code: plan9front

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ndb/mkhash: handle database= reordering, check offset overflow, remove file

when opening /lib/ndb/local, the db returned is the first entry
in the database= tuple, not the file passed to ndbopen(),
so search for the file in question.

make sure the file-offset doesnt exceed the NDBSPEC bit (23-bit).

remove the created hash file on error, and set TMP bit.

--- a/sys/src/cmd/ndb/mkhash.c

+++ b/sys/src/cmd/ndb/mkhash.c

@@ -11,16 +11,8 @@

 ulong hlen;

 Ndb *db;

 ulong nextchain;

+char err[ERRMAX];

-char*

-syserr(void)

-{

-	static char buf[ERRMAX];

-

-	errstr(buf, sizeof buf);

-	return buf;

-}

-

 void

 enter(char *val, ulong dboff)

 {

@@ -28,6 +20,8 @@

 	uchar *last;

 	ulong ptr;

+	assert(dboff < NDBSPEC);

+

 	h = ndbhash(val, hlen);

 	h *= NDBPLEN;

 	last = &ht[h];

@@ -37,6 +31,8 @@

 		return;

 	}

+	assert(nextchain < NDBSPEC);

+

 	if(ptr & NDBCHAIN){

 		/* walk the chain to the last entry */

 		for(;;){

@@ -61,16 +57,14 @@

 	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];

+	Dir *d;

+	uchar buf[NDBHLEN];

+	char *file;

 	int fd;

 	ulong off;

 	uchar *p;

@@ -80,14 +74,14 @@

 		exits("usage");

 	}

 	db = ndbopen(argv[1]);

-	if(db == 0){

+	while(db != nil && strcmp(db->file, argv[1]) != 0)

+		db = db->next;

+	if(db == nil){

+		errstr(err, sizeof(err));

 		fprint(2, "mkhash: can't open %s\n", argv[1]);

-		exits(syserr());

+		exits(err);

 	}

-	/* try a bigger than normal buffer */

-	Binits(&db->b, Bfildes(&db->b), OREAD, nbuf, sizeof(nbuf));

-

 	/* count entries to calculate hash size */

 	n = 0;

@@ -99,13 +93,18 @@

 		ndbfree(nt);

 	}

+	if(Boffset(&db->b) >= NDBSPEC){

+		fprint(2, "mkhash: db file offset overflow\n");

+		exits("overflow");

+	}

+

 	/* 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){

+	if(ht == nil){

 		fprint(2, "mkhash: not enough memory\n");

-		exits(syserr());

+		exits("not enougth memory");

 	}

 	for(p = ht; p < &ht[n]; p += NDBPLEN)

 		NDBPUTP(NDBNAP, p);

@@ -124,32 +123,36 @@

 	}

 	/* create the hash file */

-	snprint(file, sizeof(file), "%s.%s", argv[1], argv[2]);

-	fd = create(file, ORDWR, 0664);

+	file = smprint("%s.%s", argv[1], argv[2]);

+	fd = create(file, OWRITE, DMTMP|0664);

 	if(fd < 0){

-		fprint(2, "mkhash: can't create %s\n", file);

-		exits(syserr());

+		errstr(err, sizeof(err));

+		fprint(2, "mkhash: can't create %s: %s\n", file, err);

+		exits(err);

 	}

 	NDBPUTUL(db->mtime, buf);

 	NDBPUTUL(hlen, buf+NDBULLEN);

 	if(write(fd, buf, NDBHLEN) != NDBHLEN){

-		fprint(2, "mkhash: writing %s\n", file);

-		exits(syserr());

+		errstr(err, sizeof(err));

+		fprint(2, "mkhash: writing %s: %s\n", file, err);

+		remove(file);

+		exits(err);

 	}

 	if(write(fd, ht, nextchain) != nextchain){

-		fprint(2, "mkhash: writing %s\n", file);

-		exits(syserr());

+		errstr(err, sizeof(err));

+		fprint(2, "mkhash: writing %s: %s\n", file, err);

+		remove(file);

+		exits(err);

 	}

 	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){

+	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);

+	exits(nil);

 }