Ticket #47313 - Indexed search with filter containing '&' and "!" with attribute subtypes gives wrong result

Description: commit fae006821bd6e524c0f7f8d5f023f4fe5e160ef0 introduced
a bug, which occurs when a filter includes NOT and one of the results
from the subfilters returns NONE. This patch backoffs the last section
of the commit fae006821bd6e524c0f7f8d5f023f4fe5e160ef0 with an improvement
-- avoiding unnecessary idl duplication.

Also, adding (NULL == idl) checks to idl_common.c.

https://fedorahosted.org/389/ticket/47313

Reviewed by [email protected] (Thank you, Rich!)

ldap/servers/slapd/back-ldbm/filterindex.c

@@ -852,17 +852,19 @@ list_candidates(
                 break; /* We can exit the loop now, since the candidate list is small already */
             }
         } else if ( ftype == LDAP_FILTER_AND ) {
-            if (isnot && !idl_is_allids(tmp)) {
-                IDList *new_idl = NULL;
-                int notin_result = 0;
-                /* 
-                 * If the given tmp is ALLIDs (due to subtype in filter),
-                 * we cannot use idl_notin.
+            if (isnot) {
+                /*
+                 * If tmp is NULL or ALLID, idl_notin just duplicates idl.
+                 * We don't have to do it.
                  */
-                notin_result = idl_notin( be, idl, tmp, &new_idl );
-                if (notin_result) {
-                    idl_free(idl);
-                    idl = new_idl;
+                if (!tmp && !idl_is_allids(tmp)) {
+                    IDList *new_idl = NULL;
+                    int notin_result = 0;
+                    notin_result = idl_notin( be, idl, tmp, &new_idl );
+                    if (notin_result) {
+                        idl_free(idl);
+                        idl = new_idl;
+                    }
                 }
             } else {
                 idl = idl_intersection(be, idl, tmp);

ldap/servers/slapd/back-ldbm/idl_common.c

@@ -46,16 +46,25 @@
 
 size_t idl_sizeof(IDList *idl)
 {
+	if (NULL == idl) {
+		return 0;
+	}
 	return (2 + idl->b_nmax) * sizeof(ID);
 }
 
 NIDS idl_length(IDList *idl)
 {
+	if (NULL == idl) {
+		return 0;
+	}
     return (idl->b_nmax == ALLIDSBLOCK) ? UINT_MAX : idl->b_nids;
 }
 
 int idl_is_allids(IDList *idl)
 {
+	if (NULL == idl) {
+		return 0;
+	}
     return (idl->b_nmax == ALLIDSBLOCK);
 }
 
@@ -110,6 +119,9 @@ idl_free( IDList *idl ) /* JCM - pass in ** */
 int
 idl_append( IDList *idl, ID id)
 {
+	if (NULL == idl) {
+		return 2;
+	}
 	if ( ALLIDS( idl ) || ( (idl->b_nids) && (idl->b_ids[idl->b_nids - 1] == id)) ) {
 		return( 1 );	/* already there */
 	}
@@ -321,7 +333,7 @@ idl_notin(
     backend *be,
     IDList 		*a,
     IDList 		*b,
-	IDList **new_result
+    IDList **new_result
 )
 {
 	NIDS	ni, ai, bi;
@@ -435,6 +447,9 @@ idl_nextid( IDList *idl, ID id )
 {
 	NIDS	i;
 
+	if (NULL == idl) {
+		return NOID;
+	}
 	if ( ALLIDS( idl ) ) {
 		return( ++id < idl->b_nids ? id : NOID );
 	}