Reworked again the caching in case of failure.

Now operations that set the status of an entry to CREATING (add.c, modrdn.c)
need to set it to COMMIT, by calling cache_entry_commit, before returning
the entry itself, otherwise the entry is removed from the cache
and its private data is freed.
Should fix crashes due to add failures as in ITS#1245

servers/slapd/back-ldbm/add.c

@@ -354,7 +354,12 @@ ldbm_back_add(
 
 	send_ldap_result( conn, op, LDAP_SUCCESS,
 		NULL, NULL, NULL, NULL );
+
+	/* marks the entry as committed, so it is added to the cache;
+	 * otherwise it is removed from the cache, but not destroyed;
+	 * it will be destroyed by the caller */
 	rc = 0;
+	cache_entry_commit( e );
 
 return_results:;
 	if (p != NULL) {
@@ -368,10 +373,8 @@ return_results:;
 	}
 
 	if ( rc ) {
-		/* FIXME: remove from cache? */
+		/* in case of error, writer lock is freed 
-		cache_entry_private_destroy_mark( e );
+		 * and entry's private data is destroyed */
-
-		/* free entry and writer lock */
 		cache_return_entry_w( &li->li_cache, e );
 	}
 

servers/slapd/back-ldbm/cache.c

@@ -29,9 +29,9 @@ typedef struct ldbm_entry_info {
 	int		lei_state;	/* for the cache */
 #define	CACHE_ENTRY_UNDEFINED	0
 #define CACHE_ENTRY_CREATING	1
-#define CACHE_ENTRY_READY		2
+#define CACHE_ENTRY_READY	2
-#define CACHE_ENTRY_DELETED		3
+#define CACHE_ENTRY_DELETED	3
-#define CACHE_ENTRY_DESTROY_PRIVATE	4
+#define CACHE_ENTRY_COMMITTED	4
 	
 	int		lei_refcnt;	/* # threads ref'ing this entry */
 	Entry	*lei_lrunext;	/* for cache lru list */
@@ -136,17 +136,20 @@ cache_entry_private_init( Entry*e )
 }
 
 /*
- * assumes that the entry is write-locked;marks it i a manner that
+ * marks an entry in CREATING state as committed, so it is really returned
- * makes e_private be destroyed at the following cache_return_entry_w,
+ * to the cache. Otherwise an entry in CREATING state is removed.
+ * Makes e_private be destroyed at the following cache_return_entry_w,
  * but lets the entry untouched (owned by someone else)
  */
 void
-cache_entry_private_destroy_mark( Entry *e )
+cache_entry_commit( Entry *e )
 {
 	assert( e );
 	assert( e->e_private );
+	assert( LEI(e)->lei_state == CACHE_ENTRY_CREATING );
+	/* assert( LEI(e)->lei_refcnt == 1 ); */
 
-	LEI(e)->lei_state = CACHE_ENTRY_DESTROY_PRIVATE;
+	LEI(e)->lei_state = CACHE_ENTRY_COMMITTED;
 }
 
 static int
@@ -165,7 +168,7 @@ void
 cache_return_entry_rw( Cache *cache, Entry *e, int rw )
 {
 	ID id;
-	int refcnt;
+	int refcnt, freeit = 1;
 
 	/* set cache mutex */
 	ldap_pvt_thread_mutex_lock( &cache->c_mutex );
@@ -177,7 +180,18 @@ cache_return_entry_rw( Cache *cache, Entry *e, int rw )
 	id = e->e_id;
 	refcnt = --LEI(e)->lei_refcnt;
 
-	if ( LEI(e)->lei_state == CACHE_ENTRY_CREATING ) {
+	/*
+	 * if the entry is returned when in CREATING state, it is deleted
+	 * but not freed because it may belong to someone else (do_add,
+	 * for instance)
+	 */
+	if (  LEI(e)->lei_state == CACHE_ENTRY_CREATING ) {
+		cache_delete_entry_internal( cache, e );
+		freeit = 0;
+		/* now the entry is in DELETED state */
+	}
+
+	if ( LEI(e)->lei_state == CACHE_ENTRY_COMMITTED ) {
 		LEI(e)->lei_state = CACHE_ENTRY_READY;
 
 		/* free cache mutex */
@@ -194,8 +208,7 @@ cache_return_entry_rw( Cache *cache, Entry *e, int rw )
 #endif
 
 
-	} else if ( LEI(e)->lei_state == CACHE_ENTRY_DELETED
+	} else if ( LEI(e)->lei_state == CACHE_ENTRY_DELETED ) {
-		 || LEI(e)->lei_state == CACHE_ENTRY_DESTROY_PRIVATE ) {
 		if( refcnt > 0 ) {
 			/* free cache mutex */
 			ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
@@ -212,10 +225,8 @@ cache_return_entry_rw( Cache *cache, Entry *e, int rw )
 
 
 		} else {
-			int state = LEI(e)->lei_state;
-
 			cache_entry_private_destroy( e );
-			if ( state == CACHE_ENTRY_DELETED ) {
+			if ( freeit ) {
 				entry_free( e );
 			}
 

servers/slapd/back-ldbm/id2entry.c

@@ -274,6 +274,9 @@ id2entry_rw( Backend *be, ID id, int rw )
 		rw ? "w" : "r", id, (unsigned long) e );
 #endif
 
+	/* marks the entry as committed, so it will get added to the cache
+	 * when the lock is released */
+	cache_entry_commit( e );
 
 	return( e );
 }

servers/slapd/back-ldbm/modrdn.c

@@ -847,6 +847,7 @@ ldbm_back_modrdn(
 	    
 	    goto return_results;
 	}
+	rc = -1;
 	
 	(void) cache_update_entry( &li->li_cache, e );
 
@@ -856,7 +857,6 @@ ldbm_back_modrdn(
 
 	/* id2entry index */
 	if ( id2entry_add( be, e ) != 0 ) {
-		entry_free( e );
 		send_ldap_result( conn, op, LDAP_OTHER,
 			NULL, "entry update failed", NULL, NULL );
 		goto return_results;
@@ -865,6 +865,7 @@ ldbm_back_modrdn(
 	send_ldap_result( conn, op, LDAP_SUCCESS,
 		NULL, NULL, NULL, NULL );
 	rc = 0;
+	cache_entry_commit( e );
 
 return_results:
 	if( new_dn != NULL ) free( new_dn );
@@ -917,5 +918,10 @@ return_results:
 
 	/* free entry and writer lock */
 	cache_return_entry_w( &li->li_cache, e );
+	if ( rc ) {
+		/* if rc != 0 the entry is uncached and its private data 
+		 * is destroyed; the entry must be freed */
+		entry_free( e );
+	}
 	return( rc );
 }

servers/slapd/back-ldbm/proto-back-ldbm.h

@@ -51,7 +51,7 @@ int cache_update_entry LDAP_P(( Cache *cache, Entry *e ));
 void cache_return_entry_rw LDAP_P(( Cache *cache, Entry *e, int rw ));
 #define cache_return_entry_r(c, e) cache_return_entry_rw((c), (e), 0)
 #define cache_return_entry_w(c, e) cache_return_entry_rw((c), (e), 1)
-void cache_entry_private_destroy_mark LDAP_P(( Entry *e ));
+void cache_entry_commit LDAP_P(( Entry *e ));
 
 ID cache_find_entry_dn2id LDAP_P(( Backend *be, Cache *cache, const char *dn ));
 ID cache_find_entry_ndn2id LDAP_P(( Backend *be, Cache *cache, const char *ndn ));