void
respond(Req *r, char *error)
{
int i, m, n;
char errbuf[ERRMAX];
Srv *srv;
srv = r->srv;
assert(srv != nil);
if(r->responded){
assert(r->pool);
goto free;
}
assert(r->responded == 0);
r->error = error;
switch(r->ifcall.type){
default:
assert(0);
/*
* Flush is special. If the handler says so, we return
* without further processing. Respond will be called
* again once it is safe.
*/
case Tflush:
if(rflush(r, error)<0)
return;
break;
case Tversion: rversion(r, error); break;
case Tauth: rauth(r, error); break;
case Tattach: rattach(r, error); break;
case Twalk: rwalk(r, error); break;
case Topen: ropen(r, error); break;
case Tcreate: rcreate(r, error); break;
case Tread: rread(r, error); break;
case Twrite: rwrite(r, error); break;
case Tclunk: rclunk(r, error); break;
case Tremove: rremove(r, error, errbuf); break;
case Tstat: rstat(r, error); break;
case Twstat: rwstat(r, error); break;
}
r->ofcall.tag = r->ifcall.tag;
r->ofcall.type = r->ifcall.type+1;
if(r->error)
setfcallerror(&r->ofcall, r->error);
if(chatty9p)
fprint(2, "-%d-> %F\n", srv->outfd, &r->ofcall);
qlock(&srv->wlock);
n = convS2M(&r->ofcall, srv->wbuf, srv->msize);
if(n <= 0){
fprint(2, "n = %d %F\n", n, &r->ofcall);
abort();
}
assert(n > 2);
/*
* There is a race here - we must remove the entry before
* the write, so that if the client is very fast and reuses the
* tag, the read loop won't think it is still in use.
*
* By removing the entry before the write, we open up a
* race with incoming Tflush messages. Specifically, an
* incoming Tflush might not see r even though it has not
* yet been responded to. It would then send an Rflush
* immediately, potentially before we do the write. This can't
* happen because we already old srv->wlock, so nothing
* is going out on the wire before this write.
*/
if(r->pool) /* not a fake */
closereq(removereq(r->pool, r->ifcall.tag));
qlock(&r->lk);
r->responded = 1;
if(r->pool)
if(r->ref.ref == 1+r->nflush)
if(r->fid){
/*
* There are no references other than in our r->flush array,
* so no one else should be accessing r concurrently.
* Close the fid now, before responding to the message.
*
* If the client is behaving (there are no outstanding T-messages
* that reference r->fid) and the message is a Tclunk or Tremove,
* then this closefid will call destroyfid.
*
* This means destroyfid can't piddle around
* indefinitely (we're holding srv->wlock!), but it provides
* for tighter semantics as to when destroyfid is called.
*
* LANL has observed cases where waiting until after the write
* can delay a closefid on a Twrite for many 9P transactions,
* so that a handful of transactions can happen including a Tclunk
* and a Topen, and the original fid will still not be destroyed.
*/
closefid(r->fid);
r->fid = nil;
}
qunlock(&r->lk);
m = write(srv->outfd, srv->wbuf, n);
if(m != n)
sysfatal("lib9p srv: write %d returned %d on fd %d: %r", n, m, srv->outfd);
qunlock(&srv->wlock);
free:
qlock(&r->lk); /* no one will add flushes now */
for(i=0; i<r->nflush; i++){
r->flush[i]->oldreq = nil; /* so it doesn't try to lock us! */
respond(r->flush[i], nil);
}
free(r->flush);
r->flush = nil;
r->nflush = 0;
qunlock(&r->lk);
if(r->pool)
closereq(r);
else
free(r);
}
void
respond(Req *r, char *error)
{
int i, m, n;
char errbuf[ERRMAX];
Srv *srv;
srv = r->srv;
assert(srv != nil);
assert(r->responded == 0);
r->error = error;
switch(r->ifcall.type){
default:
assert(0);
/*
* Flush is special. If the handler says so, we return
* without further processing. Respond will be called
* again once it is safe.
*/
case Tflush:
if(rflush(r, error)<0)
return;
break;
case Tversion: rversion(r, error); break;
case Tauth: rauth(r, error); break;
case Tattach: rattach(r, error); break;
case Twalk: rwalk(r, error); break;
case Topen: ropen(r, error); break;
case Tcreate: rcreate(r, error); break;
case Tread: rread(r, error); break;
case Twrite: rwrite(r, error); break;
case Tclunk: rclunk(r, error); break;
case Tremove: rremove(r, error, errbuf); break;
case Tstat: rstat(r, error); break;
case Twstat: rwstat(r, error); break;
}
r->ofcall.tag = r->ifcall.tag;
r->ofcall.type = r->ifcall.type+1;
if(r->error)
setfcallerror(&r->ofcall, r->error);
if(chatty9p)
fprint(2, "-%d-> %F\n", srv->outfd, &r->ofcall);
qlock(&srv->wlock);
n = convS2M(&r->ofcall, srv->wbuf, srv->msize);
if(n <= 0){
fprint(2, "n = %d %F\n", n, &r->ofcall);
abort();
}
assert(n > 2);
if(r->pool) /* not a fake */
closereq(removereq(r->pool, r->ifcall.tag));
m = write(srv->outfd, srv->wbuf, n);
if(m != n)
sysfatal("lib9p srv: write %d returned %d on fd %d: %r", n, m, srv->outfd);
qunlock(&srv->wlock);
qlock(&r->lk); /* no one will add flushes now */
r->responded = 1;
qunlock(&r->lk);
for(i=0; i<r->nflush; i++)
respond(r->flush[i], nil);
free(r->flush);
r->flush = nil;
r->nflush = 0;
if(r->pool)
closereq(r);
else
free(r);
}