/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #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;} voidenter(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]; voidmain(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, "usage: mkhash 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);}