2 files changed, 34 insertions(+), 0 deletions(-)

M port/dev.c
M port/sysproc.c

@@ 50,8 50,39 @@ devdir(Chan *c, Qid qid, char *n, vlong length, char *user, long perm, Dir *db)
 }
 
 /*
+ * (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)
 {

@@ 16,6 16,9 @@ sysr1(ulong *arg)
 {
 	long a;
 
+extern int devdebug;
+devdebug = !devdebug;
+
 	a = *arg;
 	if(a > 0)
 		return incref(&sysr1ref);