ref: 3084c76351b83338becd8a36d691ce076ea31c89
dir: /kern/devpipe.c/
#include "u.h"
#include "lib.h"
#include "dat.h"
#include "fns.h"
#include "error.h"
#include "netif.h"
typedef struct Pipe Pipe;
struct Pipe
{
QLock lk;
Pipe *next;
int ref;
ulong path;
Queue *q[2];
int qref[2];
};
struct
{
Lock lk;
ulong path;
} pipealloc;
enum
{
Qdir,
Qdata0,
Qdata1,
};
Dirtab pipedir[] =
{
".", {Qdir,0,QTDIR}, 0, DMDIR|0500,
"data", {Qdata0}, 0, 0600,
"data1", {Qdata1}, 0, 0600,
};
#define NPIPEDIR 3
static void
pipeinit(void)
{
if(conf.pipeqsize == 0){
if(conf.nmach > 1)
conf.pipeqsize = 256*1024;
else
conf.pipeqsize = 32*1024;
}
}
/*
* create a pipe, no streams are created until an open
*/
static Chan*
pipeattach(char *spec)
{
Pipe *p;
Chan *c;
c = devattach('|', spec);
p = malloc(sizeof(Pipe));
if(p == 0)
exhausted("memory");
p->ref = 1;
p->q[0] = qopen(conf.pipeqsize, 0, 0, 0);
if(p->q[0] == 0){
free(p);
exhausted("memory");
}
p->q[1] = qopen(conf.pipeqsize, 0, 0, 0);
if(p->q[1] == 0){
free(p->q[0]);
free(p);
exhausted("memory");
}
lock(&pipealloc.lk);
p->path = ++pipealloc.path;
unlock(&pipealloc.lk);
mkqid(&c->qid, NETQID(2*p->path, Qdir), 0, QTDIR);
c->aux = p;
c->dev = 0;
return c;
}
static int
pipegen(Chan *c, char *name, Dirtab *tab, int ntab, int i, Dir *dp)
{
Qid q;
int len;
Pipe *p;
USED(name);
if(i == DEVDOTDOT){
devdir(c, c->qid, "#|", 0, eve, DMDIR|0555, dp);
return 1;
}
i++; /* skip . */
if(tab==0 || i>=ntab)
return -1;
tab += i;
p = c->aux;
switch((ulong)tab->qid.path){
case Qdata0:
len = qlen(p->q[0]);
break;
case Qdata1:
len = qlen(p->q[1]);
break;
default:
len = tab->length;
break;
}
mkqid(&q, NETQID(NETID(c->qid.path), tab->qid.path), 0, QTFILE);
devdir(c, q, tab->name, len, eve, tab->perm, dp);
return 1;
}
static Walkqid*
pipewalk(Chan *c, Chan *nc, char **name, int nname)
{
Walkqid *wq;
Pipe *p;
wq = devwalk(c, nc, name, nname, pipedir, NPIPEDIR, pipegen);
if(wq != nil && wq->clone != nil && wq->clone != c){
p = c->aux;
qlock(&p->lk);
p->ref++;
if(c->flag & COPEN){
print("channel open in pipewalk\n");
switch(NETTYPE(c->qid.path)){
case Qdata0:
p->qref[0]++;
break;
case Qdata1:
p->qref[1]++;
break;
}
}
qunlock(&p->lk);
}
return wq;
}
static int
pipestat(Chan *c, uchar *db, int n)
{
Pipe *p;
Dir dir;
p = c->aux;
switch(NETTYPE(c->qid.path)){
case Qdir:
devdir(c, c->qid, ".", 0, eve, DMDIR|0555, &dir);
break;
case Qdata0:
devdir(c, c->qid, "data", qlen(p->q[0]), eve, 0600, &dir);
break;
case Qdata1:
devdir(c, c->qid, "data1", qlen(p->q[1]), eve, 0600, &dir);
break;
default:
panic("pipestat");
}
n = convD2M(&dir, db, n);
if(n < BIT16SZ)
error(Eshortstat);
return n;
}
/*
* if the stream doesn't exist, create it
*/
static Chan*
pipeopen(Chan *c, int omode)
{
Pipe *p;
if(c->qid.type & QTDIR){
if(omode != OREAD)
error(Ebadarg);
c->mode = omode;
c->flag |= COPEN;
c->offset = 0;
return c;
}
p = c->aux;
qlock(&p->lk);
switch(NETTYPE(c->qid.path)){
case Qdata0:
p->qref[0]++;
break;
case Qdata1:
p->qref[1]++;
break;
}
qunlock(&p->lk);
c->mode = openmode(omode);
c->flag |= COPEN;
c->offset = 0;
c->iounit = qiomaxatomic;
return c;
}
static void
pipeclose(Chan *c)
{
Pipe *p;
p = c->aux;
qlock(&p->lk);
if(c->flag & COPEN){
/*
* closing either side hangs up the stream
*/
switch(NETTYPE(c->qid.path)){
case Qdata0:
p->qref[0]--;
if(p->qref[0] == 0){
qhangup(p->q[1], 0);
qclose(p->q[0]);
}
break;
case Qdata1:
p->qref[1]--;
if(p->qref[1] == 0){
qhangup(p->q[0], 0);
qclose(p->q[1]);
}
break;
}
}
/*
* if both sides are closed, they are reusable
*/
if(p->qref[0] == 0 && p->qref[1] == 0){
qreopen(p->q[0]);
qreopen(p->q[1]);
}
/*
* free the structure on last close
*/
p->ref--;
if(p->ref == 0){
qunlock(&p->lk);
free(p->q[0]);
free(p->q[1]);
free(p);
} else
qunlock(&p->lk);
}
static long
piperead(Chan *c, void *va, long n, vlong offset)
{
Pipe *p;
USED(offset);
p = c->aux;
switch(NETTYPE(c->qid.path)){
case Qdir:
return devdirread(c, va, n, pipedir, NPIPEDIR, pipegen);
case Qdata0:
return qread(p->q[0], va, n);
case Qdata1:
return qread(p->q[1], va, n);
default:
panic("piperead");
}
return -1; /* not reached */
}
static Block*
pipebread(Chan *c, long n, ulong offset)
{
Pipe *p;
p = c->aux;
switch(NETTYPE(c->qid.path)){
case Qdata0:
return qbread(p->q[0], n);
case Qdata1:
return qbread(p->q[1], n);
}
return devbread(c, n, offset);
}
/*
* a write to a closed pipe causes a note to be sent to
* the process.
*/
static long
pipewrite(Chan *c, void *va, long n, vlong offset)
{
Pipe *p;
USED(offset);
if(waserror()) {
/* avoid notes when pipe is a mounted queue */
if((c->flag & CMSG) == 0)
postnote(up, 1, "sys: write on closed pipe", NUser);
nexterror();
}
p = c->aux;
switch(NETTYPE(c->qid.path)){
case Qdata0:
n = qwrite(p->q[1], va, n);
break;
case Qdata1:
n = qwrite(p->q[0], va, n);
break;
default:
panic("pipewrite");
}
poperror();
return n;
}
static long
pipebwrite(Chan *c, Block *bp, ulong offset)
{
long n;
Pipe *p;
USED(offset);
if(waserror()) {
/* avoid notes when pipe is a mounted queue */
if((c->flag & CMSG) == 0)
postnote(up, 1, "sys: write on closed pipe", NUser);
nexterror();
}
p = c->aux;
switch(NETTYPE(c->qid.path)){
case Qdata0:
n = qbwrite(p->q[1], bp);
break;
case Qdata1:
n = qbwrite(p->q[0], bp);
break;
default:
n = 0;
panic("pipebwrite");
}
poperror();
return n;
}
Dev pipedevtab = {
'|',
"pipe",
devreset,
pipeinit,
devshutdown,
pipeattach,
pipewalk,
pipestat,
pipeopen,
devcreate,
pipeclose,
piperead,
pipebread,
pipewrite,
pipebwrite,
devremove,
devwstat,
};