROR) != 0)
error((char*)l->rp);
if(BLEN(l) == 0){
qhangup(s->rq, nil);
poperror();
goto Done;
}
s->roff += s->noseek ? s->iounit : BLEN(l);
*ll = l->next;
l->next = nil;
qbwrite(s->rq, l);
}
n = s->iounit;
o = s->roff;
l = s->rlist;
if(s->noseek) {
o = 0;
b->next = l;
s->rlist = b;
} else if(l == nil) {
b->next = nil;
s->rlist = b;
} else {
if(o < BOFF(l)){
n = BOFF(l) - o;
b->next = l;
s->rlist = b;
} else {
for(;; l = l->next){
if((l->flag & BDONE) != 0 && BLEN(l) == 0)
goto Done;
o = BOFF(l) + ((l->flag & BDONE) == 0 ? s->iounit : BLEN(l));
if(l->next == nil)
break;
if(o < BOFF(l->next)){
n = BOFF(l->next) - o;
break;
}
}
b->next = l->next;
l->next = b;
}
}
BOFF(b) = o;
qunlock(&s->rql);
if(waserror()){
poperror();
goto Exit;
}
ioq(&io, &s->rcl);
io.b = b;
io.s = s;
if(waserror()){
strncpy((char*)b->wp, up->errstr, s->iounit-1);
b->wp[s->iounit-1] = 0;
n = -1;
} else {
n = devtab[f->type]->read(f, b->wp, n, o);
if(n < 0)
error(Eio);
poperror();
}
iocom(&io, 1);
poperror();
l = b;
b = sblock(s);
qlock(&s->rql);
if(n >= 0)
l->wp += n;
else
l->flag |= BERROR;
l->flag |= BDONE;
}
poperror();
Done:
qunlock(&s->rql);
freeb(b);
Exit:
s->rp[id] = nil;
putstream(s);
pexit("closed", 1);
}
static void
streamwriter(void *arg)
{
Stream *s = arg;
Iocom io;
Block *b;
Chan *f;
vlong o;
int id, n;
id = incref(&s->nwp) % nelem(s->wp);
s->wp[id] = up;
f = s->f;
while(!qisclosed(s->wq)) {
if(incref(&s->nwq) == s->nwp.ref && qlen(s->wq) == 0)
wakeup(&s->wz); /* queue drained */
if(waserror()){
decref(&s->nwq);
break;
}
ioq(&io, &s->wcl);
b = qbread(s->wq, s->iounit);
decref(&s->nwq);
if(b == nil){
iocom(&io, 1);
break;
}
poperror();
if(waserror()){
qhangup(s->wq, up->errstr);
iocom(&io, 1);
freeb(b);
break;
}
n = BLEN(b);
o = s->woff;
s->woff += n;
if(devtab[f->type]->write(f, b->rp, n, o) != n)
error(Eio);
iocom(&io, 1);
freeb(b);
poperror();
}
s->wp[id] = nil;
wakeup(&s->wz);
putstream(s);
pexit("closed", 1);
}
static int
streamgen(Chan *c, char *, Dirtab*, int, int s, Dir *dp)
{
static int perm[] = { 0400, 0200, 0600, 0 };
Fgrp *fgrp = up->fgrp;
Chan *f;
Qid q;
if(s == DEVDOTDOT){
devdir(c, c->qid, ".", 0, eve, DMDIR|0555, dp);
return 1;
}
if(s == 0)
return 0;
s--;
if(s > fgrp->maxfd)
return -1;
if((f=fgrp->fd[s]) == nil)
return 0;
sprint(up->genbuf, "%dstream", s);
mkqid(&q, s+1, 0, QTFILE);
devdir(c, q, up->genbuf, 0, eve, perm[f->mode&3], dp);
return 1;
}
static Chan*
streamattach(char *spec)
{
return devattach(L'¶', spec);
}
static Walkqid*
streamwalk(Chan *c, Chan *nc, char **name, int nname)
{
return devwalk(c, nc, name, nname, (Dirtab *)0, 0, streamgen);
}
static int
streamstat(Chan *c, uchar *db, int n)
{
return devstat(c, db, n, (Dirtab *)0, 0L, streamgen);
}
static Chan*
streamopen(Chan *c, int omode)
{
Stream *s;
c->aux = nil;
if(c->qid.type & QTDIR){
if(omode != 0)
error(Eisdir);
c->mode = 0;
c->flag |= COPEN;
c->offset = 0;
return c;
}
s = mallocz(sizeof(*s), 1);
if(s == nil)
error(Enomem);
incref(s);
if(waserror()){
putstream(s);
nexterror();
}
omode = openmode(omode);
s->f = fdtochan(c->qid.path - 1, omode, 0, 1);
if(s->f == nil || s->f->qid.type != QTFILE)
error(Eperm);
s->noseek = -1;
s->roff = s->f->offset;
s->woff = s->f->offset;
s->iounit = s->f->iounit;
if(s->iounit <= 0 || s->iounit > qiomaxatomic)
s->iounit = qiomaxatomic;
c->iounit = s->iounit;
c->aux = s;
c->mode = omode;
c->flag |= COPEN;
c->offset = 0;
poperror();
return c;
}
static int
isdrained(void *a)
{
Stream *s;
int i;
s = a;
if(s->wq == nil)
return 1;
if(qisclosed(s->wq) == 0)
return qlen(s->wq) == 0 && s->nwq.ref == s->nwp.ref;
for(i=0; i<nelem(s->wp); i++)
if(s->wp[i] != nil)
return 0;
return 1;
}
static void
streamdrain(Chan *c)
{
Stream *s;
if((s = c->aux) == nil)
return;
eqlock(&s->wql);
if(waserror()){
qunlock(&s->wql);
nexterror();
}
while(!isdrained(s))
sleep(&s->wz, isdrained, s);
qunlock(&s->wql);
poperror();
}
static void
streamclose(Chan *c)
{
Stream *s;
int i;
if((c->flag & COPEN) == 0 || (s = c->aux) == nil)
return;
if(s->rq != nil){
qclose(s->rq);
for(i=0; i<nelem(s->rp); i++)
postnote(s->rp[i], 1, "streamclose", 0);
}
if(s->wq != nil){
qhangup(s->wq, nil);
if(!waserror()){
streamdrain(c);
poperror();
}
qclose(s->wq); /* discard the data */
for(i=0; i<nelem(s->wp); i++)
postnote(s->wp[i], 1, "streamclose", 0);
}
c->aux = nil;
putstream(s);
}
static int
canpipeline(Chan *f, int mode)
{
USED(mode);
return devtab[f->type]->dc == 'M';
}
static Queue*
streamqueue(Chan *c, int mode)
{
Stream *s;
int i, n;
s = c->aux;
if(s == nil || c->qid.type != QTFILE)
error(Eperm);
switch(mode){
case OREAD:
while(s->rq == nil){
qlock(&s->rql);
if(s->rq != nil){
qunlock(&s->rql);
break;
}
s->rq = qopen(conf.pipeqsize, 0, 0, 0);
if(s->rq == nil){
qunlock(&s->rql);
error(Enomem);
}
n = canpipeline(s->f, mode) ? nelem(s->rp) : 1;
for(i=0; i<n; i++){
incref(s);
kproc("streamreader", streamreader, s);
}
while(s->nrp.ref != n)
sched();
qunlock(&s->rql);
break;
}
return s->rq;
case OWRITE:
while(s->wq == nil){
qlock(&s->wql);
if(s->wq != nil){
qunlock(&s->wql);
break;
}
s->wq = qopen(conf.pipeqsize, 0, 0, 0);
if(s->wq == nil){
qunlock(&s->wql);
error(Enomem);
}
n = canpipeline(s->f, mode) ? nelem(s->wp) : 1;
for(i=0; i<n; i++){
incref(s);
kproc("streamwriter", streamwriter, s);
}
while(s->nwp.ref != n)
sched();
qunlock(&s->wql);
break;
}
return s->wq;
}
error(Egreg);
return nil;
}
static long
streamread(Chan *c, void *va, long n, vlong)
{
if(c->qid.type == QTDIR)
return devdirread(c, va, n, (Dirtab *)0, 0L, streamgen);
return qread(streamqueue(c, OREAD), va, n);
}
static Block*
streambread(Chan *c, long n, ulong)
{
return qbread(streamqueue(c, OREAD), n);
}
static long
streamwrite(Chan *c, void *va, long n, vlong)
{
if(n == 0)
streamdrain(c);
return qwrite(streamqueue(c, OWRITE), va, n);
}
static long
streambwrite(Chan *c, Block *b, ulong)
{
if(BLEN(b) == 0)
streamdrain(c);
return qbwrite(streamqueue(c, OWRITE), b);
}
Dev streamdevtab = {
L'¶',
"stream",
devreset,
devinit,
devshutdown,
streamattach,
streamwalk,
streamstat,
streamopen,
devcreate,
streamclose,
streamread,
streambread,
streamwrite,
streambwrite,
devremove,
devwstat,
};