From 61e1efeb850ba4765780a9977bde801f469e3213 Mon Sep 17 00:00:00 2001
From: Leo Yuriev <leo@yuriev.ru>
Date: Tue, 31 Jan 2017 02:47:54 +0300
Subject: [PATCH] mdbx: add mdbx_dbi_open_ex() for libfpta.

---
 mdb.c  | 29 ++++++++++++++++++-----------
 mdbx.c | 13 +++++++++++++
 mdbx.h |  3 +++
 3 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/mdb.c b/mdb.c
index b9f8277e..5dc61cc8 100644
--- a/mdb.c
+++ b/mdb.c
@@ -1183,7 +1183,6 @@ static void	mdb_xcursor_init1(MDB_cursor *mc, MDB_node *node);
 static void	mdb_xcursor_init2(MDB_cursor *mc, MDB_xcursor *src_mx, int force);
 
 static int	mdb_drop0(MDB_cursor *mc, int subs);
-static void	mdb_default_cmp(MDB_txn *txn, MDB_dbi dbi);
 static int	mdb_reader_check0(MDB_env *env, int rlocked, int *dead);
 
 /** @cond */
@@ -10024,6 +10023,21 @@ mdb_env_info(MDB_env *env, MDB_envinfo *arg)
 	return mdbx_env_info(env, (MDBX_envinfo*) arg, sizeof(MDB_envinfo));
 }
 
+static MDB_cmp_func*
+mdbx_default_keycmp(unsigned flags)
+{
+	return	(flags & MDB_REVERSEKEY) ? mdb_cmp_memnr :
+		(flags & MDB_INTEGERKEY) ? mdb_cmp_int_a2 : mdb_cmp_memn;
+}
+
+static MDB_cmp_func*
+mdbx_default_datacmp(unsigned flags)
+{
+	return	!(flags & MDB_DUPSORT) ? 0 :
+		((flags & MDB_INTEGERDUP) ? mdb_cmp_int_ua :
+		((flags & MDB_REVERSEDUP) ? mdb_cmp_memnr : mdb_cmp_memn));
+}
+
 /** Set the default comparison functions for a database.
  * Called immediately after a database is opened to set the defaults.
  * The user can then override them with #mdb_set_compare() or
@@ -10034,16 +10048,9 @@ mdb_env_info(MDB_env *env, MDB_envinfo *arg)
 static void
 mdb_default_cmp(MDB_txn *txn, MDB_dbi dbi)
 {
-	unsigned f = txn->mt_dbs[dbi].md_flags;
-
-	txn->mt_dbxs[dbi].md_cmp =
-		(f & MDB_REVERSEKEY) ? mdb_cmp_memnr :
-		(f & MDB_INTEGERKEY) ? mdb_cmp_int_a2 : mdb_cmp_memn;
-
-	txn->mt_dbxs[dbi].md_dcmp =
-		!(f & MDB_DUPSORT) ? 0 :
-		((f & MDB_INTEGERDUP) ? mdb_cmp_int_ua :
-		((f & MDB_REVERSEDUP) ? mdb_cmp_memnr : mdb_cmp_memn));
+	unsigned flags = txn->mt_dbs[dbi].md_flags;
+	txn->mt_dbxs[dbi].md_cmp = mdbx_default_keycmp(flags);
+	txn->mt_dbxs[dbi].md_dcmp = mdbx_default_datacmp(flags);
 }
 
 int mdb_dbi_open(MDB_txn *txn, const char *name, unsigned flags, MDB_dbi *dbi)
diff --git a/mdbx.c b/mdbx.c
index 3e8f93d4..dd0bff5f 100644
--- a/mdbx.c
+++ b/mdbx.c
@@ -654,3 +654,16 @@ int mdbx_is_dirty(const MDB_txn *txn, const void* ptr)
 	 * проверяемый адрес "не грязный". */
 	return MDBX_RESULT_FALSE;
 }
+
+int mdbx_dbi_open_ex(MDB_txn *txn, const char *name, unsigned flags,
+	MDB_dbi *pdbi, MDB_cmp_func *keycmp, MDB_cmp_func *datacmp)
+{
+	int rc = mdbx_dbi_open(txn, name, flags, pdbi);
+	if (likely(rc == MDB_SUCCESS)) {
+		MDB_dbi dbi = *pdbi;
+		unsigned flags = txn->mt_dbs[dbi].md_flags;
+		txn->mt_dbxs[dbi].md_cmp = keycmp ? keycmp : mdbx_default_keycmp(flags);
+		txn->mt_dbxs[dbi].md_dcmp = datacmp ? datacmp : mdbx_default_datacmp(flags);
+	}
+	return rc;
+}
diff --git a/mdbx.h b/mdbx.h
index f312d677..6a266395 100644
--- a/mdbx.h
+++ b/mdbx.h
@@ -237,6 +237,9 @@ int mdbx_get_ex(MDB_txn *txn, MDB_dbi dbi, MDB_val *key, MDB_val *data, int* val
 
 int mdbx_is_dirty(const MDB_txn *txn, const void* ptr);
 
+int mdbx_dbi_open_ex(MDB_txn *txn, const char *name, unsigned flags,
+	MDB_dbi *dbi, MDB_cmp_func *keycmp, MDB_cmp_func *datacmp);
+
 /**	@} */
 
 #ifdef __cplusplus