Further robustify nscd database lookup.

We can compute an absolute maximum for the number of elements which can fit into the currently mapped database. Stop after that many iterations.
git-mirror · May 16, 2009 · 831a404 · 831a404
1 parent cfe1fc1
commit 831a404
Show file tree

Hide file tree

Showing 4 changed files with 17 additions and 7 deletions.
diff --git a/ChangeLog b/ChangeLog
@@ -1,3 +1,12 @@
+2009-05-15  Ulrich Drepper  <drepper@redhat.com>
+
+	* nscd/nscd.h: Move Definition for BLOCK_ALIGN_LOG, BLOCK_ALIGN, and
+	BLOCK_ALIGN_M1 to ...
+	* nscd/nscd-client.h: ...here.
+	* nscd/nscd_helper.c (__nscd_cache_search): Introduce loop counter.
+	Use it if we absolutely cannot reach any more correct list elements
+	because that many do not fit into the currently mapped database.
+
 2009-05-14  Jakub Jelinek  <jakub@redhat.com>
 
 	* nscd/nscd_helper.c: Include stddef.h.

diff --git a/nscd/nscd-client.h b/nscd/nscd-client.h
@@ -44,9 +44,14 @@
 /* Path for the configuration file.  */
 #define _PATH_NSCDCONF	 "/etc/nscd.conf"
 
-/* Maximu allowed length for the key.  */
+/* Maximum allowed length for the key.  */
 #define MAXKEYLEN 1024
 
+/* Maximum alignment requirement we will encounter.  */
+#define BLOCK_ALIGN_LOG 3
+#define BLOCK_ALIGN (1 << BLOCK_ALIGN_LOG)
+#define BLOCK_ALIGN_M1 (BLOCK_ALIGN - 1)
+
 
 /* Available services.  */
 typedef enum

diff --git a/nscd/nscd.h b/nscd/nscd.h
@@ -111,11 +111,6 @@ struct database_dyn
 /* Path used when not using persistent storage.  */
 #define _PATH_NSCD_XYZ_DB_TMP	"/var/run/nscd/dbXXXXXX"
 
-/* Maximum alignment requirement we will encounter.  */
-#define BLOCK_ALIGN_LOG 3
-#define BLOCK_ALIGN (1 << BLOCK_ALIGN_LOG)
-#define BLOCK_ALIGN_M1 (BLOCK_ALIGN - 1)
-
 /* Default value for the maximum size of the database files.  */
 #define DEFAULT_MAX_DB_SIZE	(32 * 1024 * 1024)
 

diff --git a/nscd/nscd_helper.c b/nscd/nscd_helper.c
@@ -481,6 +481,7 @@ __nscd_cache_search (request_type type, const char *key, size_t keylen,
   ref_t trail = mapped->head->array[hash];
   trail = atomic_forced_read (trail);
   ref_t work = trail;
+  size_t loop_cnt = datasize / (offsetof (struct datahead, data) + datalen);
   int tick = 0;
 
   while (work != ENDREF && work + sizeof (struct hashentry) <= datasize)
@@ -527,7 +528,7 @@ __nscd_cache_search (request_type type, const char *key, size_t keylen,
       work = atomic_forced_read (here->next);
       /* Prevent endless loops.  This should never happen but perhaps
 	 the database got corrupted, accidentally or deliberately.  */
-      if (work == trail)
+      if (work == trail || loop_cnt-- > 0)
 	break;
       if (tick)
 	{