1 files changed, 155 insertions, 0 deletions
diff --git a/src/cmd/ndb/ndbmkhash.c b/src/cmd/ndb/ndbmkhash.c
new file mode 100644
index 00000000..507bd7c7
--- /dev/null
+++ b/src/cmd/ndb/ndbmkhash.c
@@ -0,0 +1,155 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include <ndb.h>
+
+/*
+ *  make the hash table completely in memory and then write as a file
+ */
+
+uchar *ht;
+ulong hlen;
+Ndb *db;
+ulong nextchain;
+
+char*
+syserr(void)
+{
+	static char buf[ERRMAX];
+
+	errstr(buf, sizeof buf);
+	return buf;
+}
+
+void
+enter(char *val, ulong dboff)
+{
+	ulong h;
+	uchar *last;
+	ulong ptr;
+
+	h = ndbhash(val, hlen);
+	h *= NDBPLEN;
+	last = &ht[h];
+	ptr = NDBGETP(last);
+	if(ptr == NDBNAP){
+		NDBPUTP(dboff, last);
+		return;
+	}
+
+	if(ptr & NDBCHAIN){
+		/* walk the chain to the last entry */
+		for(;;){
+			ptr &= ~NDBCHAIN;
+			last = &ht[ptr+NDBPLEN];
+			ptr = NDBGETP(last);
+			if(ptr == NDBNAP){
+				NDBPUTP(dboff, last);
+				return;
+			}
+			if(!(ptr & NDBCHAIN)){
+				NDBPUTP(nextchain|NDBCHAIN, last);
+				break;
+			}
+		}
+	} else
+		NDBPUTP(nextchain|NDBCHAIN, last);
+
+	/* add a chained entry */
+	NDBPUTP(ptr, &ht[nextchain]);
+	NDBPUTP(dboff, &ht[nextchain + NDBPLEN]);
+	nextchain += 2*NDBPLEN;
+}
+
+uchar nbuf[16*1024];
+
+void
+main(int argc, char **argv)
+{
+	Ndbtuple *t, *nt;
+	int n;
+	Dir *d;	
+	uchar buf[8];
+	char file[128];
+	int fd;
+	ulong off;
+	uchar *p;
+
+	if(argc != 3){
+		fprint(2, "mkhash: usage file attribute\n");
+		exits("usage");
+	}
+	db = ndbopen(argv[1]);
+	if(db == 0){
+		fprint(2, "mkhash: can't open %s\n", argv[1]);
+		exits(syserr());
+	}
+
+	/* try a bigger than normal buffer */
+	Binits(&db->b, Bfildes(&db->b), OREAD, nbuf, sizeof(nbuf));
+
+	/* count entries to calculate hash size */
+	n = 0;
+
+	while(nt = ndbparse(db)){
+		for(t = nt; t; t = t->entry){
+			if(strcmp(t->attr, argv[2]) == 0)
+				n++;
+		}
+		ndbfree(nt);
+	}
+
+	/* allocate an array large enough for worst case */
+	hlen = 2*n+1;
+	n = hlen*NDBPLEN + hlen*2*NDBPLEN;
+	ht = mallocz(n, 1);
+	if(ht == 0){
+		fprint(2, "mkhash: not enough memory\n");
+		exits(syserr());
+	}
+	for(p = ht; p < &ht[n]; p += NDBPLEN)
+		NDBPUTP(NDBNAP, p);
+	nextchain = hlen*NDBPLEN;
+
+	/* create the in core hash table */
+	Bseek(&db->b, 0, 0);
+	off = 0;
+	while(nt = ndbparse(db)){
+		for(t = nt; t; t = t->entry){
+			if(strcmp(t->attr, argv[2]) == 0)
+				enter(t->val, off);
+		}
+		ndbfree(nt);
+		off = Boffset(&db->b);
+	}
+
+	/* create the hash file */
+	snprint(file, sizeof(file), "%s.%s", argv[1], argv[2]);
+	fd = create(file, ORDWR, 0664);
+	if(fd < 0){
+		fprint(2, "mkhash: can't create %s\n", file);
+		exits(syserr());
+	}
+	NDBPUTUL(db->mtime, buf);
+	NDBPUTUL(hlen, buf+NDBULLEN);
+	if(write(fd, buf, NDBHLEN) != NDBHLEN){
+		fprint(2, "mkhash: writing %s\n", file);
+		exits(syserr());
+	}
+	if(write(fd, ht, nextchain) != nextchain){
+		fprint(2, "mkhash: writing %s\n", file);
+		exits(syserr());
+	}
+	close(fd);
+
+	/* make sure file didn't change while we were making the hash */
+	d = dirstat(argv[1]);
+	if(d == nil || d->qid.path != db->qid.path
+	   || d->qid.vers != db->qid.vers){
+		fprint(2, "mkhash: %s changed underfoot\n", argv[1]);
+		remove(file);
+		exits("changed");
+	}
+
+	exits(0);
+}