fix edit pipe bug

src/cmd/acme/dat.h

@@ -269,6 +269,7 @@ struct Window
 	int		tagexpand;
 	int		taglines;
 	Rectangle	tagtop;
+	QLock	editoutlk;
 };
 
 void	wininit(Window*, Window*, Rectangle);
@@ -562,4 +563,6 @@ Channel	*cerr;		/* chan(char*) */
 Channel	*cedit;		/* chan(int) */
 Channel	*cwarn;		/* chan(void*)[1] (really chan(unit)[1]) */
 
+QLock	editoutlk;
+
 #define	STACK	32768

src/cmd/acme/ecmd.c

@@ -592,6 +592,7 @@ runpipe(Text *t, int cmd, Rune *cr, int ncr, int state)
 	int n;
 	Runestr dir;
 	Window *w;
+	QLock *q;
 
 	r = skipbl(cr, ncr, &n);
 	if(n == 0)
@@ -626,6 +627,23 @@ runpipe(Text *t, int cmd, Rune *cr, int ncr, int state)
 		winunlock(t->w);
 	qunlock(&row.lk);
 	recvul(cedit);
+	/*
+	 * The editoutlk exists only so that we can tell when
+	 * the editout file has been closed.  It can get closed *after*
+	 * the process exits because, since the process cannot be 
+	 * connected directly to editout (no 9P kernel support), 
+	 * the process is actually connected to a pipe to another
+	 * process (arranged via 9pserve) that reads from the pipe
+	 * and then writes the data in the pipe to editout using
+	 * 9P transactions.  This process might still have a couple
+	 * writes left to copy after the original process has exited.
+	 */
+	if(w)
+		q = &w->editoutlk;
+	else
+		q = &editoutlk;
+	qlock(q);	/* wait for file to close */
+	qunlock(q);
 	qlock(&row.lk);
 	editing = Inactive;
 	if(t!=nil && t->w!=nil)

src/cmd/acme/xfid.c

@@ -98,9 +98,9 @@ xfidopen(Xfid *x)
 
 	w = x->f->w;
 	t = &w->body;
+	q = FILE(x->f->qid);
 	if(w){
 		winlock(w, 'E');
-		q = FILE(x->f->qid);
 		switch(q){
 		case QWaddr:
 			if(w->nopen[q]++ == 0){
@@ -174,11 +174,26 @@ xfidopen(Xfid *x)
 				respond(x, &fc, Eperm);
 				return;
 			}
+			if(!canqlock(&w->editoutlk)){
+				winunlock(w);
+				respond(x, &fc, Einuse);
+				return;
+			}
 			w->wrselrange = range(t->q1, t->q1);
 			break;
 		}
 		winunlock(w);
 	}
+	else{
+		switch(q){
+		case Qeditout:
+			if(!canqlock(&editoutlk)){
+				respond(x, &fc, Einuse);
+				return;
+			}
+			break;
+		}
+	}
 	fc.qid = x->f->qid;
 	fc.iounit = messagesize-IOHDRSZ;
 	x->f->open = TRUE;
@@ -203,10 +218,10 @@ xfidclose(Xfid *x)
 		return;
 	}
 
+	q = FILE(x->f->qid);
 	x->f->open = FALSE;
 	if(w){
 		winlock(w, 'E');
-		q = FILE(x->f->qid);
 		switch(q){
 		case QWctl:
 			if(w->ctlfid!=~0 && w->ctlfid==x->f->fid){
@@ -247,10 +262,20 @@ xfidclose(Xfid *x)
 				min(w->wrselrange.q1, t->file->b.nc), 1);
 			textscrdraw(t);
 			break;
+		case QWeditout:
+			qunlock(&w->editoutlk);
+			break;
 		}
 		winunlock(w);
 		winclose(w);
 	}
+	else{
+		switch(q){
+		case Qeditout:
+			qunlock(&editoutlk);
+			break;
+		}
+	}
 	respond(x, &fc, nil);
 }