From e47e366450cb6a99f5c845ac6a77d14156ee0e3b Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Mon, 19 Mar 1990 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1990-03-19

---
 gnot/devdk.c    | 46 +++++++++++++++++++++++++++++++++-------------
 port/devdk.c    | 46 +++++++++++++++++++++++++++++++++-------------
 port/devlance.c |  2 +-
 3 files changed, 67 insertions(+), 27 deletions(-)

diff --git a/gnot/devdk.c b/gnot/devdk.c
index 047b73b095d2412b770f2a1fe2716e5646f47f3d..f0db2a6c82e96b978e80f0bcc1505fd11e590be8 100644
--- a/gnot/devdk.c
+++ b/gnot/devdk.c
@@ -644,7 +644,14 @@ dkopen(Chan *c, int omode)
 	Dk *dp;
 	int line;
 
-	if(c->qid == Dcloneqid){
+	if(c->qid & CHDIR){
+		/*
+		 *  directories are read only
+		 */
+		if(omode != OREAD)
+			error(0, Ebadarg);
+	} else switch(STREAMTYPE(c->qid)){
+	case Dcloneqid:
 		/*
 		 *  get an unused device and open it's control file
 		 */
@@ -665,7 +672,8 @@ dkopen(Chan *c, int omode)
 			error(0, Enodev);
 		streamopen(c, &dkinfo);
 		pushq(c->stream, &urpinfo);
-	} else if(STREAMTYPE(c->qid) == Dlistenqid){
+		break;
+	case Dlistenqid:
 		/*
 		 *  listen for a call and open the control file for the
 		 *  channel on which the call arrived.
@@ -675,13 +683,25 @@ dkopen(Chan *c, int omode)
 		streamopen(c, &dkinfo);
 		pushq(c->stream, &urpinfo);
 		dkwindow(c);
-	} else if(c->qid != CHDIR){
+		break;
+	case Daddrqid:
+	case Draddrqid:
+	case Duserqid:
+	case Dotherqid:
+		/*
+		 *  read only files
+		 */
+		if(omode != OREAD)
+			error(0, Ebadarg);
+		break;
+	default:
 		/*
 		 *  open whatever c points to, make sure it has an urp
 		 */
 		streamopen(c, &dkinfo);
 		if(strcmp(c->stream->procq->next->info->name, "urp")!=0)
 			pushq(c->stream, &urpinfo);
+		break;
 	}
 
 	c->mode = openmode(omode);
@@ -702,7 +722,7 @@ dkclose(Chan *c)
 	Dk *dp;
 
 	/* real closing happens in lancestclose */
-	if(c->qid != CHDIR)
+	if(c->stream)
 		streamclose(c);
 
 	dp = &dk[c->dev];
@@ -714,17 +734,20 @@ dkclose(Chan *c)
 long	 
 dkread(Chan *c, void *a, long n)
 {
-	int t;
 	Line *lp;
 
-	t = STREAMTYPE(c->qid);
-	if(t>=Slowqid || t==Dlineqid)
+	if(c->stream)
 		return streamread(c, a, n);
-	if(c->qid == CHDIR)
-		return devdirread(c, a, n, dkdir, dk[c->dev].lines, devgen);
+
+	if(c->qid & CHDIR){
+		if(c->qid == CHDIR)
+			return devdirread(c, a, n, dkdir, dk[c->dev].lines, devgen);
+		else
+			return devdirread(c, a, n, dksubdir, Nsubdir, streamgen);
+	}
 
 	lp = &dk[c->dev].line[STREAMID(c->qid)];
-	switch(t){
+	switch(STREAMTYPE(c->qid)){
 	case Daddrqid:
 		return stringread(c, a, n, lp->addr);
 	case Draddrqid:
@@ -782,9 +805,6 @@ dkwrite(Chan *c, void *a, long n)
 		return n;
 	}
 
-	if(t >= Slowqid)
-		return streamwrite(c, a, n, 0);
-
 	error(0, Eperm);
 }
 
diff --git a/port/devdk.c b/port/devdk.c
index 047b73b095d2412b770f2a1fe2716e5646f47f3d..f0db2a6c82e96b978e80f0bcc1505fd11e590be8 100644
--- a/port/devdk.c
+++ b/port/devdk.c
@@ -644,7 +644,14 @@ dkopen(Chan *c, int omode)
 	Dk *dp;
 	int line;
 
-	if(c->qid == Dcloneqid){
+	if(c->qid & CHDIR){
+		/*
+		 *  directories are read only
+		 */
+		if(omode != OREAD)
+			error(0, Ebadarg);
+	} else switch(STREAMTYPE(c->qid)){
+	case Dcloneqid:
 		/*
 		 *  get an unused device and open it's control file
 		 */
@@ -665,7 +672,8 @@ dkopen(Chan *c, int omode)
 			error(0, Enodev);
 		streamopen(c, &dkinfo);
 		pushq(c->stream, &urpinfo);
-	} else if(STREAMTYPE(c->qid) == Dlistenqid){
+		break;
+	case Dlistenqid:
 		/*
 		 *  listen for a call and open the control file for the
 		 *  channel on which the call arrived.
@@ -675,13 +683,25 @@ dkopen(Chan *c, int omode)
 		streamopen(c, &dkinfo);
 		pushq(c->stream, &urpinfo);
 		dkwindow(c);
-	} else if(c->qid != CHDIR){
+		break;
+	case Daddrqid:
+	case Draddrqid:
+	case Duserqid:
+	case Dotherqid:
+		/*
+		 *  read only files
+		 */
+		if(omode != OREAD)
+			error(0, Ebadarg);
+		break;
+	default:
 		/*
 		 *  open whatever c points to, make sure it has an urp
 		 */
 		streamopen(c, &dkinfo);
 		if(strcmp(c->stream->procq->next->info->name, "urp")!=0)
 			pushq(c->stream, &urpinfo);
+		break;
 	}
 
 	c->mode = openmode(omode);
@@ -702,7 +722,7 @@ dkclose(Chan *c)
 	Dk *dp;
 
 	/* real closing happens in lancestclose */
-	if(c->qid != CHDIR)
+	if(c->stream)
 		streamclose(c);
 
 	dp = &dk[c->dev];
@@ -714,17 +734,20 @@ dkclose(Chan *c)
 long	 
 dkread(Chan *c, void *a, long n)
 {
-	int t;
 	Line *lp;
 
-	t = STREAMTYPE(c->qid);
-	if(t>=Slowqid || t==Dlineqid)
+	if(c->stream)
 		return streamread(c, a, n);
-	if(c->qid == CHDIR)
-		return devdirread(c, a, n, dkdir, dk[c->dev].lines, devgen);
+
+	if(c->qid & CHDIR){
+		if(c->qid == CHDIR)
+			return devdirread(c, a, n, dkdir, dk[c->dev].lines, devgen);
+		else
+			return devdirread(c, a, n, dksubdir, Nsubdir, streamgen);
+	}
 
 	lp = &dk[c->dev].line[STREAMID(c->qid)];
-	switch(t){
+	switch(STREAMTYPE(c->qid)){
 	case Daddrqid:
 		return stringread(c, a, n, lp->addr);
 	case Draddrqid:
@@ -782,9 +805,6 @@ dkwrite(Chan *c, void *a, long n)
 		return n;
 	}
 
-	if(t >= Slowqid)
-		return streamwrite(c, a, n, 0);
-
 	error(0, Eperm);
 }
 
diff --git a/port/devlance.c b/port/devlance.c
index b50c957250c78a8b407556e43d9bf23e6338a2b0..e92a08218d64f8382edb7c06fb2d979715e74ffc 100644
--- a/port/devlance.c
+++ b/port/devlance.c
@@ -605,7 +605,7 @@ lancewalk(Chan *c, char *name)
 void	 
 lancestat(Chan *c, char *dp)
 {
-	if(c->qid == CHDIR)
+	if(c->qid==CHDIR || c->qid==Ltraceqid)
 		devstat(c, dp, lancedir, Ndir, devgen);
 	else
 		devstat(c, dp, 0, 0, streamgen);