From 9af584b5250e67128ba0300846948516e4022fbd Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sun, 22 Dec 2002 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 2002-12-22

---
 port/dev.c     | 31 +++++++++++++++++++++++++++++++
 port/sysproc.c |  3 +++
 2 files changed, 34 insertions(+)

diff --git a/port/dev.c b/port/dev.c
index 3fda0aad34ea256bcbe7e6823a652c7ba56b0560..0fb920300b71c19d99b62a4596d62d2b3d4c4a44 100644
--- a/port/dev.c
+++ b/port/dev.c
@@ -49,9 +49,40 @@ devdir(Chan *c, Qid qid, char *n, vlong length, char *user, long perm, Dir *db)
 	db->muid = user;
 }
 
+/*
+ * (here, Devgen is the prototype; devgen is the function in dev.c.)
+ * 
+ * a Devgen is expected to return the directory entry for ".."
+ * if you pass it s==DEVDOTDOT (-1).  otherwise...
+ * 
+ * there are two contradictory rules.
+ * 
+ * (i) if c is a directory, a Devgen is expected to list its children
+ * as you iterate s.
+ * 
+ * (ii) whether or not c is a directory, a Devgen is expected to list
+ * its siblings as you iterate s.
+ * 
+ * devgen always returns the list of children in the root
+ * directory.  thus it follows (i) when c is the root and (ii) otherwise.
+ * many other Devgens follow (i) when c is a directory and (ii) otherwise.
+ * 
+ * devwalk assumes (i).  it knows that devgen breaks (i)
+ * for children that are themselves directories, and explicitly catches them.
+ * 
+ * devstat assumes (ii).  if the Devgen in question follows (i)
+ * for this particular c, devstat will not find the necessary info.
+ * with our particular Devgen functions, this happens only for
+ * directories, so devstat makes something up, assuming
+ * c->name, c->qid, eve, DMDIR|0555.
+ * 
+ * devdirread assumes (i).  the callers have to make sure
+ * that the Devgen satisfies (i) for the chan being read.
+ */
 /*
  * the zeroth element of the table MUST be the directory itself for ..
 */
+int devdebug;
 int
 devgen(Chan *c, char*, Dirtab *tab, int ntab, int i, Dir *dp)
 {
diff --git a/port/sysproc.c b/port/sysproc.c
index c23d205790aa7e547b9cd81db81a0b5887efc50c..1a4fd455cc997037ec3239ea5bb1329cefe20d78 100644
--- a/port/sysproc.c
+++ b/port/sysproc.c
@@ -16,6 +16,9 @@ sysr1(ulong *arg)
 {
 	long a;
 
+extern int devdebug;
+devdebug = !devdebug;
+
 	a = *arg;
 	if(a > 0)
 		return incref(&sysr1ref);