From a7d193a236bb16c992a97065730576156cd9b417 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Tue, 16 Jan 1996 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1996-01-16

---
 port/devtinyfs.c | 171 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 171 insertions(+)
 create mode 100644 port/devtinyfs.c

diff --git a/port/devtinyfs.c b/port/devtinyfs.c
new file mode 100644
index 0000000000000000000000000000000000000000..2063ca215c6d3aa7162a5a06d904cf5ce7620c09
--- /dev/null
+++ b/port/devtinyfs.c
@@ -0,0 +1,171 @@
+/*
+ *  template for making a new device
+ */
+
+#include	"u.h"
+#include	"../port/lib.h"
+#include	"mem.h"
+#include	"dat.h"
+#include	"fns.h"
+#include	"../port/error.h"
+
+#include	"devtab.h"
+
+enum{
+	Qdir,
+	Qmedium,
+
+	Nfile=	32,
+};
+
+
+struct {
+	QLock;
+	Chan	*c;
+	Dirtab	file[Nfile];
+	int	nfile;
+} tinyfs;
+
+void
+tinyfsreset(void)
+{
+	Dirtab *d;
+
+	d = tinyfs.file;
+	memmove(d->name, "medium");
+	d->qid.vers = 0;
+	d->qid.path = Qdata;
+	d->perm = 0666;
+}
+
+void
+tinyfsinit(void)
+{
+}
+
+Chan *
+tinyfsattach(char *spec)
+{
+	return devattach('E', spec);
+}
+
+Chan *
+tinyfsclone(Chan *c, Chan *nc)
+{
+	return devclone(c, nc);
+}
+
+int
+tinyfswalk(Chan *c, char *name)
+{
+	return devwalk(c, name, tinyfs.file, tinyfs.nfile, devgen);
+}
+
+void
+tinyfsstat(Chan *c, char *db)
+{
+	devstat(c, db, tinyfs.file, tinyfs.nfile, devgen);
+}
+
+Chan *
+tinyfsopen(Chan *c, int omode)
+{
+	return devopen(c, omode, tinyfs.file, tinyfs.nfile, devgen);
+}
+
+void
+tinyfscreate(Chan *c, char *name, int omode, ulong perm)
+{
+	Dirtab	*d;
+
+	if(perm & CHDIR)
+		error("directory creation illegal");
+
+	if(waserror()){
+		qunlock(&tinyfs);
+		nexterror();
+	}
+	qlock(&tinyfs);
+
+	if(tinyfs.nfile == Nfile)
+		error("out of space");
+	for(d = tinyfs.file; d < tinyfs.file[tinyfs.nfile]; d++)
+		if(strcmp(name, d->name) == 0)
+			error("create race");
+	strncpy(d->name, name, sizeof(d->name)-1);
+	d->perm = perm;
+	d->qid.vers = 0;
+	d->qid.path = tinyfs.high++;
+	tinyfs.nfile++;
+			
+	qunlock(&tinyfs);
+
+	c->mode = openmode(omode);
+	c->flag |= COPEN;
+	c->qid = d->qid;
+}
+
+void
+tinyfsremove(Chan *c)
+{
+	USED(c);
+	error(Eperm);
+}
+
+void
+tinyfswstat(Chan *c, char *dp)
+{
+	USED(c, dp);
+	error(Eperm);
+}
+
+void
+tinyfsclose(Chan *c)
+{
+}
+
+long
+tinyfsread(Chan *c, void *a, long n, ulong offset)
+{
+	switch(c->qid.path & ~CHDIR){
+	case Qdir:
+		return devdirread(c, a, n, tinyfstab, Ntinyfstab, devgen);
+	case Qdata:
+		break;
+	default:
+		n=0;
+		break;
+	}
+	return n;
+}
+
+Block*
+tinyfsbread(Chan *c, long n, ulong offset)
+{
+	return devbread(c, n, offset);
+}
+
+long
+tinyfswrite(Chan *c, char *a, long n, ulong offset)
+{
+	if(waserror()){
+		qunlock(&tinyfs);
+		nexterror();
+	}
+	qlock(&tinyfs);
+	qunlock(&tinyfs);
+
+	switch(c->qid.path & ~CHDIR){
+	case Qdata:
+		break;
+	default:
+		error(Ebadusefd);
+	}
+	return n;
+}
+
+long
+tinyfsbwrite(Chan *c, Block *bp, ulong offset)
+{
+	return devbwrite(c, bp, offset);
+}