From 37da2899f40661e3e9631e497da8dc59b971cbd0 Mon Sep 17 00:00:00 2001
From: "Charles.Forsyth" <devnull@localhost>
Date: Fri, 22 Dec 2006 17:07:39 +0000
Subject: 20060303a

---
 appl/cmd/ndb/mkhash.b | 119 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)
 create mode 100644 appl/cmd/ndb/mkhash.b

(limited to 'appl/cmd/ndb/mkhash.b')

diff --git a/appl/cmd/ndb/mkhash.b b/appl/cmd/ndb/mkhash.b
new file mode 100644
index 00000000..f1876355
--- /dev/null
+++ b/appl/cmd/ndb/mkhash.b
@@ -0,0 +1,119 @@
+implement Mkhash;
+
+#
+# for compatibility, this is closely modelled on Plan 9's ndb/mkhash
+#
+
+include "sys.m";
+	sys: Sys;
+
+include "draw.m";
+
+include "bufio.m";
+include "attrdb.m";
+	attrdb: Attrdb;
+	Db, Dbf, Dbentry, Tuples, Attr: import attrdb;
+	attrhash: Attrhash;
+	NDBPLEN, NDBHLEN, NDBCHAIN, NDBNAP: import Attrhash;
+
+Mkhash: module
+{
+	init:	fn(nil: ref Draw->Context, nil: list of string);
+};
+
+init(nil: ref Draw->Context, args: list of string)
+{
+	sys = load Sys Sys->PATH;
+	attrdb = load Attrdb Attrdb->PATH;
+	if(attrdb == nil)
+		error(sys->sprint("can't load %s: %r", Attrdb->PATH));
+	attrdb->init();
+	attrhash = load Attrhash Attrhash->PATH;
+	if(attrhash == nil)
+		error(sys->sprint("can't load %s: %r", Attrhash->PATH));
+
+	if(len args != 3)
+		error("usage: mkhash file attr");
+	args = tl args;
+	dbname := hd args;
+	args = tl args;
+	attr := hd args;
+	dbf := Dbf.open(dbname);
+	if(dbf == nil)
+		error(sys->sprint("can't open %s: %r", dbname));
+	offset := 0;
+	n := 0;
+	for(;;){
+		(e, nil, next) := dbf.readentry(offset, nil, nil, 0);
+		if(e == nil)
+			break;
+		m := len e.find(attr);
+		if(0 && m != 0)
+			sys->fprint(sys->fildes(2), "%ud [%d]\n", offset, m);
+		n += m;
+		offset = next;
+	}
+	hlen := 2*n+1;
+	chains := n*2*NDBPLEN;
+	file := array[NDBHLEN + hlen*NDBPLEN + chains] of byte;
+	tab := file[NDBHLEN:];
+	for(i:=0; i<len tab; i+=NDBPLEN)
+		put3(tab[i:], NDBNAP);
+	offset = 0;
+	chain := hlen*NDBPLEN;
+	for(;;){
+		(e, nil, next) := dbf.readentry(offset, nil, nil, 0);
+		if(e == nil)
+			break;
+		for(l := e.find(attr); l != nil; l = tl l)
+			for((nil, al) := hd l; al != nil; al = tl al)
+				chain = enter(tab, hd al, hlen, chain, offset);
+		offset = next;
+	}
+	hashfile := dbname+"."+attr;
+	hfd := sys->create(hashfile, Sys->OWRITE, 8r666);
+	if(hfd == nil)
+		error(sys->sprint("can't create %s: %r", hashfile));
+	mtime := 0;
+	if(dbf.dir != nil)
+		mtime = dbf.dir.mtime;
+	put4(file, mtime);
+	put4(file[4:], hlen);
+	if(sys->write(hfd, file, NDBHLEN+chain) != NDBHLEN+chain)
+		error(sys->sprint("error writing %s: %r", hashfile));
+}
+
+error(s: string)
+{
+	sys->fprint(sys->fildes(2), "mkhash: %s\n", s);
+	raise "fail:error";
+}
+
+enter(tab: array of byte, a: ref Attr, hlen: int, chain: int, offset: int): int
+{
+	o := attrhash->hash(a.val, hlen)*NDBPLEN;
+	for(; (p := attrhash->get3(tab[o:])) != NDBNAP; o = p & ~NDBCHAIN)
+		if((p & NDBCHAIN) == 0){
+			put3(tab[o:], chain | NDBCHAIN);
+			put3(tab[chain:], p);
+			put3(tab[chain+NDBPLEN:], offset);
+			return chain+2*NDBPLEN;
+		}
+	put3(tab[o:], offset);
+	return chain;
+}
+
+put3(a: array of byte, v: int)
+{
+	a[0] = byte v;
+	a[1] = byte (v>>8);
+	a[2] = byte (v>>16);
+}
+
+put4(a: array of byte, v: int)
+{
+	a[0] = byte v;
+	a[1] = byte (v>>8);
+	a[2] = byte (v>>16);
+	a[3] = byte (v>>24);
+}
-- 
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