Import c1c0ede32dc00ed619d1cf5fda40a9de43995f3a from ctdb:

   tdb: add TDB_DISALLOW_NESTING and make TDB_ALLOW_NESTING the default behavior

    We need to keep TDB_ALLOW_NESTING as default behavior,
    so that existing code continues to work.

    However we may change the default together with a major version
    number change in future.

    metze
    (cherry picked from samba commit 3b9f19ed919fef2e88b2f92ae541e07bc7379cd1)

    Signed-off-by: Stefan Metzmacher <metze@samba.org>

diff --git a/ccan/tdb/open.c b/ccan/tdb/open.c
index 77c6936fc2f5bac28b6c421f3d61f730cba71129..1d6b3ed75ab084033723122c71857a1f8d5e84d5 100644 (file)
--- a/ccan/tdb/open.c
+++ b/ccan/tdb/open.c
@@ -203,6 +203,23 @@ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
                tdb->flags &= ~TDB_CLEAR_IF_FIRST;
        }
 
+       if ((tdb->flags & TDB_ALLOW_NESTING) &&
+           (tdb->flags & TDB_DISALLOW_NESTING)) {
+               tdb->ecode = TDB_ERR_NESTING;
+               TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
+                       "allow_nesting and disallow_nesting are not allowed together!"));
+               errno = EINVAL;
+               goto fail;
+       }
+
+       /*
+        * TDB_ALLOW_NESTING is the default behavior.
+        * Note: this may change in future versions!
+        */
+       if (!(tdb->flags & TDB_DISALLOW_NESTING)) {
+               tdb->flags |= TDB_ALLOW_NESTING;
+       }
+
        /* internal databases don't mmap or lock, and start off cleared */
        if (tdb->flags & TDB_INTERNAL) {
                tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);

diff --git a/ccan/tdb/tdb.c b/ccan/tdb/tdb.c
index a09d567c45dc4b74391f6dabdff1cbee9e90757e..cb0b88519d961ea292bcfd7d2b8db2772f50ad37 100644 (file)
--- a/ccan/tdb/tdb.c
+++ b/ccan/tdb/tdb.c
@@ -735,11 +735,41 @@ int tdb_get_flags(struct tdb_context *tdb)
 
 void tdb_add_flags(struct tdb_context *tdb, unsigned flags)
 {
+       if ((flags & TDB_ALLOW_NESTING) &&
+           (flags & TDB_DISALLOW_NESTING)) {
+               tdb->ecode = TDB_ERR_NESTING;
+               TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_add_flags: "
+                       "allow_nesting and disallow_nesting are not allowed together!"));
+               return;
+       }
+
+       if (flags & TDB_ALLOW_NESTING) {
+               tdb->flags &= ~TDB_DISALLOW_NESTING;
+       }
+       if (flags & TDB_DISALLOW_NESTING) {
+               tdb->flags &= ~TDB_ALLOW_NESTING;
+       }
+
        tdb->flags |= flags;
 }
 
 void tdb_remove_flags(struct tdb_context *tdb, unsigned flags)
 {
+       if ((flags & TDB_ALLOW_NESTING) &&
+           (flags & TDB_DISALLOW_NESTING)) {
+               tdb->ecode = TDB_ERR_NESTING;
+               TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_remove_flags: "
+                       "allow_nesting and disallow_nesting are not allowed together!"));
+               return;
+       }
+
+       if (flags & TDB_ALLOW_NESTING) {
+               tdb->flags |= TDB_DISALLOW_NESTING;
+       }
+       if (flags & TDB_DISALLOW_NESTING) {
+               tdb->flags |= TDB_ALLOW_NESTING;
+       }
+
        tdb->flags &= ~flags;
 }
 

diff --git a/ccan/tdb/tdb.h b/ccan/tdb/tdb.h
index 1254115548d49eca97d1e8683e8d1b2b33400277..b84e20560021d45034bb4f29df78da30fb4cba30 100644 (file)
--- a/ccan/tdb/tdb.h
+++ b/ccan/tdb/tdb.h
@@ -56,6 +56,7 @@ extern "C" {
 #define TDB_SEQNUM   128 /* maintain a sequence number */
 #define TDB_VOLATILE   256 /* Activate the per-hashchain freelist, default 5 */
 #define TDB_ALLOW_NESTING 512 /* Allow transactions to nest */
+#define TDB_DISALLOW_NESTING 1024 /* Disallow transactions to nest */
 
 /* error codes */
 enum TDB_ERROR {TDB_SUCCESS=0, TDB_ERR_CORRUPT, TDB_ERR_IO, TDB_ERR_LOCK, 

diff --git a/ccan/tdb/transaction.c b/ccan/tdb/transaction.c
index e8b0e6856110a401d89a93c9e1336bb6acb5190f..742f188f500dbd4bba8dcbe4f6d080a2663ca7ab 100644 (file)
--- a/ccan/tdb/transaction.c
+++ b/ccan/tdb/transaction.c
@@ -86,12 +86,20 @@
     fsync/msync calls are made.
 
   - if TDB_ALLOW_NESTING is passed to flags in tdb open, or added using
-    tdb_add_flags() transaction is enabled.
-    The default is that transaction nesting is not allowed and an attempt
-    to create a nested transaction will fail with TDB_ERR_NESTING.
+    tdb_add_flags() transaction nesting is enabled.
+    It resets the TDB_DISALLOW_NESTING flag, as both cannot be used together.
+    The default is that transaction nesting is allowed.
+    Note: this default may change in future versions of tdb.
 
     Beware. when transactions are nested a transaction successfully
     completed with tdb_transaction_commit() can be silently unrolled later.
+
+  - if TDB_DISALLOW_NESTING is passed to flags in tdb open, or added using
+    tdb_add_flags() transaction nesting is disabled.
+    It resets the TDB_ALLOW_NESTING flag, as both cannot be used together.
+    An attempt create a nested transaction will fail with TDB_ERR_NESTING.
+    The default is that transaction nesting is allowed.
+    Note: this default may change in future versions of tdb.
 */