wip lib9p bitfields

1 files changed, 33 insertions, 2 deletions

diff --git a/lib9p/9P2000.txt b/lib9p/9P2000.txt
index 5f93cdf..3f1f10a 100644
--- a/lib9p/9P2000.txt
+++ b/lib9p/9P2000.txt
@@ -30,8 +30,39 @@ d = "len[4] len*(dat[1])"
 # string (u16le `n`, then `n` bytes of UTF-8)
 s = "len[2] len*(utf8[1])"
 
-# qid (TODO)
-qid = "type[1] vers[4] path[8]"
+bitfield qid_type 8
+	7/DIR
+	6/APPEND
+	5/EXCL
+	# QTMOUNT has been around in Plan 9 forever, but is
+	# undocumented, and is explicitly excluded from the 9P2000
+	# draft RFC.  As I understand it, QTMOUNT indicates that the
+	# file is mounted by the kernel as a 9P transport; that the
+	# kernel has a lock on doing I/O on it, so userspace can't do
+	# I/O on it.
+	4/_PLAN9_MOUNT
+	3/AUTH
+	# Fun historical fact: QTTMP was a relatively late addition to
+	# Plan 9, in 2003-12.
+	2/TMP
+	#1/unused
+	FILE=0
+
+# uniQue IDentification - "two files on the same server hierarchy are
+# the same if and only if their qids are the same"
+#
+#  - "path" is a unique uint64_t that does most of the work in the
+#    above statement about files being the same if their QIDs are the
+#    same; " If a file is deleted and recreated with the same name in
+#    the same directory, the old and new path components of the qids
+#    should be different"
+#
+#  - "vers" "is a version number for a file; typically, it is
+#    incremented every time the file is modified.
+#
+#  - "type" indicates "whether the file is a directory, append-only
+#    file, etc."; is an instance of the qid_type bitfield.
+qid = "type[qid_type] vers[4] path[8]"
 
 # stat (TODO)
 stat = "stat_size[2]"