From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <6f6e9584590fddc728079369c8a098af@quintile.net>
From: "Steve Simon" <steve@quintile.net>
Date: Tue,  5 Feb 2019 17:26:46 +0000
To: 9fans@9fans.net
In-Reply-To: <5421E6F7082F34B3BF0A4DEC931F9AA5@felloff.net>
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Subject: Re: [9fans] cifs buglet - take 2
Topicbox-Message-UUID: f4c8504c-ead9-11e9-9d60-3106f5b1d025

> that looks like a bug to me.

Yep,

In fact it turned out to be rather more subtle than I first though, my bad.

sorry for the noise.

-Steve


diff /n/dump/2019/0205/sys/src/cmd/cifs/main.c /sys/src/cmd/cifs/main.c
216a217,222
> /* remove "." and ".." from the cache */
> static int
> rmdots(Aux *a, int got)
> {
> 	int i, num;
> 	FInfo *fi;
217a224,237
> 	num = 0;
> 	fi = (FInfo *)a->cache;
> 	for(i = 0; i < got; i++){
> 		if(strcmp(fi->name, ".") == 0 || strcmp(fi->name, "..") == 0){
> 			memmove(fi, fi+1, got * sizeof(FInfo));
> 			continue;
> 		}
> 		fi++;
> 		num++;
> 	}
>
> 	return num;
> }
>
250d269
< 		fi = (FInfo *)a->cache;
257a277
> 		got = rmdots(a, got);
260,266d279
<
< 		if(got >= 2 && strcmp(fi[0].name, ".") == 0 &&
< 		    strcmp(fi[1].name, "..") == 0){
< 			a->end = (got - 2) * sizeof(FInfo);
< 			memmove(a->cache, a->cache + sizeof(FInfo)*2,
< 				a->end - a->off);
< 		}
278a292
> 		got = rmdots(a, got);
288a303,304
>
> from_cache:
292d307
< from_cache:


------------------------------------------------------------------
or as a snippet:


/* remove "." and ".." from the cache */
static int
rmdots(Aux *a, int got)
{
	int i, num;
	FInfo *fi;

	num = 0;
	fi = (FInfo *)a->cache;
	for(i = 0; i < got; i++){
		if(strcmp(fi->name, ".") == 0 || strcmp(fi->name, "..") == 0){
			memmove(fi, fi+1, got * sizeof(FInfo));
			continue;
		}
		fi++;
		num++;
	}

	return num;
}

static int
dirgen(int slot, Dir *d, void *aux)
{
	long off;
	FInfo *fi;
	int rc, got;
	Aux *a = aux;
	char *npath;
	int numinf = numinfo();
	int slots;

	slots = 32;		/* number of dir entries to fetch at one time */

	if(strcmp(a->path, "/") == 0){
		if(slot < numinf){
			dirgeninfo(slot, d);
			return 0;
		} else
			slot -= numinf;

		if(slot >= Nshares)
			return -1;
		V2D(d, mkqid(Shares[slot].name, 1, 1, Pshare, slot),
			Shares[slot].name);
		return 0;
	}

	off = slot * sizeof(FInfo);
	if(off >= a->off && off < a->end && time(nil) < a->expire)
		goto from_cache;

	if(off == 0){
		npath = smprint("%s/*", mapfile(a->path));
		a->sh = T2findfirst(Sess, a->sp, slots, npath, &got, &a->srch,
			(FInfo *)a->cache);
		free(npath);
		if(a->sh == -1)
			return -1;

		got = rmdots(a, got);
		a->off = 0;
		a->end = got * sizeof(FInfo);
		goto from_cache;
	}

	while(off >= a->end && a->sh != -1){
		fi = (FInfo *)(a->cache + (a->end - a->off) - sizeof(FInfo));
		a->off = a->end;
		npath = smprint("%s/%s", mapfile(a->path), fi->name);
		rc = T2findnext(Sess, a->sp, slots, npath,
			&got, &a->srch, (FInfo *)a->cache, a->sh);
		free(npath);
		if(rc == -1 || got == 0)
			break;
		got = rmdots(a, got);
		a->end = a->off + got * sizeof(FInfo);
	}
	a->expire = time(nil) + CACHETIME;

	if(got < slots){
		if(a->sh != -1)
			CIFSfindclose2(Sess, a->sp, a->sh);
		a->sh = -1;
	}


from_cache:
	if(off >= a->end)
		return -1;

	fi = (FInfo *)(a->cache + (off - a->off));
	npath = smprint("%s/%s", mapfile(a->path), fi->name);
	I2D(d, a->sp, npath, realmtime(npath), fi);
	if(Billtrog == 0)
		upd_names(Sess, a->sp, npath, d);
	free(npath);
	return 0;
}