From b90060d134b09aff84d0bd1312850abb9fc6fb9e Mon Sep 17 00:00:00 2001
From: Florent Bruneau <florent.bruneau@polytechnique.org>
Date: Wed, 17 Sep 2008 19:27:49 +0200
Subject: [PATCH] Fix loop detection (we're on oriented graph).

Signed-off-by: Florent Bruneau <florent.bruneau@polytechnique.org>
---
 postlicyd/filter.c | 29 ++++++++---------------------
 postlicyd/filter.h |  7 +++----
 2 files changed, 11 insertions(+), 25 deletions(-)

diff --git a/postlicyd/filter.c b/postlicyd/filter.c
index dea4436..de6ba03 100644
--- a/postlicyd/filter.c
+++ b/postlicyd/filter.c
@@ -56,8 +56,6 @@ filter_type_t filter_register(const char *type, filter_constructor_t constructor
     filter_token tok = filter_tokenize(type, m_strlen(type));
     CHECK_FILTER(tok);
 
-    syslog(LOG_DEBUG, "filter type %s registered", type);
-
     runners[tok] = runner;
     constructors[tok] = constructor;
     destructors[tok] = destructor;
@@ -71,9 +69,6 @@ filter_result_t filter_hook_register(filter_type_t filter,
     CHECK_FILTER(filter);
     CHECK_HOOK(tok);
 
-    syslog(LOG_DEBUG, "hook %s registered for filter type %s", name,
-           ftokens[filter]);
-
     hooks[filter][tok] = true;
     return tok;
 }
@@ -85,9 +80,6 @@ filter_param_id_t filter_param_register(filter_type_t filter,
     CHECK_FILTER(filter);
     CHECK_PARAM(tok);
 
-    syslog(LOG_INFO, "param %s registered for filter type %s", name,
-           ftokens[filter]);
-
     params[filter][tok] = true;
     return tok;
 }
@@ -129,35 +121,30 @@ bool filter_update_references(filter_t *filter, A(filter_t) *filter_list)
     return true;
 }
 
-static inline bool filter_check_loop(filter_t *filter, A(filter_t) *array, bool cleanup)
+static inline bool filter_check_loop(filter_t *filter, A(filter_t) *array, int level)
 {
-    if (cleanup) {
-        foreach (filter_t *filter2, *array) {
-            filter2->seen = false;
-        }}
-    } else if (filter->seen) {
-        return false;
-    }
-    if (filter->safe) {
+    if (filter->last_seen == level) {
         return true;
     }
-    filter->seen = true;
+    filter->last_seen = level;
     foreach (filter_hook_t *hook, filter->hooks) {
         if (hook->postfix) {
             continue;
         }
-        if (!filter_check_loop(array_ptr(*array, hook->filter_id), array, false)) {
+        if (hook->filter_id == level) {
+            return false;
+        }
+        if (!filter_check_loop(array_ptr(*array, hook->filter_id), array, level)) {
             return false;
         }
     }}
-    filter->safe = true;
     return true;
 }
 
 bool filter_check_safety(A(filter_t) *array)
 {
     foreach (filter_t *filter, *array) {
-        if (!filter_check_loop(filter, array, true)) {
+        if (!filter_check_loop(filter, array, __Ai)) {
             syslog(LOG_ERR, "the filter tree contains a loop");
             return false;
         }
diff --git a/postlicyd/filter.h b/postlicyd/filter.h
index f53b917..c950402 100644
--- a/postlicyd/filter.h
+++ b/postlicyd/filter.h
@@ -72,14 +72,13 @@ typedef struct filter_t {
 
     A(filter_param_t) params;
 
-    /* Internal: to check the filter tree structure.
+    /* Loop checking flags.
      */
-    unsigned safe   :1;
-    unsigned seen   :1;
+    int last_seen;
 } filter_t;
 ARRAY(filter_t)
 
-#define FILTER_INIT { NULL, FTK_UNKNOWN, ARRAY_INIT, NULL, ARRAY_INIT, false, false }
+#define FILTER_INIT { NULL, FTK_UNKNOWN, ARRAY_INIT, NULL, ARRAY_INIT, -1 }
 #define CHECK_FILTER(Filter)                                                   \
     assert(Filter != FTK_UNKNOWN && Filter != FTK_count                        \
            && "Unknown filter type")
-- 
2.20.1