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cifs: fix pruning of . and .. directory entries (thanks steve simon)

steve wrote:

> I cam across a bug in cifs.
>
> An empty directory under windows 7 pro contains a single entry "." but it
> doesn't appear to contain "..". As a result "." is not removed on dirscan
> and plan9 gets when trying to traverse the hierarchy.

--- a/sys/src/cmd/cifs/main.c

+++ b/sys/src/cmd/cifs/main.c

@@ -189,7 +189,28 @@

 	return smprint("%s/%s", path, name);

 }

+/* 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;

@@ -200,7 +221,7 @@

 	int numinf = numinfo();

 	int slots;

-	slots = 128;		/* number of dir entries to fetch at one time */

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

 	if(strcmp(a->path, "/") == 0){

 		if(slot < numinf){

@@ -221,7 +242,6 @@

 		goto from_cache;

 	if(off == 0){

-		fi = (FInfo *)a->cache;

 		npath = smprint("%s/*", mapfile(a->path));

 		a->sh = T2findfirst(Sess, a->sp, slots, npath, &got, &a->srch,

 			(FInfo *)a->cache);

@@ -229,15 +249,10 @@

 		if(a->sh == -1)

 			return -1;

+		got = rmdots(a, got);

 		a->off = 0;

 		a->end = got * sizeof(FInfo);

-

-		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);

-		}

+		goto from_cache;

 	}

 	while(off >= a->end && a->sh != -1){

@@ -249,6 +264,7 @@

 		free(npath);

 		if(rc == -1 || got == 0)

 			break;

+		got = rmdots(a, got);

 		a->end = a->off + got * sizeof(FInfo);

 	}

 	a->expire = time(nil) + CACHETIME;

@@ -259,10 +275,11 @@

 		a->sh = -1;

 	}

+

+from_cache:

 	if(off >= a->end)

 		return -1;

-from_cache:

 	fi = (FInfo *)(a->cache + (off - a->off));

 	npath = smprint("%s/%s", mapfile(a->path), fi->name);

 	I2D(d, a->sp, npath, fi);